Add simple JSON parser
This commit is contained in:
Alexey Andreev
@@ -0,0 +1,364 @@
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/*
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* Copyright 2010-2017 JetBrains s.r.o.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jetbrains.kotlin.js.parser.sourcemaps
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import java.io.Reader
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import java.io.StringReader
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import java.io.StringWriter
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import java.io.Writer
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sealed class JsonNode {
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abstract fun write(writer: Writer)
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override fun toString(): String = StringWriter().also { write(it) }.toString()
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}
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object JsonNull : JsonNode() {
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override fun write(writer: Writer) {
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writer.append("null")
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}
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}
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class JsonBoolean private constructor(val value: Boolean) : JsonNode() {
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private val stringValue = value.toString()
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override fun write(writer: Writer) {
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writer.append(stringValue)
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}
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companion object {
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val TRUE = JsonBoolean(true)
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val FALSE = JsonBoolean(false)
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fun of(value: Boolean): JsonBoolean = if (value) TRUE else FALSE
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}
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}
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data class JsonObject(val properties: MutableMap<String, JsonNode>) : JsonNode() {
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constructor(vararg properties: Pair<String, JsonNode>) : this(properties.toMap().toMutableMap())
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override fun write(writer: Writer) {
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writer.append('{')
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var first = true
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for ((key, value) in properties) {
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if (!first) {
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writer.append(',')
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}
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first = false
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JsonString(key).write(writer)
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writer.append(':')
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value.write(writer)
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}
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writer.append('}')
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}
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override fun toString(): String = super.toString()
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}
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data class JsonArray(val elements: MutableList<JsonNode>) : JsonNode() {
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constructor(vararg elements: JsonNode) : this(elements.toMutableList())
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override fun write(writer: Writer) {
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writer.append('[')
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var first = true
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for (element in elements) {
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if (!first) {
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writer.append(',')
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}
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first = false
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element.write(writer)
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}
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writer.append(']')
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}
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}
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data class JsonString(val value: String) : JsonNode() {
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override fun write(writer: Writer) {
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writer.append('"')
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for (c in value) {
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when (c) {
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'\\' -> writer.append("\\\\")
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'"' -> writer.append("\\\"")
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'\r' -> writer.append("\\r")
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'\n' -> writer.append("\\n")
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'\t' -> writer.append("\\t")
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'\b' -> writer.append("\\b")
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'\u000C' -> writer.append("\\f")
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in ' '..126.toChar() -> writer.append(c)
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else -> {
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writer.append("\\u")
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var shift = 16
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repeat(4) {
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shift -= 4
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val digit = (c.toInt() ushr shift) and 0xF
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writer.append(if (digit < 10) (digit + '0'.toInt()).toChar() else (digit - 10 + 'a'.toInt()).toChar())
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}
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}
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}
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}
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writer.append('"')
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}
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override fun toString(): String = super.toString()
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}
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data class JsonNumber(val value: Double) : JsonNode() {
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override fun write(writer: Writer) {
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if (value.toLong().toDouble() == value) {
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writer.append(value.toLong().toString())
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}
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else {
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writer.append(value.toString())
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}
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}
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override fun toString(): String = super.toString()
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}
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class JsonSyntaxException(val offset: Int, val line: Int, val column: Int, val text: String) :
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RuntimeException("JSON syntax error at ${line + 1}, ${column + 1}: $text")
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fun parseJson(reader: Reader): JsonNode = JsonParser(reader).parse()
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fun parseJson(text: String): JsonNode = parseJson(StringReader(text))
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private class JsonParser(val reader: Reader) {
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private var charCode = reader.read()
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private var offset = 0
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private var line = 0
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private var col = 0
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private var wasCR = false
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fun parse(): JsonNode {
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val result = parseNode()
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skipSpaces()
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if (charCode != -1) throw error("End of input expected")
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return result
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}
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private fun skipSpaces() {
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while (true) {
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when (charCode) {
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' '.toInt(), '\t'.toInt(), '\n'.toInt(), '\r'.toInt() -> advance()
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else -> return
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}
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}
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}
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private fun parseNode(): JsonNode {
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skipSpaces()
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return when (charCode) {
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'['.toInt() -> parseArray()
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'{'.toInt() -> parseObject()
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'"'.toInt() -> JsonString(parseString())
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'n'.toInt() -> { expectString("null"); JsonNull }
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'f'.toInt() -> { expectString("false"); JsonBoolean.FALSE }
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't'.toInt() -> { expectString("true"); JsonBoolean.TRUE }
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in '0'.toInt()..'9'.toInt() -> JsonNumber(parseNumber())
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'-'.toInt() -> { advance(); JsonNumber(-parseNumber())
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}
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else -> error("Unexpected char")
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}
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}
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private fun parseArray(): JsonArray {
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advance()
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val result = JsonArray()
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while (true) {
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skipSpaces()
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if (charCode == ']'.toInt()) {
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advance()
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break
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}
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else {
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if (result.elements.isNotEmpty()) {
