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ladybird/Libraries/LibJS/Lexer.h

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LibJS: Add Javascript lexer and parser This adds a basic Javascript lexer and parser. It can parse the currently existing demo programs. More work needs to be done to turn it into a complete parser than can parse arbitrary JS Code. The lexer outputs tokens with preceeding whitespace and comments in the trivia member. This should allow us to generate the exact source code by concatenating the generated tokens. The parser is written in a way that it always returns a complete syntax tree. Error conditions are represented as nodes in the tree. This simplifies the code and allows it to be used as an early stage parser, e.g for parsing JS documents in an IDE while editing the source code.:
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/*
* Copyright (c) 2020, Stephan Unverwerth <s.unverwerth@gmx.de>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#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);
LibJS: Allow lexer to run without logging errors
2020-04-05 11:49:25 +00:00
LibJS: Add Javascript lexer and parser This adds a basic Javascript lexer and parser. It can parse the currently existing demo programs. More work needs to be done to turn it into a complete parser than can parse arbitrary JS Code. The lexer outputs tokens with preceeding whitespace and comments in the trivia member. This should allow us to generate the exact source code by concatenating the generated tokens. The parser is written in a way that it always returns a complete syntax tree. Error conditions are represented as nodes in the tree. This simplifies the code and allows it to be used as an early stage parser, e.g for parsing JS documents in an IDE while editing the source code.:
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Token next();
private:
void consume();
LibJS: Add numeric literal parsing for different bases and exponents
2020-04-05 12:20:58 +00:00
void consume_exponent();
LibJS: Add Javascript lexer and parser This adds a basic Javascript lexer and parser. It can parse the currently existing demo programs. More work needs to be done to turn it into a complete parser than can parse arbitrary JS Code. The lexer outputs tokens with preceeding whitespace and comments in the trivia member. This should allow us to generate the exact source code by concatenating the generated tokens. The parser is written in a way that it always returns a complete syntax tree. Error conditions are represented as nodes in the tree. This simplifies the code and allows it to be used as an early stage parser, e.g for parsing JS documents in an IDE while editing the source code.:
2020-03-11 18:27:43 +00:00
bool is_eof() const;
bool is_identifier_start() const;
bool is_identifier_middle() const;
bool is_line_comment_start() const;
bool is_block_comment_start() const;
bool is_block_comment_end() const;
LibJS: Add numeric literal parsing for different bases and exponents
2020-04-05 12:20:58 +00:00
bool is_numeric_literal_start() const;
LibJS: Handle HTML-style comments
2020-04-13 17:50:58 +00:00
bool match(char, char) const;
bool match(char, char, char) const;
bool match(char, char, char, char) const;
LibJS: Add Javascript lexer and parser This adds a basic Javascript lexer and parser. It can parse the currently existing demo programs. More work needs to be done to turn it into a complete parser than can parse arbitrary JS Code. The lexer outputs tokens with preceeding whitespace and comments in the trivia member. This should allow us to generate the exact source code by concatenating the generated tokens. The parser is written in a way that it always returns a complete syntax tree. Error conditions are represented as nodes in the tree. This simplifies the code and allows it to be used as an early stage parser, e.g for parsing JS documents in an IDE while editing the source code.:
2020-03-11 18:27:43 +00:00
StringView m_source;
size_t m_position = 0;
Token m_current_token;
LibJS: Plumb line and column information through Lexer / Parser While debugging test failures, it's pretty frustrating to have to go do printf debugging to figure out what test is failing right now. While watching your JS Raytracer stream it seemed like this was pretty furstrating as well. So I wanted to start working on improving the diagnostics here. In the future I hope we can eventually be able to plumb the info down to the Error classes so any thrown exceptions will contain enough metadata to know where they came from.
2020-04-05 09:34:03 +00:00
int m_current_char = 0;
size_t m_line_number = 1;
size_t m_line_column = 1;
LibJS: Add Javascript lexer and parser This adds a basic Javascript lexer and parser. It can parse the currently existing demo programs. More work needs to be done to turn it into a complete parser than can parse arbitrary JS Code. The lexer outputs tokens with preceeding whitespace and comments in the trivia member. This should allow us to generate the exact source code by concatenating the generated tokens. The parser is written in a way that it always returns a complete syntax tree. Error conditions are represented as nodes in the tree. This simplifies the code and allows it to be used as an early stage parser, e.g for parsing JS documents in an IDE while editing the source code.:
2020-03-11 18:27:43 +00:00
LibJS: Add template literals Adds fully functioning template literals. Because template literals contain expressions, most of the work has to be done in the Lexer rather than the Parser. And because of the complexity of template literals (expressions, nesting, escapes, etc), the Lexer needs to have some template-related state. When entering a new template literal, a TemplateLiteralStart token is emitted. When inside a literal, all text will be parsed up until a '${' or '`' (or EOF, but that's a syntax error) is seen, and then a TemplateLiteralExprStart token is emitted. At this point, the Lexer proceeds as normal, however it keeps track of the number of opening and closing curly braces it has seen in order to determine the close of the expression. Once it finds a matching curly brace for the '${', a TemplateLiteralExprEnd token is emitted and the state is updated accordingly. When the Lexer is inside of a template literal, but not an expression, and sees a '`', this must be the closing grave: a TemplateLiteralEnd token is emitted. The state required to correctly parse template strings consists of a vector (for nesting) of two pieces of information: whether or not we are in a template expression (as opposed to a template string); and the count of the number of unmatched open curly braces we have seen (only applicable if the Lexer is currently in a template expression). TODO: Add support for template literal newlines in the JS REPL (this will cause a syntax error currently): > `foo > bar` 'foo bar'
2020-05-03 22:41:14 +00:00
struct TemplateState {
bool in_expr;
u8 open_bracket_count;
};
Vector<TemplateState> m_template_states;
LibJS: Add Javascript lexer and parser This adds a basic Javascript lexer and parser. It can parse the currently existing demo programs. More work needs to be done to turn it into a complete parser than can parse arbitrary JS Code. The lexer outputs tokens with preceeding whitespace and comments in the trivia member. This should allow us to generate the exact source code by concatenating the generated tokens. The parser is written in a way that it always returns a complete syntax tree. Error conditions are represented as nodes in the tree. This simplifies the code and allows it to be used as an early stage parser, e.g for parsing JS documents in an IDE while editing the source code.:
2020-03-11 18:27:43 +00:00
static HashMap<String, TokenType> s_keywords;
LibJS: Parse === and !== binary operators
2020-03-12 12:11:33 +00:00
static HashMap<String, TokenType> s_three_char_tokens;
LibJS: Add Javascript lexer and parser This adds a basic Javascript lexer and parser. It can parse the currently existing demo programs. More work needs to be done to turn it into a complete parser than can parse arbitrary JS Code. The lexer outputs tokens with preceeding whitespace and comments in the trivia member. This should allow us to generate the exact source code by concatenating the generated tokens. The parser is written in a way that it always returns a complete syntax tree. Error conditions are represented as nodes in the tree. This simplifies the code and allows it to be used as an early stage parser, e.g for parsing JS documents in an IDE while editing the source code.:
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static HashMap<String, TokenType> s_two_char_tokens;
static HashMap<char, TokenType> s_single_char_tokens;
};
}
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