🔨 small parser performance improvements
- replaced list of pairs by flat list in next_byte_in_range - implemented early exit in case of parse errors - reused memory for object keys - direct calls to embedded objects/arrays for insertions
This commit is contained in:
Niels Lohmann
parent
c819a2d732
commit
7737a29518
1 changed files with 41 additions and 27 deletions
68
src/json.hpp
68
src/json.hpp
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@ -1675,14 +1675,15 @@ class lexer
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@return true iff no range violation was detected
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@return true iff no range violation was detected
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*/
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*/
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bool next_byte_in_range(std::initializer_list<std::pair<int, int>> ranges)
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bool next_byte_in_range(std::initializer_list<int> ranges)
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{
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{
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assert(ranges.size() == 2 or ranges.size() == 4 or ranges.size() == 6);
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add(current);
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add(current);
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for (const auto& range : ranges)
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for (auto range = ranges.begin(); range != ranges.end(); ++range)
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{
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{
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get();
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get();
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if (JSON_LIKELY(range.first <= current and current <= range.second))
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if (JSON_LIKELY(*range <= current and current <= *(++range)))
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{
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{
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add(current);
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add(current);
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}
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}
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@ -2053,7 +2054,7 @@ class lexer
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case 0xde:
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case 0xde:
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case 0xdf:
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case 0xdf:
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{
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{
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if (JSON_UNLIKELY(not next_byte_in_range({{0x80, 0xBF}})))
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if (JSON_UNLIKELY(not next_byte_in_range({0x80, 0xBF})))
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{
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{
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return token_type::parse_error;
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return token_type::parse_error;
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}
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}
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@ -2063,7 +2064,7 @@ class lexer
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// U+0800..U+0FFF: bytes E0 A0..BF 80..BF
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// U+0800..U+0FFF: bytes E0 A0..BF 80..BF
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case 0xe0:
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case 0xe0:
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{
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{
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if (JSON_UNLIKELY(not (next_byte_in_range({{0xA0, 0xBF}, {0x80, 0xBF}}))))
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if (JSON_UNLIKELY(not (next_byte_in_range({0xA0, 0xBF, 0x80, 0xBF}))))
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{
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{
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return token_type::parse_error;
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return token_type::parse_error;
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}
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}
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@ -2087,7 +2088,7 @@ class lexer
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case 0xee:
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case 0xee:
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case 0xef:
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case 0xef:
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{
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{
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if (JSON_UNLIKELY(not (next_byte_in_range({{0x80, 0xBF}, {0x80, 0xBF}}))))
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if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF}))))
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{
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{
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return token_type::parse_error;
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return token_type::parse_error;
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}
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}
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@ -2097,7 +2098,7 @@ class lexer
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// U+D000..U+D7FF: bytes ED 80..9F 80..BF
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// U+D000..U+D7FF: bytes ED 80..9F 80..BF
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case 0xed:
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case 0xed:
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{
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{
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if (JSON_UNLIKELY(not (next_byte_in_range({{0x80, 0x9F}, {0x80, 0xBF}}))))
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if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x9F, 0x80, 0xBF}))))
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{
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{
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return token_type::parse_error;
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return token_type::parse_error;
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}
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}
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@ -2107,7 +2108,7 @@ class lexer
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// U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
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// U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
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case 0xf0:
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case 0xf0:
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{
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{
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if (JSON_UNLIKELY(not (next_byte_in_range({{0x90, 0xBF}, {0x80, 0xBF}, {0x80, 0xBF}}))))
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if (JSON_UNLIKELY(not (next_byte_in_range({0x90, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
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{
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{
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return token_type::parse_error;
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return token_type::parse_error;
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}
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}
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@ -2119,7 +2120,7 @@ class lexer
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case 0xf2:
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case 0xf2:
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case 0xf3:
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case 0xf3:
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{
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{
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if (JSON_UNLIKELY(not (next_byte_in_range({{0x80, 0xBF}, {0x80, 0xBF}, {0x80, 0xBF}}))))
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if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
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{
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{
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return token_type::parse_error;
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return token_type::parse_error;
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}
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}
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@ -2129,7 +2130,7 @@ class lexer
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// U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
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// U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
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case 0xf4:
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case 0xf4:
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{
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{
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if (JSON_UNLIKELY(not (next_byte_in_range({{0x80, 0x8F}, {0x80, 0xBF}, {0x80, 0xBF}}))))
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if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x8F, 0x80, 0xBF, 0x80, 0xBF}))))
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{
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{
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return token_type::parse_error;
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return token_type::parse_error;
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}
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}
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@ -2166,12 +2167,11 @@ class lexer
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This function scans a string according to Sect. 6 of RFC 7159.
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This function scans a string according to Sect. 6 of RFC 7159.
