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https://github.com/SerenityOS/serenity
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![Andreas Kling](/assets/img/avatar_default.png)
Also add slightly richer parse errors now that we can include a string literal with returned errors. This will allow us to use TRY() when working with JSON data.
348 lines
9.8 KiB
C++
348 lines
9.8 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/CharacterTypes.h>
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#include <AK/JsonArray.h>
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#include <AK/JsonObject.h>
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#include <AK/JsonParser.h>
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namespace AK {
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constexpr bool is_space(int ch)
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{
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return ch == '\t' || ch == '\n' || ch == '\r' || ch == ' ';
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}
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ErrorOr<String> JsonParser::consume_and_unescape_string()
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{
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if (!consume_specific('"'))
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return Error::from_string_literal("JsonParser: Expected '\"'"sv);
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StringBuilder final_sb;
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for (;;) {
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size_t peek_index = m_index;
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char ch = 0;
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for (;;) {
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if (peek_index == m_input.length())
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break;
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ch = m_input[peek_index];
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if (ch == '"' || ch == '\\')
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break;
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if (is_ascii_c0_control(ch))
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return Error::from_string_literal("JsonParser: Error while parsing string"sv);
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++peek_index;
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}
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while (peek_index != m_index) {
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final_sb.append(m_input[m_index]);
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m_index++;
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}
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if (m_index == m_input.length())
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break;
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if (ch == '"')
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break;
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if (ch != '\\') {
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final_sb.append(consume());
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continue;
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}
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ignore();
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if (next_is('"')) {
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ignore();
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final_sb.append('"');
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continue;
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}
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if (next_is('\\')) {
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ignore();
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final_sb.append('\\');
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continue;
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}
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if (next_is('/')) {
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ignore();
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final_sb.append('/');
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continue;
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}
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if (next_is('n')) {
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ignore();
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final_sb.append('\n');
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continue;
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}
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if (next_is('r')) {
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ignore();
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final_sb.append('\r');
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continue;
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}
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if (next_is('t')) {
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ignore();
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final_sb.append('\t');
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continue;
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}
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if (next_is('b')) {
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ignore();
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final_sb.append('\b');
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continue;
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}
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if (next_is('f')) {
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ignore();
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final_sb.append('\f');
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continue;
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}
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if (next_is('u')) {
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ignore();
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if (tell_remaining() < 4)
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return Error::from_string_literal("JsonParser: EOF while parsing Unicode escape"sv);
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auto code_point = AK::StringUtils::convert_to_uint_from_hex(consume(4));
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if (code_point.has_value()) {
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final_sb.append_code_point(code_point.value());
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continue;
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}
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return Error::from_string_literal("JsonParser: Error while parsing Unicode escape"sv);
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}
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return Error::from_string_literal("JsonParser: Error while parsing string"sv);
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}
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if (!consume_specific('"'))
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return Error::from_string_literal("JsonParser: Expected '\"'"sv);
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return final_sb.to_string();
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}
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ErrorOr<JsonValue> JsonParser::parse_object()
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{
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JsonObject object;
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if (!consume_specific('{'))
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return Error::from_string_literal("JsonParser: Expected '{'"sv);
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for (;;) {
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ignore_while(is_space);
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if (peek() == '}')
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break;
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ignore_while(is_space);
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auto name = TRY(consume_and_unescape_string());
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if (name.is_null())
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return Error::from_string_literal("JsonParser: Expected object property name"sv);
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ignore_while(is_space);
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if (!consume_specific(':'))
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return Error::from_string_literal("JsonParser: Expected ':'"sv);
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ignore_while(is_space);
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auto value = TRY(parse_helper());
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object.set(name, move(value));
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ignore_while(is_space);
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if (peek() == '}')
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break;
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if (!consume_specific(','))
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return Error::from_string_literal("JsonParser: Expected ','"sv);
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ignore_while(is_space);
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if (peek() == '}')
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return Error::from_string_literal("JsonParser: Unexpected '}'"sv);
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}
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if (!consume_specific('}'))
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return Error::from_string_literal("JsonParser: Expected '}'"sv);
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return JsonValue { move(object) };
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}
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ErrorOr<JsonValue> JsonParser::parse_array()
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{
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JsonArray array;
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if (!consume_specific('['))
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return Error::from_string_literal("JsonParser: Expected '['"sv);
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for (;;) {
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ignore_while(is_space);
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if (peek() == ']')
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break;
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auto element = TRY(parse_helper());
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array.append(move(element));
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ignore_while(is_space);
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if (peek() == ']')
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break;
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if (!consume_specific(','))
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return Error::from_string_literal("JsonParser: Expected ','"sv);
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ignore_while(is_space);
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if (peek() == ']')
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return Error::from_string_literal("JsonParser: Unexpected ']'"sv);
