299 lines
7.0 KiB
Go
299 lines
7.0 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// The json package implements encoding and decoding of JSON objects as
|
|
// defined in RFC 4627.
|
|
package json
|
|
|
|
import (
|
|
"os"
|
|
"bytes"
|
|
"reflect"
|
|
"runtime"
|
|
"sort"
|
|
"strconv"
|
|
)
|
|
|
|
// Marshal returns the JSON encoding of v.
|
|
//
|
|
// Marshal traverses the value v recursively.
|
|
// If an encountered value implements the Marshaler interface,
|
|
// Marshal calls its MarshalJSON method to produce JSON.
|
|
//
|
|
// Otherwise, Marshal uses the following type-dependent default encodings:
|
|
//
|
|
// Boolean values encode as JSON booleans.
|
|
//
|
|
// Floating point and integer values encode as JSON numbers.
|
|
//
|
|
// String values encode as JSON strings, with each invalid UTF-8 sequence
|
|
// replaced by the encoding of the Unicode replacement character U+FFFD.
|
|
//
|
|
// Array and slice values encode as JSON arrays.
|
|
//
|
|
// Struct values encode as JSON objects. Each struct field becomes
|
|
// a member of the object. By default the object's key name is the
|
|
// struct field name converted to lower case. If the struct field
|
|
// has a tag, that tag will be used as the name instead.
|
|
//
|
|
// Map values encode as JSON objects.
|
|
// The map's key type must be string; the object keys are used directly
|
|
// as map keys.
|
|
//
|
|
// Pointer values encode as the value pointed to.
|
|
// A nil pointer encodes as the null JSON object.
|
|
//
|
|
// Interface values encode as the value contained in the interface.
|
|
// A nil interface value encodes as the null JSON object.
|
|
//
|
|
// Channel, complex, and function values cannot be encoded in JSON.
|
|
// Attempting to encode such a value causes Marshal to return
|
|
// an InvalidTypeError.
|
|
//
|
|
// JSON cannot represent cyclic data structures and Marshal does not
|
|
// handle them. Passing cyclic structures to Marshal will result in
|
|
// an infinite recursion.
|
|
//
|
|
func Marshal(v interface{}) ([]byte, os.Error) {
|
|
e := &encodeState{}
|
|
err := e.marshal(v)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return e.Bytes(), nil
|
|
}
|
|
|
|
// MarshalIndent is like Marshal but applies Indent to format the output.
|
|
func MarshalIndent(v interface{}, prefix, indent string) ([]byte, os.Error) {
|
|
b, err := Marshal(v)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
var buf bytes.Buffer
|
|
err = Indent(&buf, b, prefix, indent)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return buf.Bytes(), nil
|
|
}
|
|
|
|
// MarshalForHTML is like Marshal but applies HTMLEscape to the output.
|
|
func MarshalForHTML(v interface{}) ([]byte, os.Error) {
|
|
b, err := Marshal(v)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
var buf bytes.Buffer
|
|
HTMLEscape(&buf, b)
|
|
return buf.Bytes(), nil
|
|
}
|
|
|
|
// HTMLEscape appends to dst the JSON-encoded src with <, >, and &
|
|
// characters inside string literals changed to \u003c, \u003e, \u0026
|
|
// so that the JSON will be safe to embed inside HTML <script> tags.
|
|
// For historical reasons, web browsers don't honor standard HTML
|
|
// escaping within <script> tags, so an alternative JSON encoding must
|
|
// be used.
|
|
func HTMLEscape(dst *bytes.Buffer, src []byte) {
|
|
// < > & can only appear in string literals,
|
|
// so just scan the string one byte at a time.
|
|
start := 0
|
|
for i, c := range src {
|
|
if c == '<' || c == '>' || c == '&' {
|
|
if start < i {
|
|
dst.Write(src[start:i])
|
|
}
|
|
dst.WriteString(`\u00`)
|
|
dst.WriteByte(hex[c>>4])
|
|
dst.WriteByte(hex[c&0xF])
|
|
start = i + 1
|
|
}
|
|
}
|
|
if start < len(src) {
|
|
dst.Write(src[start:])
|
|
}
|
|
}
|
|
|
|
// Marshaler is the interface implemented by objects that
|
|
// can marshal themselves into valid JSON.
|
|
type Marshaler interface {
|
|
MarshalJSON() ([]byte, os.Error)
|
|
}
|
|
|
|
type UnsupportedTypeError struct {
|
|
Type reflect.Type
|
|
}
|
|
|
|
func (e *UnsupportedTypeError) String() string {
|
|
return "json: unsupported type: " + e.Type.String()
|
|
}
|
|
|
|
type MarshalerError struct {
|
|
Type reflect.Type
|
|
Error os.Error
|
|
}
|
|
|
|
func (e *MarshalerError) String() string {
|
|
return "json: error calling MarshalJSON for type " + e.Type.String() + ": " + e.Error.String()
|
|
}
|
|
|
|
type interfaceOrPtrValue interface {
|
|
IsNil() bool
|
|
Elem() reflect.Value
|
|
}
|
|
|
|
var hex = "0123456789abcdef"
|
|
|
|
// An encodeState encodes JSON into a bytes.Buffer.
