// 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.
//go:build goexperiment.jsonv2
package json
import (
"errors"
"io"
"strings"
"encoding/json/internal"
"encoding/json/internal/jsonflags"
"encoding/json/jsontext"
)
// export exposes internal functionality of the "jsontext" package.
var export = jsontext.Internal.Export(&internal.AllowInternalUse)
// Valid reports whether data is a valid JSON encoding.
func Valid(data []byte) bool {
return checkValid(data) == nil
}
func checkValid(data []byte) error {
d := export.GetBufferedDecoder(data)
defer export.PutBufferedDecoder(d)
xd := export.Decoder(d)
xd.Struct.Flags.Set(jsonflags.AllowDuplicateNames | jsonflags.AllowInvalidUTF8 | 1)
if _, err := d.ReadValue(); err != nil {
if err == io.EOF {
offset := d.InputOffset() + int64(len(d.UnreadBuffer()))
err = &jsontext.SyntacticError{ByteOffset: offset, Err: io.ErrUnexpectedEOF}
}
return transformSyntacticError(err)
}
if err := xd.CheckEOF(); err != nil {
return transformSyntacticError(err)
}
return nil
}
// A SyntaxError is a description of a JSON syntax error.
// [Unmarshal] will return a SyntaxError if the JSON can't be parsed.
type SyntaxError struct {
msg string // description of error
Offset int64 // error occurred after reading Offset bytes
}
func (e *SyntaxError) Error() string { return e.msg }
var errUnexpectedEnd = errors.New("unexpected end of JSON input")
func transformSyntacticError(err error) error {
switch serr, ok := err.(*jsontext.SyntacticError); {
case serr != nil:
if serr.Err == io.ErrUnexpectedEOF {
serr.Err = errUnexpectedEnd
}
msg := serr.Err.Error()
if i := strings.Index(msg, " (expecting"); i >= 0 && !strings.Contains(msg, " in literal") {
msg = msg[:i]
}
return &SyntaxError{Offset: serr.ByteOffset, msg: syntaxErrorReplacer.Replace(msg)}
case ok:
return (*SyntaxError)(nil)
case export.IsIOError(err):
return errors.Unwrap(err) // v1 historically did not wrap IO errors
default:
return err
}
}
// syntaxErrorReplacer replaces certain string literals in the v2 error
// to better match the historical string rendering of syntax errors.
// In particular, v2 uses the terminology "object name" to match RFC 8259,
// while v1 uses "object key", which is not a term found in JSON literature.
var syntaxErrorReplacer = strings.NewReplacer(
"object name", "object key",
"at start of value", "looking for beginning of value",
"at start of string", "looking for beginning of object key string",
"after object value", "after object key:value pair",
"in number", "in numeric literal",
)
