good good study, day day up!

vendor/gopl.io/ch7/xmlselect/main.go

@@ -0,0 +1,56 @@
+// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+// See page 214.
+//!+
+
+// Xmlselect prints the text of selected elements of an XML document.
+package main
+
+import (
+	"encoding/xml"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+func main() {
+	dec := xml.NewDecoder(os.Stdin)
+	var stack []string // stack of element names
+	for {
+		tok, err := dec.Token()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			fmt.Fprintf(os.Stderr, "xmlselect: %v\n", err)
+			os.Exit(1)
+		}
+		switch tok := tok.(type) {
+		case xml.StartElement:
+			stack = append(stack, tok.Name.Local) // push
+		case xml.EndElement:
+			stack = stack[:len(stack)-1] // pop
+		case xml.CharData:
+			if containsAll(stack, os.Args[1:]) {
+				fmt.Printf("%s: %s\n", strings.Join(stack, " "), tok)
+			}
+		}
+	}
+}
+
+// containsAll reports whether x contains the elements of y, in order.
+func containsAll(x, y []string) bool {
+	for len(y) <= len(x) {
+		if len(y) == 0 {
+			return true
+		}
+		if x[0] == y[0] {
+			y = y[1:]
+		}
+		x = x[1:]
+	}
+	return false
+}
+
+//!-