mirror of
https://github.com/LadybirdBrowser/ladybird.git
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356 lines
10 KiB
C++
356 lines
10 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/FloatingPointStringConversions.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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#include <math.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<DeprecatedString> 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 '\"'");
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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");
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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");
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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");
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}
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return Error::from_string_literal("JsonParser: Error while parsing string");
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}
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if (!consume_specific('"'))
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return Error::from_string_literal("JsonParser: Expected '\"'");
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return final_sb.to_deprecated_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 '{'");
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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");
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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 ':'");
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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 ','");
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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 '}'");
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}
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if (!consume_specific('}'))
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return Error::from_string_literal("JsonParser: Expected '}'");
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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 '['");
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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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TRY(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 ','");
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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 ']'");
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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 ']'");
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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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Vector<char, 32> number_buffer;
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auto start_index = tell();
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bool negative = false;
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if (peek() == '-') {
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number_buffer.append('-');
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++m_index;
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negative = true;
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if (!is_ascii_digit(peek()))
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return Error::from_string_literal("JsonParser: Unexpected '-' without further digits");
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}
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auto fallback_to_double_parse = [&]() -> ErrorOr<JsonValue> {
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#ifdef KERNEL
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# error JSONParser is currently not available for the Kernel because it disallows floating point. \
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If you want to make this KERNEL compatible you can just make this fallback_to_double \
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function fail with an error in KERNEL mode.
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#endif
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// FIXME: Since we know all the characters so far are ascii digits (and one . or e) we could
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// use that in the floating point parser.
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// The first part should be just ascii digits
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StringView view = m_input.substring_view(start_index);
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char const* start = view.characters_without_null_termination();
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auto parse_result = parse_first_floating_point(start, start + view.length());
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if (parse_result.parsed_value()) {
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auto characters_parsed = parse_result.end_ptr - start;
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m_index = start_index + characters_parsed;
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return JsonValue(parse_result.value);
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}
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return Error::from_string_literal("JsonParser: Invalid floating point");
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};
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if (peek() == '0') {
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if (is_ascii_digit(peek(1)))
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return Error::from_string_literal("JsonParser: Cannot have leading zeros");
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// Leading zeros are not allowed, however we can have a '.' or 'e' with
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// valid digits after just a zero. These cases will be detected by having the next element
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// start with a '.' or 'e'.
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}
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bool all_zero = true;
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for (;;) {
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char ch = peek();
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if (ch == '.') {
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if (!is_ascii_digit(peek(1)))
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return Error::from_string_literal("JsonParser: Must have digits after decimal point");
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return fallback_to_double_parse();
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}
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if (ch == 'e' || ch == 'E') {
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char next = peek(1);
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if (!is_ascii_digit(next) && ((next != '+' && next != '-') || !is_ascii_digit(peek(2))))
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return Error::from_string_literal("JsonParser: Must have digits after exponent with an optional sign inbetween");
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return fallback_to_double_parse();
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}
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if (is_ascii_digit(ch)) {
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if (ch != '0')
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all_zero = false;
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number_buffer.append(ch);
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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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// Negative zero is always a double
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if (negative && all_zero)
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return JsonValue(-0.0);
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StringView number_string(number_buffer.data(), number_buffer.size());
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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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if (*to_unsigned_result <= NumericLimits<u32>::max())
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return JsonValue((u32)*to_unsigned_result);
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return JsonValue(*to_unsigned_result);
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} else if (auto signed_number = number_string.to_int<i64>(); signed_number.has_value()) {
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if (*signed_number <= NumericLimits<i32>::max())
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return JsonValue((i32)*signed_number);
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return JsonValue(*signed_number);
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}
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// It's possible the unsigned value is bigger than u64 max
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return fallback_to_double_parse();
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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'");
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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'");
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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'");
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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");
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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");
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return result;
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}
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}
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