A Lua parser in JavaScript
npm install luaparseA Lua parser written in JavaScript, originally written by Oskar Schöldström for his bachelor's thesis at Arcada.
Install through npm install luaparse.
CommonJS
``js`
var parser = require('luaparse');
var ast = parser.parse('i = 0');
console.log(JSON.stringify(ast));
AMD
`js`
require(['luaparse'], function(parser) {
var ast = parser.parse('i = 0');
console.log(JSON.stringify(ast));
});
Browser
`html`
Basic usage:
`js`
luaparse.parse(code, options);
The output of the parser is an Abstract Syntax Tree (AST) formatted in JSON.
The available options are:
- wait: false Explicitly tell the parser when the input ends.comments: true
- Store comments as an array in the chunk object.scope: false
- Track identifier scopes.locations: false
- Store location information on each syntax node.ranges: false
- Store the start and end character locations on each syntaxonCreateNode: null
node.
- A callback which will be invoked when a syntax nodeonCreateScope: null
has been completed. The node which has been created will be passed as the
only parameter.
- A callback which will be invoked when a new scope isonDestroyScope: null
created.
- A callback which will be invoked when the currentonLocalDeclaration: null
scope is destroyed.
- A callback which will be invoked when a localluaVersion: '5.1'
variable is declared. The identifier will be passed as the only parameter.
- The version of Lua the parser will target; supported'5.1'
values are , '5.2', '5.3' and 'LuaJIT'.extendedIdentifiers: false
- Whether to allow code points ≥ U+0080 inluaVersion: 'LuaJIT'
identifiers, like LuaJIT does. Note: setting
currently does not enable this option; this may change in the future.
- Defines the relation between code points ≥ U+0080
appearing in parser input and raw bytes in source code, and how Lua escape
sequences in JavaScript strings should be interpreted. See the
Encoding modes section below for more information.
The default options are also exposed through luaparse.defaultOptions where
they can be overriden globally.
There is a second interface which might be preferable when using the wait
option.
`js`
var parser = luaparse.parse({ wait: true });
parser.write('foo = "');
parser.write('bar');
var ast = parser.end('"');
This would be identical to:
`js`
var ast = luaparse.parse('foo = "bar"');
If the following code is executed:
`js`
luaparse.parse('foo = "bar"');
then the returned value will be:
`js`
{
"type": "Chunk",
"body": [
{
"type": "AssignmentStatement",
"variables": [
{
"type": "Identifier",
"name": "foo"
}
],
"init": [
{
"type": "StringLiteral",
"value": "bar",
"raw": "\"bar\""
}
]
}
],
"comments": []
}
Unlike strings in JavaScript, Lua strings are not Unicode strings, but
bytestrings (sequences of 8-bit values); likewise, implementations of Lua
parse the source code as a sequence of octets. However, the input to this
parser is a JavaScript string, i.e. a sequence of 16-bit code units (not
necessarily well-formed UTF-16). This poses a problem of how those code
units should be interpreted, particularly if they are outside the Basic
Latin block ('ASCII').
The encodingMode option specifies how these issues should be handled.
Possible values are as follows:
- 'none': Source code characters all pass through as-is and stringnull
literals are not interpreted at all; the string literal nodes contain
the value . This is the default mode.'x-user-defined'
- : Source code has been decoded with the WHATWGx-user-defined
encoding; escapes of bytes in the range \[0x80, 0xff]'pseudo-latin1'
are mapped to the Unicode range \[U+F780, U+F7FF].
- : Source code has been decoded with the IANAiso-8859-1
encoding; escapes of bytes in the range \[0x80, 0xff]iso-8859-1
are mapped to Unicode range \[U+0080, U+00FF]. Note that this is
not the same as how WHATWG standards define the
encoding, which is to say, as a synonym of .