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expectCharAndAdvance(',')
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}
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result.elements += parseNode()
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}
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}
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return result
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}
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private fun parseObject(): JsonObject {
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advance()
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val result = JsonObject()
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while (true) {
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skipSpaces()
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if (charCode == '}'.toInt()) {
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advance()
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break
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}
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else {
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if (result.properties.isNotEmpty()) {
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expectCharAndAdvance(',')
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}
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skipSpaces()
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val key = parseString()
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if (key in result.properties) {
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error("Duplicate property name: $key")
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}
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skipSpaces()
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expectCharAndAdvance(':')
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result.properties[key] = parseNode()
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}
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}
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return result
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}
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private fun parseString(): String {
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expectCharAndAdvance('"')
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val sb = StringBuilder()
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while (true) {
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when (charCode) {
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'"'.toInt() -> { advance(); return sb.toString() }
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'\\'.toInt() -> sb.append(parseEscapeSequence())
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else -> {
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if (charCode >= ' '.toInt()) {
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sb.append(charCode.toChar())
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advance()
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}
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else {
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error("Invalid character in string literal")
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}
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}
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}
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}
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}
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private fun parseEscapeSequence(): Char {
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advance()
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return when (charCode) {
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'"'.toInt() -> advanceAndThen { '"' }
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'\\'.toInt() -> advanceAndThen { '\\' }
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'/'.toInt() -> advanceAndThen { '/' }
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'b'.toInt() -> advanceAndThen { '\b' }
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'n'.toInt() -> advanceAndThen { '\n' }
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'r'.toInt() -> advanceAndThen { '\r' }
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'f'.toInt() -> advanceAndThen { '\u000C' }
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't'.toInt() -> advanceAndThen { '\t' }
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'u'.toInt() -> parseHexEscapeSequence()
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else -> error("Invalid escape sequence")
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}
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}
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private fun parseHexEscapeSequence(): Char {
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advance()
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var value = 0
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repeat(4) {
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value *= 16
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value += when (charCode) {
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in '0'.toInt()..'9'.toInt() -> charCode - '0'.toInt()
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in 'a'.toInt()..'f'.toInt() -> charCode - 'a'.toInt() + 10
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in 'A'.toInt()..'F'.toInt() -> charCode - 'A'.toInt() + 10
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else -> error("Invalid escape sequence, hexadecimal char expected")
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}
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advance()
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}
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return value.toChar()
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}
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private fun parseNumber(): Double {
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val sb = StringBuilder()
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takeIntegerDigitsTo(sb)
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if (sb.startsWith('0') && sb.length > 1) error("Number must not start with zero")
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return when (charCode) {
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'.'.toInt() -> {
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sb.append('.')
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advance()
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takeIntegerDigitsTo(sb)
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if (charCode == 'e'.toInt() || charCode == 'E'.toInt()) {
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takeExponentTo(sb)
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}
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sb.toString().toDouble()
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}
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'e'.toInt(), 'E'.toInt() -> {
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takeExponentTo(sb)
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sb.toString().toDouble()
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}
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else -> return sb.toString().toDouble()
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}
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}
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private fun takeIntegerDigitsTo(buffer: StringBuilder) {
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var size = 0
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while (charCode in '0'.toInt()..'9'.toInt()) {
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buffer.append(charCode.toChar())
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advance()
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size++
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}
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if (size == 0) error("Invalid char, decimal digit expected")
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}
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private fun takeExponentTo(buffer: StringBuilder) {
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buffer.append('e')
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advance()
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if (charCode == '-'.toInt() || charCode == '+'.toInt()) {
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buffer.append(charCode.toChar())
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advance()
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}
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takeIntegerDigitsTo(buffer)
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}
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private fun expectString(expected: String) {
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for (c in expected) {
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if (charCode != c.toInt()) error("Unexpected char, '$expected' expected here")
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advance()
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}
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}
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private fun expectCharAndAdvance(expected: Char) {
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if (charCode != expected.toInt()) error("Unexpected char, '$expected' expected here")
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advance()
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}
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private inline fun <T> advanceAndThen(f: () -> T): T {
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advance()
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return f()
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}
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private fun advance() {
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if (charCode == -1) return
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when (charCode) {
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'\r'.toInt() -> {
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line++
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col = 0
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wasCR = true
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}
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'\n'.toInt() -> {
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if (!wasCR) {
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line++
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col = 0
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wasCR = false
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}
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}
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else -> {
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col++
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wasCR = false
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}
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}
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charCode = reader.read()
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offset++
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}
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private fun error(text: String): Nothing = throw JsonSyntaxException(offset, line, col, text)
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}
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