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ladybird/Userland/js.cpp

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LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* 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.
*/
js: Take the script file as a command-line argument Now that we have the beginnings of a parser, let's take the script to run as a command-line argument and move all the test scripts into /home/anon/js :^) To run a script, simply use "js": $ js my-script.js To get an AST dump before execution, you can use "js -A"
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#include <AK/ByteBuffer.h>
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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#include <AK/NonnullOwnPtr.h>
js: Take the script file as a command-line argument Now that we have the beginnings of a parser, let's take the script to run as a command-line argument and move all the test scripts into /home/anon/js :^) To run a script, simply use "js": $ js my-script.js To get an AST dump before execution, you can use "js -A"
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#include <LibCore/ArgsParser.h>
#include <LibCore/File.h>
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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#include <LibJS/AST.h>
#include <LibJS/Interpreter.h>
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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#include <LibJS/Parser.h>
LibJS: Add "Heap" and "Runtime" subdirectories Let's try to keep LibJS tidy as it expands. :^)
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#include <LibJS/Runtime/Object.h>
#include <LibJS/Runtime/PrimitiveString.h>
#include <LibJS/Runtime/Value.h>
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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#include <stdio.h>
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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#define PROGRAM 6
js: Make it a little easier to add new AST builder functions
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js: Take the script file as a command-line argument Now that we have the beginnings of a parser, let's take the script to run as a command-line argument and move all the test scripts into /home/anon/js :^) To run a script, simply use "js": $ js my-script.js To get an AST dump before execution, you can use "js -A"
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int main(int argc, char** argv)
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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{
js: Take the script file as a command-line argument Now that we have the beginnings of a parser, let's take the script to run as a command-line argument and move all the test scripts into /home/anon/js :^) To run a script, simply use "js": $ js my-script.js To get an AST dump before execution, you can use "js -A"
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bool dump_ast = false;
const char* script_path = nullptr;
Core::ArgsParser args_parser;
args_parser.add_option(dump_ast, "Dump the AST", "ast-dump", 'A');
args_parser.add_positional_argument(script_path, "Path to script file", "script");
args_parser.parse(argc, argv);
auto file = Core::File::construct(script_path);
if (!file->open(Core::IODevice::ReadOnly)) {
fprintf(stderr, "Failed to open %s: %s\n", script_path, file->error_string());
return 1;
}
auto file_contents = file->read_all();
LibJS: Support "hello friends".length The above snippet is a MemberExpression that necessitates the implicit construction of a StringObject wrapper around a PrimitiveString. We then do a property lookup (a "get") on the StringObject, where we find the "length" property. This is pretty neat! :^)
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JS::Interpreter interpreter;
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 18:42:11 +00:00
js: Take the script file as a command-line argument Now that we have the beginnings of a parser, let's take the script to run as a command-line argument and move all the test scripts into /home/anon/js :^) To run a script, simply use "js": $ js my-script.js To get an AST dump before execution, you can use "js -A"
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auto program = JS::Parser(JS::Lexer(file_contents)).parse_program();
if (dump_ast)
program->dump(0);
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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auto result = interpreter.run(*program);
dbg() << "Interpreter returned " << result;
printf("%s\n", result.to_string().characters());
js: Exercise the garbage collector a little bit
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js: Add another little test AST to exercise marking of locals
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dbg() << "Collecting garbage on exit...";
js: Exercise the garbage collector a little bit
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interpreter.heap().collect_garbage();
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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return 0;
}
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