package json import ( "errors" "math" ) type intDecoder struct { op func(uintptr, int64) } func newIntDecoder(op func(uintptr, int64)) *intDecoder { return &intDecoder{op: op} } func (d *intDecoder) parseInt(b []byte) int64 { isNegative := false if b[0] == '-' { b = b[1:] isNegative = true } maxDigit := len(b) sum := int64(0) for i := 0; i < maxDigit; i++ { c := int64(b[i]) - 48 digitValue := int64(math.Pow10(maxDigit - i - 1)) sum += c * digitValue } if isNegative { return -1 * sum } return sum } func (d *intDecoder) decodeByte(ctx *context) ([]byte, error) { ctx.skipWhiteSpace() buf := ctx.buf cursor := ctx.cursor buflen := ctx.buflen switch buf[cursor] { case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': start := ctx.cursor cursor++ for ; cursor < buflen; cursor++ { tk := int(buf[cursor]) if int('0') <= tk && tk <= int('9') { continue } break } num := ctx.buf[start:cursor] ctx.cursor = cursor //fmt.Printf("number = [%s]\n", string(num)) return num, nil } return nil, errors.New("unexpected error number") } func (d *intDecoder) decode(ctx *context, p uintptr) error { bytes, err := d.decodeByte(ctx) if err != nil { return err } d.op(p, d.parseInt(bytes)) return nil }