123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216 |
- package jsoniter
-
- import (
- "fmt"
- "unicode/utf16"
- )
-
- // ReadString read string from iterator
- func (iter *Iterator) ReadString() (ret string) {
- c := iter.nextToken()
- if c == '"' {
- for i := iter.head; i < iter.tail; i++ {
- c := iter.buf[i]
- if c == '"' {
- ret = string(iter.buf[iter.head:i])
- iter.head = i + 1
- return ret
- } else if c == '\\' {
- break
- } else if c < ' ' {
- iter.ReportError("ReadString",
- fmt.Sprintf(`invalid control character found: %d`, c))
- return
- }
- }
- return iter.readStringSlowPath()
- } else if c == 'n' {
- iter.skipThreeBytes('u', 'l', 'l')
- return ""
- }
- iter.ReportError("ReadString", `expects " or n, but found `+string([]byte{c}))
- return
- }
-
- func (iter *Iterator) readStringSlowPath() (ret string) {
- var str []byte
- var c byte
- for iter.Error == nil {
- c = iter.readByte()
- if c == '"' {
- return string(str)
- }
- if c == '\\' {
- c = iter.readByte()
- str = iter.readEscapedChar(c, str)
- } else {
- str = append(str, c)
- }
- }
- iter.ReportError("readStringSlowPath", "unexpected end of input")
- return
- }
-
- func (iter *Iterator) readEscapedChar(c byte, str []byte) []byte {
- switch c {
- case 'u':
- r := iter.readU4()
- if utf16.IsSurrogate(r) {
- c = iter.readByte()
- if iter.Error != nil {
- return nil
- }
- if c != '\\' {
- iter.unreadByte()
- str = appendRune(str, r)
- return str
- }
- c = iter.readByte()
- if iter.Error != nil {
- return nil
- }
- if c != 'u' {
- str = appendRune(str, r)
- return iter.readEscapedChar(c, str)
- }
- r2 := iter.readU4()
- if iter.Error != nil {
- return nil
- }
- combined := utf16.DecodeRune(r, r2)
- if combined == '\uFFFD' {
- str = appendRune(str, r)
- str = appendRune(str, r2)
- } else {
- 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("readEscapedChar",
- `invalid escape char after \`)
- return nil
- }
- return str
- }
-
- // ReadStringAsSlice read string from iterator without copying into string form.
- // The []byte can not be kept, as it will change after next iterator call.
- func (iter *Iterator) ReadStringAsSlice() (ret []byte) {
- c := iter.nextToken()
- if c == '"' {
- for i := iter.head; i < iter.tail; i++ {
- // require ascii string and no escape
- // for: field name, base64, number
- if iter.buf[i] == '"' {
- // fast path: reuse the underlying buffer
- ret = iter.buf[iter.head:i]
- iter.head = i + 1
- return ret
- }
- }
- readLen := iter.tail - iter.head
- copied := make([]byte, readLen, readLen*2)
- copy(copied, iter.buf[iter.head:iter.tail])
- iter.head = iter.tail
- for iter.Error == nil {
- c := iter.readByte()
- if c == '"' {
- return copied
- }
- copied = append(copied, c)
- }
- return copied
- }
- iter.ReportError("ReadStringAsSlice", `expects " or n, but found `+string([]byte{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' {
- ret = ret*16 + rune(c-'0')
- } else if c >= 'a' && c <= 'f' {
- ret = ret*16 + rune(c-'a'+10)
- } else if c >= 'A' && c <= 'F' {
- ret = ret*16 + rune(c-'A'+10)
- } else {
- iter.ReportError("readU4", "expects 0~9 or a~f, but found "+string([]byte{c}))
- 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
- }
- }
|