mirror of
https://github.com/antonmedv/fx
synced 2024-11-11 07:10:28 +00:00
382 lines
7.2 KiB
Go
382 lines
7.2 KiB
Go
package main
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import (
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"fmt"
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"strconv"
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"strings"
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"unicode/utf8"
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)
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type jsonParser struct {
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data []byte
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end int
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lastChar byte
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lineNumber uint
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sourceTail *ring
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depth uint8
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skipFirstIdent bool
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}
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func parse(data []byte) (head *node, err error) {
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p := &jsonParser{
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data: data,
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lineNumber: 1,
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sourceTail: &ring{},
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}
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defer func() {
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if r := recover(); r != nil {
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err = p.errorSnippet(fmt.Sprintf("%v", r))
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}
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}()
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p.next()
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var next *node
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for p.lastChar != 0 {
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value := p.parseValue()
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if head == nil {
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head = value
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next = head
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} else {
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value.index = -1
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next.adjacent(value)
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next = value
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}
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}
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return
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}
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func (p *jsonParser) next() {
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if p.end < len(p.data) {
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p.lastChar = p.data[p.end]
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p.end++
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} else {
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p.lastChar = 0
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}
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if p.lastChar == '\n' {
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p.lineNumber++
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}
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p.sourceTail.writeByte(p.lastChar)
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}
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func (p *jsonParser) parseValue() *node {
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p.skipWhitespace()
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var l *node
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switch p.lastChar {
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case '"':
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l = p.parseString()
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-':
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l = p.parseNumber()
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case '{':
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l = p.parseObject()
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case '[':
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l = p.parseArray()
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case 't':
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l = p.parseKeyword("true")
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case 'f':
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l = p.parseKeyword("false")
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case 'n':
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l = p.parseKeyword("null")
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default:
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panic(fmt.Sprintf("Unexpected character %q", p.lastChar))
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}
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p.skipWhitespace()
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return l
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}
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func (p *jsonParser) parseString() *node {
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str := &node{depth: p.depth}
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start := p.end - 1
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p.next()
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escaped := false
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for {
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if escaped {
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switch p.lastChar {
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case 'u':
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var unicode string
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for i := 0; i < 4; i++ {
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p.next()
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if !isHexDigit(p.lastChar) {
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panic(fmt.Sprintf("Invalid Unicode escape sequence '\\u%s%c'", unicode, p.lastChar))
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}
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unicode += string(p.lastChar)
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}
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_, err := strconv.ParseInt(unicode, 16, 32)
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if err != nil {
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panic(fmt.Sprintf("Invalid Unicode escape sequence '\\u%s'", unicode))
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}
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case '"', '\\', '/', 'b', 'f', 'n', 'r', 't':
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default:
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panic(fmt.Sprintf("Invalid escape sequence '\\%c'", p.lastChar))
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}
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escaped = false
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} else if p.lastChar == '\\' {
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escaped = true
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} else if p.lastChar == '"' {
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break
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} else if p.lastChar == 0 {
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panic("Unexpected end of input in string")
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} else if p.lastChar < 0x1F {
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panic(fmt.Sprintf("Invalid character %q in string", p.lastChar))
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}
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p.next()
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}
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str.value = p.data[start:p.end]
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p.next()
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return str
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}
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func (p *jsonParser) parseNumber() *node {
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num := &node{depth: p.depth}
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start := p.end - 1
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// Handle negative numbers
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if p.lastChar == '-' {
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p.next()
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if !isDigit(p.lastChar) {
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panic(fmt.Sprintf("Invalid character %q in number", p.lastChar))
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}
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}
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// Leading zero
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if p.lastChar == '0' {
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p.next()
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} else {
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for isDigit(p.lastChar) {
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p.next()
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}
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}
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// Decimal portion
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if p.lastChar == '.' {
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p.next()
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if !isDigit(p.lastChar) {
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panic(fmt.Sprintf("Invalid character %q in number", p.lastChar))
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}
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for isDigit(p.lastChar) {
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p.next()
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}
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}
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// Exponent
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if p.lastChar == 'e' || p.lastChar == 'E' {
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p.next()
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if p.lastChar == '+' || p.lastChar == '-' {
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p.next()
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}
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if !isDigit(p.lastChar) {
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panic(fmt.Sprintf("Invalid character %q in number", p.lastChar))
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}
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for isDigit(p.lastChar) {
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p.next()
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}
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}
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num.value = p.data[start : p.end-1]
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return num
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}
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func (p *jsonParser) parseObject() *node {
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object := &node{depth: p.depth}
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object.value = []byte{'{'}
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p.next()
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p.skipWhitespace()
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// Empty object
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if p.lastChar == '}' {
