forked from mirror/go-json
63 lines
1.3 KiB
Go
63 lines
1.3 KiB
Go
package json
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import (
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"errors"
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)
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type uintDecoder struct {
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op func(uintptr, uint64)
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}
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func newUintDecoder(op func(uintptr, uint64)) *uintDecoder {
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return &uintDecoder{op: op}
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}
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var pow10u64 = [...]uint64{
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1e00, 1e01, 1e02, 1e03, 1e04, 1e05, 1e06, 1e07, 1e08, 1e09,
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1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
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}
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func (d *uintDecoder) parseUint(b []byte) uint64 {
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maxDigit := len(b)
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sum := uint64(0)
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for i := 0; i < maxDigit; i++ {
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c := uint64(b[i]) - 48
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digitValue := pow10u64[maxDigit-i-1]
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sum += c * digitValue
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}
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return sum
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}
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func (d *uintDecoder) decodeByte(buf []byte, cursor int) ([]byte, int, error) {
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buflen := len(buf)
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for ; cursor < buflen; cursor++ {
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switch buf[cursor] {
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case ' ', '\n', '\t', '\r':
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continue
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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start := cursor
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cursor++
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for ; cursor < buflen; cursor++ {
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tk := int(buf[cursor])
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if int('0') <= tk && tk <= int('9') {
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continue
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}
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break
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}
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num := buf[start:cursor]
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return num, cursor, nil
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}
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}
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return nil, 0, errors.New("unexpected error number")
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}
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func (d *uintDecoder) decode(buf []byte, cursor int, p uintptr) (int, error) {
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bytes, c, err := d.decodeByte(buf, cursor)
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if err != nil {
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return 0, err
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}
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cursor = c
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d.op(p, d.parseUint(bytes))
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return cursor, nil
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}
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