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LibJS: Avoid DeprecatedString allocation in Token::double_value()

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Instead of allocating a DeprecatedString just so we can call strtoull()
on it, we now collect the relevant token characters in a vector and add
a null terminator manually.

2% speed-up on Kraken/imaging-darkroom.js :^)
This commit is contained in:
Andreas Kling 2023-09-03 18:08:16 +02:00
parent 008b9f4c9f
commit b52cbf673d
1 changed files with 8 additions and 7 deletions
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15
Userland/Libraries/LibJS/Token.cpp
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@ -55,29 +55,30 @@ double Token::double_value() const
{
VERIFY(type() == TokenType::NumericLiteral);
StringBuilder builder;
Vector<char, 32> buffer;
for (auto ch : value()) {
if (ch == '_')
continue;
builder.append(ch);
buffer.append(ch);
}
buffer.append('\0');
auto value_string = builder.to_deprecated_string();
auto value_string = StringView { buffer.data(), buffer.size() - 1 };
if (value_string[0] == '0' && value_string.length() >= 2) {
if (value_string[1] == 'x' || value_string[1] == 'X') {
// hexadecimal
return static_cast<double>(strtoul(value_string.characters() + 2, nullptr, 16));
return static_cast<double>(strtoul(value_string.characters_without_null_termination() + 2, nullptr, 16));
} else if (value_string[1] == 'o' || value_string[1] == 'O') {
// octal
return static_cast<double>(strtoul(value_string.characters() + 2, nullptr, 8));
return static_cast<double>(strtoul(value_string.characters_without_null_termination() + 2, nullptr, 8));
} else if (value_string[1] == 'b' || value_string[1] == 'B') {
// binary
return static_cast<double>(strtoul(value_string.characters() + 2, nullptr, 2));
return static_cast<double>(strtoul(value_string.characters_without_null_termination() + 2, nullptr, 2));
} else if (is_ascii_digit(value_string[1])) {
// also octal, but syntax error in strict mode
if (!value().contains('8') && !value().contains('9'))
return static_cast<double>(strtoul(value_string.characters() + 1, nullptr, 8));
return static_cast<double>(strtoul(value_string.characters_without_null_termination() + 1, nullptr, 8));
}
}
// This should always be a valid double