remove unused file
chai2010
parent
745a165b6f
commit
2284164524
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@ -14,3 +14,11 @@ _book
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*.epub
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*.mobi
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*.pdf
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# user defined
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vendor
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docs
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cover_bgd.png
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cover_patch.png
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/images/cover.png
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/images/gopher/go_lang_mascot_by_kirael_art-d7kunhu.gif
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@ -1 +0,0 @@
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TODO
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@ -1,2 +0,0 @@
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**練習 1.1:** 脩改echo程序，使其能夠打印os.Args[0]。
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@ -1 +0,0 @@
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**練習 1.2:** 脩改echo程序，使其打印value和index，每個value和index顯示一行。
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@ -1,2 +0,0 @@
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**練習 1.3:** 上手實踐前麫提到的strings.Join和直接Println，併觀察輸齣結果的區彆。
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@ -1,2 +0,0 @@
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**練習 1.4:** 脩改dup2，使其可以打印重復的行分彆齣現在哪些文件。
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@ -1 +0,0 @@
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**練習 1.5:** 脩改前麫的Lissajous程序裏的調色闆，由緑色改為黑色。我們可以用color.RGBA{0xRR, 0xGG, 0xBB}來得到#RRGGBB這個色值，三個十六進製的字符串分彆代錶紅、緑、藍像素。
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@ -1,2 +0,0 @@
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**練習 1.6:** 脩改Lissajous程序，脩改其調色闆來生成更豐富的顔色，然後脩改SetColorIndex的第三個參數，看看顯示結果吧。
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@ -1,2 +0,0 @@
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**練習 1.7:** 函數調用io.Copy(dst, src)會從src中讀取內容，併將讀到的結果寫入到dst中，使用這個函數替代掉例子中的ioutil.ReadAll來拷貝響應結構體到os.Stdout，避免申請一個緩衝區(例子中的b)來存儲。記得處理io.Copy返迴結果中的錯誤。
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@ -1,2 +0,0 @@
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**練習 1.8:** 脩改fetch這個範例，如果輸入的url參數沒有http://前綴的話，為這個url加上該前綴。你可能會用到strings.HasPrefix這個函數。
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@ -1,2 +0,0 @@
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**練習 1.9:** 脩改fetch打印齣HTTP協議的狀態碼，可以從resp.Status變量得到該狀態碼。
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@ -1,2 +0,0 @@
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**練習 1.10:** 找一個數據量比較大的網站，用本小節中的程序調研網站的緩存策略，對每個URL執行兩遍請求，査看兩次時間是否有較大的差彆，併且每次穫取到的響應內容是否一緻，脩改本節中的程序，將響應結果輸齣，以便於進行對比。
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@ -1,2 +0,0 @@
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**練習 1.11:** Try fetchall with longer argument lists, such as samples from the top million web sites available at alexa.com. How does the program behave if a web site just doesn’t respond? (Section 8.9 describes mechanisms for coping in such cases.)
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@ -1,2 +0,0 @@
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**練習 1.12:** 脩改Lissajour服務，從URL讀取變量，比如你可以訪問http://localhost:8000/?cycles=20這個URL，這樣訪問可以將程序裏的cycles默認的5脩改為20。字符串轉換為數字可以調用strconv.Atoi函數。你可以在dodoc裏査看strconv.Atoi的詳細說明。
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2123
exercise/ex-ch1.html
2123
exercise/ex-ch1.html
File diff suppressed because it is too large
Load Diff
2111
exercise/ex.html
2111
exercise/ex.html
File diff suppressed because it is too large
Load Diff
48933
tools/STPhrases.txt
48933
tools/STPhrases.txt
File diff suppressed because it is too large
Load Diff
File diff suppressed because it is too large
Load Diff
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@ -1,62 +0,0 @@
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// Copyright 2013 <chaishushan{AT}gmail.com>. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ingore
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package main
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import (
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"bufio"
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"bytes"
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"fmt"
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"io/ioutil"
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"log"
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"os"
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"strings"
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"unicode/utf8"
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)
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func main() {
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f, err := os.Open("./TSCharacters.txt")
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if err != nil {
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log.Fatal("open failed:", err)
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}
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defer f.Close()
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br := bufio.NewReader(f)
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var out bytes.Buffer
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fmt.Fprintf(&out, `
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// Copyright 2013 <chaishushan{AT}gmail.com>. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Auto generated by go generate, DO NOT EDIT !!!
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package main
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var _TSCharactersMap = map[rune]rune{
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`[1:])
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for i := 0; i < 1<<20; i++ {
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data, isPrefix, err := br.ReadLine()
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if err != nil || isPrefix {
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break
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}
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if !utf8.ValidString(string(data)) {
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continue
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}
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line := strings.Replace(string(data), "\t", " ", -1)
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ss := strings.Split(string(line), " ")
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if len(ss) >= 2 {
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tw := strings.TrimSpace(ss[0])
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zh := strings.TrimSpace(ss[1])
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fmt.Fprintf(&out, "\t'%s': '%s',\n", tw, zh)
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}
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}
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fmt.Fprintf(&out, "}\n")
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ioutil.WriteFile("z_TSCharacters.go", []byte(out.Bytes()), 0666)
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}
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@ -1,21 +0,0 @@
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# The Go Programming Language
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This repository provides the downloadable example programs
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for the book, "The Go Programming Language"; see http://www.gopl.io.
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These example programs are licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>.<br/>
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<a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png"/></a>
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You can download, build, and run the programs with the following commands:
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$ export GOPATH=$HOME/gobook # choose workspace directory
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$ go get gopl.io/ch1/helloworld # fetch, build, install
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$ $GOPATH/bin/helloworld # run
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Hello, 世界
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Many of the programs contain comments of the form `//!+` and `//!-`.
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These comments bracket the parts of the programs that are excerpted in the
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book; you can safely ignore them. In a few cases, programs
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have been reformatted in an unnatural way so that they can be presented
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in stages in the book.
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 8.
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//!+
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// Dup1 prints the text of each line that appears more than
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// once in the standard input, preceded by its count.
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package main
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import (
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"bufio"
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"fmt"
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"os"
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)
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func main() {
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counts := make(map[string]int)
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input := bufio.NewScanner(os.Stdin)
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for input.Scan() {
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counts[input.Text()]++
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}
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// NOTE: ignoring potential errors from input.Err()
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for line, n := range counts {
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if n > 1 {
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fmt.Printf("%d\t%s\n", n, line)
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}
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}
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}
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//!-
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 10.
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//!+
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// Dup2 prints the count and text of lines that appear more than once
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// in the input. It reads from stdin or from a list of named files.
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package main
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import (
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"bufio"
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"fmt"
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"os"
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)
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func main() {
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counts := make(map[string]int)
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files := os.Args[1:]
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if len(files) == 0 {
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countLines(os.Stdin, counts)
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} else {
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for _, arg := range files {
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f, err := os.Open(arg)
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if err != nil {
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fmt.Fprintf(os.Stderr, "dup2: %v\n", err)
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continue
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}
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countLines(f, counts)
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f.Close()
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}
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}
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for line, n := range counts {
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if n > 1 {
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fmt.Printf("%d\t%s\n", n, line)
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}
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}
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}
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func countLines(f *os.File, counts map[string]int) {
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input := bufio.NewScanner(f)
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for input.Scan() {
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counts[input.Text()]++
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}
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// NOTE: ignoring potential errors from input.Err()
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}
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//!-
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 12.
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//!+
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// Dup3 prints the count and text of lines that
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// appear more than once in the named input files.
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package main
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import (
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"fmt"
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"io/ioutil"
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"os"
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"strings"
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)
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func main() {
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counts := make(map[string]int)
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for _, filename := range os.Args[1:] {
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data, err := ioutil.ReadFile(filename)
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if err != nil {
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fmt.Fprintf(os.Stderr, "dup3: %v\n", err)
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continue
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}
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for _, line := range strings.Split(string(data), "\n") {
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counts[line]++
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}
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}
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for line, n := range counts {
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if n > 1 {
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fmt.Printf("%d\t%s\n", n, line)
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}
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}
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}
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//!-
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 4.
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//!+
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// Echo1 prints its command-line arguments.
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package main
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import (
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"fmt"
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"os"
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)
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func main() {
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var s, sep string
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for i := 1; i < len(os.Args); i++ {
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s += sep + os.Args[i]
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sep = " "
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}
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fmt.Println(s)
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}
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//!-
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 6.
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//!+
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// Echo2 prints its command-line arguments.
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package main
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import (
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"fmt"
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"os"
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)
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func main() {
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s, sep := "", ""
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for _, arg := range os.Args[1:] {
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s += sep + arg
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sep = " "
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}
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fmt.Println(s)
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}
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//!-
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@ -1,20 +0,0 @@
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 8.
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// Echo3 prints its command-line arguments.
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package main
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import (
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"fmt"
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"os"
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"strings"
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)
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//!+
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func main() {
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fmt.Println(strings.Join(os.Args[1:], " "))
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}
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//!-
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 16.
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//!+
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// Fetch prints the content found at each specified URL.
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package main
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import (
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"fmt"
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"io/ioutil"
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"net/http"
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"os"
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)
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func main() {
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for _, url := range os.Args[1:] {
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resp, err := http.Get(url)
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if err != nil {
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fmt.Fprintf(os.Stderr, "fetch: %v\n", err)
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os.Exit(1)
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}
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b, err := ioutil.ReadAll(resp.Body)
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resp.Body.Close()
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if err != nil {
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fmt.Fprintf(os.Stderr, "fetch: reading %s: %v\n", url, err)
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os.Exit(1)
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}
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fmt.Printf("%s", b)
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}
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}
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//!-
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 17.
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//!+
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// Fetchall fetches URLs in parallel and reports their times and sizes.
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package main
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import (
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"fmt"
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"io"
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"io/ioutil"
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"net/http"
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"os"
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"time"
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)
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func main() {
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start := time.Now()
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ch := make(chan string)
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for _, url := range os.Args[1:] {
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go fetch(url, ch) // start a goroutine
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}
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for range os.Args[1:] {
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fmt.Println(<-ch) // receive from channel ch
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}
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fmt.Printf("%.2fs elapsed\n", time.Since(start).Seconds())
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}
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func fetch(url string, ch chan<- string) {
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start := time.Now()
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resp, err := http.Get(url)
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if err != nil {
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ch <- fmt.Sprint(err) // send to channel ch
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return
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}
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nbytes, err := io.Copy(ioutil.Discard, resp.Body)
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resp.Body.Close() // don't leak resources
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if err != nil {
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ch <- fmt.Sprintf("while reading %s: %v", url, err)
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return
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}
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secs := time.Since(start).Seconds()
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ch <- fmt.Sprintf("%.2fs %7d %s", secs, nbytes, url)
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}
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//!-
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@ -1,16 +0,0 @@
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 1.
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// Helloworld is our first Go program.
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//!+
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package main
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import "fmt"
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func main() {
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fmt.Println("Hello, 世界")
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}
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//!-
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|
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@ -1,86 +0,0 @@
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// Run with "web" command-line argument for web server.
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// See page 13.
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//!+main
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// Lissajous generates GIF animations of random Lissajous figures.
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package main
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import (
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"image"
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"image/color"
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"image/gif"
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"io"
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"math"
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"math/rand"
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"os"
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)
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//!-main
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// Packages not needed by version in book.
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import (
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"log"
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"net/http"
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"time"
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)
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//!+main
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var palette = []color.Color{color.White, color.Black}
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const (
|
||||
whiteIndex = 0 // first color in palette
|
||||
blackIndex = 1 // next color in palette
|
||||
)
|
||||
|
||||
func main() {
|
||||
//!-main
|
||||
// The sequence of images is deterministic unless we seed
|
||||
// the pseudo-random number generator using the current time.
|
||||
// Thanks to Randall McPherson for pointing out the omission.
|
||||
rand.Seed(time.Now().UTC().UnixNano())
|
||||
|
||||
if len(os.Args) > 1 && os.Args[1] == "web" {
|
||||
//!+http
|
||||
handler := func(w http.ResponseWriter, r *http.Request) {
|
||||
lissajous(w)
|
||||
}
|
||||
http.HandleFunc("/", handler)
|
||||
//!-http
|
||||
log.Fatal(http.ListenAndServe("localhost:8000", nil))
|
||||
return
|
||||
}
|
||||
//!+main
|
||||
lissajous(os.Stdout)
|
||||
}
|
||||
|
||||
func lissajous(out io.Writer) {
|
||||
const (
|
||||
cycles = 5 // number of complete x oscillator revolutions
|
||||
res = 0.001 // angular resolution
|
||||
size = 100 // image canvas covers [-size..+size]
|
||||
nframes = 64 // number of animation frames
|
||||
delay = 8 // delay between frames in 10ms units
|
||||
)
|
||||
freq := rand.Float64() * 3.0 // relative frequency of y oscillator
|
||||
anim := gif.GIF{LoopCount: nframes}
|
||||
phase := 0.0 // phase difference
|
||||
for i := 0; i < nframes; i++ {
|
||||
rect := image.Rect(0, 0, 2*size+1, 2*size+1)
|
||||
img := image.NewPaletted(rect, palette)
|
||||
for t := 0.0; t < cycles*2*math.Pi; t += res {
|
||||
x := math.Sin(t)
|
||||
y := math.Sin(t*freq + phase)
|
||||
img.SetColorIndex(size+int(x*size+0.5), size+int(y*size+0.5),
|
||||
blackIndex)
|
||||
}
|
||||
phase += 0.1
|
||||
anim.Delay = append(anim.Delay, delay)
|
||||
anim.Image = append(anim.Image, img)
|
||||
}
|
||||
gif.EncodeAll(out, &anim) // NOTE: ignoring encoding errors
|
||||
}
|
||||
|
||||
//!-main
|
||||
|
|
@ -1,26 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 19.
|
||||
//!+
|
||||
|
||||
// Server1 is a minimal "echo" server.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"net/http"
|
||||
)
|
||||
|
||||
func main() {
|
||||
http.HandleFunc("/", handler) // each request calls handler
|
||||
log.Fatal(http.ListenAndServe("localhost:8000", nil))
|
||||
}
|
||||
|
||||
// handler echoes the Path component of the requested URL.
|
||||
func handler(w http.ResponseWriter, r *http.Request) {
|
||||
fmt.Fprintf(w, "URL.Path = %q\n", r.URL.Path)
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,41 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 20.
|
||||
//!+
|
||||
|
||||
// Server2 is a minimal "echo" and counter server.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"net/http"
|
||||
"sync"
|
||||
)
|
||||
|
||||
var mu sync.Mutex
|
||||
var count int
|
||||
|
||||
func main() {
|
||||
http.HandleFunc("/", handler)
|
||||
http.HandleFunc("/count", counter)
|
||||
log.Fatal(http.ListenAndServe("localhost:8000", nil))
|
||||
}
|
||||
|
||||
// handler echoes the Path component of the requested URL.
|
||||
func handler(w http.ResponseWriter, r *http.Request) {
|
||||
mu.Lock()
|
||||
count++
|
||||
mu.Unlock()
|
||||
fmt.Fprintf(w, "URL.Path = %q\n", r.URL.Path)
|
||||
}
|
||||
|
||||
// counter echoes the number of calls so far.
|
||||
func counter(w http.ResponseWriter, r *http.Request) {
|
||||
mu.Lock()
|
||||
fmt.Fprintf(w, "Count %d\n", count)
|
||||
mu.Unlock()
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,37 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 21.
|
||||
|
||||
// Server3 is an "echo" server that displays request parameters.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"net/http"
|
||||
)
|
||||
|
||||
func main() {
|
||||
http.HandleFunc("/", handler)
|
||||
log.Fatal(http.ListenAndServe("localhost:8000", nil))
|
||||
}
|
||||
|
||||
//!+handler
|
||||
// handler echoes the HTTP request.
|
||||
func handler(w http.ResponseWriter, r *http.Request) {
|
||||
fmt.Fprintf(w, "%s %s %s\n", r.Method, r.URL, r.Proto)
|
||||
for k, v := range r.Header {
|
||||
fmt.Fprintf(w, "Header[%q] = %q\n", k, v)
|
||||
}
|
||||
fmt.Fprintf(w, "Host = %q\n", r.Host)
|
||||
fmt.Fprintf(w, "RemoteAddr = %q\n", r.RemoteAddr)
|
||||
if err := r.ParseForm(); err != nil {
|
||||
log.Print(err)
|
||||
}
|
||||
for k, v := range r.Form {
|
||||
fmt.Fprintf(w, "Form[%q] = %q\n", k, v)
|
||||
}
|
||||
}
|
||||
|
||||
//!-handler
|
||||
|
|
@ -1,19 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 295.
