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serenity/Userland/Libraries/LibJS/Lexer.h
Timothy Flynn 1259dc3623 LibJS: Allow Unicode escape sequences in identifiers
For example, "property.br\u{64}wn" should resolve to "property.brown".

To support this behavior, this commit changes the Token class to hold
both the evaluated identifier name and a view into the original source
for the unevaluated name. There are some contexts in which identifiers
are not allowed to contain Unicode escape sequences; for example, export
statements of the form "export {} from foo.js" forbid escapes in the
identifier "from".

The test file is added to .prettierignore because prettier will replace
all escaped Unicode sequences with their unescaped value.
2021-08-19 23:49:25 +02:00

90 lines
2.6 KiB
C++

/*
* Copyright (c) 2020, Stephan Unverwerth <s.unverwerth@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include "Token.h"
#include <AK/HashMap.h>
#include <AK/String.h>
#include <AK/StringView.h>
namespace JS {
class Lexer {
public:
explicit Lexer(StringView source, StringView filename = "(unknown)", size_t line_number = 1, size_t line_column = 0);
Token next();
const StringView& source() const { return m_source; };
const StringView& filename() const { return m_filename; };
void disallow_html_comments() { m_allow_html_comments = false; };
Token force_slash_as_regex();
private:
void consume();
bool consume_exponent();
bool consume_octal_number();
bool consume_hexadecimal_number();
bool consume_binary_number();
bool consume_decimal_number();
bool is_unicode_character() const;
u32 current_code_point() const;
bool is_eof() const;
bool is_line_terminator() const;
bool is_whitespace() const;
Optional<u32> is_unicode_escape(size_t& identifier_length) const;
Optional<u32> is_identifier_start(size_t& identifier_length) const;
Optional<u32> is_identifier_middle(size_t& identifier_length) const;
bool is_line_comment_start(bool line_has_token_yet) const;
bool is_block_comment_start() const;
bool is_block_comment_end() const;
bool is_numeric_literal_start() const;
bool match(char, char) const;
bool match(char, char, char) const;
bool match(char, char, char, char) const;
template<typename Callback>
bool match_numeric_literal_separator_followed_by(Callback) const;
bool slash_means_division() const;
TokenType consume_regex_literal();
StringView m_source;
size_t m_position { 0 };
Token m_current_token;
char m_current_char { 0 };
bool m_eof { false };
StringView m_filename;
size_t m_line_number { 1 };
size_t m_line_column { 0 };
bool m_regex_is_in_character_class { false };
struct TemplateState {
bool in_expr;
u8 open_bracket_count;
};
Vector<TemplateState> m_template_states;
bool m_allow_html_comments { true };
static HashMap<String, TokenType> s_keywords;
static HashMap<String, TokenType> s_three_char_tokens;
static HashMap<String, TokenType> s_two_char_tokens;
static HashMap<char, TokenType> s_single_char_tokens;
// Resolved identifiers must be kept alive for the duration of the parsing stage, otherwise
// the only references to these strings are deleted by the Token destructor.
Vector<FlyString> m_parsed_identifiers;
};
}