go-json/decode_string.go

69 lines
1.5 KiB
Go

package json
import (
"unsafe"
)
type stringDecoder struct {
}
func newStringDecoder() *stringDecoder {
return &stringDecoder{}
}
func (d *stringDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
bytes, c, err := d.decodeByte(buf, cursor)
if err != nil {
return 0, err
}
cursor = c
*(*string)(unsafe.Pointer(p)) = *(*string)(unsafe.Pointer(&bytes))
return cursor, nil
}
func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
for {
switch buf[cursor] {
case ' ', '\n', '\t', '\r':
cursor++
case '"':
cursor++
start := cursor
for {
switch buf[cursor] {
case '\\':
cursor++
case '"':
literal := buf[start:cursor]
cursor++
return literal, cursor, nil
case '\000':
return nil, 0, errUnexpectedEndOfJSON("string", cursor)
}
cursor++
}
return nil, 0, errUnexpectedEndOfJSON("string", cursor)
case 'n':
buflen := int64(len(buf))
if cursor+3 >= buflen {
return nil, 0, errUnexpectedEndOfJSON("null", cursor)
}
if buf[cursor+1] != 'u' {
return nil, 0, errInvalidCharacter(buf[cursor+1], "null", cursor)
}
if buf[cursor+2] != 'l' {
return nil, 0, errInvalidCharacter(buf[cursor+2], "null", cursor)
}
if buf[cursor+3] != 'l' {
return nil, 0, errInvalidCharacter(buf[cursor+3], "null", cursor)
}
cursor += 5
return []byte{'n', 'u', 'l', 'l'}, cursor, nil
default:
goto ERROR
}
}
ERROR:
return nil, 0, errNotAtBeginningOfValue(cursor)
}