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LibJS: Handle hex and unicode escape sequences in string literals

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Introduces the following syntax:

'\x55'
'\u26a0'
'\u{1f41e}'
This commit is contained in:
Matthew Olsson 2020-05-16 23:27:25 -07:00 • committed by Andreas Kling
parent b3090678a9
commit e415dd4e9c
5 changed files with 118 additions and 9 deletions
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72
Libraries/LibJS/Token.cpp
View file

@ -27,6 +27,7 @@
#include "Token.h"
#include <AK/Assertions.h>
#include <AK/StringBuilder.h>
#include <AK/Utf32View.h>
#include <ctype.h>
namespace JS {
@ -72,13 +73,26 @@ double Token::double_value() const
return strtod(value_string.characters(), nullptr);
}
String Token::string_value() const
static u32 hex2int(char x)
{
ASSERT(isxdigit(x));
if (x >= '0' && x <= '9')
return x - '0';
return 10u + (tolower(x) - 'a');
}
String Token::string_value(StringValueStatus& status) const
{
ASSERT(type() == TokenType::StringLiteral || type() == TokenType::TemplateLiteralString);
auto is_template = type() == TokenType::TemplateLiteralString;
auto offset = type() == TokenType::TemplateLiteralString ? 0 : 1;
auto encoding_failure = [&status](StringValueStatus parse_status) -> String {
status = parse_status;
return {};
};
StringBuilder builder;
for (size_t i = offset; i < m_value.length() - offset; ++i) {
if (m_value[i] == '\\' && i + 1 < m_value.length() - offset) {
@ -114,14 +128,62 @@ String Token::string_value() const
case '\\':
builder.append('\\');
break;
case 'x': {
if (i + 2 >= m_value.length() - offset)
return encoding_failure(StringValueStatus::MalformedHexEscape);
auto digit1 = m_value[++i];
auto digit2 = m_value[++i];
if (!isxdigit(digit1) || !isxdigit(digit2))
return encoding_failure(StringValueStatus::MalformedHexEscape);
builder.append(static_cast<char>(hex2int(digit1) * 16 + hex2int(digit2)));
break;
}
case 'u': {
if (i + 1 >= m_value.length() - offset)
return encoding_failure(StringValueStatus::MalformedUnicodeEscape);
u32 code_point = m_value[++i];
if (code_point == '{') {
code_point = 0;
do {
if (i + 1 >= m_value.length() - offset)
return encoding_failure(StringValueStatus::MalformedUnicodeEscape);
auto ch = m_value[++i];
if (!isxdigit(ch))
return encoding_failure(StringValueStatus::MalformedUnicodeEscape);
auto new_code_point = (code_point << 4u) | hex2int(ch);
if (new_code_point < code_point)
return encoding_failure(StringValueStatus::UnicodeEscapeOverflow);
code_point = new_code_point;
} while (m_value[i + 1] != '}');
++i;
} else {
if (i + 3 >= m_value.length() - offset || !isxdigit(code_point))
return encoding_failure(StringValueStatus::MalformedUnicodeEscape);
code_point = hex2int(code_point);
for (int j = 0; j < 3; ++j) {
auto ch = m_value[++i];
if (!isxdigit(ch))
return encoding_failure(StringValueStatus::MalformedUnicodeEscape);
code_point = (code_point << 4u) | hex2int(ch);
}
}
builder.append({ &code_point, 1 });
break;
}
default:
if (is_template && (m_value[i] == '$' || m_value[i] == '`')) {
builder.append(m_value[i]);
} else {
// FIXME: Also parse octal, hex and unicode sequences
// should anything else generate a syntax error?
builder.append(m_value[i]);
break;
}
// FIXME: Also parse octal. Should anything else generate a syntax error?
builder.append(m_value[i]);
}
} else {
builder.append(m_value[i]);