mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-29 07:29:42 -08:00
340 lines
7.4 KiB
Go
340 lines
7.4 KiB
Go
package jsoniter
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import (
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"encoding/json"
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"io"
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"math/big"
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"strconv"
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"strings"
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"unsafe"
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)
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var floatDigits []int8
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const invalidCharForNumber = int8(-1)
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const endOfNumber = int8(-2)
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const dotInNumber = int8(-3)
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func init() {
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floatDigits = make([]int8, 256)
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for i := 0; i < len(floatDigits); i++ {
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floatDigits[i] = invalidCharForNumber
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}
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for i := int8('0'); i <= int8('9'); i++ {
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floatDigits[i] = i - int8('0')
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}
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floatDigits[','] = endOfNumber
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floatDigits[']'] = endOfNumber
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floatDigits['}'] = endOfNumber
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floatDigits[' '] = endOfNumber
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floatDigits['\t'] = endOfNumber
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floatDigits['\n'] = endOfNumber
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floatDigits['.'] = dotInNumber
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}
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// ReadBigFloat read big.Float
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func (iter *Iterator) ReadBigFloat() (ret *big.Float) {
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str := iter.readNumberAsString()
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if iter.Error != nil && iter.Error != io.EOF {
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return nil
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}
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prec := 64
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if len(str) > prec {
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prec = len(str)
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}
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val, _, err := big.ParseFloat(str, 10, uint(prec), big.ToZero)
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if err != nil {
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iter.Error = err
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return nil
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}
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return val
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}
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// ReadBigInt read big.Int
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func (iter *Iterator) ReadBigInt() (ret *big.Int) {
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str := iter.readNumberAsString()
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if iter.Error != nil && iter.Error != io.EOF {
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return nil
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}
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ret = big.NewInt(0)
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var success bool
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ret, success = ret.SetString(str, 10)
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if !success {
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iter.ReportError("ReadBigInt", "invalid big int")
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return nil
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}
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return ret
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}
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//ReadFloat32 read float32
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func (iter *Iterator) ReadFloat32() (ret float32) {
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c := iter.nextToken()
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if c == '-' {
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return -iter.readPositiveFloat32()
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}
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iter.unreadByte()
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return iter.readPositiveFloat32()
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}
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func (iter *Iterator) readPositiveFloat32() (ret float32) {
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i := iter.head
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// first char
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if i == iter.tail {
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return iter.readFloat32SlowPath()
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}
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c := iter.buf[i]
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i++
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ind := floatDigits[c]
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switch ind {
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case invalidCharForNumber:
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return iter.readFloat32SlowPath()
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case endOfNumber:
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iter.ReportError("readFloat32", "empty number")
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return
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case dotInNumber:
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iter.ReportError("readFloat32", "leading dot is invalid")
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return
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case 0:
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if i == iter.tail {
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return iter.readFloat32SlowPath()
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}
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c = iter.buf[i]
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switch c {
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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iter.ReportError("readFloat32", "leading zero is invalid")
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return
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}
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}
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value := uint64(ind)
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// chars before dot
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non_decimal_loop:
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for ; i < iter.tail; i++ {
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c = iter.buf[i]
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ind := floatDigits[c]
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switch ind {
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case invalidCharForNumber:
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return iter.readFloat32SlowPath()
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case endOfNumber:
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iter.head = i
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return float32(value)
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case dotInNumber:
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break non_decimal_loop
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}
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if value > uint64SafeToMultiple10 {
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return iter.readFloat32SlowPath()
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}
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value = (value << 3) + (value << 1) + uint64(ind) // value = value * 10 + ind;
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}
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// chars after dot
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if c == '.' {
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i++
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decimalPlaces := 0
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if i == iter.tail {
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return iter.readFloat32SlowPath()
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}
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for ; i < iter.tail; i++ {
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c = iter.buf[i]
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ind := floatDigits[c]
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switch ind {
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case endOfNumber:
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if decimalPlaces > 0 && decimalPlaces < len(pow10) {
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iter.head = i
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return float32(float64(value) / float64(pow10[decimalPlaces]))
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}
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// too many decimal places
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return iter.readFloat32SlowPath()
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case invalidCharForNumber, dotInNumber:
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return iter.readFloat32SlowPath()
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}
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decimalPlaces++
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if value > uint64SafeToMultiple10 {
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return iter.readFloat32SlowPath()
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}
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value = (value << 3) + (value << 1) + uint64(ind)
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}
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}
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return iter.readFloat32SlowPath()
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}
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func (iter *Iterator) readNumberAsString() (ret string) {
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strBuf := [16]byte{}
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str := strBuf[0:0]
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load_loop:
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for {
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for i := iter.head; i < iter.tail; i++ {
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c := iter.buf[i]
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switch c {
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case '+', '-', '.', 'e', 'E', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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str = append(str, c)
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continue
