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Various parsers for ECMA standards.
| ویژگی | مقدار |
|---|---|
| سیستم عامل | - |
| نام فایل | calmjs.parse-1.3.0 |
| نام | calmjs.parse |
| نسخه کتابخانه | 1.3.0 |
| نگهدارنده | [] |
| ایمیل نگهدارنده | [] |
| نویسنده | Tommy Yu |
| ایمیل نویسنده | tommy.yu@auckland.ac.nz |
| آدرس صفحه اصلی | https://github.com/calmjs/calmjs.parse |
| آدرس اینترنتی | https://pypi.org/project/calmjs.parse/ |
| مجوز | mit |
calmjs.parse
============
A collection of parsers and helper libraries for understanding
ECMAScript; a near feature complete fork of |slimit|_. A CLI front-end
for this package is shipped separately as |crimp|_.
.. image:: https://github.com/calmjs/calmjs.parse/actions/workflows/build.yml/badge.svg?branch=1.3.0
:target: https://github.com/calmjs/calmjs.parse/actions/workflows/build.yml?query=branch:1.3.0
.. image:: https://ci.appveyor.com/api/projects/status/5dj8dnu9gmj02msu/branch/1.3.0?svg=true
:target: https://ci.appveyor.com/project/metatoaster/calmjs-parse/branch/1.3.0
.. image:: https://coveralls.io/repos/github/calmjs/calmjs.parse/badge.svg?branch=1.3.0
:target: https://coveralls.io/github/calmjs/calmjs.parse?branch=1.3.0
.. |calmjs.parse| replace:: ``calmjs.parse``
.. |crimp| replace:: ``crimp``
.. |ply| replace:: ``ply``
.. |slimit| replace:: ``slimit``
.. _crimp: https://pypi.python.org/pypi/crimp
.. _ply: https://pypi.python.org/pypi/ply
.. _slimit: https://pypi.python.org/pypi/slimit
Introduction
------------
For any kind of build system that operates with JavaScript code in
conjunction with a module system, the ability to understand what modules
a given set of sources require or provide is paramount. As the Calmjs
project provides a framework that produces and consume these module
definitions, the the ability to have a comprehensive understanding of
given JavaScript sources is a given. This goal was originally achieved
using |slimit|_, a JavaScript minifier library that also provided a
comprehensive parser class that was built using Python Lex-Yacc (i.e.
|ply|_).
However, as of mid-2017, it was noted that |slimit| remained in a
minimum state of maintenance for more than four years (its most recent
release, 0.8.1, was made 2013-03-26), along with a number of serious
outstanding issues have left unattended and unresolved for the duration
of that time span. As the development of the Calmjs framework require
those issues to be rectified as soon as possible, a decision to fork the
parser portion of |slimit| was made. This was done in order to cater to
the interests current to Calmjs project at that moment in time.
The fork was initial cut from another fork of |slimit| (specifically
`lelit/slimit <https://github.com/lelit/slimit>`_), as it introduced and
aggregated a number of bug fixes from various sources. To ensure a
better quality control and assurance, a number of problematic changes
introduced by that fork were removed. Also, new tests were created to
bring coverage to full, and issues reported on the |slimit| tracker were
noted and formalized into test cases where applicable. Finally, grammar
rules were updated to ensure better conformance with the ECMA-262 (ES5)
specification.
The goal of |calmjs.parse| is to provide a similar API that |slimit| had
provided, except done in a much more extensible manner with more
correctness checks in place. This however resulted in some operations
that might take longer than what |slimit| had achieved, such as the
pretty printing of output.
A CLI front-end that makes use of this package is provided through
|crimp|_.
Installation
------------
The following command may be executed to source the latest stable
version of |calmjs.parse| wheel from PyPI for installation into the
current Python environment.
.. code:: console
$ pip install calmjs.parse
As this package uses |ply|, it requires the generation of optimization
modules for its lexer. The wheel distribution of |calmjs.parse| does
not require this extra step as it contains these pre-generated modules
for |ply| up to version 3.11 (the latest version available at the time
of previous release), however the source tarball or if |ply| version
that is installed lies outside of the supported versions, the following
caveats will apply.
If a more recent release of |ply| becomes available and the environment
upgrades to that version, those pre-generated modules may become
incompatible, which may result in a decreased performance and/or errors.
A corrective action can be achieved through a `manual optimization`_
step if a newer version of |calmjs.parse| is not available, or |ply| may
be downgraded back to version 3.11 if possible.
Once the package is installed, the installation may be `tested`_ or be
`used directly`_.
Alternative installation methods (for developers, advanced users)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Development is still ongoing with |calmjs.parse|, for the latest
features and bug fixes, the development version may be installed through
git like so:
.. code:: console
$ pip install git+https://github.com/calmjs/calmjs.parse.git#egg=calmjs.parse
Alternatively, the git repository can be cloned directly and execute
``python setup.py develop`` while inside the root of the source
directory.
A manual optimization step may need to be performed for platforms and
systems that do not have utf8 as their default encoding.