|
||||
|
||||
// The cross command prints the values of GOOS and GOARCH for this target.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"runtime"
|
||||
)
|
||||
|
||||
//!+
|
||||
func main() {
|
||||
fmt.Println(runtime.GOOS, runtime.GOARCH)
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,52 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 287.
|
||||
|
||||
//!+main
|
||||
|
||||
// The jpeg command reads a PNG image from the standard input
|
||||
// and writes it as a JPEG image to the standard output.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"image"
|
||||
"image/jpeg"
|
||||
_ "image/png" // register PNG decoder
|
||||
"io"
|
||||
"os"
|
||||
)
|
||||
|
||||
func main() {
|
||||
if err := toJPEG(os.Stdin, os.Stdout); err != nil {
|
||||
fmt.Fprintf(os.Stderr, "jpeg: %v\n", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
}
|
||||
|
||||
func toJPEG(in io.Reader, out io.Writer) error {
|
||||
img, kind, err := image.Decode(in)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
fmt.Fprintln(os.Stderr, "Input format =", kind)
|
||||
return jpeg.Encode(out, img, &jpeg.Options{Quality: 95})
|
||||
}
|
||||
|
||||
//!-main
|
||||
|
||||
/*
|
||||
//!+with
|
||||
$ go build gopl.io/ch3/mandelbrot
|
||||
$ go build gopl.io/ch10/jpeg
|
||||
$ ./mandelbrot | ./jpeg >mandelbrot.jpg
|
||||
Input format = png
|
||||
//!-with
|
||||
|
||||
//!+without
|
||||
$ go build gopl.io/ch10/jpeg
|
||||
$ ./mandelbrot | ./jpeg >mandelbrot.jpg
|
||||
jpeg: image: unknown format
|
||||
//!-without
|
||||
*/
|
||||
|
|
@ -1,41 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 308.
|
||||
//!+
|
||||
|
||||
// Echo prints its command-line arguments.
|
||||
package main
|
||||
|
||||
import (
|
||||
"flag"
|
||||
"fmt"
|
||||
"io"
|
||||
"os"
|
||||
"strings"
|
||||
)
|
||||
|
||||
var (
|
||||
n = flag.Bool("n", false, "omit trailing newline")
|
||||
s = flag.String("s", " ", "separator")
|
||||
)
|
||||
|
||||
var out io.Writer = os.Stdout // modified during testing
|
||||
|
||||
func main() {
|
||||
flag.Parse()
|
||||
if err := echo(!*n, *s, flag.Args()); err != nil {
|
||||
fmt.Fprintf(os.Stderr, "echo: %v\n", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
}
|
||||
|
||||
func echo(newline bool, sep string, args []string) error {
|
||||
fmt.Fprint(out, strings.Join(args, sep))
|
||||
if newline {
|
||||
fmt.Fprintln(out)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,45 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// Test of echo command. Run with: go test gopl.io/ch11/echo
|
||||
|
||||
//!+
|
||||
package main
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestEcho(t *testing.T) {
|
||||
var tests = []struct {
|
||||
newline bool
|
||||
sep string
|
||||
args []string
|
||||
want string
|
||||
}{
|
||||
{true, "", []string{}, "\n"},
|
||||
{false, "", []string{}, ""},
|
||||
{true, "\t", []string{"one", "two", "three"}, "one\ttwo\tthree\n"},
|
||||
{true, ",", []string{"a", "b", "c"}, "a,b,c\n"},
|
||||
{false, ":", []string{"1", "2", "3"}, "1:2:3"},
|
||||
}
|
||||
|
||||
for _, test := range tests {
|
||||
descr := fmt.Sprintf("echo(%v, %q, %q)",
|
||||
test.newline, test.sep, test.args)
|
||||
|
||||
out = new(bytes.Buffer) // captured output
|
||||
if err := echo(test.newline, test.sep, test.args); err != nil {
|
||||
t.Errorf("%s failed: %v", descr, err)
|
||||
continue
|
||||
}
|
||||
got := out.(*bytes.Buffer).String()
|
||||
if got != test.want {
|
||||
t.Errorf("%s = %q, want %q", descr, got, test.want)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,45 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 311.
|
||||
|
||||
// Package storage is part of a hypothetical cloud storage server.
|
||||
//!+main
|
||||
package storage
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"net/smtp"
|
||||
)
|
||||
|
||||
var usage = make(map[string]int64)
|
||||
|
||||
func bytesInUse(username string) int64 { return usage[username] }
|
||||
|
||||
// Email sender configuration.
|
||||
// NOTE: never put passwords in source code!
|
||||
const sender = "notifications@example.com"
|
||||
const password = "correcthorsebatterystaple"
|
||||
const hostname = "smtp.example.com"
|
||||
|
||||
const template = `Warning: you are using %d bytes of storage,
|
||||
%d%% of your quota.`
|
||||
|
||||
func CheckQuota(username string) {
|
||||
used := bytesInUse(username)
|
||||
const quota = 1000000000 // 1GB
|
||||
percent := 100 * used / quota
|
||||
if percent < 90 {
|
||||
return // OK
|
||||
}
|
||||
msg := fmt.Sprintf(template, used, percent)
|
||||
auth := smtp.PlainAuth("", sender, password, hostname)
|
||||
err := smtp.SendMail(hostname+":587", auth, sender,
|
||||
[]string{username}, []byte(msg))
|
||||
if err != nil {
|
||||
log.Printf("smtp.SendMail(%s) failed: %s", username, err)
|
||||
}
|
||||
}
|
||||
|
||||
//!-main
|
||||
|
|
@ -1,53 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
//!+test
|
||||
package storage
|
||||
|
||||
import (
|
||||
"strings"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestCheckQuotaNotifiesUser(t *testing.T) {
|
||||
var notifiedUser, notifiedMsg string
|
||||
notifyUser = func(user, msg string) {
|
||||
notifiedUser, notifiedMsg = user, msg
|
||||
}
|
||||
|
||||
const user = "joe@example.org"
|
||||
usage[user] = 980000000 // simulate a 980MB-used condition
|
||||
|
||||
CheckQuota(user)
|
||||
if notifiedUser == "" && notifiedMsg == "" {
|
||||
t.Fatalf("notifyUser not called")
|
||||
}
|
||||
if notifiedUser != user {
|
||||
t.Errorf("wrong user (%s) notified, want %s",
|
||||
notifiedUser, user)
|
||||
}
|
||||
const wantSubstring = "98% of your quota"
|
||||
if !strings.Contains(notifiedMsg, wantSubstring) {
|
||||
t.Errorf("unexpected notification message <<%s>>, "+
|
||||
"want substring %q", notifiedMsg, wantSubstring)
|
||||
}
|
||||
}
|
||||
|
||||
//!-test
|
||||
|
||||
/*
|
||||
//!+defer
|
||||
func TestCheckQuotaNotifiesUser(t *testing.T) {
|
||||
// Save and restore original notifyUser.
|
||||
saved := notifyUser
|
||||
defer func() { notifyUser = saved }()
|
||||
|
||||
// Install the test's fake notifyUser.
|
||||
var notifiedUser, notifiedMsg string
|
||||
notifyUser = func(user, msg string) {
|
||||
notifiedUser, notifiedMsg = user, msg
|
||||
}
|
||||
// ...rest of test...
|
||||
}
|
||||
//!-defer
|
||||
*/
|
||||
|
|
@ -1,49 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 312.
|
||||
|
||||
// Package storage is part of a hypothetical cloud storage server.
|
||||
package storage
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"net/smtp"
|
||||
)
|
||||
|
||||
var usage = make(map[string]int64)
|
||||
|
||||
func bytesInUse(username string) int64 { return usage[username] }
|
||||
|
||||
// E-mail sender configuration.
|
||||
// NOTE: never put passwords in source code!
|
||||
const sender = "notifications@example.com"
|
||||
const password = "correcthorsebatterystaple"
|
||||
const hostname = "smtp.example.com"
|
||||
|
||||
const template = `Warning: you are using %d bytes of storage,
|
||||
%d%% of your quota.`
|
||||
|
||||
//!+factored
|
||||
var notifyUser = func(username, msg string) {
|
||||
auth := smtp.PlainAuth("", sender, password, hostname)
|
||||
err := smtp.SendMail(hostname+":587", auth, sender,
|
||||
[]string{username}, []byte(msg))
|
||||
if err != nil {
|
||||
log.Printf("smtp.SendEmail(%s) failed: %s", username, err)
|
||||
}
|
||||
}
|
||||
|
||||
func CheckQuota(username string) {
|
||||
used := bytesInUse(username)
|
||||
const quota = 1000000000 // 1GB
|
||||
percent := 100 * used / quota
|
||||
if percent < 90 {
|
||||
return // OK
|
||||
}
|
||||
msg := fmt.Sprintf(template, used, percent)
|
||||
notifyUser(username, msg)
|
||||
}
|
||||
|
||||
//!-factored
|
||||
|
|
@ -1,21 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 303.
|
||||
//!+
|
||||
|
||||
// Package word provides utilities for word games.
|
||||
package word
|
||||
|
||||
// IsPalindrome reports whether s reads the same forward and backward.
|
||||
// (Our first attempt.)
|
||||
func IsPalindrome(s string) bool {
|
||||
for i := range s {
|
||||
if s[i] != s[len(s)-1-i] {
|
||||
return false
|
||||
}
|
||||
}
|
||||
return true
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,43 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
//!+test
|
||||
package word
|
||||
|
||||
import "testing"
|
||||
|
||||
func TestPalindrome(t *testing.T) {
|
||||
if !IsPalindrome("detartrated") {
|
||||
t.Error(`IsPalindrome("detartrated") = false`)
|
||||
}
|
||||
if !IsPalindrome("kayak") {
|
||||
t.Error(`IsPalindrome("kayak") = false`)
|
||||
}
|
||||
}
|
||||
|
||||
func TestNonPalindrome(t *testing.T) {
|
||||
if IsPalindrome("palindrome") {
|
||||
t.Error(`IsPalindrome("palindrome") = true`)
|
||||
}
|
||||
}
|
||||
|
||||
//!-test
|
||||
|
||||
// The tests below are expected to fail.
|
||||
// See package gopl.io/ch11/word2 for the fix.
|
||||
|
||||
//!+more
|
||||
func TestFrenchPalindrome(t *testing.T) {
|
||||
if !IsPalindrome("été") {
|
||||
t.Error(`IsPalindrome("été") = false`)
|
||||
}
|
||||
}
|
||||
|
||||
func TestCanalPalindrome(t *testing.T) {
|
||||
input := "A man, a plan, a canal: Panama"
|
||||
if !IsPalindrome(input) {
|
||||
t.Errorf(`IsPalindrome(%q) = false`, input)
|
||||
}
|
||||
}
|
||||
|
||||
//!-more
|
||||
|
|
@ -1,29 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 305.
|
||||
//!+
|
||||
|
||||
// Package word provides utilities for word games.
|
||||
package word
|
||||
|
||||
import "unicode"
|
||||
|
||||
// IsPalindrome reports whether s reads the same forward and backward.
|
||||
// Letter case is ignored, as are non-letters.
|
||||
func IsPalindrome(s string) bool {
|
||||
var letters []rune
|
||||
for _, r := range s {
|
||||
if unicode.IsLetter(r) {
|
||||
letters = append(letters, unicode.ToLower(r))
|
||||
}
|
||||
}
|
||||
for i := range letters {
|
||||
if letters[i] != letters[len(letters)-1-i] {
|
||||
return false
|
||||
}
|
||||
}
|
||||
return true
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,148 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package word
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"math/rand"
|
||||
"time"
|
||||
)
|
||||
|
||||
//!+bench
|
||||
|
||||
import "testing"
|
||||
|
||||
//!-bench
|
||||
|
||||
//!+test
|
||||
func TestIsPalindrome(t *testing.T) {
|
||||
var tests = []struct {
|
||||
input string
|
||||
want bool
|
||||
}{
|
||||
{"", true},
|
||||
{"a", true},
|
||||
{"aa", true},
|
||||
{"ab", false},
|
||||
{"kayak", true},
|
||||
{"detartrated", true},
|
||||
{"A man, a plan, a canal: Panama", true},
|
||||
{"Evil I did dwell; lewd did I live.", true},
|
||||
{"Able was I ere I saw Elba", true},
|
||||
{"été", true},
|
||||
{"Et se resservir, ivresse reste.", true},
|
||||
{"palindrome", false}, // non-palindrome
|
||||
{"desserts", false}, // semi-palindrome
|
||||
}
|
||||
for _, test := range tests {
|
||||
if got := IsPalindrome(test.input); got != test.want {
|
||||
t.Errorf("IsPalindrome(%q) = %v", test.input, got)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
//!-test
|
||||
|
||||
//!+bench
|
||||
func BenchmarkIsPalindrome(b *testing.B) {
|
||||
for i := 0; i < b.N; i++ {
|
||||
IsPalindrome("A man, a plan, a canal: Panama")
|
||||
}
|
||||
}
|
||||
|
||||
//!-bench
|
||||
|
||||
//!+example
|
||||
|
||||
func ExampleIsPalindrome() {
|
||||
fmt.Println(IsPalindrome("A man, a plan, a canal: Panama"))
|
||||
fmt.Println(IsPalindrome("palindrome"))
|
||||
// Output:
|
||||
// true
|
||||
// false
|
||||
}
|
||||
|
||||
//!-example
|
||||
|
||||
/*
|
||||
//!+random
|
||||
import "math/rand"
|
||||
|
||||
//!-random
|
||||
*/
|
||||
|
||||
//!+random
|
||||
// randomPalindrome returns a palindrome whose length and contents
|
||||
// are derived from the pseudo-random number generator rng.
|
||||
func randomPalindrome(rng *rand.Rand) string {
|
||||
n := rng.Intn(25) // random length up to 24
|
||||
runes := make([]rune, n)
|
||||
for i := 0; i < (n+1)/2; i++ {
|
||||
r := rune(rng.Intn(0x1000)) // random rune up to '\u0999'
|
||||
runes[i] = r
|
||||
runes[n-1-i] = r
|
||||
}
|
||||
return string(runes)
|
||||
}
|
||||
|
||||
func TestRandomPalindromes(t *testing.T) {
|
||||
// Initialize a pseudo-random number generator.
|
||||
seed := time.Now().UTC().UnixNano()
|
||||
t.Logf("Random seed: %d", seed)
|
||||
rng := rand.New(rand.NewSource(seed))
|
||||
|
||||
for i := 0; i < 1000; i++ {
|
||||
p := randomPalindrome(rng)
|
||||
if !IsPalindrome(p) {
|
||||
t.Errorf("IsPalindrome(%q) = false", p)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
//!-random
|
||||
|
||||
/*
|
||||
// Answer for Exercicse 11.1: Modify randomPalindrome to exercise
|
||||
// IsPalindrome's handling of punctuation and spaces.
|
||||
|
||||
// WARNING: the conversion r -> upper -> lower doesn't preserve
|
||||
// the value of r in some cases, e.g., µ Μ, ſ S, ı I
|
||||
|
||||
// randomPalindrome returns a palindrome whose length and contents
|
||||
// are derived from the pseudo-random number generator rng.
|
||||
func randomNoisyPalindrome(rng *rand.Rand) string {
|
||||
n := rng.Intn(25) // random length up to 24
|
||||
runes := make([]rune, n)
|
||||
for i := 0; i < (n+1)/2; i++ {
|
||||
r := rune(rng.Intn(0x200)) // random rune up to \u99
|
||||
runes[i] = r
|
||||
r1 := r
|
||||
if unicode.IsLetter(r) && unicode.IsLower(r) {
|
||||
r = unicode.ToUpper(r)
|
||||
if unicode.ToLower(r) != r1 {
|
||||
fmt.Printf("cap? %c %c\n", r1, r)
|
||||
}
|
||||
}
|
||||
runes[n-1-i] = r
|
||||
}
|
||||
return "?" + string(runes) + "!"
|
||||
}
|
||||
|
||||
func TestRandomNoisyPalindromes(t *testing.T) {
|
||||
// Initialize a pseudo-random number generator.
