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mirror of https://github.com/json-iterator/go.git synced 2024-11-27 08:30:57 +02:00
json-iterator/jsoniter.go
2017-01-05 09:16:41 +08:00

894 lines
17 KiB
Go

package jsoniter
import (
"io"
"fmt"
"unicode/utf16"
"strconv"
"unsafe"
"encoding/base64"
)
type ValueType int
const (
Invalid ValueType = iota
String
Number
Null
Bool
Array
Object
)
var digits []byte
var valueTypes []ValueType
func init() {
digits = make([]byte, 256)
for i := 0; i < len(digits); i++ {
digits[i] = 255
}
for i := '0'; i <= '9'; i++ {
digits[i] = byte(i - '0');
}
for i := 'a'; i <= 'f'; i++ {
digits[i] = byte((i - 'a') + 10);
}
for i := 'A'; i <= 'F'; i++ {
digits[i] = byte((i - 'A') + 10);
}
valueTypes = make([]ValueType, 256)
for i := 0; i < len(valueTypes); i++ {
valueTypes[i] = Invalid
}
valueTypes['"'] = String;
valueTypes['-'] = Number;
valueTypes['0'] = Number;
valueTypes['1'] = Number;
valueTypes['2'] = Number;
valueTypes['3'] = Number;
valueTypes['4'] = Number;
valueTypes['5'] = Number;
valueTypes['6'] = Number;
valueTypes['7'] = Number;
valueTypes['8'] = Number;
valueTypes['9'] = Number;
valueTypes['t'] = Bool;
valueTypes['f'] = Bool;
valueTypes['n'] = Null;
valueTypes['['] = Array;
valueTypes['{'] = Object;
}
type Iterator struct {
reader io.Reader
buf []byte
head int
tail int
Error error
}
func Parse(reader io.Reader, bufSize int) *Iterator {
iter := &Iterator{
reader: reader,
buf: make([]byte, bufSize),
head: 0,
tail: 0,
}
return iter
}
func ParseBytes(input []byte) *Iterator {
iter := &Iterator{
reader: nil,
buf: input,
head: 0,
tail: len(input),
}
return iter
}
func ParseString(input string) *Iterator {
return ParseBytes([]byte(input))
}
func (iter *Iterator) Reset(reader io.Reader) *Iterator {
iter.reader = reader
iter.head = 0
iter.tail = 0
return iter
}
func (iter *Iterator) ResetBytes(input []byte) *Iterator {
// only for benchmarking
iter.reader = nil
iter.Error = nil
iter.buf = input
iter.head = 0
iter.tail = len(input)
return iter
}
func (iter *Iterator) WhatIsNext() ValueType {
valueType := valueTypes[iter.readByte()];
iter.unreadByte();
return valueType;
}
func (iter *Iterator) skipWhitespacesWithoutLoadMore() bool {
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
switch c {
case ' ', '\n', '\t', '\r':
continue
}
iter.head = i
return false
}
return true
}
func (iter *Iterator) nextToken() byte {
// a variation of skip whitespaces, returning the next non-whitespace token
for {
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
switch c {
case ' ', '\n', '\t', '\r':
continue
}
iter.head = i+1
return c
}
if !iter.loadMore() {
return 0
}
}
}
func (iter *Iterator) ReportError(operation string, msg string) {
if iter.Error != nil {
return
}
peekStart := iter.head - 10
if peekStart < 0 {
peekStart = 0
}
iter.Error = fmt.Errorf("%s: %s, parsing %v ...%s... at %s", operation, msg, iter.head,
string(iter.buf[peekStart: iter.head]), string(iter.buf[0:iter.tail]))
}
func (iter *Iterator) CurrentBuffer() string {
peekStart := iter.head - 10
if peekStart < 0 {
peekStart = 0
}
return fmt.Sprintf("parsing %v ...|%s|... at %s", iter.head,
string(iter.buf[peekStart: iter.head]), string(iter.buf[0:iter.tail]))
}
func (iter *Iterator) readByte() (ret byte) {
if iter.head == iter.tail {
if iter.loadMore() {
ret = iter.buf[iter.head]
iter.head++
return ret
} else {
return 0
}
}
ret = iter.buf[iter.head]
iter.head++
return ret
}
func (iter *Iterator) loadMore() bool {
if iter.reader == nil {
iter.Error = io.EOF
return false
}
for {
n, err := iter.reader.Read(iter.buf)
if n == 0 {
if err != nil {
iter.Error = err
return false
} else {
// n == 0, err == nil is not EOF
continue
}
} else {
iter.head = 0
iter.tail = n
return true
}
}
}
func (iter *Iterator) unreadByte() {
if iter.head == 0 {
iter.ReportError("unreadByte", "unread too many bytes")
return
}
iter.head -= 1
return
}
const maxUint64 = (1 << 64 - 1)
const cutoffUint64 = maxUint64 / 10 + 1
const maxUint32 = (1 << 32 - 1)
const cutoffUint32 = maxUint32 / 10 + 1
func (iter *Iterator) ReadUint() (ret uint) {
val := iter.ReadUint64()
converted := uint(val)
if uint64(converted) != val {
iter.ReportError("ReadUint", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadUint8() (ret uint8) {
val := iter.ReadUint64()
converted := uint8(val)
if uint64(converted) != val {