Manual optimization
~~~~~~~~~~~~~~~~~~~
As lex and yacc require the generation of symbol tables, a way to
optimize the performance is to cache the results. For |ply|, this is
done using an auto-generated module. However, the generated file is
marked with a version number, as the results may be specific to the
installed version of |ply|. In |calmjs.parse| this is handled by giving
them a name specific to the version of |ply| and the major Python
version, as both together does result in subtle differences in the
outputs and expectations of the auto-generated modules.
Typically, the process for this optimization is automatic and a correct
symbol table will be generated, however there are cases where this will
fail, so for this reason |calmjs.parse| provide a helper module and
executable that can be optionally invoked to ensure that the correct
encoding be used to generate that file. Other reasons where this may be
necessary is to allow system administrators to do so for their end
users, as they may not have write privileges at that level.
To execute the optimizer from the shell, the provided helper script may
be used like so:
.. code:: console
$ python -m calmjs.parse.parsers.optimize
If warnings appear that warn that tokens are defined but not used, they
may be safely ignored.
This step is generally optionally for users who installed this package
from PyPI via a Python wheel, provided the caveats as outlined in the
installation section are addressed.
.. _tested:
Testing the installation
~~~~~~~~~~~~~~~~~~~~~~~~
To ensure that the |calmjs.parse| installation is functioning correctly,
the built-in testsuite can be executed by the following:
.. code:: console
$ python -m unittest calmjs.parse.tests.make_suite
If there are failures, please file an issue on the `issue tracker
<https://github.com/calmjs/calmjs.parse/issues>`_ with the full
traceback, and/or the method of installation. Please also include
applicable information about the environment, such as the version of
this software, Python version, operating system environments, the
version of |ply| that was installed, plus other information related to
the issue at hand.
Usage
-----
.. _used directly:
As this is a parser library, no executable shell commands are provided.
There is however a helper callable object provided at the top level for
immediate access to the parsing feature. It may be used like so:
.. code:: pycon
>>> from calmjs.parse import es5
>>> program_source = '''
... // simple program
... var main = function(greet) {
... var hello = "hello " + greet;
... return hello;
... };
... console.log(main('world'));
... '''
>>> program = es5(program_source)
>>> # for a simple repr-like nested view of the ast
>>> program # equivalent to repr(program)
<ES5Program @3:1 ?children=[
<VarStatement @3:1 ?children=[
<VarDecl @3:5 identifier=<Identifier ...>, initializer=<FuncExpr ...>>
]>,
<ExprStatement @7:1 expr=<FunctionCall @7:1 args=<Arguments ...>,
identifier=<DotAccessor ...>>>
]>
>>> # automatic reconstruction of ast into source, without having to
>>> # call something like `.to_ecma()`
>>> print(program) # equivalent to str(program)
var main = function(greet) {
var hello = "hello " + greet;
return hello;
};
console.log(main('world'));
>>>
Please note the change in indentation as the default printer has its own
indentation scheme. If comments are needed, the parser can be called
using ``with_comments=True``:
.. code:: pycon
>>> program_wc = es5(program_source, with_comments=True)
>>> print(program_wc)
// simple program
var main = function(greet) {
var hello = "hello " + greet;
return hello;
};
console.log(main('world'));
>>>
Also note that there are limitations with the capturing of comments as
documented in the `Limitations`_ section.
The parser classes are organized under the ``calmjs.parse.parsers``
module, with each language being under their own module. A
corresponding lexer class with the same name is also provided under the
``calmjs.parse.lexers`` module. For the moment, only ES5 support is
implemented.
Pretty/minified printing
~~~~~~~~~~~~~~~~~~~~~~~~
There is also a set of pretty printing helpers for turning the AST back
into a string. These are available as functions or class constructors,
and are produced by composing various lower level classes available in
the ``calmjs.parse.unparsers`` and related modules.
There is a default short-hand helper for turning the previously produced
AST back into a string, which can be manually invoked with certain
parameters, such as what characters to use for indentation: (note that
the ``__str__`` call implicitly invoked through ``print`` shown
previously is implemented through this).
.. code:: pycon
>>> from calmjs.parse.unparsers.es5 import pretty_print
>>> print(pretty_print(program, indent_str=' '))
var main = function(greet) {
var hello = "hello " + greet;
return hello;
};
console.log(main('world'));
>>>
There is also one for printing without any unneeded whitespaces, works
as a source minifier:
.. code:: pycon
>>> from calmjs.parse.unparsers.es5 import minify_print
>>> print(minify_print(program))
var main=function(greet){var hello="hello "+greet;return hello;};...
>>> print(minify_print(program, obfuscate=True, obfuscate_globals=True))
var a=function(b){var a="hello "+b;return a;};console.log(a('world'));
Note that in the second example, the ``obfuscate_globals`` option was
only enabled to demonstrate the source obfuscation on the global scope,
and this is generally not an option that should be enabled on production
library code that is meant to be reused by other packages (other sources
referencing the original unobfuscated names will be unable to do so).