|
||||
seed := time.Now().UTC().UnixNano()
|
||||
t.Logf("Random seed: %d", seed)
|
||||
rng := rand.New(rand.NewSource(seed))
|
||||
|
||||
n := 0
|
||||
for i := 0; i < 1000; i++ {
|
||||
p := randomNoisyPalindrome(rng)
|
||||
if !IsPalindrome(p) {
|
||||
t.Errorf("IsNoisyPalindrome(%q) = false", p)
|
||||
n++
|
||||
}
|
||||
}
|
||||
fmt.Fprintf(os.Stderr, "fail = %d\n", n)
|
||||
}
|
||||
*/
|
||||
|
|
@ -1,90 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 333.
|
||||
|
||||
// Package display provides a means to display structured data.
|
||||
package display
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"reflect"
|
||||
"strconv"
|
||||
)
|
||||
|
||||
//!+Display
|
||||
|
||||
func Display(name string, x interface{}) {
|
||||
fmt.Printf("Display %s (%T):\n", name, x)
|
||||
display(name, reflect.ValueOf(x))
|
||||
}
|
||||
|
||||
//!-Display
|
||||
|
||||
// formatAtom formats a value without inspecting its internal structure.
|
||||
// It is a copy of the the function in gopl.io/ch11/format.
|
||||
func formatAtom(v reflect.Value) string {
|
||||
switch v.Kind() {
|
||||
case reflect.Invalid:
|
||||
return "invalid"
|
||||
case reflect.Int, reflect.Int8, reflect.Int16,
|
||||
reflect.Int32, reflect.Int64:
|
||||
return strconv.FormatInt(v.Int(), 10)
|
||||
case reflect.Uint, reflect.Uint8, reflect.Uint16,
|
||||
reflect.Uint32, reflect.Uint64, reflect.Uintptr:
|
||||
return strconv.FormatUint(v.Uint(), 10)
|
||||
// ...floating-point and complex cases omitted for brevity...
|
||||
case reflect.Bool:
|
||||
if v.Bool() {
|
||||
return "true"
|
||||
}
|
||||
return "false"
|
||||
case reflect.String:
|
||||
return strconv.Quote(v.String())
|
||||
case reflect.Chan, reflect.Func, reflect.Ptr,
|
||||
reflect.Slice, reflect.Map:
|
||||
return v.Type().String() + " 0x" +
|
||||
strconv.FormatUint(uint64(v.Pointer()), 16)
|
||||
default: // reflect.Array, reflect.Struct, reflect.Interface
|
||||
return v.Type().String() + " value"
|
||||
}
|
||||
}
|
||||
|
||||
//!+display
|
||||
func display(path string, v reflect.Value) {
|
||||
switch v.Kind() {
|
||||
case reflect.Invalid:
|
||||
fmt.Printf("%s = invalid\n", path)
|
||||
case reflect.Slice, reflect.Array:
|
||||
for i := 0; i < v.Len(); i++ {
|
||||
display(fmt.Sprintf("%s[%d]", path, i), v.Index(i))
|
||||
}
|
||||
case reflect.Struct:
|
||||
for i := 0; i < v.NumField(); i++ {
|
||||
fieldPath := fmt.Sprintf("%s.%s", path, v.Type().Field(i).Name)
|
||||
display(fieldPath, v.Field(i))
|
||||
}
|
||||
case reflect.Map:
|
||||
for _, key := range v.MapKeys() {
|
||||
display(fmt.Sprintf("%s[%s]", path,
|
||||
formatAtom(key)), v.MapIndex(key))
|
||||
}
|
||||
case reflect.Ptr:
|
||||
if v.IsNil() {
|
||||
fmt.Printf("%s = nil\n", path)
|
||||
} else {
|
||||
display(fmt.Sprintf("(*%s)", path), v.Elem())
|
||||
}
|
||||
case reflect.Interface:
|
||||
if v.IsNil() {
|
||||
fmt.Printf("%s = nil\n", path)
|
||||
} else {
|
||||
fmt.Printf("%s.type = %s\n", path, v.Elem().Type())
|
||||
display(path+".value", v.Elem())
|
||||
}
|
||||
default: // basic types, channels, funcs
|
||||
fmt.Printf("%s = %s\n", path, formatAtom(v))
|
||||
}
|
||||
}
|
||||
|
||||
//!-display
|
||||
|
|
@ -1,259 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package display
|
||||
|
||||
import (
|
||||
"io"
|
||||
"net"
|
||||
"os"
|
||||
"reflect"
|
||||
"sync"
|
||||
"testing"
|
||||
|
||||
"gopl.io/ch7/eval"
|
||||
)
|
||||
|
||||
// NOTE: we can't use !+..!- comments to excerpt these tests
|
||||
// into the book because it defeats the Example mechanism,
|
||||
// which requires the // Output comment to be at the end
|
||||
// of the function.
|
||||
|
||||
func Example_expr() {
|
||||
e, _ := eval.Parse("sqrt(A / pi)")
|
||||
Display("e", e)
|
||||
// Output:
|
||||
// Display e (eval.call):
|
||||
// e.fn = "sqrt"
|
||||
// e.args[0].type = eval.binary
|
||||
// e.args[0].value.op = 47
|
||||
// e.args[0].value.x.type = eval.Var
|
||||
// e.args[0].value.x.value = "A"
|
||||
// e.args[0].value.y.type = eval.Var
|
||||
// e.args[0].value.y.value = "pi"
|
||||
}
|
||||
|
||||
func Example_slice() {
|
||||
Display("slice", []*int{new(int), nil})
|
||||
// Output:
|
||||
// Display slice ([]*int):
|
||||
// (*slice[0]) = 0
|
||||
// slice[1] = nil
|
||||
}
|
||||
|
||||
func Example_nilInterface() {
|
||||
var w io.Writer
|
||||
Display("w", w)
|
||||
// Output:
|
||||
// Display w (<nil>):
|
||||
// w = invalid
|
||||
}
|
||||
|
||||
func Example_ptrToInterface() {
|
||||
var w io.Writer
|
||||
Display("&w", &w)
|
||||
// Output:
|
||||
// Display &w (*io.Writer):
|
||||
// (*&w) = nil
|
||||
}
|
||||
|
||||
func Example_struct() {
|
||||
Display("x", struct{ x interface{} }{3})
|
||||
// Output:
|
||||
// Display x (struct { x interface {} }):
|
||||
// x.x.type = int
|
||||
// x.x.value = 3
|
||||
}
|
||||
|
||||
func Example_interface() {
|
||||
var i interface{} = 3
|
||||
Display("i", i)
|
||||
// Output:
|
||||
// Display i (int):
|
||||
// i = 3
|
||||
}
|
||||
|
||||
func Example_ptrToInterface2() {
|
||||
var i interface{} = 3
|
||||
Display("&i", &i)
|
||||
// Output:
|
||||
// Display &i (*interface {}):
|
||||
// (*&i).type = int
|
||||
// (*&i).value = 3
|
||||
}
|
||||
|
||||
func Example_array() {
|
||||
Display("x", [1]interface{}{3})
|
||||
// Output:
|
||||
// Display x ([1]interface {}):
|
||||
// x[0].type = int
|
||||
// x[0].value = 3
|
||||
}
|
||||
|
||||
func Example_movie() {
|
||||
//!+movie
|
||||
type Movie struct {
|
||||
Title, Subtitle string
|
||||
Year int
|
||||
Color bool
|
||||
Actor map[string]string
|
||||
Oscars []string
|
||||
Sequel *string
|
||||
}
|
||||
//!-movie
|
||||
//!+strangelove
|
||||
strangelove := Movie{
|
||||
Title: "Dr. Strangelove",
|
||||
Subtitle: "How I Learned to Stop Worrying and Love the Bomb",
|
||||
Year: 1964,
|
||||
Color: false,
|
||||
Actor: map[string]string{
|
||||
"Dr. Strangelove": "Peter Sellers",
|
||||
"Grp. Capt. Lionel Mandrake": "Peter Sellers",
|
||||
"Pres. Merkin Muffley": "Peter Sellers",
|
||||
"Gen. Buck Turgidson": "George C. Scott",
|
||||
"Brig. Gen. Jack D. Ripper": "Sterling Hayden",
|
||||
`Maj. T.J. "King" Kong`: "Slim Pickens",
|
||||
},
|
||||
|
||||
Oscars: []string{
|
||||
"Best Actor (Nomin.)",
|
||||
"Best Adapted Screenplay (Nomin.)",
|
||||
"Best Director (Nomin.)",
|
||||
"Best Picture (Nomin.)",
|
||||
},
|
||||
}
|
||||
//!-strangelove
|
||||
Display("strangelove", strangelove)
|
||||
|
||||
// We don't use an Output: comment since displaying
|
||||
// a map is nondeterministic.
|
||||
/*
|
||||
//!+output
|
||||
Display strangelove (display.Movie):
|
||||
strangelove.Title = "Dr. Strangelove"
|
||||
strangelove.Subtitle = "How I Learned to Stop Worrying and Love the Bomb"
|
||||
strangelove.Year = 1964
|
||||
strangelove.Color = false
|
||||
strangelove.Actor["Gen. Buck Turgidson"] = "George C. Scott"
|
||||
strangelove.Actor["Brig. Gen. Jack D. Ripper"] = "Sterling Hayden"
|
||||
strangelove.Actor["Maj. T.J. \"King\" Kong"] = "Slim Pickens"
|
||||
strangelove.Actor["Dr. Strangelove"] = "Peter Sellers"
|
||||
strangelove.Actor["Grp. Capt. Lionel Mandrake"] = "Peter Sellers"
|
||||
strangelove.Actor["Pres. Merkin Muffley"] = "Peter Sellers"
|
||||
strangelove.Oscars[0] = "Best Actor (Nomin.)"
|
||||
strangelove.Oscars[1] = "Best Adapted Screenplay (Nomin.)"
|
||||
strangelove.Oscars[2] = "Best Director (Nomin.)"
|
||||
strangelove.Oscars[3] = "Best Picture (Nomin.)"
|
||||
strangelove.Sequel = nil
|
||||
//!-output
|
||||
*/
|
||||
}
|
||||
|
||||
// This test ensures that the program terminates without crashing.
|
||||
func Test(t *testing.T) {
|
||||
// Some other values (YMMV)
|
||||
Display("os.Stderr", os.Stderr)
|
||||
// Output:
|
||||
// Display os.Stderr (*os.File):
|
||||
// (*(*os.Stderr).file).fd = 2
|
||||
// (*(*os.Stderr).file).name = "/dev/stderr"
|
||||
// (*(*os.Stderr).file).nepipe = 0
|
||||
|
||||
var w io.Writer = os.Stderr
|
||||
Display("&w", &w)
|
||||
// Output:
|
||||
// Display &w (*io.Writer):
|
||||
// (*&w).type = *os.File
|
||||
// (*(*(*&w).value).file).fd = 2
|
||||
// (*(*(*&w).value).file).name = "/dev/stderr"
|
||||
// (*(*(*&w).value).file).nepipe = 0
|
||||
|
||||
var locker sync.Locker = new(sync.Mutex)
|
||||
Display("(&locker)", &locker)
|
||||
// Output:
|
||||
// Display (&locker) (*sync.Locker):
|
||||
// (*(&locker)).type = *sync.Mutex
|
||||
// (*(*(&locker)).value).state = 0
|
||||
// (*(*(&locker)).value).sema = 0
|
||||
|
||||
Display("locker", locker)
|
||||
// Output:
|
||||
// Display locker (*sync.Mutex):
|
||||
// (*locker).state = 0
|
||||
// (*locker).sema = 0
|
||||
// (*(&locker)) = nil
|
||||
|
||||
locker = nil
|
||||
Display("(&locker)", &locker)
|
||||
// Output:
|
||||
// Display (&locker) (*sync.Locker):
|
||||
// (*(&locker)) = nil
|
||||
|
||||
ips, _ := net.LookupHost("golang.org")
|
||||
Display("ips", ips)
|
||||
// Output:
|
||||
// Display ips ([]string):
|
||||
// ips[0] = "173.194.68.141"
|
||||
// ips[1] = "2607:f8b0:400d:c06::8d"
|
||||
|
||||
// Even metarecursion! (YMMV)
|
||||
Display("rV", reflect.ValueOf(os.Stderr))
|
||||
// Output:
|
||||
// Display rV (reflect.Value):
|
||||
// (*rV.typ).size = 8
|
||||
// (*rV.typ).ptrdata = 8
|
||||
// (*rV.typ).hash = 871609668
|
||||
// (*rV.typ)._ = 0
|
||||
// ...
|
||||
|
||||
// a pointer that points to itself
|
||||
type P *P
|
||||
var p P
|
||||
p = &p
|
||||
if false {
|
||||
Display("p", p)
|
||||
// Output:
|
||||
// Display p (display.P):
|
||||
// ...stuck, no output...
|
||||
}
|
||||
|
||||
// a map that contains itself
|
||||
type M map[string]M
|
||||
m := make(M)
|
||||
m[""] = m
|
||||
if false {
|
||||
Display("m", m)
|
||||
// Output:
|
||||
// Display m (display.M):
|
||||
// ...stuck, no output...
|
||||
}
|
||||
|
||||
// a slice that contains itself
|
||||
type S []S
|
||||
s := make(S, 1)
|
||||
s[0] = s
|
||||
if false {
|
||||
Display("s", s)
|
||||
// Output:
|
||||
// Display s (display.S):
|
||||
// ...stuck, no output...
|
||||
}
|
||||
|
||||
// a linked list that eats its own tail
|
||||
type Cycle struct {
|
||||
Value int
|
||||
Tail *Cycle
|
||||
}
|
||||
var c Cycle
|
||||
c = Cycle{42, &c}
|
||||
if false {
|
||||
Display("c", c)
|
||||
// Output:
|
||||
// Display c (display.Cycle):
|
||||
// c.Value = 42
|
||||
// (*c.Tail).Value = 42
|
||||
// (*(*c.Tail).Tail).Value = 42
|
||||
// ...ad infinitum...
|
||||
}
|
||||
}
|
||||
|
|
@ -1,44 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 332.
|
||||
|
||||
// Package format provides an Any function that can format any value.
|
||||
//!+
|
||||
package format
|
||||
|
||||
import (
|
||||
"reflect"
|
||||
"strconv"
|
||||
)
|
||||
|
||||
// Any formats any value as a string.
|
||||
func Any(value interface{}) string {
|
||||
return formatAtom(reflect.ValueOf(value))
|
||||
}
|
||||
|
||||
// formatAtom formats a value without inspecting its internal structure.
|
||||
func formatAtom(v reflect.Value) string {
|
||||
switch v.Kind() {
|
||||
case reflect.Invalid:
|
||||
return "invalid"
|
||||
case reflect.Int, reflect.Int8, reflect.Int16,
|
||||
reflect.Int32, reflect.Int64:
|
||||
return strconv.FormatInt(v.Int(), 10)
|
||||
case reflect.Uint, reflect.Uint8, reflect.Uint16,
|
||||
reflect.Uint32, reflect.Uint64, reflect.Uintptr:
|
||||
return strconv.FormatUint(v.Uint(), 10)
|
||||
// ...floating-point and complex cases omitted for brevity...
|
||||
case reflect.Bool:
|
||||
return strconv.FormatBool(v.Bool())
|
||||
case reflect.String:
|
||||
return strconv.Quote(v.String())
|
||||
case reflect.Chan, reflect.Func, reflect.Ptr, reflect.Slice, reflect.Map:
|
||||
return v.Type().String() + " 0x" +
|
||||
strconv.FormatUint(uint64(v.Pointer()), 16)
|
||||
default: // reflect.Array, reflect.Struct, reflect.Interface
|
||||
return v.Type().String() + " value"
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,24 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package format_test
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"testing"
|
||||
"time"
|
||||
|
||||
"gopl.io/ch12/format"
|
||||
)
|
||||
|
||||
func Test(t *testing.T) {
|
||||
// The pointer values are just examples, and may vary from run to run.
|
||||
//!+time
|
||||
var x int64 = 1
|
||||
var d time.Duration = 1 * time.Nanosecond
|
||||
fmt.Println(format.Any(x)) // "1"
|
||||
fmt.Println(format.Any(d)) // "1"
|
||||
fmt.Println(format.Any([]int64{x})) // "[]int64 0x8202b87b0"
|
||||
fmt.Println(format.Any([]time.Duration{d})) // "[]time.Duration 0x8202b87e0"
|
||||
//!-time
|
||||
}
|
||||
|
|
@ -1,29 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 351.
|
||||
|
||||
// Package methods provides a function to print the methods of any value.
|
||||
package methods
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"reflect"
|
||||
"strings"
|
||||
)
|
||||
|
||||
//!+print
|
||||
// Print prints the method set of the value x.
