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Merged
jviotti merged 1 commit into from
Feb 12, 2026
Merged

Use JSON grammar constants as much as possible in the parser #2245

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3 changes: 3 additions & 0 deletions src/core/json/grammar.h
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Original file line number Diff line number Diff line change
Expand Up @@ -72,14 +72,17 @@ static constexpr CharT token_object_delimiter{'\u002C'};
// https://www.ecma-international.org/wp-content/uploads/ECMA-404_2nd_edition_december_2017.pdf

// Boolean
template <typename CharT> static constexpr CharT token_true{'\u0074'};
template <typename CharT, typename Traits>
static constexpr std::basic_string_view<CharT, Traits> constant_true{
"\u0074\u0072\u0075\u0065"};
template <typename CharT> static constexpr CharT token_false{'\u0066'};
template <typename CharT, typename Traits>
static constexpr std::basic_string_view<CharT, Traits> constant_false{
"\u0066\u0061\u006C\u0073\u0065"};

// Null
template <typename CharT> static constexpr CharT token_null{'\u006E'};
template <typename CharT, typename Traits>
static constexpr std::basic_string_view<CharT, Traits> constant_null{
"\u006E\u0075\u006C\u006C"};
Expand Down
152 changes: 82 additions & 70 deletions src/core/json/parser.h
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Original file line number Diff line number Diff line change
Expand Up @@ -229,9 +229,11 @@ inline auto scan_string_escape(const std::uint64_t line, std::uint64_t &column,
template <bool TrackPositions>
inline auto scan_string(const std::uint64_t line, std::uint64_t &column,
const char *&cursor, const char *end) -> void {
using CharT = typename JSON::Char;
while (cursor < end) {
const char *scan{cursor};
while (scan < end && *scan != '"' && *scan != '\\' &&
while (scan < end && *scan != internal::token_string_quote<CharT> &&
*scan != internal::token_string_escape<CharT> &&
static_cast<unsigned char>(*scan) >= 0x20) {
scan++;
}
Expand Down Expand Up @@ -276,8 +278,10 @@ template <bool TrackPositions>
inline auto scan_digits(const std::uint64_t line, std::uint64_t &column,
const char *&cursor, const char *end,
const bool at_least_one) -> void {
using CharT = typename JSON::Char;
bool found{false};
while (cursor < end && *cursor >= '0' && *cursor <= '9') {
while (cursor < end && *cursor >= internal::token_number_zero<CharT> &&
*cursor <= internal::token_number_nine<CharT>) {
found = true;
if constexpr (TrackPositions) {
column += 1;
Expand All @@ -296,25 +300,29 @@ template <bool TrackPositions>
inline auto scan_number(const std::uint64_t line, std::uint64_t &column,
const char *&cursor, const char *end, const char first)
-> void {
if (first == '-') {
if (cursor >= end || *cursor < '0' || *cursor > '9') {
using CharT = typename JSON::Char;
if (first == internal::token_number_minus<CharT>) {
if (cursor >= end || *cursor < internal::token_number_zero<CharT> ||
*cursor > internal::token_number_nine<CharT>) {
if constexpr (TrackPositions) {
column += 1;
}
throw JSONParseError(line, column);
}
}

const char int_start{first == '-' ? *cursor : first};
if (first == '-') {
const char int_start{first == internal::token_number_minus<CharT> ? *cursor
: first};
if (first == internal::token_number_minus<CharT>) {
if constexpr (TrackPositions) {
column += 1;
}
cursor++;
}

if (int_start == '0') {
if (cursor < end && *cursor >= '0' && *cursor <= '9') {
if (int_start == internal::token_number_zero<CharT>) {
if (cursor < end && *cursor >= internal::token_number_zero<CharT> &&
*cursor <= internal::token_number_nine<CharT>) {
if constexpr (TrackPositions) {
column += 1;
}
Expand All @@ -324,20 +332,23 @@ inline auto scan_number(const std::uint64_t line, std::uint64_t &column,
scan_digits<TrackPositions>(line, column, cursor, end, false);
}

