iter_skip.go

Documentation: github.com/json-iterator/go

     1  package jsoniter
     2  
     3  import "fmt"
     4  
     5  // ReadNil reads a json object as nil and
     6  // returns whether it's a nil or not
     7  func (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
    18  func (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.
    34  func (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.
    42  func (iter *Iterator) SkipAndAppendBytes(buf []byte) []byte {
    43  	iter.startCaptureTo(buf, iter.head)
    44  	iter.Skip()
    45  	return iter.stopCapture()
    46  }
    47  
    48  func (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  
    56  func (iter *Iterator) startCapture(captureStartedAt int) {
    57  	iter.startCaptureTo(make([]byte, 0, 32), captureStartedAt)
    58  }
    59  
    60  func (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
    72  func (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  
    98  func (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  
   117  func (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
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