|
||||
func Print(x interface{}) {
|
||||
v := reflect.ValueOf(x)
|
||||
t := v.Type()
|
||||
fmt.Printf("type %s\n", t)
|
||||
|
||||
for i := 0; i < v.NumMethod(); i++ {
|
||||
methType := v.Method(i).Type()
|
||||
fmt.Printf("func (%s) %s%s\n", t, t.Method(i).Name,
|
||||
strings.TrimPrefix(methType.String(), "func"))
|
||||
}
|
||||
}
|
||||
|
||||
//!-print
|
||||
|
|
@ -1,49 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package methods_test
|
||||
|
||||
import (
|
||||
"strings"
|
||||
"time"
|
||||
|
||||
"gopl.io/ch12/methods"
|
||||
)
|
||||
|
||||
func ExamplePrintDuration() {
|
||||
methods.Print(time.Hour)
|
||||
// Output:
|
||||
// type time.Duration
|
||||
// func (time.Duration) Hours() float64
|
||||
// func (time.Duration) Minutes() float64
|
||||
// func (time.Duration) Nanoseconds() int64
|
||||
// func (time.Duration) Seconds() float64
|
||||
// func (time.Duration) String() string
|
||||
}
|
||||
|
||||
func ExamplePrintReplacer() {
|
||||
methods.Print(new(strings.Replacer))
|
||||
// Output:
|
||||
// type *strings.Replacer
|
||||
// func (*strings.Replacer) Replace(string) string
|
||||
// func (*strings.Replacer) WriteString(io.Writer, string) (int, error)
|
||||
}
|
||||
|
||||
/*
|
||||
//!+output
|
||||
methods.Print(time.Hour)
|
||||
// Output:
|
||||
// type time.Duration
|
||||
// func (time.Duration) Hours() float64
|
||||
// func (time.Duration) Minutes() float64
|
||||
// func (time.Duration) Nanoseconds() int64
|
||||
// func (time.Duration) Seconds() float64
|
||||
// func (time.Duration) String() string
|
||||
|
||||
methods.Print(new(strings.Replacer))
|
||||
// Output:
|
||||
// type *strings.Replacer
|
||||
// func (*strings.Replacer) Replace(string) string
|
||||
// func (*strings.Replacer) WriteString(io.Writer, string) (int, error)
|
||||
//!-output
|
||||
*/
|
||||
|
|
@ -1,90 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 349.
|
||||
|
||||
// Package params provides a reflection-based parser for URL parameters.
|
||||
package params
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"net/http"
|
||||
"reflect"
|
||||
"strconv"
|
||||
"strings"
|
||||
)
|
||||
|
||||
//!+Unpack
|
||||
|
||||
// Unpack populates the fields of the struct pointed to by ptr
|
||||
// from the HTTP request parameters in req.
|
||||
func Unpack(req *http.Request, ptr interface{}) error {
|
||||
if err := req.ParseForm(); err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
// Build map of fields keyed by effective name.
|
||||
fields := make(map[string]reflect.Value)
|
||||
v := reflect.ValueOf(ptr).Elem() // the struct variable
|
||||
for i := 0; i < v.NumField(); i++ {
|
||||
fieldInfo := v.Type().Field(i) // a reflect.StructField
|
||||
tag := fieldInfo.Tag // a reflect.StructTag
|
||||
name := tag.Get("http")
|
||||
if name == "" {
|
||||
name = strings.ToLower(fieldInfo.Name)
|
||||
}
|
||||
fields[name] = v.Field(i)
|
||||
}
|
||||
|
||||
// Update struct field for each parameter in the request.
|
||||
for name, values := range req.Form {
|
||||
f := fields[name]
|
||||
if !f.IsValid() {
|
||||
continue // ignore unrecognized HTTP parameters
|
||||
}
|
||||
for _, value := range values {
|
||||
if f.Kind() == reflect.Slice {
|
||||
elem := reflect.New(f.Type().Elem()).Elem()
|
||||
if err := populate(elem, value); err != nil {
|
||||
return fmt.Errorf("%s: %v", name, err)
|
||||
}
|
||||
f.Set(reflect.Append(f, elem))
|
||||
} else {
|
||||
if err := populate(f, value); err != nil {
|
||||
return fmt.Errorf("%s: %v", name, err)
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
//!-Unpack
|
||||
|
||||
//!+populate
|
||||
func populate(v reflect.Value, value string) error {
|
||||
switch v.Kind() {
|
||||
case reflect.String:
|
||||
v.SetString(value)
|
||||
|
||||
case reflect.Int:
|
||||
i, err := strconv.ParseInt(value, 10, 64)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
v.SetInt(i)
|
||||
|
||||
case reflect.Bool:
|
||||
b, err := strconv.ParseBool(value)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
v.SetBool(b)
|
||||
|
||||
default:
|
||||
return fmt.Errorf("unsupported kind %s", v.Type())
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
//!-populate
|
||||
|
|
@ -1,60 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 348.
|
||||
|
||||
// Search is a demo of the params.Unpack function.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"net/http"
|
||||
)
|
||||
|
||||
//!+
|
||||
|
||||
import "gopl.io/ch12/params"
|
||||
|
||||
// search implements the /search URL endpoint.
|
||||
func search(resp http.ResponseWriter, req *http.Request) {
|
||||
var data struct {
|
||||
Labels []string `http:"l"`
|
||||
MaxResults int `http:"max"`
|
||||
Exact bool `http:"x"`
|
||||
}
|
||||
data.MaxResults = 10 // set default
|
||||
if err := params.Unpack(req, &data); err != nil {
|
||||
http.Error(resp, err.Error(), http.StatusBadRequest) // 400
|
||||
return
|
||||
}
|
||||
|
||||
// ...rest of handler...
|
||||
fmt.Fprintf(resp, "Search: %+v\n", data)
|
||||
}
|
||||
|
||||
//!-
|
||||
|
||||
func main() {
|
||||
http.HandleFunc("/search", search)
|
||||
log.Fatal(http.ListenAndServe(":12345", nil))
|
||||
}
|
||||
|
||||
/*
|
||||
//!+output
|
||||
$ go build gopl.io/ch12/search
|
||||
$ ./search &
|
||||
$ ./fetch 'http://localhost:12345/search'
|
||||
Search: {Labels:[] MaxResults:10 Exact:false}
|
||||
$ ./fetch 'http://localhost:12345/search?l=golang&l=programming'
|
||||
Search: {Labels:[golang programming] MaxResults:10 Exact:false}
|
||||
$ ./fetch 'http://localhost:12345/search?l=golang&l=programming&max=100'
|
||||
Search: {Labels:[golang programming] MaxResults:100 Exact:false}
|
||||
$ ./fetch 'http://localhost:12345/search?x=true&l=golang&l=programming'
|
||||
Search: {Labels:[golang programming] MaxResults:10 Exact:true}
|
||||
$ ./fetch 'http://localhost:12345/search?q=hello&x=123'
|
||||
x: strconv.ParseBool: parsing "123": invalid syntax
|
||||
$ ./fetch 'http://localhost:12345/search?q=hello&max=lots'
|
||||
max: strconv.ParseInt: parsing "lots": invalid syntax
|
||||
//!-output
|
||||
*/
|
||||
|
|
@ -1,162 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 344.
|
||||
|
||||
// Package sexpr provides a means for converting Go objects to and
|
||||
// from S-expressions.
|
||||
package sexpr
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"reflect"
|
||||
"strconv"
|
||||
"text/scanner"
|
||||
)
|
||||
|
||||
//!+Unmarshal
|
||||
// Unmarshal parses S-expression data and populates the variable
|
||||
// whose address is in the non-nil pointer out.
|
||||
func Unmarshal(data []byte, out interface{}) (err error) {
|
||||
lex := &lexer{scan: scanner.Scanner{Mode: scanner.GoTokens}}
|
||||
lex.scan.Init(bytes.NewReader(data))
|
||||
lex.next() // get the first token
|
||||
defer func() {
|
||||
// NOTE: this is not an example of ideal error handling.
|
||||
if x := recover(); x != nil {
|
||||
err = fmt.Errorf("error at %s: %v", lex.scan.Position, x)
|
||||
}
|
||||
}()
|
||||
read(lex, reflect.ValueOf(out).Elem())
|
||||
return nil
|
||||
}
|
||||
|
||||
//!-Unmarshal
|
||||
|
||||
//!+lexer
|
||||
type lexer struct {
|
||||
scan scanner.Scanner
|
||||
token rune // the current token
|
||||
}
|
||||
|
||||
func (lex *lexer) next() { lex.token = lex.scan.Scan() }
|
||||
func (lex *lexer) text() string { return lex.scan.TokenText() }
|
||||
|
||||
func (lex *lexer) consume(want rune) {
|
||||
if lex.token != want { // NOTE: Not an example of good error handling.
|
||||
panic(fmt.Sprintf("got %q, want %q", lex.text(), want))
|
||||
}
|
||||
lex.next()
|
||||
}
|
||||
|
||||
//!-lexer
|
||||
|
||||
// The read function is a decoder for a small subset of well-formed
|
||||
// S-expressions. For brevity of our example, it takes many dubious
|
||||
// shortcuts.
|
||||
//
|
||||
// The parser assumes
|
||||
// - that the S-expression input is well-formed; it does no error checking.
|
||||
// - that the S-expression input corresponds to the type of the variable.
|
||||
// - that all numbers in the input are non-negative decimal integers.
|
||||
// - that all keys in ((key value) ...) struct syntax are unquoted symbols.
|
||||
// - that the input does not contain dotted lists such as (1 2 . 3).
|
||||
// - that the input does not contain Lisp reader macros such 'x and #'x.
|
||||
//
|
||||
// The reflection logic assumes
|
||||
// - that v is always a variable of the appropriate type for the
|
||||
// S-expression value. For example, v must not be a boolean,
|
||||
// interface, channel, or function, and if v is an array, the input
|
||||
// must have the correct number of elements.
|
||||
// - that v in the top-level call to read has the zero value of its
|
||||
// type and doesn't need clearing.
|
||||
// - that if v is a numeric variable, it is a signed integer.
|
||||
|
||||
//!+read
|
||||
func read(lex *lexer, v reflect.Value) {
|
||||
switch lex.token {
|
||||
case scanner.Ident:
|
||||
// The only valid identifiers are
|
||||
// "nil" and struct field names.
|
||||
if lex.text() == "nil" {
|
||||
v.Set(reflect.Zero(v.Type()))
|
||||
lex.next()
|
||||
return
|
||||
}
|
||||
case scanner.String:
|
||||
s, _ := strconv.Unquote(lex.text()) // NOTE: ignoring errors
|
||||
v.SetString(s)
|
||||
lex.next()
|
||||
return
|
||||
case scanner.Int:
|
||||
i, _ := strconv.Atoi(lex.text()) // NOTE: ignoring errors
|
||||
v.SetInt(int64(i))
|
||||
lex.next()
|
||||
return
|
||||
case '(':
|
||||
lex.next()
|
||||
readList(lex, v)
|
||||
lex.next() // consume ')'
|
||||
return
|
||||
}
|
||||
panic(fmt.Sprintf("unexpected token %q", lex.text()))
|
||||
}
|
||||
|
||||
//!-read
|
||||
|
||||
//!+readlist
|
||||
func readList(lex *lexer, v reflect.Value) {
|
||||
switch v.Kind() {
|
||||
case reflect.Array: // (item ...)
|
||||
for i := 0; !endList(lex); i++ {
|
||||
read(lex, v.Index(i))
|
||||
}
|
||||
|
||||
case reflect.Slice: // (item ...)
|
||||
for !endList(lex) {
|
||||
item := reflect.New(v.Type().Elem()).Elem()
|
||||
read(lex, item)
|
||||
v.Set(reflect.Append(v, item))
|
||||
}
|
||||
|
||||
case reflect.Struct: // ((name value) ...)
|
||||
for !endList(lex) {
|
||||
lex.consume('(')
|
||||
if lex.token != scanner.Ident {
|
||||
panic(fmt.Sprintf("got token %q, want field name", lex.text()))
|
||||
}
|
||||
name := lex.text()
|
||||
lex.next()
|
||||
read(lex, v.FieldByName(name))
|
||||
lex.consume(')')
|
||||
}
|
||||
|
||||
case reflect.Map: // ((key value) ...)
|
||||
v.Set(reflect.MakeMap(v.Type()))
|
||||
for !endList(lex) {
|
||||
lex.consume('(')
|
||||
key := reflect.New(v.Type().Key()).Elem()
|
||||
read(lex, key)
|
||||
value := reflect.New(v.Type().Elem()).Elem()
|
||||
read(lex, value)
|
||||
v.SetMapIndex(key, value)
|
||||
lex.consume(')')
|
||||
}
|
||||
|
||||
default:
|
||||
panic(fmt.Sprintf("cannot decode list into %v", v.Type()))
|
||||
}
|
||||
}
|
||||
|
||||
func endList(lex *lexer) bool {
|
||||
switch lex.token {
|
||||
case scanner.EOF:
|
||||
panic("end of file")
|
||||
case ')':
|
||||
return true
|
||||
}
|
||||
return false
|
||||
}
|
||||
|
||||
//!-readlist
|
||||
|
|
@ -1,97 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 339.
|
||||
|
||||
package sexpr
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"reflect"
|
||||
)
|
||||
|
||||
//!+Marshal
|
||||
// Marshal encodes a Go value in S-expression form.
|
||||
func Marshal(v interface{}) ([]byte, error) {
|
||||
var buf bytes.Buffer
|
||||
if err := encode(&buf, reflect.ValueOf(v)); err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return buf.Bytes(), nil
|
||||
}
|
||||
|
||||
//!-Marshal
|
||||
|
||||
// encode writes to buf an S-expression representation of v.
|
||||
//!+encode
|
||||
func encode(buf *bytes.Buffer, v reflect.Value) error {
|
||||
switch v.Kind() {
|
||||
case reflect.Invalid:
|
||||
buf.WriteString("nil")
|
||||
|
||||
case reflect.Int, reflect.Int8, reflect.Int16,
|
||||
reflect.Int32, reflect.Int64:
|
||||
fmt.Fprintf(buf, "%d", v.Int())
|
||||
|
||||
case reflect.Uint, reflect.Uint8, reflect.Uint16,
|
||||
reflect.Uint32, reflect.Uint64, reflect.Uintptr:
|
||||
fmt.Fprintf(buf, "%d", v.Uint())
|
||||
|
||||
case reflect.String:
|
||||
fmt.Fprintf(buf, "%q", v.String())
|
||||
|
||||
case reflect.Ptr:
|
||||
return encode(buf, v.Elem())
|
||||
|
||||
case reflect.Array, reflect.Slice: // (value ...)
|
||||
buf.WriteByte('(')
|
||||
for i := 0; i < v.Len(); i++ {
|
||||
if i > 0 {
|
||||
buf.WriteByte(' ')
|
||||
}
|
||||
if err := encode(buf, v.Index(i)); err != nil {
|
||||
return err
|
||||
}
|
||||
}
|
||||
buf.WriteByte(')')
|
||||
|
||||
case reflect.Struct: // ((name value) ...)
|
||||
buf.WriteByte('(')
|
||||
for i := 0; i < v.NumField(); i++ {
|
||||
if i > 0 {
|
||||
buf.WriteByte(' ')
|
||||
}
|
||||
fmt.Fprintf(buf, "(%s ", v.Type().Field(i).Name)
|
||||
if err := encode(buf, v.Field(i)); err != nil {
|
||||
return err
|
||||
}
|
||||
buf.WriteByte(')')
|
||||
}
|
||||
buf.WriteByte(')')
|
||||
|
||||
case reflect.Map: // ((key value) ...)
|
||||
buf.WriteByte('(')
|
||||
for i, key := range v.MapKeys() {
|
||||
if i > 0 {
|
||||
buf.WriteByte(' ')
|
||||
}
|
||||
buf.WriteByte('(')
|
||||
if err := encode(buf, key); err != nil {
|
||||
return err
|
||||
}
|
||||
buf.WriteByte(' ')
|
||||
if err := encode(buf, v.MapIndex(key)); err != nil {
|
||||
return err
|
||||
}
|
||||
buf.WriteByte(')')
|
||||
}
|
||||
buf.WriteByte(')')
|
||||
|
||||
default: // float, complex, bool, chan, func, interface
|
||||
return fmt.Errorf("unsupported type: %s", v.Type())
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
//!-encode
|
||||
|
|
@ -1,183 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package sexpr
|
||||
|
||||
// This file implements the algorithm described in Derek C. Oppen's
|
||||
// 1979 Stanford technical report, "Pretty Printing".