if (cursor < end && *cursor == '.') {
if (cursor < end && *cursor == internal::token_number_decimal_point<CharT>) {
if constexpr (TrackPositions) {
column += 1;
}
cursor++;
scan_digits<TrackPositions>(line, column, cursor, end, true);
}

if (cursor < end && (*cursor == 'e' || *cursor == 'E')) {
if (cursor < end &&
(*cursor == internal::token_number_exponent_lowercase<CharT> ||
*cursor == internal::token_number_exponent_uppercase<CharT>)) {
if constexpr (TrackPositions) {
column += 1;
}
cursor++;
if (cursor < end && (*cursor == '+' || *cursor == '-')) {
if (cursor < end && (*cursor == internal::token_number_plus<CharT> ||
*cursor == internal::token_number_minus<CharT>)) {
if constexpr (TrackPositions) {
column += 1;
}
Expand All @@ -361,6 +372,7 @@ inline auto scan_json(const char *&cursor, const char *end,
std::uint32_t child_count;
};

using CharT = typename JSON::Char;
char character = 0;
std::vector<ContainerFrame> container_stack;
container_stack.reserve(32);
Expand All @@ -381,19 +393,19 @@ inline auto scan_json(const char *&cursor, const char *end,
const auto value_line{line};
const auto value_column{column};
switch (character) {
case 't':
case internal::token_true<CharT>:
internal::scan_true<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::True, 0, 0, 0, value_line, value_column});
return;
case 'f':
case internal::token_false<CharT>:
internal::scan_false<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::False, 0, 0, 0, value_line, value_column});
return;
case 'n':
case internal::token_null<CharT>:
internal::scan_null<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::Null, 0, 0, 0, value_line, value_column});
return;
case '"': {
case internal::token_string_quote<CharT>: {
const auto string_start{
static_cast<std::uint32_t>(cursor - buffer_start)};
internal::scan_string<TrackPositions>(line, column, cursor, end);
Expand All @@ -403,21 +415,21 @@ inline auto scan_json(const char *&cursor, const char *end,
value_line, value_column});
return;
}
case '[':
case internal::token_array_begin<CharT>:
goto do_scan_array;
case '{':
case internal::token_object_begin<CharT>:
goto do_scan_object;
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9': {
case internal::token_number_minus<CharT>:
case internal::token_number_zero<CharT>:
case internal::token_number_one<CharT>:
case internal::token_number_two<CharT>:
case internal::token_number_three<CharT>:
case internal::token_number_four<CharT>:
case internal::token_number_five<CharT>:
case internal::token_number_six<CharT>:
case internal::token_number_seven<CharT>:
case internal::token_number_eight<CharT>:
case internal::token_number_nine<CharT>: {
const auto number_start{
static_cast<std::uint32_t>(cursor - buffer_start - 1)};
internal::scan_number<TrackPositions>(line, column, cursor, end,
Expand Down Expand Up @@ -450,7 +462,7 @@ do_scan_array: {
throw JSONParseError(line, column);
}

if (*cursor == ']') {
if (*cursor == internal::token_array_end<CharT>) {
if constexpr (TrackPositions) {
column += 1;
}
Expand Down Expand Up @@ -484,23 +496,23 @@ do_scan_array: {
const auto value_line{line};
const auto value_column{column};
switch (character) {
case '[':
case internal::token_array_begin<CharT>:
goto do_scan_array;
case '{':
case internal::token_object_begin<CharT>:
goto do_scan_object;
case 't':
case internal::token_true<CharT>:
internal::scan_true<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::True, 0, 0, 0, value_line, value_column});
goto do_scan_array_item_separator;
case 'f':
case internal::token_false<CharT>:
internal::scan_false<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::False, 0, 0, 0, value_line, value_column});
goto do_scan_array_item_separator;
case 'n':
case internal::token_null<CharT>:
internal::scan_null<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::Null, 0, 0, 0, value_line, value_column});
goto do_scan_array_item_separator;
case '"': {
case internal::token_string_quote<CharT>: {
const auto string_start{
static_cast<std::uint32_t>(cursor - buffer_start)};
internal::scan_string<TrackPositions>(line, column, cursor, end);
Expand All @@ -510,17 +522,17 @@ do_scan_array: {
value_line, value_column});
goto do_scan_array_item_separator;
}
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9': {
case internal::token_number_minus<CharT>:
case internal::token_number_zero<CharT>:
case internal::token_number_one<CharT>:
case internal::token_number_two<CharT>:
case internal::token_number_three<CharT>:
case internal::token_number_four<CharT>:
case internal::token_number_five<CharT>:
case internal::token_number_six<CharT>:
case internal::token_number_seven<CharT>:
case internal::token_number_eight<CharT>:
case internal::token_number_nine<CharT>: {
const auto number_start{
static_cast<std::uint32_t>(cursor - buffer_start - 1)};
internal::scan_number<TrackPositions>(line, column, cursor, end,
Expand Down Expand Up @@ -549,9 +561,9 @@ do_scan_array: {
}
character = *cursor++;
switch (character) {
case ',':
case internal::token_array_delimiter<CharT>:
goto do_scan_array_item;
case ']': {
case internal::token_array_end<CharT>: {
assert(!container_stack.empty());
auto &frame{container_stack.back()};
tape[frame.tape_index].count = frame.child_count;
Expand Down Expand Up @@ -580,7 +592,7 @@ do_scan_object: {
throw JSONParseError(line, column);
}

