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mirror of https://github.com/json-iterator/go.git synced 2024-12-09 08:55:35 +02:00
json-iterator/feature_iter_skip.go
2017-06-20 15:11:01 +08:00

241 lines
4.8 KiB
Go

package jsoniter
import "fmt"
// ReadNil reads a json object as nil and
// returns whether it's a nil or not
func (iter *Iterator) ReadNil() (ret bool) {
c := iter.nextToken()
if c == 'n' {
iter.skipFixedBytes(3) // null
return true
}
iter.unreadByte()
return false
}
// ReadBool reads a json object as Bool
func (iter *Iterator) ReadBool() (ret bool) {
c := iter.nextToken()
if c == 't' {
iter.skipFixedBytes(3)
return true
}
if c == 'f' {
iter.skipFixedBytes(4)
return false
}
iter.ReportError("ReadBool", "expect t or f")
return
}
func (iter *Iterator) SkipAndReturnBytes() []byte {
iter.startCapture(iter.head)
iter.Skip()
return iter.stopCapture()
}
type captureBuffer struct {
startedAt int
captured []byte
}
func (iter *Iterator) startCapture(captureStartedAt int) {
if iter.captured != nil {
panic("already in capture mode")
}
iter.captureStartedAt = captureStartedAt
iter.captured = make([]byte, 0, 32)
}
func (iter *Iterator) stopCapture() []byte {
if iter.captured == nil {
panic("not in capture mode")
}
captured := iter.captured
remaining := iter.buf[iter.captureStartedAt:iter.head]
iter.captureStartedAt = -1
iter.captured = nil
if len(captured) == 0 {
return remaining
} else {
captured = append(captured, remaining...)
return captured
}
}
// Skip skips a json object and positions to relatively the next json object
func (iter *Iterator) Skip() {
c := iter.nextToken()
switch c {
case '"':
iter.skipString()
case 'n', 't':
iter.skipFixedBytes(3) // null or true
case 'f':
iter.skipFixedBytes(4) // false
case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
iter.skipNumber()
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() {
iter.ReportError("skipString", "incomplete string")
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
}
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) 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() {
iter.ReportError("skipObject", "incomplete array")
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() {
iter.ReportError("skipObject", "incomplete object")
return
}
}
}
func (iter *Iterator) skipNumber() {
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
}
}
}
func (iter *Iterator) skipFixedBytes(n int) {
iter.head += n
if iter.head >= iter.tail {
more := iter.head - iter.tail
if !iter.loadMore() {
if more > 0 {
iter.ReportError("skipFixedBytes", "unexpected end")
}
return
}
iter.head += more
}
}