The default AST structure is somewhat inspired by the Mozilla Parser API but
can easily be overriden to customize the structure or to inject custom logic.
luaparse.ast is an object containing all functions used to create the AST, if
you for example wanted to trigger an event on node creations you could use the
following:
`js
var luaparse = require('luaparse'),
events = new (require('events').EventEmitter);
Object.keys(luaparse.ast).forEach(function(type) {
var original = luaparse.ast[type];
luaparse.ast[type] = function() {
var node = original.apply(null, arguments);
events.emit(node.type, node);
return node;
};
});
events.on('Identifier', function(node) { console.log(node); });
luaparse.parse('i = "foo"');
`
_this is only an example to illustrate what is possible and this particular
example might not suit your needs as the end location of the node has not been
determined yet. If you desire events you should use the onCreateNode callback
instead)._
The lexer used by luaparse can be used independently of the recursive descent
parser. The lex function is exposed as luaparse.lex() and it will return theEOF
next token up until is reached.
Each token consists of:
- type expressed as an enum flag which can be matched with luaparse.tokenTypes.value
-
- , lineStart
- can be used to slice out raw values, eg. foo = "bar" will return aStringLiteral token with the value bar. Slicing out the range on the other"bar"
hand will return .
`js`
var parser = luaparse.parse('foo = "bar"', { wait: true });
parser.lex(); // { type: 8, value: "foo", line: 1, lineStart: 0, range: [0, 3] }
parser.lex(); // { type: 32, value: "=", line: 1, lineStart: 0, range: [4, 5]}
parser.lex(); // { type: 2, value: "bar", line: 1, lineStart: 0, range: [6, 11] }
parser.lex(); // { type: 1, value: "
parser.lex(); // { type: 1, value: "
Have a look in the examples directory
of the repository for some code examples or check them out live.
The luaparse executable can be used in your shell by installing luaparse globally using npm:
`bash
$ npm install -g luaparse
$ luaparse --help
Usage: luaparse [option]... [file|code]...
Options:
-c|--code [code] parse code snippet
-f|--file [file] parse from file
-b|--beautify output an indenteted AST
--[no]-comments store comments. defaults to true
--[no]-scope store variable scope. defaults to false
--[no]-locations store location data on syntax nodes. defaults to false
--[no]-ranges store start and end character locations. defaults to false
-q|--quiet suppress output
-h|--help
-v|--version
--verbose
Examples:
luaparse --no-comments -c "locale foo = \"bar\""
luaparse foo.lua bar.lua
`
Example usage
`bash
$ luaparse "i = 0"
{"type":"Chunk","body":[{"type":"AssignmentStatement","variables":[{"type":"Identifier","name":"i"}],"init":[{"type":"NumericLiteral","value":0,"raw":"0"}]}],"comments":[]}
`
Has been tested in at least IE6+, Firefox 3+, Safari 4+, Chrome 10+, Opera 10+,
Node 0.4.0+, RingoJS 0.8-0.9, Rhino 1.7R4-1.7R5, Nashorn 1.8.0.
_TL;DR simply run make qa. This will run all quality assurance scripts but
assumes you have it set up correctly._
Begin by cloning the repository and installing the development dependencies
with npm install.
The luaparse test suite uses testem as a
test runner, and because of this it's very easy to run the tests using
different javascript engines or even on locally installed browsers.
- make test uses node.make testem-engines
- uses node, ringo and rhinomake test-node
1.7R5. This requires that you have the engines installed.
- uses a custom command line reporter to make the outputtestem
easier on the eyes while practicing TDD.
- By installing globally you can also run the tests in a locally
installed browser.
- You can check the function complexity using complexity-report
using make complexity-analysis
- Running will generate the coverage report.make coverage-analysis
To simply check that all code has coverage you can run .make lint
- , make benchmark, make profile.
By running make docs` all documentation
will be generated.
- luamin, a Lua minifier written by Mathias Bynens.
- Ace, an online code editor.
* Initial tests are scaffolded from [yueliang][yueliang] and then manually checked for error.
* Much of the code is based on [LuaMinify][luaminify], the [Lua][lua] source and [Esprima][esprima]. All awesome projects.
MIT
[luaminify]: https://github.com/stravant/LuaMinify
[yueliang]: http://yueliang.luaforge.net/
[lua]: https://www.lua.org
[esprima]: http://esprima.org
[wtf8]: https://simonsapin.github.io/wtf-8/