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perf(lex): use linear search over regex #514

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Merged
merged 1 commit into from
Jun 16, 2023
Merged

perf(lex): use linear search over regex #514

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72 changes: 37 additions & 35 deletions source/lex.h
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Original file line number Diff line number Diff line change
Expand Up @@ -933,17 +933,19 @@ auto lex_line(
//G any Cpp1-and-Cpp2 keyword
//G one of: 'import' 'module' 'export' 'is' 'as'
//G
auto do_is_keyword = [&](std::regex const& r) {
std::cmatch m;
if (std::regex_search(&line[i], m, r)) {
assert (m.position(0) == 0);
auto do_is_keyword = [&](std::vector<std::string_view> const& r) {
auto remaining_line = std::string_view(line).substr(unsafe_narrow<std::size_t>(i));
auto m = std::find_if(r.begin(), r.end(), [&](std::string_view s) {
return remaining_line.starts_with(s);
});
if (m != r.end()) {
// If we matched and what's next is EOL or a non-identifier char, we matched!
if (
i+m[0].length() == std::ssize(line) // EOL
|| !is_identifier_continue(line[i+m[0].length()]) // non-identifier char
i+std::ssize(*m) == std::ssize(line) // EOL
|| !is_identifier_continue(line[unsafe_narrow<std::size_t>(i)+std::size(*m)]) // non-identifier char
)
{
return static_cast<int>(m[0].length());
return static_cast<int>(std::ssize(*m));
}
}
return 0;
Expand All @@ -955,46 +957,46 @@ auto lex_line(
// reserve all the ones Cpp1 has both for compatibility and to not give up a keyword
// Some keywords like "delete" and "union" are not in this list because we reject them elsewhere
// Cpp2 also adds a couple, notably "is" and "as"
const auto keys = std::regex(
"^alignas|^alignof|^asm|^as|^auto|"
"^bool|^break|"
"^case|^catch|^char16_t|^char32_t|^char8_t|^char|^co_await|^co_return|"
"^co_yield|^concept|^const_cast|^consteval|^constexpr|^constinit|^const|^continue|"
"^decltype|^default|^double|^do|^dynamic_cast|"
"^else|^enum|^explicit|^export|^extern|"
"^float|^for|^friend|"
"^goto|"
"^if|^import|^inline|^int|^is|"
"^long|"
"^module|^mutable|"
"^namespace|^noexcept|"
"^operator|"
"^private|^protected|^public|"
"^register|^reinterpret_cast|^requires|^return|"
"^short|^signed|^sizeof|^static_assert|^static_cast|^static|^switch|"
"^template|^this|^thread_local|^throws|^throw|^try|^typedef|^typeid|^typename|"
"^unsigned|^using|"
"^virtual|^void|^volatile|"
"^wchar_t|^while"
);
static const auto keys = std::vector<std::string_view>{
"alignas", "alignof", "asm", "as", "auto",
"bool", "break",
"case", "catch", "char16_t", "char32_t", "char8_t", "char", "co_await", "co_return",
"co_yield", "concept", "const_cast", "consteval", "constexpr", "constinit", "const", "continue",
"decltype", "default", "double", "do", "dynamic_cast",
"else", "enum", "explicit", "export", "extern",
"float", "for", "friend",
"goto",
"if", "import", "inline", "int", "is",
"long",
"module", "mutable",
"namespace", "noexcept",
"operator",
"private", "protected", "public",
"register", "reinterpret_cast", "requires", "return",
"short", "signed", "sizeof", "static_assert", "static_cast", "static", "switch",
"template", "this", "thread_local", "throws", "throw", "try", "typedef", "typeid", "typename",
"unsigned", "using",
"virtual", "void", "volatile",
"wchar_t", "while"
};

return do_is_keyword(keys);
};

auto peek_is_cpp2_fundamental_type_keyword = [&]
{
const auto keys = std::regex(
"^i8|^i16|^i32|^i64|^longdouble|^longlong|^u8|^u16|^u32|^u64|^ulong|^ulonglong|^ushort"
);
static const auto keys = std::vector<std::string_view>{
"i8", "i16", "i32", "i64", "longdouble", "longlong", "u8", "u16", "u32", "u64", "ulong", "ulonglong", "ushort"
};

return do_is_keyword(keys);
};

auto peek_is_cpp1_multi_token_fundamental_keyword = [&]
{
const auto multi_keys = std::regex(
"^char16_t|^char32_t|^char8_t|^char|^double|^float|^int|^long|^short|^signed|^unsigned"
);
static const auto multi_keys = std::vector<std::string_view>{
"char16_t", "char32_t", "char8_t", "char", "double", "float", "int", "long", "short", "signed", "unsigned"
};
return do_is_keyword(multi_keys);
};

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