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"reflect"
|
||||
)
|
||||
|
||||
func MarshalIndent(v interface{}) ([]byte, error) {
|
||||
p := printer{width: margin}
|
||||
if err := pretty(&p, reflect.ValueOf(v)); err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return p.Bytes(), nil
|
||||
}
|
||||
|
||||
const margin = 80
|
||||
|
||||
type token struct {
|
||||
kind rune // one of "s ()" (string, blank, start, end)
|
||||
str string
|
||||
size int
|
||||
}
|
||||
|
||||
type printer struct {
|
||||
tokens []*token // FIFO buffer
|
||||
stack []*token // stack of open ' ' and '(' tokens
|
||||
rtotal int // total number of spaces needed to print stream
|
||||
|
||||
bytes.Buffer
|
||||
indents []int
|
||||
width int // remaining space
|
||||
}
|
||||
|
||||
func (p *printer) string(str string) {
|
||||
tok := &token{kind: 's', str: str, size: len(str)}
|
||||
if len(p.stack) == 0 {
|
||||
p.print(tok)
|
||||
} else {
|
||||
p.tokens = append(p.tokens, tok)
|
||||
p.rtotal += len(str)
|
||||
}
|
||||
}
|
||||
func (p *printer) pop() (top *token) {
|
||||
last := len(p.stack) - 1
|
||||
top, p.stack = p.stack[last], p.stack[:last]
|
||||
return
|
||||
}
|
||||
func (p *printer) begin() {
|
||||
if len(p.stack) == 0 {
|
||||
p.rtotal = 1
|
||||
}
|
||||
t := &token{kind: '(', size: -p.rtotal}
|
||||
p.tokens = append(p.tokens, t)
|
||||
p.stack = append(p.stack, t) // push
|
||||
p.string("(")
|
||||
}
|
||||
func (p *printer) end() {
|
||||
p.string(")")
|
||||
p.tokens = append(p.tokens, &token{kind: ')'})
|
||||
x := p.pop()
|
||||
x.size += p.rtotal
|
||||
if x.kind == ' ' {
|
||||
p.pop().size += p.rtotal
|
||||
}
|
||||
if len(p.stack) == 0 {
|
||||
for _, tok := range p.tokens {
|
||||
p.print(tok)
|
||||
}
|
||||
p.tokens = nil
|
||||
}
|
||||
}
|
||||
func (p *printer) space() {
|
||||
last := len(p.stack) - 1
|
||||
x := p.stack[last]
|
||||
if x.kind == ' ' {
|
||||
x.size += p.rtotal
|
||||
p.stack = p.stack[:last] // pop
|
||||
}
|
||||
t := &token{kind: ' ', size: -p.rtotal}
|
||||
p.tokens = append(p.tokens, t)
|
||||
p.stack = append(p.stack, t)
|
||||
p.rtotal++
|
||||
}
|
||||
func (p *printer) print(t *token) {
|
||||
switch t.kind {
|
||||
case 's':
|
||||
p.WriteString(t.str)
|
||||
p.width -= len(t.str)
|
||||
case '(':
|
||||
p.indents = append(p.indents, p.width)
|
||||
case ')':
|
||||
p.indents = p.indents[:len(p.indents)-1] // pop
|
||||
case ' ':
|
||||
if t.size > p.width {
|
||||
p.width = p.indents[len(p.indents)-1] - 1
|
||||
fmt.Fprintf(&p.Buffer, "\n%*s", margin-p.width, "")
|
||||
} else {
|
||||
p.WriteByte(' ')
|
||||
p.width--
|
||||
}
|
||||
}
|
||||
}
|
||||
func (p *printer) stringf(format string, args ...interface{}) {
|
||||
p.string(fmt.Sprintf(format, args...))
|
||||
}
|
||||
|
||||
func pretty(p *printer, v reflect.Value) error {
|
||||
switch v.Kind() {
|
||||
case reflect.Invalid:
|
||||
p.string("nil")
|
||||
|
||||
case reflect.Int, reflect.Int8, reflect.Int16,
|
||||
reflect.Int32, reflect.Int64:
|
||||
p.stringf("%d", v.Int())
|
||||
|
||||
case reflect.Uint, reflect.Uint8, reflect.Uint16,
|
||||
reflect.Uint32, reflect.Uint64, reflect.Uintptr:
|
||||
p.stringf("%d", v.Uint())
|
||||
|
||||
case reflect.String:
|
||||
p.stringf("%q", v.String())
|
||||
|
||||
case reflect.Array, reflect.Slice: // (value ...)
|
||||
p.begin()
|
||||
for i := 0; i < v.Len(); i++ {
|
||||
if i > 0 {
|
||||
p.space()
|
||||
}
|
||||
if err := pretty(p, v.Index(i)); err != nil {
|
||||
return err
|
||||
}
|
||||
}
|
||||
p.end()
|
||||
|
||||
case reflect.Struct: // ((name value ...)
|
||||
p.begin()
|
||||
for i := 0; i < v.NumField(); i++ {
|
||||
if i > 0 {
|
||||
p.space()
|
||||
}
|
||||
p.begin()
|
||||
p.string(v.Type().Field(i).Name)
|
||||
p.space()
|
||||
if err := pretty(p, v.Field(i)); err != nil {
|
||||
return err
|
||||
}
|
||||
p.end()
|
||||
}
|
||||
p.end()
|
||||
|
||||
case reflect.Map: // ((key value ...)
|
||||
p.begin()
|
||||
for i, key := range v.MapKeys() {
|
||||
if i > 0 {
|
||||
p.space()
|
||||
}
|
||||
p.begin()
|
||||
if err := pretty(p, key); err != nil {
|
||||
return err
|
||||
}
|
||||
p.space()
|
||||
if err := pretty(p, v.MapIndex(key)); err != nil {
|
||||
return err
|
||||
}
|
||||
p.end()
|
||||
}
|
||||
p.end()
|
||||
|
||||
case reflect.Ptr:
|
||||
return pretty(p, v.Elem())
|
||||
|
||||
default: // float, complex, bool, chan, func, interface
|
||||
return fmt.Errorf("unsupported type: %s", v.Type())
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
|
@ -1,74 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package sexpr
|
||||
|
||||
import (
|
||||
"reflect"
|
||||
"testing"
|
||||
)
|
||||
|
||||
// Test verifies that encoding and decoding a complex data value
|
||||
// produces an equal result.
|
||||
//
|
||||
// The test does not make direct assertions about the encoded output
|
||||
// because the output depends on map iteration order, which is
|
||||
// nondeterministic. The output of the t.Log statements can be
|
||||
// inspected by running the test with the -v flag:
|
||||
//
|
||||
// $ go test -v gopl.io/ch12/sexpr
|
||||
//
|
||||
func Test(t *testing.T) {
|
||||
type Movie struct {
|
||||
Title, Subtitle string
|
||||
Year int
|
||||
Actor map[string]string
|
||||
Oscars []string
|
||||
Sequel *string
|
||||
}
|
||||
strangelove := Movie{
|
||||
Title: "Dr. Strangelove",
|
||||
Subtitle: "How I Learned to Stop Worrying and Love the Bomb",
|
||||
Year: 1964,
|
||||
Actor: map[string]string{
|
||||
"Dr. Strangelove": "Peter Sellers",
|
||||
"Grp. Capt. Lionel Mandrake": "Peter Sellers",
|
||||
"Pres. Merkin Muffley": "Peter Sellers",
|
||||
"Gen. Buck Turgidson": "George C. Scott",
|
||||
"Brig. Gen. Jack D. Ripper": "Sterling Hayden",
|
||||
`Maj. T.J. "King" Kong`: "Slim Pickens",
|
||||
},
|
||||
Oscars: []string{
|
||||
"Best Actor (Nomin.)",
|
||||
"Best Adapted Screenplay (Nomin.)",
|
||||
"Best Director (Nomin.)",
|
||||
"Best Picture (Nomin.)",
|
||||
},
|
||||
}
|
||||
|
||||
// Encode it
|
||||
data, err := Marshal(strangelove)
|
||||
if err != nil {
|
||||
t.Fatalf("Marshal failed: %v", err)
|
||||
}
|
||||
t.Logf("Marshal() = %s\n", data)
|
||||
|
||||
// Decode it
|
||||
var movie Movie
|
||||
if err := Unmarshal(data, &movie); err != nil {
|
||||
t.Fatalf("Unmarshal failed: %v", err)
|
||||
}
|
||||
t.Logf("Unmarshal() = %+v\n", movie)
|
||||
|
||||
// Check equality.
|
||||
if !reflect.DeepEqual(movie, strangelove) {
|
||||
t.Fatal("not equal")
|
||||
}
|
||||
|
||||
// Pretty-print it:
|
||||
data, err = MarshalIndent(strangelove)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
t.Logf("MarshalIdent() = %s\n", data)
|
||||
}
|
||||
|
|
@ -1,28 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 362.
|
||||
// This is the version that appears in print,
|
||||
// but it does not comply with the proposed
|
||||
// rules for passing pointers between Go and C.
|
||||
// (https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md)
|
||||
// See gopl.io/ch13/bzip for an updated version.
|
||||
|
||||
//!+
|
||||
/* This file is gopl.io/ch13/bzip/bzip2.c, */
|
||||
/* a simple wrapper for libbzip2 suitable for cgo. */
|
||||
#include <bzlib.h>
|
||||
|
||||
int bz2compress(bz_stream *s, int action,
|
||||
char *in, unsigned *inlen, char *out, unsigned *outlen) {
|
||||
s->next_in = in;
|
||||
s->avail_in = *inlen;
|
||||
s->next_out = out;
|
||||
s->avail_out = *outlen;
|
||||
int r = BZ2_bzCompress(s, action);
|
||||
*inlen -= s->avail_in;
|
||||
*outlen -= s->avail_out;
|
||||
return r;
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,96 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 362.
|
||||
// This is the version that appears in print,
|
||||
// but it does not comply with the proposed
|
||||
// rules for passing pointers between Go and C.
|
||||
// (https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md)
|
||||
// See gopl.io/ch13/bzip for an updated version.
|
||||
//!+
|
||||
|
||||
// Package bzip provides a writer that uses bzip2 compression (bzip.org).
|
||||
package bzip
|
||||
|
||||
/*
|
||||
#cgo CFLAGS: -I/usr/include
|
||||
#cgo LDFLAGS: -L/usr/lib -lbz2
|
||||
#include <bzlib.h>
|
||||
int bz2compress(bz_stream *s, int action,
|
||||
char *in, unsigned *inlen, char *out, unsigned *outlen);
|
||||
*/
|
||||
import "C"
|
||||
|
||||
import (
|
||||
"io"
|
||||
"unsafe"
|
||||
)
|
||||
|
||||
type writer struct {
|
||||
w io.Writer // underlying output stream
|
||||
stream *C.bz_stream
|
||||
outbuf [64 * 1024]byte
|
||||
}
|
||||
|
||||
// NewWriter returns a writer for bzip2-compressed streams.
|
||||
func NewWriter(out io.Writer) io.WriteCloser {
|
||||
const (
|
||||
blockSize = 9
|
||||
verbosity = 0
|
||||
workFactor = 30
|
||||
)
|
||||
w := &writer{w: out, stream: new(C.bz_stream)}
|
||||
C.BZ2_bzCompressInit(w.stream, blockSize, verbosity, workFactor)
|
||||
return w
|
||||
}
|
||||
|
||||
//!-
|
||||
|
||||
//!+write
|
||||
func (w *writer) Write(data []byte) (int, error) {
|
||||
if w.stream == nil {
|
||||
panic("closed")
|
||||
}
|
||||
var total int // uncompressed bytes written
|
||||
|
||||
for len(data) > 0 {
|
||||
inlen, outlen := C.uint(len(data)), C.uint(cap(w.outbuf))
|
||||
C.bz2compress(w.stream, C.BZ_RUN,
|
||||
(*C.char)(unsafe.Pointer(&data[0])), &inlen,
|
||||
(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
|
||||
total += int(inlen)
|
||||
data = data[inlen:]
|
||||
if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
|
||||
return total, err
|
||||
}
|
||||
}
|
||||
return total, nil
|
||||
}
|
||||
|
||||
//!-write
|
||||
|
||||
//!+close
|
||||
// Close flushes the compressed data and closes the stream.
|
||||
// It does not close the underlying io.Writer.
|
||||
func (w *writer) Close() error {
|
||||
if w.stream == nil {
|
||||
panic("closed")
|
||||
}
|
||||
defer func() {
|
||||
C.BZ2_bzCompressEnd(w.stream)
|
||||
w.stream = nil
|
||||
}()
|
||||
for {
|
||||
inlen, outlen := C.uint(0), C.uint(cap(w.outbuf))
|
||||
r := C.bz2compress(w.stream, C.BZ_FINISH, nil, &inlen,
|
||||
(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
|
||||
if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
|
||||
return err
|
||||
}
|
||||
if r == C.BZ_STREAM_END {
|
||||
return nil
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
//!-close
|
||||
|
|
@ -1,40 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package bzip_test
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"compress/bzip2" // reader
|
||||
"io"
|
||||
"testing"
|
||||
|
||||
"gopl.io/ch13/bzip" // writer
|
||||
)
|
||||
|
||||
func TestBzip2(t *testing.T) {
|
||||
var compressed, uncompressed bytes.Buffer
|
||||
w := bzip.NewWriter(&compressed)
|
||||
|
||||
// Write a repetitive message in a million pieces,
|
||||
// compressing one copy but not the other.
|
||||
tee := io.MultiWriter(w, &uncompressed)
|
||||
for i := 0; i < 1000000; i++ {
|
||||
io.WriteString(tee, "hello")
|
||||
}
|
||||
if err := w.Close(); err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Check the size of the compressed stream.
|
||||
if got, want := compressed.Len(), 255; got != want {
|
||||
t.Errorf("1 million hellos compressed to %d bytes, want %d", got, want)
|
||||
}
|
||||
|
||||
// Decompress and compare with original.
|
||||
var decompressed bytes.Buffer
|
||||
io.Copy(&decompressed, bzip2.NewReader(&compressed))
|
||||
if !bytes.Equal(uncompressed.Bytes(), decompressed.Bytes()) {
|
||||
t.Error("decompression yielded a different message")
|
||||
}
|
||||
}
|
||||
|
|
@ -1,32 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 362.
|
||||
//
|
||||
// The version of this program that appeared in the first and second
|
||||
// printings did not comply with the proposed rules for passing
|
||||
// pointers between Go and C, described here:
|
||||
// https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md
|
||||
//
|
||||
// The version below, which appears in the third printing,
|
||||
// has been corrected. See bzip2.go for explanation.
|
||||
|
||||
//!+
|
||||
/* This file is gopl.io/ch13/bzip/bzip2.c, */
|
||||
/* a simple wrapper for libbzip2 suitable for cgo. */
|
||||
#include <bzlib.h>
|
||||
|
||||
int bz2compress(bz_stream *s, int action,
|
||||
char *in, unsigned *inlen, char *out, unsigned *outlen) {
|
||||
s->next_in = in;
|
||||
s->avail_in = *inlen;
|
||||
s->next_out = out;
|
||||
s->avail_out = *outlen;
|
||||
int r = BZ2_bzCompress(s, action);
|
||||
*inlen -= s->avail_in;
|
||||
*outlen -= s->avail_out;
|
||||
s->next_in = s->next_out = NULL;
|
||||
return r;
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,111 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 362.
|
||||
//
|
||||
// The version of this program that appeared in the first and second
|
||||
// printings did not comply with the proposed rules for passing
|
||||
// pointers between Go and C, described here:
|
||||
// https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md
|
||||
//
|
||||
// The rules forbid a C function like bz2compress from storing 'in'
|
||||
// and 'out' (pointers to variables allocated by Go) into the Go
|
||||
// variable 's', even temporarily.
|
||||
//
|
||||
// The version below, which appears in the third printing, has been
|
||||
// corrected. To comply with the rules, the bz_stream variable must
|
||||
// be allocated by C code. We have introduced two C functions,
|
||||
// bz2alloc and bz2free, to allocate and free instances of the
|
||||
// bz_stream type. Also, we have changed bz2compress so that before
|
||||
// it returns, it clears the fields of the bz_stream that contain
|
||||
// pointers to Go variables.
|
||||
|
||||
//!+
|
||||
|
||||
// Package bzip provides a writer that uses bzip2 compression (bzip.org).
