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LibJS: Avoid creating temporary Strings to look up tokens while lexing

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It would be cool to solve this in a general way so that looking up
a string literal or StringView in a HashMap with String keys avoids
creating a temp string.

For now, this patch simply addresses the issue in JS::Lexer.
This is a 2-3% speed-up on test-js.
This commit is contained in:
Andreas Kling 2020-10-17 23:44:41 +02:00
parent d3dfd55472
commit d8269c343c
Notes: sideshowbarker 2024-07-19 01:52:00 +09:00
1 changed files with 5 additions and 3 deletions
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8
Libraries/LibJS/Lexer.cpp
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@ -347,7 +347,7 @@ Token Lexer::next()
} while (is_identifier_middle());
StringView value = m_source.substring_view(value_start - 1, m_position - value_start);
auto it = s_keywords.find(value);
auto it = s_keywords.find(value.hash(), [&](auto& entry) { return entry.key == value; });
if (it == s_keywords.end()) {
token_type = TokenType::Identifier;
} else {
@ -465,7 +465,8 @@ Token Lexer::next()
char second_char = m_source[m_position];
char third_char = m_source[m_position + 1];
char three_chars[] { (char)m_current_char, second_char, third_char, 0 };
auto it = s_three_char_tokens.find(three_chars);
StringView three_chars_view { three_chars };
auto it = s_three_char_tokens.find(three_chars_view.hash(), [&](auto& entry) { return entry.key == three_chars_view; });
if (it != s_three_char_tokens.end()) {
found_three_char_token = true;
consume();
@ -479,7 +480,8 @@ Token Lexer::next()
if (!found_four_char_token && !found_three_char_token && m_position < m_source.length()) {
char second_char = m_source[m_position];
char two_chars[] { (char)m_current_char, second_char, 0 };
auto it = s_two_char_tokens.find(two_chars);
StringView two_chars_view = { two_chars };
auto it = s_two_char_tokens.find(two_chars_view.hash(), [&](auto& entry) { return entry.key == two_chars_view; });
if (it != s_two_char_tokens.end()) {
found_two_char_token = true;
consume();