if (*cursor == '}') {
if (*cursor == internal::token_object_end<CharT>) {
if constexpr (TrackPositions) {
column += 1;
}
Expand Down Expand Up @@ -610,7 +622,7 @@ do_scan_object: {
}
character = *cursor++;
switch (character) {
case '"': {
case internal::token_string_quote<CharT>: {
const auto key_start{static_cast<std::uint32_t>(cursor - buffer_start)};
const auto key_line{line};
const auto key_column{column};
Expand Down Expand Up @@ -638,7 +650,7 @@ do_scan_object: {
}
character = *cursor++;
switch (character) {
case ':':
case internal::token_object_key_delimiter<CharT>:
goto do_scan_object_value;
default:
throw JSONParseError(line, column);
Expand All @@ -661,23 +673,23 @@ do_scan_object: {
const auto value_line{line};
const auto value_column{column};
switch (character) {
case '[':
case internal::token_array_begin<CharT>:
goto do_scan_array;
case '{':
case internal::token_object_begin<CharT>:
goto do_scan_object;
case 't':
case internal::token_true<CharT>:
internal::scan_true<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::True, 0, 0, 0, value_line, value_column});
goto do_scan_object_property_end;
case 'f':
case internal::token_false<CharT>:
internal::scan_false<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::False, 0, 0, 0, value_line, value_column});
goto do_scan_object_property_end;
case 'n':
case internal::token_null<CharT>:
internal::scan_null<TrackPositions>(line, column, cursor, end);
tape.push_back({TapeType::Null, 0, 0, 0, value_line, value_column});
goto do_scan_object_property_end;
case '"': {
case internal::token_string_quote<CharT>: {
const auto string_start{
static_cast<std::uint32_t>(cursor - buffer_start)};
internal::scan_string<TrackPositions>(line, column, cursor, end);
Expand All @@ -687,17 +699,17 @@ do_scan_object: {
value_line, value_column});
goto do_scan_object_property_end;
}
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9': {
case internal::token_number_minus<CharT>:
case internal::token_number_zero<CharT>:
case internal::token_number_one<CharT>:
case internal::token_number_two<CharT>:
case internal::token_number_three<CharT>:
case internal::token_number_four<CharT>:
case internal::token_number_five<CharT>:
case internal::token_number_six<CharT>:
case internal::token_number_seven<CharT>:
case internal::token_number_eight<CharT>:
case internal::token_number_nine<CharT>: {
const auto number_start{
static_cast<std::uint32_t>(cursor - buffer_start - 1)};
internal::scan_number<TrackPositions>(line, column, cursor, end,
Expand Down Expand Up @@ -726,9 +738,9 @@ do_scan_object: {
}
character = *cursor++;
switch (character) {
case ',':
case internal::token_object_delimiter<CharT>:
goto do_scan_object_key;
case '}': {
case internal::token_object_end<CharT>: {
assert(!container_stack.empty());
auto &frame{container_stack.back()};
tape[frame.tape_index].count = frame.child_count;
Expand Down