389 lines
11 KiB
C++
389 lines
11 KiB
C++
#include "JsonParse.h"
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#include "JsonError.h"
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#include "JsonValue.h"
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#include <cstddef>
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class JsonValue;
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//std::string src;
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//size_t pos;
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//JsonParser::JsonParser(std::string src){
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bool isnum(char c){
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if(c >= '0' && c <= '9') return true;
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return false;
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}
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JsonValue JsonParser::parse(){
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skip_white_space();
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JsonValue result = parse_value();
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skip_white_space();
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if(peek() != '\0'){
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error(JsonErrorCode::UnexpectedToken,
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"Can't find the end of input"
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);
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}
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return result;
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}
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void JsonParser::error(JsonErrorCode e, const std::string& msg){
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throw JsonError(e, msg, pos, line, col);
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}
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void JsonParser::skip_white_space(){
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while(pos < src.size()){
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char c = src[pos];
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if(c == ' ' || c == '\n' || c == '\t' || c == '\r') consume();
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else break;
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}
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}
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char JsonParser::peek() {
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if(pos < src.size()) return src[pos];
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return '\0';
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}
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char JsonParser::consume() {
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if(pos >= src.size())return '\0';
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char c = src[pos++];
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if(c == '\n'){
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line++;
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col = 1;
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} else {
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col++;
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}
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return c;
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}
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static std::string encode_utf8(unsigned int code_point) {
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std::string out;
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if (code_point <= 0x7F) {
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// 0xxxxxxx (ASCII)
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out += static_cast<char>(code_point);
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} else if (code_point <= 0x7FF) {
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// 110xxxxx 10xxxxxx
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out += static_cast<char>(0xC0 | ((code_point >> 6) & 0x1F));
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out += static_cast<char>(0x80 | (code_point & 0x3F));
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} else if (code_point <= 0xFFFF) {
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// 1110xxxx 10xxxxxx 10xxxxxx
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out += static_cast<char>(0xE0 | ((code_point >> 12) & 0x0F));
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out += static_cast<char>(0x80 | ((code_point >> 6) & 0x3F));
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out += static_cast<char>(0x80 | (code_point & 0x3F));
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} else if (code_point <= 0x10FFFF) {
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// 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx (辅助平面，如 Emoji)
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out += static_cast<char>(0xF0 | ((code_point >> 18) & 0x07));
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out += static_cast<char>(0x80 | ((code_point >> 12) & 0x3F));
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out += static_cast<char>(0x80 | ((code_point >> 6) & 0x3F));
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out += static_cast<char>(0x80 | (code_point & 0x3F));
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}
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return out;
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}
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// 辅助函数：解析4位十六进制
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unsigned int JsonParser::parse_hex_4() {
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unsigned int code = 0;
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for (int i = 0; i < 4; i++) {
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char c = consume();
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code <<= 4;
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if (c >= '0' && c <= '9') code |= (c - '0');
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else if (c >= 'a' && c <= 'f') code |= (c - 'a' + 10);
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else if (c >= 'A' && c <= 'F') code |= (c - 'A' + 10);
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else error(JsonErrorCode::InvalidEscape, "Invalid hex digit");
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}
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return code;
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}
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JsonValue JsonParser::parse_value() {
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// *类内可以直接用 类的函数
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skip_white_space();
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char c = peek();
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// 尾部\0结尾报错
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if (c == '\0') error(JsonErrorCode::UnexpectedEnd, "Unexpected end of input");
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//正常递归解析
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if (c == '\"') return parse_string();
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if (c == '[') return parse_list();
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if (c == '{') return parse_map();
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if (c == 't' || c == 'f') return parse_bool();
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if (c == 'n') return parse_null();
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if (c == '-' || isnum(c)) return parse_number();
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//格式化其他错误并输出
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std::string msg = "Unexpected Character: \'";
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msg += c;
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msg += "\'";
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error(JsonErrorCode::UnexpectedToken, msg);
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return JsonValue(); // 理论上跑不到这里，上面已经throw error了
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}
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JsonValue JsonParser::parse_null(){
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std::string pattern = "null";
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for(char expected : pattern){
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if(peek() == expected) consume();
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else {
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std::string msg = "Expected 'null', but found unexpected character: '";
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msg += peek();
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msg += "'";
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error(JsonErrorCode::InvalidValue, msg);
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}
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}
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return JsonValue(nullptr);
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}
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JsonValue JsonParser::parse_bool() {
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//string_view { const char* ptr, size_t len} 不拷贝字符串
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if (peek() == 't') {
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for (char expected : std::string_view("true")) {
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if (peek() == expected) consume();
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else error(JsonErrorCode::InvalidValue, "Invalid boolean: expected 'true'");
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}
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return JsonValue(true);
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}
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else if (peek() == 'f') {
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for (char expected : std::string_view("false")) {
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if (peek() == expected) consume();
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else error(JsonErrorCode::InvalidValue, "Invalid boolean: expected 'false'");
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}
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return JsonValue(false);
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}
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error(JsonErrorCode::InvalidValue, "Expected 'true' or 'false'");
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return JsonValue();
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/*
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非公共前缀可以，公共前缀不行
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解决方法：
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1、增加预读深度，
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2、贪婪匹配+回滚（匹配A，不行则回滚再匹配B）
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3、提取公共前缀，直接匹配后一个字符
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* json中关键字没有重叠
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*/
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}
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std::string JsonParser::parse_string_raw(){
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consume(); // 消费开始的 "
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std::string content;
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while (peek() != '\"') {
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char c = consume(); // 取得当前字符
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if (c == '\\') {
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// 遇到转义，看下一个字符
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char next = consume();
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switch (next) {
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case 'n': content += '\n'; break;
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case 't': content += '\t'; break;
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case 'r': content += '\r'; break;
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case '\\': content += '\\'; break;
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case '\"': content += '\"'; break;
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case 'u': {
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// TODO: Unicode 处理
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// 在 parse_string_raw 的 switch (next) 中：
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unsigned int code = parse_hex_4();