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default:
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iter.head = i
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break load_loop
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}
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}
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if !iter.loadMore() {
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break
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}
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}
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if iter.Error != nil && iter.Error != io.EOF {
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return
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}
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if len(str) == 0 {
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iter.ReportError("readNumberAsString", "invalid number")
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}
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return *(*string)(unsafe.Pointer(&str))
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}
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func (iter *Iterator) readFloat32SlowPath() (ret float32) {
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str := iter.readNumberAsString()
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if iter.Error != nil && iter.Error != io.EOF {
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return
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}
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errMsg := validateFloat(str)
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if errMsg != "" {
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iter.ReportError("readFloat32SlowPath", errMsg)
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return
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}
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val, err := strconv.ParseFloat(str, 32)
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if err != nil {
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iter.Error = err
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return
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}
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return float32(val)
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}
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// ReadFloat64 read float64
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func (iter *Iterator) ReadFloat64() (ret float64) {
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c := iter.nextToken()
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if c == '-' {
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return -iter.readPositiveFloat64()
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}
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iter.unreadByte()
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return iter.readPositiveFloat64()
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}
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func (iter *Iterator) readPositiveFloat64() (ret float64) {
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i := iter.head
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// first char
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if i == iter.tail {
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return iter.readFloat64SlowPath()
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}
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c := iter.buf[i]
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i++
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ind := floatDigits[c]
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switch ind {
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case invalidCharForNumber:
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return iter.readFloat64SlowPath()
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case endOfNumber:
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iter.ReportError("readFloat64", "empty number")
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return
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case dotInNumber:
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iter.ReportError("readFloat64", "leading dot is invalid")
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return
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case 0:
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if i == iter.tail {
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return iter.readFloat64SlowPath()
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}
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c = iter.buf[i]
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switch c {
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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iter.ReportError("readFloat64", "leading zero is invalid")
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return
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}
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}
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value := uint64(ind)
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// chars before dot
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non_decimal_loop:
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for ; i < iter.tail; i++ {
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c = iter.buf[i]
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ind := floatDigits[c]
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switch ind {
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case invalidCharForNumber:
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return iter.readFloat64SlowPath()
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case endOfNumber:
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iter.head = i
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return float64(value)
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case dotInNumber:
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break non_decimal_loop
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}
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if value > uint64SafeToMultiple10 {
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return iter.readFloat64SlowPath()
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}
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value = (value << 3) + (value << 1) + uint64(ind) // value = value * 10 + ind;
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}
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// chars after dot
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if c == '.' {
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i++
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decimalPlaces := 0
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if i == iter.tail {
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return iter.readFloat64SlowPath()
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}
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for ; i < iter.tail; i++ {
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c = iter.buf[i]
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ind := floatDigits[c]
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switch ind {
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case endOfNumber:
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if decimalPlaces > 0 && decimalPlaces < len(pow10) {
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iter.head = i
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return float64(value) / float64(pow10[decimalPlaces])
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}
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// too many decimal places
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return iter.readFloat64SlowPath()
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case invalidCharForNumber, dotInNumber:
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return iter.readFloat64SlowPath()
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}
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decimalPlaces++
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if value > uint64SafeToMultiple10 {
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return iter.readFloat64SlowPath()
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}
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value = (value << 3) + (value << 1) + uint64(ind)
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}
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}
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return iter.readFloat64SlowPath()
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}
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func (iter *Iterator) readFloat64SlowPath() (ret float64) {
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str := iter.readNumberAsString()
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if iter.Error != nil && iter.Error != io.EOF {
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return
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}
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errMsg := validateFloat(str)
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if errMsg != "" {
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iter.ReportError("readFloat64SlowPath", errMsg)
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return
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}
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val, err := strconv.ParseFloat(str, 64)
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if err != nil {
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iter.Error = err
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return
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}
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return val
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}
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func validateFloat(str string) string {
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// strconv.ParseFloat is not validating `1.` or `1.e1`
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if len(str) == 0 {
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return "empty number"
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}
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if str[0] == '-' {
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return "-- is not valid"
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}
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dotPos := strings.IndexByte(str, '.')
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if dotPos != -1 {
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if dotPos == len(str)-1 {
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return "dot can not be last character"
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}
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switch str[dotPos+1] {
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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default:
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return "missing digit after dot"
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}
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}
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return ""
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}
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// ReadNumber read json.Number
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func (iter *Iterator) ReadNumber() (ret json.Number) {
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return json.Number(iter.readNumberAsString())
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}
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