iter.ReportError("ReadUint8", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadUint16() (ret uint16) {
val := iter.ReadUint64()
converted := uint16(val)
if uint64(converted) != val {
iter.ReportError("ReadUint16", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadUint32() (ret uint32) {
val := iter.ReadUint64()
converted := uint32(val)
if uint64(converted) != val {
iter.ReportError("ReadUint32", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadUint64() (ret uint64) {
c := iter.readByte()
v := digits[c]
if v == 0 {
return 0 // single zero
}
if v == 255 {
iter.ReportError("ReadUint64", "unexpected character")
return
}
for {
if ret >= cutoffUint64 {
iter.ReportError("ReadUint64", "overflow")
return
}
ret = ret * 10 + uint64(v)
c = iter.readByte()
v = digits[c]
if v == 255 {
iter.unreadByte()
break
}
}
return ret
}
func (iter *Iterator) ReadInt() (ret int) {
val := iter.ReadInt64()
converted := int(val)
if int64(converted) != val {
iter.ReportError("ReadInt", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadInt8() (ret int8) {
val := iter.ReadInt64()
converted := int8(val)
if int64(converted) != val {
iter.ReportError("ReadInt8", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadInt16() (ret int16) {
val := iter.ReadInt64()
converted := int16(val)
if int64(converted) != val {
iter.ReportError("ReadInt16", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadInt32() (ret int32) {
val := iter.ReadInt64()
converted := int32(val)
if int64(converted) != val {
iter.ReportError("ReadInt32", "int overflow")
return
}
return converted
}
func (iter *Iterator) ReadInt64() (ret int64) {
c := iter.readByte()
if iter.Error != nil {
return
}
/* optional leading minus */
if c == '-' {
n := iter.ReadUint64()
return -int64(n)
} else {
iter.unreadByte()
n := iter.ReadUint64()
return int64(n)
}
}
func (iter *Iterator) ReadString() (ret string) {
return string(iter.readStringAsBytes())
}
func (iter *Iterator) readStringAsBytes() (ret []byte) {
c := iter.nextToken()
if c == 'n' {
iter.skipUntilBreak()
return
}
if c != '"' {
iter.ReportError("ReadString", `expects " or n`)
return
}
end := iter.findStringEndWithoutEscape()
if end != -1 {
// fast path: reuse the underlying buffer
ret = iter.buf[iter.head:end-1]
iter.head = end
return ret
}
str := make([]byte, 0, 8)
for iter.Error == nil {
c = iter.readByte()
if c == '"' {
return str
}
if c == '\\' {
c = iter.readByte()
if iter.Error != nil {
return
}
switch c {
case 'u':
r := iter.readU4()
if iter.Error != nil {
return
}
if utf16.IsSurrogate(r) {
c = iter.readByte()
if iter.Error != nil {
return
}
if c != '\\' {
iter.ReportError("ReadString",
`expects \u after utf16 surrogate, but \ not found`)
return
}
c = iter.readByte()
if iter.Error != nil {
return
}
if c != 'u' {
iter.ReportError("ReadString",
`expects \u after utf16 surrogate, but \u not found`)
return
}
r2 := iter.readU4()
if iter.Error != nil {
return
}
combined := utf16.DecodeRune(r, r2)
str = appendRune(str, combined)
} else {
str = appendRune(str, r)
}
case '"':
str = append(str, '"')
case '\\':
str = append(str, '\\')
case '/':
str = append(str, '/')
case 'b':
str = append(str, '\b')
case 'f':
str = append(str, '\f')
case 'n':
str = append(str, '\n')
case 'r':
str = append(str, '\r')
case 't':
str = append(str, '\t')
default:
iter.ReportError("ReadString",
`invalid escape char after \`)
return
}
} else {
str = append(str, c)
}
}
return
}
func (iter *Iterator) readU4() (ret rune) {
for i := 0; i < 4; i++ {
c := iter.readByte()
if iter.Error != nil {
return
}
if (c >= '0' && c <= '9') {
if ret >= cutoffUint32 {
iter.ReportError("readU4", "overflow")
return
}
ret = ret * 16 + rune(c - '0')
} else if ((c >= 'a' && c <= 'f') ) {
if ret >= cutoffUint32 {
iter.ReportError("readU4", "overflow")
return
}
ret = ret * 16 + rune(c - 'a' + 10)
} else {
iter.ReportError("readU4", "expects 0~9 or a~f")
return
}
}
return ret
}
const (
t1 = 0x00 // 0000 0000
tx = 0x80 // 1000 0000
t2 = 0xC0 // 1100 0000
t3 = 0xE0 // 1110 0000
t4 = 0xF0 // 1111 0000
t5 = 0xF8 // 1111 1000
maskx = 0x3F // 0011 1111
mask2 = 0x1F // 0001 1111
mask3 = 0x0F // 0000 1111
mask4 = 0x07 // 0000 0111
rune1Max = 1 << 7 - 1
rune2Max = 1 << 11 - 1
rune3Max = 1 << 16 - 1
surrogateMin = 0xD800
surrogateMax = 0xDFFF
MaxRune = '\U0010FFFF' // Maximum valid Unicode code point.