|
||||
package bzip
|
||||
|
||||
/*
|
||||
#cgo CFLAGS: -I/usr/include
|
||||
#cgo LDFLAGS: -L/usr/lib -lbz2
|
||||
#include <bzlib.h>
|
||||
#include <stdlib.h>
|
||||
bz_stream* bz2alloc() { return calloc(1, sizeof(bz_stream)); }
|
||||
int bz2compress(bz_stream *s, int action,
|
||||
char *in, unsigned *inlen, char *out, unsigned *outlen);
|
||||
void bz2free(bz_stream* s) { free(s); }
|
||||
*/
|
||||
import "C"
|
||||
|
||||
import (
|
||||
"io"
|
||||
"unsafe"
|
||||
)
|
||||
|
||||
type writer struct {
|
||||
w io.Writer // underlying output stream
|
||||
stream *C.bz_stream
|
||||
outbuf [64 * 1024]byte
|
||||
}
|
||||
|
||||
// NewWriter returns a writer for bzip2-compressed streams.
|
||||
func NewWriter(out io.Writer) io.WriteCloser {
|
||||
const blockSize = 9
|
||||
const verbosity = 0
|
||||
const workFactor = 30
|
||||
w := &writer{w: out, stream: C.bz2alloc()}
|
||||
C.BZ2_bzCompressInit(w.stream, blockSize, verbosity, workFactor)
|
||||
return w
|
||||
}
|
||||
|
||||
//!-
|
||||
|
||||
//!+write
|
||||
func (w *writer) Write(data []byte) (int, error) {
|
||||
if w.stream == nil {
|
||||
panic("closed")
|
||||
}
|
||||
var total int // uncompressed bytes written
|
||||
|
||||
for len(data) > 0 {
|
||||
inlen, outlen := C.uint(len(data)), C.uint(cap(w.outbuf))
|
||||
C.bz2compress(w.stream, C.BZ_RUN,
|
||||
(*C.char)(unsafe.Pointer(&data[0])), &inlen,
|
||||
(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
|
||||
total += int(inlen)
|
||||
data = data[inlen:]
|
||||
if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
|
||||
return total, err
|
||||
}
|
||||
}
|
||||
return total, nil
|
||||
}
|
||||
|
||||
//!-write
|
||||
|
||||
//!+close
|
||||
// Close flushes the compressed data and closes the stream.
|
||||
// It does not close the underlying io.Writer.
|
||||
func (w *writer) Close() error {
|
||||
if w.stream == nil {
|
||||
panic("closed")
|
||||
}
|
||||
defer func() {
|
||||
C.BZ2_bzCompressEnd(w.stream)
|
||||
C.bz2free(w.stream)
|
||||
w.stream = nil
|
||||
}()
|
||||
for {
|
||||
inlen, outlen := C.uint(0), C.uint(cap(w.outbuf))
|
||||
r := C.bz2compress(w.stream, C.BZ_FINISH, nil, &inlen,
|
||||
(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
|
||||
if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
|
||||
return err
|
||||
}
|
||||
if r == C.BZ_STREAM_END {
|
||||
return nil
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
//!-close
|
||||
|
|
@ -1,40 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package bzip_test
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"compress/bzip2" // reader
|
||||
"io"
|
||||
"testing"
|
||||
|
||||
"gopl.io/ch13/bzip" // writer
|
||||
)
|
||||
|
||||
func TestBzip2(t *testing.T) {
|
||||
var compressed, uncompressed bytes.Buffer
|
||||
w := bzip.NewWriter(&compressed)
|
||||
|
||||
// Write a repetitive message in a million pieces,
|
||||
// compressing one copy but not the other.
|
||||
tee := io.MultiWriter(w, &uncompressed)
|
||||
for i := 0; i < 1000000; i++ {
|
||||
io.WriteString(tee, "hello")
|
||||
}
|
||||
if err := w.Close(); err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Check the size of the compressed stream.
|
||||
if got, want := compressed.Len(), 255; got != want {
|
||||
t.Errorf("1 million hellos compressed to %d bytes, want %d", got, want)
|
||||
}
|
||||
|
||||
// Decompress and compare with original.
|
||||
var decompressed bytes.Buffer
|
||||
io.Copy(&decompressed, bzip2.NewReader(&compressed))
|
||||
if !bytes.Equal(uncompressed.Bytes(), decompressed.Bytes()) {
|
||||
t.Error("decompression yielded a different message")
|
||||
}
|
||||
}
|
||||
|
|
@ -1,29 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 365.
|
||||
|
||||
//!+
|
||||
|
||||
// Bzipper reads input, bzip2-compresses it, and writes it out.
|
||||
package main
|
||||
|
||||
import (
|
||||
"io"
|
||||
"log"
|
||||
"os"
|
||||
|
||||
"gopl.io/ch13/bzip"
|
||||
)
|
||||
|
||||
func main() {
|
||||
w := bzip.NewWriter(os.Stdout)
|
||||
if _, err := io.Copy(w, os.Stdin); err != nil {
|
||||
log.Fatalf("bzipper: %v\n", err)
|
||||
}
|
||||
if err := w.Close(); err != nil {
|
||||
log.Fatalf("bzipper: close: %v\n", err)
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,127 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 359.
|
||||
|
||||
// Package equal provides a deep equivalence relation for arbitrary values.
|
||||
package equal
|
||||
|
||||
import (
|
||||
"reflect"
|
||||
"unsafe"
|
||||
)
|
||||
|
||||
//!+
|
||||
func equal(x, y reflect.Value, seen map[comparison]bool) bool {
|
||||
if !x.IsValid() || !y.IsValid() {
|
||||
return x.IsValid() == y.IsValid()
|
||||
}
|
||||
if x.Type() != y.Type() {
|
||||
return false
|
||||
}
|
||||
|
||||
// ...cycle check omitted (shown later)...
|
||||
|
||||
//!-
|
||||
//!+cyclecheck
|
||||
// cycle check
|
||||
if x.CanAddr() && y.CanAddr() {
|
||||
xptr := unsafe.Pointer(x.UnsafeAddr())
|
||||
yptr := unsafe.Pointer(y.UnsafeAddr())
|
||||
if xptr == yptr {
|
||||
return true // identical references
|
||||
}
|
||||
c := comparison{xptr, yptr, x.Type()}
|
||||
if seen[c] {
|
||||
return true // already seen
|
||||
}
|
||||
seen[c] = true
|
||||
}
|
||||
//!-cyclecheck
|
||||
//!+
|
||||
switch x.Kind() {
|
||||
case reflect.Bool:
|
||||
return x.Bool() == y.Bool()
|
||||
|
||||
case reflect.String:
|
||||
return x.String() == y.String()
|
||||
|
||||
// ...numeric cases omitted for brevity...
|
||||
|
||||
//!-
|
||||
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
|
||||
reflect.Int64:
|
||||
return x.Int() == y.Int()
|
||||
|
||||
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
|
||||
reflect.Uint64, reflect.Uintptr:
|
||||
return x.Uint() == y.Uint()
|
||||
|
||||
case reflect.Float32, reflect.Float64:
|
||||
return x.Float() == y.Float()
|
||||
|
||||
case reflect.Complex64, reflect.Complex128:
|
||||
return x.Complex() == y.Complex()
|
||||
//!+
|
||||
case reflect.Chan, reflect.UnsafePointer, reflect.Func:
|
||||
return x.Pointer() == y.Pointer()
|
||||
|
||||
case reflect.Ptr, reflect.Interface:
|
||||
return equal(x.Elem(), y.Elem(), seen)
|
||||
|
||||
case reflect.Array, reflect.Slice:
|
||||
if x.Len() != y.Len() {
|
||||
return false
|
||||
}
|
||||
for i := 0; i < x.Len(); i++ {
|
||||
if !equal(x.Index(i), y.Index(i), seen) {
|
||||
return false
|
||||
}
|
||||
}
|
||||
return true
|
||||
|
||||
// ...struct and map cases omitted for brevity...
|
||||
//!-
|
||||
case reflect.Struct:
|
||||
for i, n := 0, x.NumField(); i < n; i++ {
|
||||
if !equal(x.Field(i), y.Field(i), seen) {
|
||||
return false
|
||||
}
|
||||
}
|
||||
return true
|
||||
|
||||
case reflect.Map:
|
||||
if x.Len() != y.Len() {
|
||||
return false
|
||||
}
|
||||
for _, k := range x.MapKeys() {
|
||||
if !equal(x.MapIndex(k), y.MapIndex(k), seen) {
|
||||
return false
|
||||
}
|
||||
}
|
||||
return true
|
||||
//!+
|
||||
}
|
||||
panic("unreachable")
|
||||
}
|
||||
|
||||
//!-
|
||||
|
||||
//!+comparison
|
||||
// Equal reports whether x and y are deeply equal.
|
||||
//!-comparison
|
||||
//
|
||||
// Map keys are always compared with ==, not deeply.
|
||||
// (This matters for keys containing pointers or interfaces.)
|
||||
//!+comparison
|
||||
func Equal(x, y interface{}) bool {
|
||||
seen := make(map[comparison]bool)
|
||||
return equal(reflect.ValueOf(x), reflect.ValueOf(y), seen)
|
||||
}
|
||||
|
||||
type comparison struct {
|
||||
x, y unsafe.Pointer
|
||||
t reflect.Type
|
||||
}
|
||||
|
||||
//!-comparison
|
||||
|
|
@ -1,133 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package equal
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestEqual(t *testing.T) {
|
||||
one, oneAgain, two := 1, 1, 2
|
||||
|
||||
type CyclePtr *CyclePtr
|
||||
var cyclePtr1, cyclePtr2 CyclePtr
|
||||
cyclePtr1 = &cyclePtr1
|
||||
cyclePtr2 = &cyclePtr2
|
||||
|
||||
type CycleSlice []CycleSlice
|
||||
var cycleSlice CycleSlice
|
||||
cycleSlice = append(cycleSlice, cycleSlice)
|
||||
|
||||
ch1, ch2 := make(chan int), make(chan int)
|
||||
var ch1ro <-chan int = ch1
|
||||
|
||||
type mystring string
|
||||
|
||||
var iface1, iface1Again, iface2 interface{} = &one, &oneAgain, &two
|
||||
|
||||
for _, test := range []struct {
|
||||
x, y interface{}
|
||||
want bool
|
||||
}{
|
||||
// basic types
|
||||
{1, 1, true},
|
||||
{1, 2, false}, // different values
|
||||
{1, 1.0, false}, // different types
|
||||
{"foo", "foo", true},
|
||||
{"foo", "bar", false},
|
||||
{mystring("foo"), "foo", false}, // different types
|
||||
// slices
|
||||
{[]string{"foo"}, []string{"foo"}, true},
|
||||
{[]string{"foo"}, []string{"bar"}, false},
|
||||
{[]string{}, []string(nil), true},
|
||||
// slice cycles
|
||||
{cycleSlice, cycleSlice, true},
|
||||
// maps
|
||||
{
|
||||
map[string][]int{"foo": {1, 2, 3}},
|
||||
map[string][]int{"foo": {1, 2, 3}},
|
||||
true,
|
||||
},
|
||||
{
|
||||
map[string][]int{"foo": {1, 2, 3}},
|
||||
map[string][]int{"foo": {1, 2, 3, 4}},
|
||||
false,
|
||||
},
|
||||
{
|
||||
map[string][]int{},
|
||||
map[string][]int(nil),
|
||||
true,
|
||||
},
|
||||
// pointers
|
||||
{&one, &one, true},
|
||||
{&one, &two, false},
|
||||
{&one, &oneAgain, true},
|
||||
{new(bytes.Buffer), new(bytes.Buffer), true},
|
||||
// pointer cycles
|
||||
{cyclePtr1, cyclePtr1, true},
|
||||
{cyclePtr2, cyclePtr2, true},
|
||||
{cyclePtr1, cyclePtr2, true}, // they're deeply equal
|
||||
// functions
|
||||
{(func())(nil), (func())(nil), true},
|
||||
{(func())(nil), func() {}, false},
|
||||
{func() {}, func() {}, false},
|
||||
// arrays
|
||||
{[...]int{1, 2, 3}, [...]int{1, 2, 3}, true},
|
||||
{[...]int{1, 2, 3}, [...]int{1, 2, 4}, false},
|
||||
// channels
|
||||
{ch1, ch1, true},
|
||||
{ch1, ch2, false},
|
||||
{ch1ro, ch1, false}, // NOTE: not equal
|
||||
// interfaces
|
||||
{&iface1, &iface1, true},
|
||||
{&iface1, &iface2, false},
|
||||
{&iface1Again, &iface1, true},
|
||||
} {
|
||||
if Equal(test.x, test.y) != test.want {
|
||||
t.Errorf("Equal(%v, %v) = %t",
|
||||
test.x, test.y, !test.want)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func Example_equal() {
|
||||
//!+
|
||||
fmt.Println(Equal([]int{1, 2, 3}, []int{1, 2, 3})) // "true"
|
||||
fmt.Println(Equal([]string{"foo"}, []string{"bar"})) // "false"
|
||||
fmt.Println(Equal([]string(nil), []string{})) // "true"
|
||||
fmt.Println(Equal(map[string]int(nil), map[string]int{})) // "true"
|
||||
//!-
|
||||
|
||||
// Output:
|
||||
// true
|
||||
// false
|
||||
// true
|
||||
// true
|
||||
}
|
||||
|
||||
func Example_equalCycle() {
|
||||
//!+cycle
|
||||
// Circular linked lists a -> b -> a and c -> c.
|
||||
type link struct {
|
||||
value string
|
||||
tail *link
|
||||
}
|
||||
a, b, c := &link{value: "a"}, &link{value: "b"}, &link{value: "c"}
|
||||
a.tail, b.tail, c.tail = b, a, c
|
||||
fmt.Println(Equal(a, a)) // "true"
|
||||
fmt.Println(Equal(b, b)) // "true"
|
||||
fmt.Println(Equal(c, c)) // "true"
|
||||
fmt.Println(Equal(a, b)) // "false"
|
||||
fmt.Println(Equal(a, c)) // "false"
|
||||
//!-cycle
|
||||
|
||||
// Output:
|
||||
// true
|
||||
// true
|
||||
// true
|
||||
// false
|
||||
// false
|
||||
}
|
||||
|
|
@ -1,38 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 357.
|
||||
|
||||
// Package unsafeptr demonstrates basic use of unsafe.Pointer.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"unsafe"
|
||||
)
|
||||
|
||||
func main() {
|
||||
//!+main
|
||||
var x struct {
|
||||
a bool
|
||||
b int16
|
||||
c []int
|
||||
}
|
||||
|
||||
// equivalent to pb := &x.b
|
||||
pb := (*int16)(unsafe.Pointer(
|
||||
uintptr(unsafe.Pointer(&x)) + unsafe.Offsetof(x.b)))
|
||||
*pb = 42
|
||||
|
||||
fmt.Println(x.b) // "42"
|
||||
//!-main
|
||||
}
|
||||
|
||||
/*
|
||||
//!+wrong
|
||||
// NOTE: subtly incorrect!
|
||||
tmp := uintptr(unsafe.Pointer(&x)) + unsafe.Offsetof(x.b)
|
||||
pb := (*int16)(unsafe.Pointer(tmp))
|
||||
*pb = 42
|
||||
//!-wrong
|
||||
*/
|
||||
|
|
@ -1,22 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 29.
|
||||
//!+
|
||||
|
||||
// Boiling prints the boiling point of water.
|
||||
package main
|
||||
|
||||
import "fmt"
|
||||
|
||||
const boilingF = 212.0
|
||||
|
||||
func main() {
|
||||
var f = boilingF
|
||||
var c = (f - 32) * 5 / 9
|
||||
fmt.Printf("boiling point = %g°F or %g°C\n", f, c)
|
||||
// Output:
|
||||
// boiling point = 212°F or 100°C
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,32 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 43.
|
||||
//!+
|
||||
|
||||
// Cf converts its numeric argument to Celsius and Fahrenheit.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"os"
|
||||
"strconv"
|
||||
|
||||
"gopl.io/ch2/tempconv"
|
||||
)
|
||||
|
||||
func main() {
|
||||
for _, arg := range os.Args[1:] {
|
||||
t, err := strconv.ParseFloat(arg, 64)
|
||||
if err != nil {
|
||||
fmt.Fprintf(os.Stderr, "cf: %v\n", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
f := tempconv.Fahrenheit(t)
|
||||
c := tempconv.Celsius(t)
|
||||
fmt.Printf("%s = %s, %s = %s\n",
|
||||
f, tempconv.FToC(f), c, tempconv.CToF(c))
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,27 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 33.
|
||||
//!+
|
||||
|
||||
// Echo4 prints its command-line arguments.