|
|
type encodeState struct {
|
|
bytes.Buffer // accumulated output
|
|
}
|
|
|
|
func (e *encodeState) marshal(v interface{}) (err os.Error) {
|
|
defer func() {
|
|
if r := recover(); r != nil {
|
|
if _, ok := r.(runtime.Error); ok {
|
|
panic(r)
|
|
}
|
|
err = r.(os.Error)
|
|
}
|
|
}()
|
|
e.reflectValue(reflect.NewValue(v))
|
|
return nil
|
|
}
|
|
|
|
func (e *encodeState) error(err os.Error) {
|
|
panic(err)
|
|
}
|
|
|
|
func (e *encodeState) reflectValue(v reflect.Value) {
|
|
if v == nil {
|
|
e.WriteString("null")
|
|
return
|
|
}
|
|
|
|
if j, ok := v.Interface().(Marshaler); ok {
|
|
b, err := j.MarshalJSON()
|
|
if err == nil {
|
|
// copy JSON into buffer, checking validity.
|
|
err = Compact(&e.Buffer, b)
|
|
}
|
|
if err != nil {
|
|
e.error(&MarshalerError{v.Type(), err})
|
|
}
|
|
return
|
|
}
|
|
|
|
switch v := v.(type) {
|
|
case *reflect.BoolValue:
|
|
x := v.Get()
|
|
if x {
|
|
e.WriteString("true")
|
|
} else {
|
|
e.WriteString("false")
|
|
}
|
|
|
|
case *reflect.IntValue:
|
|
e.WriteString(strconv.Itoa64(v.Get()))
|
|
|
|
case *reflect.UintValue:
|
|
e.WriteString(strconv.Uitoa64(v.Get()))
|
|
|
|
case *reflect.FloatValue:
|
|
e.WriteString(strconv.FtoaN(v.Get(), 'g', -1, v.Type().Bits()))
|
|
|
|
case *reflect.StringValue:
|
|
e.string(v.Get())
|
|
|
|
case *reflect.StructValue:
|
|
e.WriteByte('{')
|
|
t := v.Type().(*reflect.StructType)
|
|
n := v.NumField()
|
|
for i := 0; i < n; i++ {
|
|
if i > 0 {
|
|
e.WriteByte(',')
|
|
}
|
|
f := t.Field(i)
|
|
if f.Tag != "" {
|
|
e.string(f.Tag)
|
|
} else {
|
|
e.string(f.Name)
|
|
}
|
|
e.WriteByte(':')
|
|
e.reflectValue(v.Field(i))
|
|
}
|
|
e.WriteByte('}')
|
|
|
|
case *reflect.MapValue:
|
|
if _, ok := v.Type().(*reflect.MapType).Key().(*reflect.StringType); !ok {
|
|
e.error(&UnsupportedTypeError{v.Type()})
|
|
}
|
|
if v.IsNil() {
|
|
e.WriteString("null")
|
|
break
|
|
}
|
|
e.WriteByte('{')
|
|
var sv stringValues = v.Keys()
|
|
sort.Sort(sv)
|
|
for i, k := range sv {
|
|
if i > 0 {
|
|
e.WriteByte(',')
|
|
}
|
|
e.string(k.(*reflect.StringValue).Get())
|
|
e.WriteByte(':')
|
|
e.reflectValue(v.Elem(k))
|
|
}
|
|
e.WriteByte('}')
|
|
|
|
case reflect.ArrayOrSliceValue:
|
|
e.WriteByte('[')
|
|
n := v.Len()
|
|
for i := 0; i < n; i++ {
|
|
if i > 0 {
|
|
e.WriteByte(',')
|
|
}
|
|
e.reflectValue(v.Elem(i))
|
|
}
|
|
e.WriteByte(']')
|
|
|
|
case interfaceOrPtrValue:
|
|
if v.IsNil() {
|
|
e.WriteString("null")
|
|
return
|
|
}
|
|
e.reflectValue(v.Elem())
|
|
|
|
default:
|
|
e.error(&UnsupportedTypeError{v.Type()})
|
|
}
|
|
return
|
|
}
|
|
|
|
// stringValues is a slice of reflect.Value holding *reflect.StringValue.
|
|
// It implements the methods to sort by string.
|
|
type stringValues []reflect.Value
|
|
|
|
func (sv stringValues) Len() int { return len(sv) }
|
|
func (sv stringValues) Swap(i, j int) { sv[i], sv[j] = sv[j], sv[i] }
|
|
func (sv stringValues) Less(i, j int) bool { return sv.get(i) < sv.get(j) }
|
|
func (sv stringValues) get(i int) string { return sv[i].(*reflect.StringValue).Get() }
|
|
|
|
func (e *encodeState) string(s string) {
|
|
e.WriteByte('"')
|
|
for _, c := range s {
|
|
switch {
|
|
case c < 0x20:
|
|
e.WriteString(`\u00`)
|
|
e.WriteByte(hex[c>>4])
|
|
e.WriteByte(hex[c&0xF])
|
|
case c == '\\' || c == '"':
|
|
e.WriteByte('\\')
|
|
fallthrough
|
|
default:
|
|
e.WriteRune(c)
|
|
}
|
|
}
|
|
e.WriteByte('"')
|
|
}
|