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// 检查是否是 UTF-16 高位代理 (Surrogate Pair)
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if (code >= 0xD800 && code <= 0xDBFF) {
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if (consume() != '\\' || consume() != 'u') {
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error(JsonErrorCode::InvalidEscape, "Expected low surrogate pair \\uXXXX");
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}
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unsigned int low = parse_hex_4();
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if (low < 0xDC00 || low > 0xDFFF) {
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error(JsonErrorCode::InvalidEscape, "Invalid low surrogate");
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}
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// 计算真实的码点: L = (H - 0xD800) * 0x400 + (L - 0xDC00) + 0x10000
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code = 0x10000 + (code - 0xD800) * 0x400 + (low - 0xDC00);
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}
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content += encode_utf8(code);
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break;
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}
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break;
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case '\0':
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error(JsonErrorCode::UnexpectedEnd, "Unexpected EOF in escape sequence");
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break;
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default:
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error(JsonErrorCode::InvalidEscape, "Invalid escape character");
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break;
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}
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}
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else if (c == '\0') {
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// 还没遇到引号就结束了
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error(JsonErrorCode::UnexpectedEnd, "String not closed before end of file");
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}
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else {
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// 普通字符
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content += c;
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}
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}
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consume(); // 消费结尾的 "
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return content;
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}
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JsonValue JsonParser::parse_string() {
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return JsonValue(parse_string_raw());
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}
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JsonValue JsonParser::parse_list(){
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consume();
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skip_white_space();
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std::vector<JsonValue> list;
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if(peek() == ']') {
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consume();
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return JsonValue(std::move(list));
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}
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while(true){
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skip_white_space();
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list.push_back(parse_value());
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skip_white_space();
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char c = peek();
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if(c == ',') {
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consume();
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} else if (c == ']') {
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consume();
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break; //正常结束循环
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}
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else {
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std::string msg = "Expected \',\' or \']\' but found \'";
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msg += c;
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msg += "\'";
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error(JsonErrorCode::UnexpectedToken, msg);
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}
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}
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return JsonValue(std::move(list));
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}
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JsonValue JsonParser::parse_map(){
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consume(); // {
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skip_white_space();
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std::map<std::string, JsonValue> mp;
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if(peek() == '}') {
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consume();
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return JsonValue(std::move(mp));
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}
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while(true){
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skip_white_space();
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char c = peek();
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if(c != '\"'){
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// 首字符非" 则报错
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std::string msg = "Expect \'\"\', but find \'";
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msg += c;
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msg += "\'";
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error(JsonErrorCode::UnexpectedToken, msg);
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}
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std::string key = parse_string_raw();
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// 处理 :
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skip_white_space();
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if(peek() != ':'){
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std::string msg = "Expected \':\' after object key";
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error(JsonErrorCode::UnexpectedToken, msg);
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}
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consume(); // :
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skip_white_space();
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// 处理 val
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JsonValue val = parse_value();
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// 检查重复 key
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if(mp.find(key) != mp.end()){
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error(JsonErrorCode::DuplicateKey, "Duplicate key found: " + key);
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}
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mp[std::move(key)] = std::move(val);
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//mp.insert({key, val});
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skip_white_space();
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//处理结束后
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char cc = peek();
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if(cc == '}'){
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consume();
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break;
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} else if(cc == ','){
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consume();
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//mp中还有，继续下一个循环
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} else {
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std::string msg = "Expected \',\' or \'}\' in object";
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error(JsonErrorCode::UnexpectedToken, msg);
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}
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}
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return JsonValue(std::move(mp));
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}
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JsonValue JsonParser::parse_number(){
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size_t start = pos;
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//符号
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if(peek() == '-'){
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consume();
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if(!isnum(peek())){
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error(JsonErrorCode::InvalidNumber, "Expected digit after \'-\'");
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}
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}
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//整数
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if(peek() == '0'){
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//前导0: 后面不能直接跟数字
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consume();
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if(isnum(peek())){
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error(JsonErrorCode::InvalidNumber, "Leading 0 is not allowed");
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}
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} else if(isnum(peek())){
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while(isnum(peek())) consume();
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} else {
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//非法字符
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error(JsonErrorCode::InvalidNumber, "Expected digit in a integer part");
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}
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//小数
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if(peek() == '.'){
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consume();
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if(!isnum(peek())){
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error(JsonErrorCode::InvalidNumber, "Expected digit after \'.\'");
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}
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while(isnum(peek())){
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consume();
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}
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}
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//指数 e/E
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if(peek() == 'e' || peek() == 'E'){
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consume();
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if(peek() == '+' || peek() == '-'){
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consume();
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}
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if(!isnum(peek())){
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error(JsonErrorCode::InvalidNumber, "Expected digit in exp");
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}
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while(isnum(peek())){
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consume();
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}
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}
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//扫描 + 字符串转换为数字 stod
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std::string num_str = src.substr(start, pos - start); // 把str丢给stod
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try {
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double val = std::stod(num_str);
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return JsonValue(val);
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} catch (...) {
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error(JsonErrorCode::InvalidNumber, "Failed to parse number");
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}
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return JsonValue();
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}
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