|
||||
package main
|
||||
|
||||
import (
|
||||
"flag"
|
||||
"fmt"
|
||||
"strings"
|
||||
)
|
||||
|
||||
var n = flag.Bool("n", false, "omit trailing newline")
|
||||
var sep = flag.String("s", " ", "separator")
|
||||
|
||||
func main() {
|
||||
flag.Parse()
|
||||
fmt.Print(strings.Join(flag.Args(), *sep))
|
||||
if !*n {
|
||||
fmt.Println()
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,22 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 29.
|
||||
//!+
|
||||
|
||||
// Ftoc prints two Fahrenheit-to-Celsius conversions.
|
||||
package main
|
||||
|
||||
import "fmt"
|
||||
|
||||
func main() {
|
||||
const freezingF, boilingF = 32.0, 212.0
|
||||
fmt.Printf("%g°F = %g°C\n", freezingF, fToC(freezingF)) // "32°F = 0°C"
|
||||
fmt.Printf("%g°F = %g°C\n", boilingF, fToC(boilingF)) // "212°F = 100°C"
|
||||
}
|
||||
|
||||
func fToC(f float64) float64 {
|
||||
return (f - 32) * 5 / 9
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,31 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 45.
|
||||
|
||||
// (Package doc comment intentionally malformed to demonstrate golint.)
|
||||
//!+
|
||||
package popcount
|
||||
|
||||
// pc[i] is the population count of i.
|
||||
var pc [256]byte
|
||||
|
||||
func init() {
|
||||
for i := range pc {
|
||||
pc[i] = pc[i/2] + byte(i&1)
|
||||
}
|
||||
}
|
||||
|
||||
// PopCount returns the population count (number of set bits) of x.
|
||||
func PopCount(x uint64) int {
|
||||
return int(pc[byte(x>>(0*8))] +
|
||||
pc[byte(x>>(1*8))] +
|
||||
pc[byte(x>>(2*8))] +
|
||||
pc[byte(x>>(3*8))] +
|
||||
pc[byte(x>>(4*8))] +
|
||||
pc[byte(x>>(5*8))] +
|
||||
pc[byte(x>>(6*8))] +
|
||||
pc[byte(x>>(7*8))])
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,83 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package popcount_test
|
||||
|
||||
import (
|
||||
"testing"
|
||||
|
||||
"gopl.io/ch2/popcount"
|
||||
)
|
||||
|
||||
// -- Alternative implementations --
|
||||
|
||||
func BitCount(x uint64) int {
|
||||
// Hacker's Delight, Figure 5-2.
|
||||
x = x - ((x >> 1) & 0x5555555555555555)
|
||||
x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333)
|
||||
x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f
|
||||
x = x + (x >> 8)
|
||||
x = x + (x >> 16)
|
||||
x = x + (x >> 32)
|
||||
return int(x & 0x7f)
|
||||
}
|
||||
|
||||
func PopCountByClearing(x uint64) int {
|
||||
n := 0
|
||||
for x != 0 {
|
||||
x = x & (x - 1) // clear rightmost non-zero bit
|
||||
n++
|
||||
}
|
||||
return n
|
||||
}
|
||||
|
||||
func PopCountByShifting(x uint64) int {
|
||||
n := 0
|
||||
for i := uint(0); i < 64; i++ {
|
||||
if x&(1<<i) != 0 {
|
||||
n++
|
||||
}
|
||||
}
|
||||
return n
|
||||
}
|
||||
|
||||
// -- Benchmarks --
|
||||
|
||||
func BenchmarkPopCount(b *testing.B) {
|
||||
for i := 0; i < b.N; i++ {
|
||||
popcount.PopCount(0x1234567890ABCDEF)
|
||||
}
|
||||
}
|
||||
|
||||
func BenchmarkBitCount(b *testing.B) {
|
||||
for i := 0; i < b.N; i++ {
|
||||
BitCount(0x1234567890ABCDEF)
|
||||
}
|
||||
}
|
||||
|
||||
func BenchmarkPopCountByClearing(b *testing.B) {
|
||||
for i := 0; i < b.N; i++ {
|
||||
PopCountByClearing(0x1234567890ABCDEF)
|
||||
}
|
||||
}
|
||||
|
||||
func BenchmarkPopCountByShifting(b *testing.B) {
|
||||
for i := 0; i < b.N; i++ {
|
||||
PopCountByShifting(0x1234567890ABCDEF)
|
||||
}
|
||||
}
|
||||
|
||||
// 2.67GHz Xeon
|
||||
// $ go test -cpu=4 -bench=. gopl.io/ch2/popcount
|
||||
// BenchmarkPopCount-4 200000000 6.30 ns/op
|
||||
// BenchmarkBitCount-4 300000000 4.15 ns/op
|
||||
// BenchmarkPopCountByClearing-4 30000000 45.2 ns/op
|
||||
// BenchmarkPopCountByShifting-4 10000000 153 ns/op
|
||||
//
|
||||
// 2.5GHz Intel Core i5
|
||||
// $ go test -cpu=4 -bench=. gopl.io/ch2/popcount
|
||||
// testing: warning: no tests to run
|
||||
// BenchmarkPopCount-4 200000000 7.52 ns/op
|
||||
// BenchmarkBitCount-4 500000000 3.36 ns/op
|
||||
// BenchmarkPopCountByClearing-4 50000000 34.3 ns/op
|
||||
// BenchmarkPopCountByShifting-4 20000000 108 ns/op
|
||||
|
|
@ -1,16 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 41.
|
||||
|
||||
//!+
|
||||
|
||||
package tempconv
|
||||
|
||||
// CToF converts a Celsius temperature to Fahrenheit.
|
||||
func CToF(c Celsius) Fahrenheit { return Fahrenheit(c*9/5 + 32) }
|
||||
|
||||
// FToC converts a Fahrenheit temperature to Celsius.
|
||||
func FToC(f Fahrenheit) Celsius { return Celsius((f - 32) * 5 / 9) }
|
||||
|
||||
//!-
|
||||
|
|
@ -1,23 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
//!+
|
||||
|
||||
// Package tempconv performs Celsius and Fahrenheit conversions.
|
||||
package tempconv
|
||||
|
||||
import "fmt"
|
||||
|
||||
type Celsius float64
|
||||
type Fahrenheit float64
|
||||
|
||||
const (
|
||||
AbsoluteZeroC Celsius = -273.15
|
||||
FreezingC Celsius = 0
|
||||
BoilingC Celsius = 100
|
||||
)
|
||||
|
||||
func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }
|
||||
func (f Fahrenheit) String() string { return fmt.Sprintf("%g°F", f) }
|
||||
|
||||
//!-
|
||||
|
|
@ -1,27 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 39.
|
||||
//!+
|
||||
|
||||
// Package tempconv performs Celsius and Fahrenheit temperature computations.
|
||||
package tempconv
|
||||
|
||||
import "fmt"
|
||||
|
||||
type Celsius float64
|
||||
type Fahrenheit float64
|
||||
|
||||
const (
|
||||
AbsoluteZeroC Celsius = -273.15
|
||||
FreezingC Celsius = 0
|
||||
BoilingC Celsius = 100
|
||||
)
|
||||
|
||||
func CToF(c Celsius) Fahrenheit { return Fahrenheit(c*9/5 + 32) }
|
||||
|
||||
func FToC(f Fahrenheit) Celsius { return Celsius((f - 32) * 5 / 9) }
|
||||
|
||||
//!-
|
||||
|
||||
func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }
|
||||
|
|
@ -1,45 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
package tempconv
|
||||
|
||||
import "fmt"
|
||||
|
||||
func Example_one() {
|
||||
{
|
||||
//!+arith
|
||||
fmt.Printf("%g\n", BoilingC-FreezingC) // "100" °C
|
||||
boilingF := CToF(BoilingC)
|
||||
fmt.Printf("%g\n", boilingF-CToF(FreezingC)) // "180" °F
|
||||
//!-arith
|
||||
}
|
||||
/*
|
||||
//!+arith
|
||||
fmt.Printf("%g\n", boilingF-FreezingC) // compile error: type mismatch
|
||||
//!-arith
|
||||
*/
|
||||
|
||||
// Output:
|
||||
// 100
|
||||
// 180
|
||||
}
|
||||
|
||||
func Example_two() {
|
||||
//!+printf
|
||||
c := FToC(212.0)
|
||||
fmt.Println(c.String()) // "100°C"
|
||||
fmt.Printf("%v\n", c) // "100°C"; no need to call String explicitly
|
||||
fmt.Printf("%s\n", c) // "100°C"
|
||||
fmt.Println(c) // "100°C"
|
||||
fmt.Printf("%g\n", c) // "100"; does not call String
|
||||
fmt.Println(float64(c)) // "100"; does not call String
|
||||
//!-printf
|
||||
|
||||
// Output:
|
||||
// 100°C
|
||||
// 100°C
|
||||
// 100°C
|
||||
// 100°C
|
||||
// 100
|
||||
// 100
|
||||
}
|
||||
|
|
@ -1,44 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 72.
|
||||
|
||||
// Basename1 reads file names from stdin and prints the base name of each one.
|
||||
package main
|
||||
|
||||
import (
|
||||
"bufio"
|
||||
"fmt"
|
||||
"os"
|
||||
)
|
||||
|
||||
func main() {
|
||||
input := bufio.NewScanner(os.Stdin)
|
||||
for input.Scan() {
|
||||
fmt.Println(basename(input.Text()))
|
||||
}
|
||||
// NOTE: ignoring potential errors from input.Err()
|
||||
}
|
||||
|
||||
//!+
|
||||
// basename removes directory components and a .suffix.
|
||||
// e.g., a => a, a.go => a, a/b/c.go => c, a/b.c.go => b.c
|
||||
func basename(s string) string {
|
||||
// Discard last '/' and everything before.
|
||||
for i := len(s) - 1; i >= 0; i-- {
|
||||
if s[i] == '/' {
|
||||
s = s[i+1:]
|
||||
break
|
||||
}
|
||||
}
|
||||
// Preserve everything before last '.'.
|
||||
for i := len(s) - 1; i >= 0; i-- {
|
||||
if s[i] == '.' {
|
||||
s = s[:i]
|
||||
break
|
||||
}
|
||||
}
|
||||
return s
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,36 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 72.
|
||||
|
||||
// Basename2 reads file names from stdin and prints the base name of each one.
|
||||
package main
|
||||
|
||||
import (
|
||||
"bufio"
|
||||
"fmt"
|
||||
"os"
|
||||
"strings"
|
||||
)
|
||||
|
||||
func main() {
|
||||
input := bufio.NewScanner(os.Stdin)
|
||||
for input.Scan() {
|
||||
fmt.Println(basename(input.Text()))
|
||||
}
|
||||
// NOTE: ignoring potential errors from input.Err()
|
||||
}
|
||||
|
||||
// basename removes directory components and a trailing .suffix.
|
||||
// e.g., a => a, a.go => a, a/b/c.go => c, a/b.c.go => b.c
|
||||
//!+
|
||||
func basename(s string) string {
|
||||
slash := strings.LastIndex(s, "/") // -1 if "/" not found
|
||||
s = s[slash+1:]
|
||||
if dot := strings.LastIndex(s, "."); dot >= 0 {
|
||||
s = s[:dot]
|
||||
}
|
||||
return s
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,40 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 73.
|
||||
|
||||
// Comma prints its argument numbers with a comma at each power of 1000.
|
||||
//
|
||||
// Example:
|
||||
// $ go build gopl.io/ch3/comma
|
||||
// $ ./comma 1 12 123 1234 1234567890
|
||||
// 1
|
||||
// 12
|
||||
// 123
|
||||
// 1,234
|
||||
// 1,234,567,890
|
||||
//
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"os"
|
||||
)
|
||||
|
||||
func main() {
|
||||
for i := 1; i < len(os.Args); i++ {
|
||||
fmt.Printf(" %s\n", comma(os.Args[i]))
|
||||
}
|
||||
}
|
||||
|
||||
//!+
|
||||
// comma inserts commas in a non-negative decimal integer string.
|
||||
func comma(s string) string {
|
||||
n := len(s)
|
||||
if n <= 3 {
|
||||
return s
|
||||
}
|
||||
return comma(s[:n-3]) + "," + s[n-3:]
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,84 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 61.
|
||||
//!+
|
||||
|
||||
// Mandelbrot emits a PNG image of the Mandelbrot fractal.
|
||||
package main
|
||||
|
||||
import (
|
||||
"image"
|
||||
"image/color"
|
||||
"image/png"
|
||||
"math/cmplx"
|
||||
"os"
|
||||
)
|
||||
|
||||
func main() {
|
||||
const (
|
||||
xmin, ymin, xmax, ymax = -2, -2, +2, +2
|
||||
width, height = 1024, 1024
|
||||
)
|
||||
|
||||
img := image.NewRGBA(image.Rect(0, 0, width, height))
|
||||
for py := 0; py < height; py++ {
|
||||
y := float64(py)/height*(ymax-ymin) + ymin
|
||||
for px := 0; px < width; px++ {
|
||||
x := float64(px)/width*(xmax-xmin) + xmin
|
||||
z := complex(x, y)
|
||||
// Image point (px, py) represents complex value z.
|
||||
img.Set(px, py, mandelbrot(z))
|
||||
}
|
||||
}
|
||||
png.Encode(os.Stdout, img) // NOTE: ignoring errors
|
||||
}
|
||||
|
||||
func mandelbrot(z complex128) color.Color {
|
||||
const iterations = 200
|
||||
const contrast = 15
|
||||
|
||||
var v complex128
|
||||
for n := uint8(0); n < iterations; n++ {
|
||||
v = v*v + z
|
||||
if cmplx.Abs(v) > 2 {
|
||||
return color.Gray{255 - contrast*n}
|
||||
}
|
||||
}
|
||||
return color.Black
|
||||
}
|
||||
|
||||
//!-
|
||||
|
||||
// Some other interesting functions:
|
||||
|
||||
func acos(z complex128) color.Color {
|
||||
v := cmplx.Acos(z)
|
||||
blue := uint8(real(v)*128) + 127
|
||||
red := uint8(imag(v)*128) + 127
|
||||
return color.YCbCr{192, blue, red}
|
||||
}
|
||||
|
||||
func sqrt(z complex128) color.Color {
|
||||
v := cmplx.Sqrt(z)
|
||||
blue := uint8(real(v)*128) + 127
|
||||
red := uint8(imag(v)*128) + 127
|
||||
return color.YCbCr{128, blue, red}
|
||||
}
|
||||
|
||||
// f(x) = x^4 - 1
|
||||
//
|
||||
// z' = z - f(z)/f'(z)
|
||||
// = z - (z^4 - 1) / (4 * z^3)
|
||||
// = z - (z - 1/z^3) / 4
|
||||
func newton(z complex128) color.Color {
|
||||
const iterations = 37
|
||||
const contrast = 7
|
||||
for i := uint8(0); i < iterations; i++ {
|
||||
z -= (z - 1/(z*z*z)) / 4
|
||||
if cmplx.Abs(z*z*z*z-1) < 1e-6 {
|
||||
return color.Gray{255 - contrast*i}
|
||||
}
|
||||
}
|
||||
return color.Black
|
||||
}
|
||||
|
|
@ -1,30 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 77.
|
||||
|
||||
// Netflag demonstrates an integer type used as a bit field.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
. "net"
|
||||
)
|
||||
|
||||
//!+
|
||||
func IsUp(v Flags) bool { return v&FlagUp == FlagUp }
|
||||
func TurnDown(v *Flags) { *v &^= FlagUp }
|
||||
func SetBroadcast(v *Flags) { *v |= FlagBroadcast }
|
||||
func IsCast(v Flags) bool { return v&(FlagBroadcast|FlagMulticast) != 0 }
|
||||
|
||||
func main() {
|
||||
var v Flags = FlagMulticast | FlagUp
|
||||
fmt.Printf("%b %t\n", v, IsUp(v)) // "10001 true"
|
||||
TurnDown(&v)
|
||||
fmt.Printf("%b %t\n", v, IsUp(v)) // "10000 false"
|
||||
SetBroadcast(&v)
|
||||
fmt.Printf("%b %t\n", v, IsUp(v)) // "10010 false"
|
||||
fmt.Printf("%b %t\n", v, IsCast(v)) // "10010 true"
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,33 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 74.
|
||||
|
||||
// Printints demonstrates the use of bytes.Buffer to format a string.
|
||||
package main
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
)
|
||||
|
||||
//!+
|
||||
// intsToString is like fmt.Sprint(values) but adds commas.