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object.value = append(object.value, '}')
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p.next()
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return object
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}
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for {
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// Expecting a key which should be a string
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if p.lastChar != '"' {
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panic(fmt.Sprintf("Expected object key to be a string, got %q", p.lastChar))
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}
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p.depth++
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key := p.parseString()
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key.key, key.value = key.value, nil
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key.directParent = object
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p.skipWhitespace()
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// Expecting colon after key
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if p.lastChar != ':' {
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panic(fmt.Sprintf("Expected colon after object key, got %q", p.lastChar))
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}
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p.next()
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p.skipFirstIdent = true
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value := p.parseValue()
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p.depth--
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key.value = value.value
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key.next = value.next
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if key.next != nil {
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key.next.prev = key
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}
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key.end = value.end
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value.indirectParent = key
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object.append(key)
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p.skipWhitespace()
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if p.lastChar == ',' {
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object.end.comma = true
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p.next()
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p.skipWhitespace()
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if p.lastChar == '}' {
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object.end.comma = false
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} else {
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continue
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}
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}
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if p.lastChar == '}' {
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closeBracket := &node{depth: p.depth}
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closeBracket.value = []byte{'}'}
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closeBracket.directParent = object
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closeBracket.index = -1
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object.append(closeBracket)
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p.next()
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return object
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}
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panic(fmt.Sprintf("Unexpected character %q in object", p.lastChar))
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}
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}
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func (p *jsonParser) parseArray() *node {
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arr := &node{depth: p.depth}
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arr.value = []byte{'['}
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p.next()
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p.skipWhitespace()
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if p.lastChar == ']' {
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arr.value = append(arr.value, ']')
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p.next()
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return arr
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}
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for i := 0; ; i++ {
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p.depth++
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value := p.parseValue()
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value.directParent = arr
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value.index = i
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p.depth--
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arr.append(value)
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p.skipWhitespace()
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if p.lastChar == ',' {
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arr.end.comma = true
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p.next()
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p.skipWhitespace()
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if p.lastChar == ']' {
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arr.end.comma = false
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} else {
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continue
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}
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}
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if p.lastChar == ']' {
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closeBracket := &node{depth: p.depth}
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closeBracket.value = []byte{']'}
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closeBracket.directParent = arr
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closeBracket.index = -1
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arr.append(closeBracket)
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p.next()
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return arr
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}
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panic(fmt.Sprintf("Invalid character %q in array", p.lastChar))
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}
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}
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func (p *jsonParser) parseKeyword(name string) *node {
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for i := 1; i < len(name); i++ {
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p.next()
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if p.lastChar != name[i] {
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panic(fmt.Sprintf("Unexpected character %q in keyword", p.lastChar))
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}
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}
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p.next()
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nextCharIsSpecial := isWhitespace(p.lastChar) || p.lastChar == ',' || p.lastChar == '}' || p.lastChar == ']' || p.lastChar == 0
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if nextCharIsSpecial {
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keyword := &node{depth: p.depth}
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keyword.value = []byte(name)
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return keyword
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}
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panic(fmt.Sprintf("Unexpected character %q in keyword", p.lastChar))
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}
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func isWhitespace(ch byte) bool {
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return ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r'
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}
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func (p *jsonParser) skipWhitespace() {
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for {
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switch p.lastChar {
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case ' ', '\t', '\n', '\r':
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p.next()
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case '/':
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p.skipComment()
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default:
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return
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}
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}
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}
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func (p *jsonParser) skipComment() {
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p.next()
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switch p.lastChar {
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case '/':
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for p.lastChar != '\n' && p.lastChar != 0 {
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p.next()
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}
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case '*':
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for {
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p.next()
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if p.lastChar == '*' {
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p.next()
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if p.lastChar == '/' {
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p.next()
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return
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}
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}
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if p.lastChar == 0 {
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panic("Unexpected end of input in comment")
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}
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}
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default:
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panic(fmt.Sprintf("Invalid comment: '/%c'", p.lastChar))
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}
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}
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func (p *jsonParser) errorSnippet(message string) error {
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lines := strings.Split(p.sourceTail.string(), "\n")
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lastLineLen := utf8.RuneCountInString(lines[len(lines)-1])
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pointer := strings.Repeat(".", lastLineLen-1) + "^"
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lines = append(lines, pointer)
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paddedLines := make([]string, len(lines))
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for i, line := range lines {
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paddedLines[i] = " " + line
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}
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return fmt.Errorf(
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"%s on line %d.\n\n%s\n\n",
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message,
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p.lineNumber,
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strings.Join(paddedLines, "\n"),
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)
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}
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