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The function is realized with a deterministic finite state machine
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The function is realized with a deterministic finite state machine derived
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derived from the grammar described in RFC 7159. Starting in state
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from the grammar described in RFC 7159. Starting in state "init", the
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"init", the input is read and used to determined the next state. Only
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input is read and used to determined the next state. Only state "done"
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state "done" accepts the number. State "error" is a trap state to model
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accepts the number. State "error" is a trap state to model errors. In the
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errors. In the table below, "anything" means any character but the ones
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table below, "anything" means any character but the ones listed before.
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listed before.
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state | 0 | 1-9 | e E | + | - | . | anything
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state | 0 | 1-9 | e E | + | - | . | anything
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---------|----------|----------|----------|---------|---------|----------|-----------
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---------|----------|----------|----------|---------|---------|----------|-----------
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@ -2486,8 +2486,8 @@ scan_number_any2:
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}
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}
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scan_number_done:
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scan_number_done:
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// unget the character after the number (we only read it to know that we
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// unget the character after the number (we only read it to know that
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// are done scanning a number)
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// we are done scanning a number)
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--chars_read;
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--chars_read;
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next_unget = true;
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next_unget = true;
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@ -2886,6 +2886,9 @@ class parser
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*/
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*/
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void parse_internal(bool keep, BasicJsonType& result)
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void parse_internal(bool keep, BasicJsonType& result)
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{
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{
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// never parse after a parse error was detected
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assert(not errored);
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// start with a discarded value
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// start with a discarded value
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if (not result.is_discarded())
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if (not result.is_discarded())
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{
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{
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@ -2919,6 +2922,7 @@ class parser
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}
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}
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// parse values
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// parse values
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std::string key;
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BasicJsonType value;
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BasicJsonType value;
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while (true)
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while (true)
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{
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{
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@ -2927,7 +2931,7 @@ class parser
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{
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{
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return;
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return;
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}
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}
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const auto key = m_lexer.get_string();
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key = m_lexer.get_string();
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bool keep_tag = false;
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bool keep_tag = false;
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if (keep)
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if (keep)
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@ -2955,9 +2959,15 @@ class parser
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value.m_value.destroy(value.m_type);
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value.m_value.destroy(value.m_type);
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value.m_type = value_t::discarded;
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value.m_type = value_t::discarded;
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parse_internal(keep, value);
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parse_internal(keep, value);
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if (JSON_UNLIKELY(errored))
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{
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return;
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}
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if (keep and keep_tag and not value.is_discarded())
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if (keep and keep_tag and not value.is_discarded())
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{
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{
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result[key] = std::move(value);
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result.m_value.object->operator[](std::move(key)) = std::move(value);
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}
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}
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// comma -> next value
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// comma -> next value
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@ -3015,9 +3025,15 @@ class parser
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value.m_value.destroy(value.m_type);
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value.m_value.destroy(value.m_type);
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value.m_type = value_t::discarded;
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value.m_type = value_t::discarded;
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parse_internal(keep, value);
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parse_internal(keep, value);
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if (JSON_UNLIKELY(errored))
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{
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return;
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}
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if (keep and not value.is_discarded())
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if (keep and not value.is_discarded())
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{
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{
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result.push_back(std::move(value));
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result.m_value.array->push_back(std::move(value));
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}
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}
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// comma -> next value
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// comma -> next value
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@ -4405,8 +4421,7 @@ class binary_reader
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@param[in] adapter input adapter to read from
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@param[in] adapter input adapter to read from
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*/
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*/
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explicit binary_reader(input_adapter_t adapter)
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explicit binary_reader(input_adapter_t adapter) : ia(adapter)
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: ia(adapter), is_little_endian(little_endianess())
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{
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{
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assert(ia);
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assert(ia);
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}
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}
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@ -5526,7 +5541,7 @@ class binary_reader
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std::size_t chars_read = 0;
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std::size_t chars_read = 0;
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/// whether we can assume little endianess
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/// whether we can assume little endianess
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const bool is_little_endian = true;
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const bool is_little_endian = little_endianess();
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};
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};
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/*!
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/*!
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@ -5541,8 +5556,7 @@ class binary_writer
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@param[in] adapter output adapter to write to
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@param[in] adapter output adapter to write to
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*/
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*/
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explicit binary_writer(output_adapter_t<CharType> adapter)
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explicit binary_writer(output_adapter_t<CharType> adapter) : oa(adapter)
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: is_little_endian(binary_reader<BasicJsonType>::little_endianess()), oa(adapter)
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{
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{
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assert(oa);
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assert(oa);
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}
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}
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@ -6067,7 +6081,7 @@ class binary_writer
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private:
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private:
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/// whether we can assume little endianess
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/// whether we can assume little endianess
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const bool is_little_endian = true;
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const bool is_little_endian = binary_reader<BasicJsonType>::little_endianess();
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/// the output
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/// the output
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output_adapter_t<CharType> oa = nullptr;
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output_adapter_t<CharType> oa = nullptr;
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