1package jsoniter
2
3import "fmt"
4
5// ReadNil reads a json object as nil and
6// returns whether it's a nil or not
7func (iter *Iterator) ReadNil() (ret bool) {
8	c := iter.nextToken()
9	if c == 'n' {
10		iter.skipThreeBytes('u', 'l', 'l') // null
11		return true
12	}
13	iter.unreadByte()
14	return false
15}
16
17// ReadBool reads a json object as BoolValue
18func (iter *Iterator) ReadBool() (ret bool) {
19	c := iter.nextToken()
20	if c == 't' {
21		iter.skipThreeBytes('r', 'u', 'e')
22		return true
23	}
24	if c == 'f' {
25		iter.skipFourBytes('a', 'l', 's', 'e')
26		return false
27	}
28	iter.ReportError("ReadBool", "expect t or f, but found "+string([]byte{c}))
29	return
30}
31
32// SkipAndReturnBytes skip next JSON element, and return its content as []byte.
33// The []byte can be kept, it is a copy of data.
34func (iter *Iterator) SkipAndReturnBytes() []byte {
35	iter.startCapture(iter.head)
36	iter.Skip()
37	return iter.stopCapture()
38}
39
40// SkipAndAppendBytes skips next JSON element and appends its content to
41// buffer, returning the result.
42func (iter *Iterator) SkipAndAppendBytes(buf []byte) []byte {
43	iter.startCaptureTo(buf, iter.head)
44	iter.Skip()
45	return iter.stopCapture()
46}
47
48func (iter *Iterator) startCaptureTo(buf []byte, captureStartedAt int) {
49	if iter.captured != nil {
50		panic("already in capture mode")
51	}
52	iter.captureStartedAt = captureStartedAt
53	iter.captured = buf
54}
55
56func (iter *Iterator) startCapture(captureStartedAt int) {
57	iter.startCaptureTo(make([]byte, 0, 32), captureStartedAt)
58}
59
60func (iter *Iterator) stopCapture() []byte {
61	if iter.captured == nil {
62		panic("not in capture mode")
63	}
64	captured := iter.captured
65	remaining := iter.buf[iter.captureStartedAt:iter.head]
66	iter.captureStartedAt = -1
67	iter.captured = nil
68	return append(captured, remaining...)
69}
70
71// Skip skips a json object and positions to relatively the next json object
72func (iter *Iterator) Skip() {
73	c := iter.nextToken()
74	switch c {
75	case '"':
76		iter.skipString()
77	case 'n':
78		iter.skipThreeBytes('u', 'l', 'l') // null
79	case 't':
80		iter.skipThreeBytes('r', 'u', 'e') // true
81	case 'f':
82		iter.skipFourBytes('a', 'l', 's', 'e') // false
83	case '0':
84		iter.unreadByte()
85		iter.ReadFloat32()
86	case '-', '1', '2', '3', '4', '5', '6', '7', '8', '9':
87		iter.skipNumber()
88	case '[':
89		iter.skipArray()
90	case '{':
91		iter.skipObject()
92	default:
93		iter.ReportError("Skip", fmt.Sprintf("do not know how to skip: %v", c))
94		return
95	}
96}
97
98func (iter *Iterator) skipFourBytes(b1, b2, b3, b4 byte) {
99	if iter.readByte() != b1 {
100		iter.ReportError("skipFourBytes", fmt.Sprintf("expect %s", string([]byte{b1, b2, b3, b4})))
101		return
102	}
103	if iter.readByte() != b2 {
104		iter.ReportError("skipFourBytes", fmt.Sprintf("expect %s", string([]byte{b1, b2, b3, b4})))
105		return
106	}
107	if iter.readByte() != b3 {
108		iter.ReportError("skipFourBytes", fmt.Sprintf("expect %s", string([]byte{b1, b2, b3, b4})))
109		return
110	}
111	if iter.readByte() != b4 {
112		iter.ReportError("skipFourBytes", fmt.Sprintf("expect %s", string([]byte{b1, b2, b3, b4})))
113		return
114	}
115}
116
117func (iter *Iterator) skipThreeBytes(b1, b2, b3 byte) {
118	if iter.readByte() != b1 {
119		iter.ReportError("skipThreeBytes", fmt.Sprintf("expect %s", string([]byte{b1, b2, b3})))
120		return
121	}
122	if iter.readByte() != b2 {
123		iter.ReportError("skipThreeBytes", fmt.Sprintf("expect %s", string([]byte{b1, b2, b3})))
124		return
125	}
126	if iter.readByte() != b3 {
127		iter.ReportError("skipThreeBytes", fmt.Sprintf("expect %s", string([]byte{b1, b2, b3})))
128		return
129	}
130}
131