mirror of
https://github.com/gopl-zh/gopl-zh.github.com.git
synced 2024-11-24 23:29:01 +00:00
98 lines
2.0 KiB
Go
98 lines
2.0 KiB
Go
// 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
|