|
||||
func intsToString(values []int) string {
|
||||
var buf bytes.Buffer
|
||||
buf.WriteByte('[')
|
||||
for i, v := range values {
|
||||
if i > 0 {
|
||||
buf.WriteString(", ")
|
||||
}
|
||||
fmt.Fprintf(&buf, "%d", v)
|
||||
}
|
||||
buf.WriteByte(']')
|
||||
return buf.String()
|
||||
}
|
||||
|
||||
func main() {
|
||||
fmt.Println(intsToString([]int{1, 2, 3})) // "[1, 2, 3]"
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,62 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 58.
|
||||
//!+
|
||||
|
||||
// Surface computes an SVG rendering of a 3-D surface function.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"math"
|
||||
)
|
||||
|
||||
const (
|
||||
width, height = 600, 320 // canvas size in pixels
|
||||
cells = 100 // number of grid cells
|
||||
xyrange = 30.0 // axis ranges (-xyrange..+xyrange)
|
||||
xyscale = width / 2 / xyrange // pixels per x or y unit
|
||||
zscale = height * 0.4 // pixels per z unit
|
||||
angle = math.Pi / 6 // angle of x, y axes (=30°)
|
||||
)
|
||||
|
||||
var sin30, cos30 = math.Sin(angle), math.Cos(angle) // sin(30°), cos(30°)
|
||||
|
||||
func main() {
|
||||
fmt.Printf("<svg xmlns='http://www.w3.org/2000/svg' "+
|
||||
"style='stroke: grey; fill: white; stroke-width: 0.7' "+
|
||||
"width='%d' height='%d'>", width, height)
|
||||
for i := 0; i < cells; i++ {
|
||||
for j := 0; j < cells; j++ {
|
||||
ax, ay := corner(i+1, j)
|
||||
bx, by := corner(i, j)
|
||||
cx, cy := corner(i, j+1)
|
||||
dx, dy := corner(i+1, j+1)
|
||||
fmt.Printf("<polygon points='%g,%g %g,%g %g,%g %g,%g'/>\n",
|
||||
ax, ay, bx, by, cx, cy, dx, dy)
|
||||
}
|
||||
}
|
||||
fmt.Println("</svg>")
|
||||
}
|
||||
|
||||
func corner(i, j int) (float64, float64) {
|
||||
// Find point (x,y) at corner of cell (i,j).
|
||||
x := xyrange * (float64(i)/cells - 0.5)
|
||||
y := xyrange * (float64(j)/cells - 0.5)
|
||||
|
||||
// Compute surface height z.
|
||||
z := f(x, y)
|
||||
|
||||
// Project (x,y,z) isometrically onto 2-D SVG canvas (sx,sy).
|
||||
sx := width/2 + (x-y)*cos30*xyscale
|
||||
sy := height/2 + (x+y)*sin30*xyscale - z*zscale
|
||||
return sx, sy
|
||||
}
|
||||
|
||||
func f(x, y float64) float64 {
|
||||
r := math.Hypot(x, y) // distance from (0,0)
|
||||
return math.Sin(r) / r
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,79 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 88.
|
||||
|
||||
// Append illustrates the behavior of the built-in append function.
|
||||
package main
|
||||
|
||||
import "fmt"
|
||||
|
||||
func appendslice(x []int, y ...int) []int {
|
||||
var z []int
|
||||
zlen := len(x) + len(y)
|
||||
if zlen <= cap(x) {
|
||||
// There is room to expand the slice.
|
||||
z = x[:zlen]
|
||||
} else {
|
||||
// There is insufficient space.
|
||||
// Grow by doubling, for amortized linear complexity.
|
||||
zcap := zlen
|
||||
if zcap < 2*len(x) {
|
||||
zcap = 2 * len(x)
|
||||
}
|
||||
z = make([]int, zlen, zcap)
|
||||
copy(z, x)
|
||||
}
|
||||
copy(z[len(x):], y)
|
||||
return z
|
||||
}
|
||||
|
||||
//!+append
|
||||
func appendInt(x []int, y int) []int {
|
||||
var z []int
|
||||
zlen := len(x) + 1
|
||||
if zlen <= cap(x) {
|
||||
// There is room to grow. Extend the slice.
|
||||
z = x[:zlen]
|
||||
} else {
|
||||
// There is insufficient space. Allocate a new array.
|
||||
// Grow by doubling, for amortized linear complexity.
|
||||
zcap := zlen
|
||||
if zcap < 2*len(x) {
|
||||
zcap = 2 * len(x)
|
||||
}
|
||||
z = make([]int, zlen, zcap)
|
||||
copy(z, x) // a built-in function; see text
|
||||
}
|
||||
z[len(x)] = y
|
||||
return z
|
||||
}
|
||||
|
||||
//!-append
|
||||
|
||||
//!+growth
|
||||
func main() {
|
||||
var x, y []int
|
||||
for i := 0; i < 10; i++ {
|
||||
y = appendInt(x, i)
|
||||
fmt.Printf("%d cap=%d\t%v\n", i, cap(y), y)
|
||||
x = y
|
||||
}
|
||||
}
|
||||
|
||||
//!-growth
|
||||
|
||||
/*
|
||||
//!+output
|
||||
0 cap=1 [0]
|
||||
1 cap=2 [0 1]
|
||||
2 cap=4 [0 1 2]
|
||||
3 cap=4 [0 1 2 3]
|
||||
4 cap=8 [0 1 2 3 4]
|
||||
5 cap=8 [0 1 2 3 4 5]
|
||||
6 cap=8 [0 1 2 3 4 5 6]
|
||||
7 cap=8 [0 1 2 3 4 5 6 7]
|
||||
8 cap=16 [0 1 2 3 4 5 6 7 8]
|
||||
9 cap=16 [0 1 2 3 4 5 6 7 8 9]
|
||||
//!-output
|
||||
*/
|
||||
|
|
@ -1,30 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 117.
|
||||
|
||||
// Autoescape demonstrates automatic HTML escaping in html/template.
|
||||
package main
|
||||
|
||||
import (
|
||||
"html/template"
|
||||
"log"
|
||||
"os"
|
||||
)
|
||||
|
||||
//!+
|
||||
func main() {
|
||||
const templ = `<p>A: {{.A}}</p><p>B: {{.B}}</p>`
|
||||
t := template.Must(template.New("escape").Parse(templ))
|
||||
var data struct {
|
||||
A string // untrusted plain text
|
||||
B template.HTML // trusted HTML
|
||||
}
|
||||
data.A = "<b>Hello!</b>"
|
||||
data.B = "<b>Hello!</b>"
|
||||
if err := t.Execute(os.Stdout, data); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,56 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 97.
|
||||
//!+
|
||||
|
||||
// Charcount computes counts of Unicode characters.
|
||||
package main
|
||||
|
||||
import (
|
||||
"bufio"
|
||||
"fmt"
|
||||
"io"
|
||||
"os"
|
||||
"unicode"
|
||||
"unicode/utf8"
|
||||
)
|
||||
|
||||
func main() {
|
||||
counts := make(map[rune]int) // counts of Unicode characters
|
||||
var utflen [utf8.UTFMax + 1]int // count of lengths of UTF-8 encodings
|
||||
invalid := 0 // count of invalid UTF-8 characters
|
||||
|
||||
in := bufio.NewReader(os.Stdin)
|
||||
for {
|
||||
r, n, err := in.ReadRune() // returns rune, nbytes, error
|
||||
if err == io.EOF {
|
||||
break
|
||||
}
|
||||
if err != nil {
|
||||
fmt.Fprintf(os.Stderr, "charcount: %v\n", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
if r == unicode.ReplacementChar && n == 1 {
|
||||
invalid++
|
||||
continue
|
||||
}
|
||||
counts[r]++
|
||||
utflen[n]++
|
||||
}
|
||||
fmt.Printf("rune\tcount\n")
|
||||
for c, n := range counts {
|
||||
fmt.Printf("%q\t%d\n", c, n)
|
||||
}
|
||||
fmt.Print("\nlen\tcount\n")
|
||||
for i, n := range utflen {
|
||||
if i > 0 {
|
||||
fmt.Printf("%d\t%d\n", i, n)
|
||||
}
|
||||
}
|
||||
if invalid > 0 {
|
||||
fmt.Printf("\n%d invalid UTF-8 characters\n", invalid)
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,33 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 96.
|
||||
|
||||
// Dedup prints only one instance of each line; duplicates are removed.
|
||||
package main
|
||||
|
||||
import (
|
||||
"bufio"
|
||||
"fmt"
|
||||
"os"
|
||||
)
|
||||
|
||||
//!+
|
||||
func main() {
|
||||
seen := make(map[string]bool) // a set of strings
|
||||
input := bufio.NewScanner(os.Stdin)
|
||||
for input.Scan() {
|
||||
line := input.Text()
|
||||
if !seen[line] {
|
||||
seen[line] = true
|
||||
fmt.Println(line)
|
||||
}
|
||||
}
|
||||
|
||||
if err := input.Err(); err != nil {
|
||||
fmt.Fprintf(os.Stderr, "dedup: %v\n", err)
|
||||
os.Exit(1)
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,46 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 106.
|
||||
|
||||
// Embed demonstrates basic struct embedding.
|
||||
package main
|
||||
|
||||
import "fmt"
|
||||
|
||||
type Point struct{ X, Y int }
|
||||
|
||||
type Circle struct {
|
||||
Point
|
||||
Radius int
|
||||
}
|
||||
|
||||
type Wheel struct {
|
||||
Circle
|
||||
Spokes int
|
||||
}
|
||||
|
||||
func main() {
|
||||
var w Wheel
|
||||
//!+
|
||||
w = Wheel{Circle{Point{8, 8}, 5}, 20}
|
||||
|
||||
w = Wheel{
|
||||
Circle: Circle{
|
||||
Point: Point{X: 8, Y: 8},
|
||||
Radius: 5,
|
||||
},
|
||||
Spokes: 20, // NOTE: trailing comma necessary here (and at Radius)
|
||||
}
|
||||
|
||||
fmt.Printf("%#v\n", w)
|
||||
// Output:
|
||||
// Wheel{Circle:Circle{Point:Point{X:8, Y:8}, Radius:5}, Spokes:20}
|
||||
|
||||
w.X = 42
|
||||
|
||||
fmt.Printf("%#v\n", w)
|
||||
// Output:
|
||||
// Wheel{Circle:Circle{Point:Point{X:42, Y:8}, Radius:5}, Spokes:20}
|
||||
//!-
|
||||
}
|
||||
|
|
@ -1,35 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 110.
|
||||
//!+
|
||||
|
||||
// Package github provides a Go API for the GitHub issue tracker.
|
||||
// See https://developer.github.com/v3/search/#search-issues.
|
||||
package github
|
||||
|
||||
import "time"
|
||||
|
||||
const IssuesURL = "https://api.github.com/search/issues"
|
||||
|
||||
type IssuesSearchResult struct {
|
||||
TotalCount int `json:"total_count"`
|
||||
Items []*Issue
|
||||
}
|
||||
|
||||
type Issue struct {
|
||||
Number int
|
||||
HTMLURL string `json:"html_url"`
|
||||
Title string
|
||||
State string
|
||||
User *User
|
||||
CreatedAt time.Time `json:"created_at"`
|
||||
Body string // in Markdown format
|
||||
}
|
||||
|
||||
type User struct {
|
||||
Login string
|
||||
HTMLURL string `json:"html_url"`
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,53 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
//!+
|
||||
|
||||
package github
|
||||
|
||||
import (
|
||||
"encoding/json"
|
||||
"fmt"
|
||||
"net/http"
|
||||
"net/url"
|
||||
"strings"
|
||||
)
|
||||
|
||||
// SearchIssues queries the GitHub issue tracker.
|
||||
func SearchIssues(terms []string) (*IssuesSearchResult, error) {
|
||||
q := url.QueryEscape(strings.Join(terms, " "))
|
||||
resp, err := http.Get(IssuesURL + "?q=" + q)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
//!-
|
||||
// For long-term stability, instead of http.Get, use the
|
||||
// variant below which adds an HTTP request header indicating
|
||||
// that only version 3 of the GitHub API is acceptable.
|
||||
//
|
||||
// req, err := http.NewRequest("GET", IssuesURL+"?q="+q, nil)
|
||||
// if err != nil {
|
||||
// return nil, err
|
||||
// }
|
||||
// req.Header.Set(
|
||||
// "Accept", "application/vnd.github.v3.text-match+json")
|
||||
// resp, err := http.DefaultClient.Do(req)
|
||||
//!+
|
||||
|
||||
// We must close resp.Body on all execution paths.
|
||||
// (Chapter 5 presents 'defer', which makes this simpler.)
|
||||
if resp.StatusCode != http.StatusOK {
|
||||
resp.Body.Close()
|
||||
return nil, fmt.Errorf("search query failed: %s", resp.Status)
|
||||
}
|
||||
|
||||
var result IssuesSearchResult
|
||||
if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
|
||||
resp.Body.Close()
|
||||
return nil, err
|
||||
}
|
||||
resp.Body.Close()
|
||||
return &result, nil
|
||||
}
|
||||
|
||||
//!-
|
||||
|
|
@ -1,43 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 99.
|
||||
|
||||
// Graph shows how to use a map of maps to represent a directed graph.
|
||||
package main
|
||||
|
||||
import "fmt"
|
||||
|
||||
//!+
|
||||
var graph = make(map[string]map[string]bool)
|
||||
|
||||
func addEdge(from, to string) {
|
||||
edges := graph[from]
|
||||
if edges == nil {
|
||||
edges = make(map[string]bool)
|
||||
graph[from] = edges
|
||||
}
|
||||
edges[to] = true
|
||||
}
|
||||
|
||||
func hasEdge(from, to string) bool {
|
||||
return graph[from][to]
|
||||
}
|
||||
|
||||
//!-
|
||||
|
||||
func main() {
|
||||
addEdge("a", "b")
|
||||
addEdge("c", "d")
|
||||
addEdge("a", "d")
|
||||
addEdge("d", "a")
|
||||
fmt.Println(hasEdge("a", "b"))
|
||||
fmt.Println(hasEdge("c", "d"))
|
||||
fmt.Println(hasEdge("a", "d"))
|
||||
fmt.Println(hasEdge("d", "a"))
|
||||
fmt.Println(hasEdge("x", "b"))
|
||||
fmt.Println(hasEdge("c", "d"))
|
||||
fmt.Println(hasEdge("x", "d"))
|
||||
fmt.Println(hasEdge("d", "x"))
|
||||
|
||||
}
|
||||
|
|
@ -1,52 +0,0 @@
|
|||
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
|
||||
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||||
|
||||
// See page 112.
|
||||
//!+
|
||||
|
||||
// Issues prints a table of GitHub issues matching the search terms.
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"os"
|
||||
|
||||
"gopl.io/ch4/github"
|
||||
)
|
||||
|
||||
//!+
|
||||
func main() {
|
||||
result, err := github.SearchIssues(os.Args[1:])
|
||||
if err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
fmt.Printf("%d issues:\n", result.TotalCount)
|
||||
for _, item := range result.Items {
|
||||
fmt.Printf("#%-5d %9.9s %.55s\n",
|
||||
item.Number, item.User.Login, item.Title)
|
||||
}
|
||||
}
|
||||
|
||||
//!-
|
||||
|
||||
/*
|
||||
//!+textoutput
|
||||
$ go build gopl.io/ch4/issues
|
||||
$ ./issues repo:golang/go is:open json decoder
|
||||
13 issues:
|
||||
#5680 eaigner encoding/json: set key converter on en/decoder
|
||||
#6050 gopherbot encoding/json: provide tokenizer
|
||||
#8658 gopherbot encoding/json: use bufio
|
||||
#8462 kortschak encoding/json: UnmarshalText confuses json.Unmarshal
|
||||
#5901 rsc encoding/json: allow override type marshaling
|
||||
#9812 klauspost encoding/json: string tag not symmetric
|
||||
#7872 extempora encoding/json: Encoder internally buffers full output
|
||||
#9650 cespare encoding/json: Decoding gives errPhase when unmarshalin
|
||||
#6716 gopherbot encoding/json: include field name in unmarshal error me
|
||||
#6901 lukescott encoding/json, encoding/xml: option to treat unknown fi
|
||||
#6384 joeshaw encoding/json: encode precise floating point integers u
|
||||
#6647 btracey x/tools/cmd/godoc: display type kind of each named type
|
||||
#4237 gjemiller encoding/base64: URLEncoding padding is optional
|
||||
//!-textoutput
|
||||
*/
|
||||
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Reference in New Issue