go-json/decode_float.go

122 lines
2.3 KiB
Go

package json
import (
"strconv"
"unsafe"
)
type floatDecoder struct {
op func(uintptr, float64)
}
func newFloatDecoder(op func(uintptr, float64)) *floatDecoder {
return &floatDecoder{op: op}
}
var floatTable = [256]bool{
'0': true,
'1': true,
'2': true,
'3': true,
'4': true,
'5': true,
'6': true,
'7': true,
'8': true,
'9': true,
'.': true,
'e': true,
'E': true,
}
func floatBytes(s *stream) []byte {
start := s.cursor
for {
s.cursor++
if floatTable[s.char()] {
continue
} else if s.char() == nul {
if s.read() {
continue
}
}
break
}
return s.buf[start:s.cursor]
}
func (d *floatDecoder) decodeStreamByte(s *stream) ([]byte, error) {
for {
switch s.char() {
case ' ', '\n', '\t', '\r':
s.cursor++
continue
case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
return floatBytes(s), nil
case nul:
if s.read() {
continue
}
goto ERROR
default:
goto ERROR
}
}
ERROR:
return nil, errUnexpectedEndOfJSON("float", s.totalOffset())
}
func (d *floatDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
buflen := int64(len(buf))
for ; cursor < buflen; cursor++ {
switch buf[cursor] {
case ' ', '\n', '\t', '\r':
continue
case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
start := cursor
cursor++
for ; cursor < buflen; cursor++ {
tk := int(buf[cursor])
if (int('0') <= tk && tk <= int('9')) || tk == '.' || tk == 'e' || tk == 'E' {
continue
}
break
}
num := buf[start:cursor]
return num, cursor, nil
default:
return nil, 0, errUnexpectedEndOfJSON("float", cursor)
}
}
return nil, 0, errUnexpectedEndOfJSON("float", cursor)
}
func (d *floatDecoder) decodeStream(s *stream, p uintptr) error {
bytes, err := d.decodeStreamByte(s)
if err != nil {
return err
}
str := *(*string)(unsafe.Pointer(&bytes))
f64, err := strconv.ParseFloat(str, 64)
if err != nil {
return err
}
d.op(p, f64)
return nil
}
func (d *floatDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
bytes, c, err := d.decodeByte(buf, cursor)
if err != nil {
return 0, err
}
cursor = c
s := *(*string)(unsafe.Pointer(&bytes))
f64, err := strconv.ParseFloat(s, 64)
if err != nil {
return 0, err
}
d.op(p, f64)
return cursor, nil
}