RuneError = '\uFFFD' // the "error" Rune or "Unicode replacement character"
)
func appendRune(p []byte, r rune) []byte {
// Negative values are erroneous. Making it unsigned addresses the problem.
switch i := uint32(r); {
case i <= rune1Max:
p = append(p, byte(r))
return p
case i <= rune2Max:
p = append(p, t2 | byte(r >> 6))
p = append(p, tx | byte(r) & maskx)
return p
case i > MaxRune, surrogateMin <= i && i <= surrogateMax:
r = RuneError
fallthrough
case i <= rune3Max:
p = append(p, t3 | byte(r >> 12))
p = append(p, tx | byte(r >> 6) & maskx)
p = append(p, tx | byte(r) & maskx)
return p
default:
p = append(p, t4 | byte(r >> 18))
p = append(p, tx | byte(r >> 12) & maskx)
p = append(p, tx | byte(r >> 6) & maskx)
p = append(p, tx | byte(r) & maskx)
return p
}
}
func (iter *Iterator) ReadArray() (ret bool) {
c := iter.nextToken()
if iter.Error != nil {
return
}
switch c {
case 'n': {
iter.skipUntilBreak()
return false // null
}
case '[': {
c = iter.nextToken()
if iter.Error != nil {
return
}
if c == ']' {
return false
} else {
iter.unreadByte()
return true
}
}
case ']': return false
case ',':
return true
default:
iter.ReportError("ReadArray", "expect [ or , or ] or n")
return
}
}
func (iter *Iterator) ReadObject() (ret string) {
c := iter.nextToken()
if iter.Error != nil {
return
}
switch c {
case 'n': {
iter.skipUntilBreak()
if iter.Error != nil {
return
}
return "" // null
}
case '{': {
c = iter.nextToken()
if iter.Error != nil {
return
}
switch c {
case '}':
return "" // end of object
case '"':
iter.unreadByte()
return iter.readObjectField()
default:
iter.ReportError("ReadObject", `expect " after {`)
return
}
}
case ',':
return iter.readObjectField()
case '}':
return "" // end of object
default:
iter.ReportError("ReadObject", `expect { or , or } or n`)
return
}
}
func (iter *Iterator) readObjectField() (ret string) {
str := iter.readStringAsBytes()
if iter.skipWhitespacesWithoutLoadMore() {
if ret == "" {
ret = string(str);
}
if !iter.loadMore() {
return
}
}
if iter.buf[iter.head] != ':' {
iter.ReportError("ReadObject", "expect : after object field")
return
}
iter.head++
if iter.skipWhitespacesWithoutLoadMore() {
if ret == "" {
ret = string(str);
}
if !iter.loadMore() {
return
}
}
if ret == "" {
return *(*string)(unsafe.Pointer(&str))
}
return ret
}
func (iter *Iterator) ReadFloat32() (ret float32) {
strBuf := [8]byte{}
str := strBuf[0:0]
hasMore := true
for(hasMore) {
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
switch c {
case '-', '+', '.', 'e', 'E', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
str = append(str, c)
continue
default:
hasMore = false
break
}
}
if hasMore {
if !iter.loadMore() {
break
}
}
}
if iter.Error != nil && iter.Error != io.EOF {
return
}
val, err := strconv.ParseFloat(*(*string)(unsafe.Pointer(&str)), 32)
if err != nil {
iter.Error = err
return
}
return float32(val)
}
func (iter *Iterator) ReadFloat64() (ret float64) {
strBuf := [8]byte{}
str := strBuf[0:0]
hasMore := true
for(hasMore) {
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
switch c {
case '-', '+', '.', 'e', 'E', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
str = append(str, c)
continue
default:
hasMore = false
break
}
}
if hasMore {
if !iter.loadMore() {
break
}
}
}
if iter.Error != nil && iter.Error != io.EOF {
return
}
val, err := strconv.ParseFloat(*(*string)(unsafe.Pointer(&str)), 64)
if err != nil {
iter.Error = err
return
}
return val
}
func (iter *Iterator) ReadBool() (ret bool) {
c := iter.readByte()
if iter.Error != nil {