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}
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ignore_while(is_space);
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if (!consume_specific(']'))
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return Error::from_string_literal("JsonParser: Expected ']'"sv);
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return JsonValue { move(array) };
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}
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ErrorOr<JsonValue> JsonParser::parse_string()
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{
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auto string = TRY(consume_and_unescape_string());
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return JsonValue(move(string));
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}
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ErrorOr<JsonValue> JsonParser::parse_number()
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{
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JsonValue value;
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Vector<char, 128> number_buffer;
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Vector<char, 128> fraction_buffer;
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bool is_double = false;
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for (;;) {
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char ch = peek();
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if (ch == '.') {
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if (is_double)
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return Error::from_string_literal("JsonParser: Multiple '.' in number"sv);
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is_double = true;
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++m_index;
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continue;
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}
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if (ch == '-' || (ch >= '0' && ch <= '9')) {
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if (is_double) {
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if (ch == '-')
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return Error::from_string_literal("JsonParser: Error while parsing number"sv);
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fraction_buffer.append(ch);
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} else {
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if (number_buffer.size() > 0) {
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if (number_buffer.at(0) == '0')
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return Error::from_string_literal("JsonParser: Error while parsing number"sv);
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}
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if (number_buffer.size() > 1) {
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if (number_buffer.at(0) == '-' && number_buffer.at(1) == '0')
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return Error::from_string_literal("JsonParser: Error while parsing number"sv);
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}
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number_buffer.append(ch);
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}
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++m_index;
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continue;
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}
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break;
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}
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StringView number_string(number_buffer.data(), number_buffer.size());
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#ifndef KERNEL
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if (is_double) {
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// FIXME: This logic looks shaky.
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int whole = 0;
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auto to_signed_result = number_string.to_uint();
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if (to_signed_result.has_value()) {
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whole = to_signed_result.value();
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} else {
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auto number = number_string.to_int();
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if (!number.has_value())
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return Error::from_string_literal("JsonParser: Error while parsing number"sv);
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whole = number.value();
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}
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StringView fraction_string(fraction_buffer.data(), fraction_buffer.size());
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auto fraction_string_uint = fraction_string.to_uint();
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if (!fraction_string_uint.has_value())
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return Error::from_string_literal("JsonParser: Error while parsing number"sv);
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int fraction = fraction_string_uint.value();
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fraction *= (whole < 0) ? -1 : 1;
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auto divider = 1;
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for (size_t i = 0; i < fraction_buffer.size(); ++i) {
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divider *= 10;
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}
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value = JsonValue((double)whole + ((double)fraction / divider));
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} else {
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#endif
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auto to_unsigned_result = number_string.to_uint<u64>();
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if (to_unsigned_result.has_value()) {
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auto number = *to_unsigned_result;
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if (number <= NumericLimits<u32>::max())
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value = JsonValue((u32)number);
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else
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value = JsonValue(number);
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} else {
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auto number = number_string.to_int<i64>();
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if (!number.has_value())
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return Error::from_string_literal("JsonParser: Error while parsing number"sv);
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if (number.value() <= NumericLimits<i32>::max()) {
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value = JsonValue((i32)number.value());
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} else {
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value = JsonValue(number.value());
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}
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}
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#ifndef KERNEL
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}
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#endif
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return value;
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}
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ErrorOr<JsonValue> JsonParser::parse_true()
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{
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if (!consume_specific("true"))
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return Error::from_string_literal("JsonParser: Expected 'true'"sv);
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return JsonValue(true);
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}
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ErrorOr<JsonValue> JsonParser::parse_false()
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{
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if (!consume_specific("false"))
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return Error::from_string_literal("JsonParser: Expected 'false'"sv);
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return JsonValue(false);
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}
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ErrorOr<JsonValue> JsonParser::parse_null()
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{
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if (!consume_specific("null"))
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return Error::from_string_literal("JsonParser: Expected 'null'"sv);
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return JsonValue(JsonValue::Type::Null);
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}
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ErrorOr<JsonValue> JsonParser::parse_helper()
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{
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ignore_while(is_space);
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auto type_hint = peek();
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switch (type_hint) {
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case '{':
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return parse_object();
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case '[':
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return parse_array();
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case '"':
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return parse_string();
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case '-':
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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case '8':
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case '9':
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return parse_number();
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case 'f':
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return parse_false();
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case 't':
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return parse_true();
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case 'n':
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return parse_null();
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}
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return Error::from_string_literal("JsonParser: Unexpected character"sv);
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}
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ErrorOr<JsonValue> JsonParser::parse()
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{
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auto result = TRY(parse_helper());
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ignore_while(is_space);
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if (!is_eof())
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return Error::from_string_literal("JsonParser: Didn't consume all input"sv);
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return result;
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}
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}
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