return
}
switch c {
case 't':
iter.skipUntilBreak()
return true
case 'f':
iter.skipUntilBreak()
return false
default:
iter.ReportError("ReadBool", "expect t or f")
return
}
}
func (iter *Iterator) ReadBase64() (ret []byte) {
src := iter.readStringAsBytes()
if iter.Error != nil {
return
}
b64 := base64.StdEncoding
ret = make([]byte, b64.DecodedLen(len(src)))
n, err := b64.Decode(ret, src)
if err != nil {
iter.Error = err
return
}
return ret[:n]
}
func (iter *Iterator) ReadNull() (ret bool) {
c := iter.readByte()
if c == 'n' {
iter.skipUntilBreak()
return true
}
iter.unreadByte()
return false
}
func (iter *Iterator) Skip() {
c := iter.readByte()
switch c {
case '"':
iter.skipString()
case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 't', 'f', 'n':
iter.skipUntilBreak()
case '[':
iter.skipArray()
case '{':
iter.skipObject()
default:
iter.ReportError("Skip", fmt.Sprintf("do not know how to skip: %v", c))
return
}
}
func (iter *Iterator) skipString() {
for {
end, escaped := iter.findStringEnd()
if end == -1 {
if !iter.loadMore() {
return
}
if escaped {
iter.head = 1 // skip the first char as last char read is \
}
} else {
iter.head = end
return
}
}
}
// adapted from: https://github.com/buger/jsonparser/blob/master/parser.go
// Tries to find the end of string
// Support if string contains escaped quote symbols.
func (iter *Iterator) findStringEnd() (int, bool) {
escaped := false
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
if c == '"' {
if !escaped {
return i + 1, false
} else {
j := i - 1
for {
if j < iter.head || iter.buf[j] != '\\' {
// even number of backslashes
// either end of buffer, or " found
return i + 1, true
}
j--
if j < iter.head || iter.buf[j] != '\\' {
// odd number of backslashes
// it is \" or \\\"
break
}
j--
}
}
} else if c == '\\' {
escaped = true
}
}
j := iter.tail - 1
for {
if j < iter.head || iter.buf[j] != '\\' {
// even number of backslashes
// either end of buffer, or " found
return -1, false // do not end with \
}
j--
if j < iter.head || iter.buf[j] != '\\' {
// odd number of backslashes
// it is \" or \\\"
break
}
j--
}
return -1, true // end with \
}
func (iter *Iterator) findStringEndWithoutEscape() int {
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
if c == '"' {
return i + 1
} else if c == '\\' {
return -1
}
}
return -1
}
func (iter *Iterator) skipArray() {
level := 1
for {
for i := iter.head; i < iter.tail; i++ {
switch iter.buf[i] {
case '"': // If inside string, skip it
iter.head = i + 1
iter.skipString()
i = iter.head - 1 // it will be i++ soon
case '[': // If open symbol, increase level
level++
case ']': // If close symbol, increase level
level--
// If we have returned to the original level, we're done
if level == 0 {
iter.head = i + 1
return
}
}
}
if (!iter.loadMore()) {
return
}
}
}
func (iter *Iterator) skipObject() {
level := 1
for {
for i := iter.head; i < iter.tail; i++ {
switch iter.buf[i] {
case '"': // If inside string, skip it
iter.head = i + 1
iter.skipString()
i = iter.head - 1 // it will be i++ soon
case '{': // If open symbol, increase level
level++
case '}': // If close symbol, increase level
level--
// If we have returned to the original level, we're done
if level == 0 {
iter.head = i + 1
return
}
}
}
if (!iter.loadMore()) {
return
}
}
}
func (iter *Iterator) skipUntilBreak() {
// true, false, null, number
for {
for i := iter.head; i < iter.tail; i++ {
c := iter.buf[i]
switch c {
case ' ', '\n', '\r', '\t', ',', '}', ']':
iter.head = i
return
}
}
if (!iter.loadMore()) {
return
}
}
}