Alternatively, direct invocation on a raw string can be done using the
attributes provided under the same name as the above base objects that
were imported initially. Relevant keyword arguments would be diverted
to the appropriate underlying functions, for example:
.. code:: pycon
>>> # pretty print without comments being parsed
>>> print(es5.pretty_print(program_source))
var main = function(greet) {
var hello = "hello " + greet;
return hello;
};
console.log(main('world'));
>>> # pretty print with comments parsed
>>> print(es5.pretty_print(program_source, with_comments=True))
// simple program
var main = function(greet) {
var hello = "hello " + greet;
return hello;
};
console.log(main('world'));
>>> # minify print
>>> print(es5.minify_print(program_source, obfuscate=True))
var main=function(b){var a="hello "+b;return a;};console.log(main('world'));
Source map generation
~~~~~~~~~~~~~~~~~~~~~
For the generation of source maps, a lower level unparser instance can
be constructed through one of the printer factory functions. Passing
in an AST node will produce a generator which produces tuples containing
the yielded text fragment, plus other information which will aid in the
generation of source maps. There are helper functions from the
``calmjs.parse.sourcemap`` module can be used like so to write the
regenerated source code to some stream, along with processing the
results into a sourcemap file. An example:
.. code:: pycon
>>> import json
>>> from io import StringIO
>>> from calmjs.parse.unparsers.es5 import pretty_printer
>>> from calmjs.parse.sourcemap import encode_sourcemap, write
>>> stream_p = StringIO()
>>> print_p = pretty_printer()
>>> rawmap_p, _, names_p = write(print_p(program), stream_p)
>>> sourcemap_p = encode_sourcemap(
... 'demo.min.js', rawmap_p, ['custom_name.js'], names_p)
>>> print(json.dumps(sourcemap_p, indent=2, sort_keys=True))
{
"file": "demo.min.js",
"mappings": "AAEA;IACI;IACA;AACJ;AACA;",
"names": [],
"sources": [
"custom_name.js"
],
"version": 3
}
>>> print(stream_p.getvalue())
var main = function(greet) {
...
Likewise, this works similarly for the minify printer, which provides
the ability to create out a minified output with unneeded whitespaces
removed and identifiers obfuscated with the shortest possible value.
Note that in previous example, the second return value in the write
method was not used and that a custom value was passed in. This is
simply due to how the ``program`` was generated from a string and thus
the ``sourcepath`` attribute was not assigned with a usable value for
populating the ``"sources"`` list in the resulting source map. For the
following example, assign a value to that attribute on the program
directly.
.. code:: pycon
>>> from calmjs.parse.unparsers.es5 import minify_printer
>>> program.sourcepath = 'demo.js' # say this was opened there
>>> stream_m = StringIO()
>>> print_m = minify_printer(obfuscate=True, obfuscate_globals=True)
>>> sourcemap_m = encode_sourcemap(
... 'demo.min.js', *write(print_m(program), stream_m))
>>> print(json.dumps(sourcemap_m, indent=2, sort_keys=True))
{
"file": "demo.min.js",
"mappings": "AAEA,IAAIA,CAAK,CAAE,SAASC,CAAK,CAAE,CACvB,...,YAAYF,CAAI",
"names": [
"main",
"greet",
"hello"
],
"sources": [
"demo.js"
],
"version": 3
}
>>> print(stream_m.getvalue())
var a=function(b){var a="hello "+b;return a;};console.log(a('world'));
A high level API for working with named streams (i.e. opened files, or
stream objects like ``io.StringIO`` assigned with a name attribute) is
provided by the ``read`` and ``write`` functions from ``io`` module.
The following example shows how to use the function to read from a
stream and write out the relevant items back out to the write only
streams:
.. code:: pycon
>>> from calmjs.parse import io
>>> h4_program_src = open('/tmp/html4.js')
>>> h4_program_min = open('/tmp/html4.min.js', 'w+')
>>> h4_program_map = open('/tmp/html4.min.js.map', 'w+')
>>> h4_program = io.read(es5, h4_program_src)
>>> print(h4_program)
var bold = function(s) {
return '<b>' + s + '</b>';
};
var italics = function(s) {
return '<i>' + s + '</i>';
};
>>> io.write(print_m, h4_program, h4_program_min, h4_program_map)
>>> pos = h4_program_map.seek(0)
>>> print(h4_program_map.read())
{"file": "html4.min.js", "mappings": ..., "version": 3}
>>> pos = h4_program_min.seek(0)
>>> print(h4_program_min.read())
var b=function(a){return'<b>'+a+'</b>';};var a=function(a){...};
//# sourceMappingURL=html4.min.js.map
For a simple concatenation of multiple sources into one file, along with
inline source map (i.e. where the sourceMappingURL is a ``data:`` URL of
the base64 encoding of the JSON string), the following may be done:
.. code:: pycon
>>> files = [open('/tmp/html4.js'), open('/tmp/legacy.js')]
>>> combined = open('/tmp/combined.js', 'w+')
>>> io.write(print_p, (io.read(es5, f) for f in files), combined, combined)
>>> pos = combined.seek(0)
>>> print(combined.read())
var bold = function(s) {
return '<b>' + s + '</b>';
};
var italics = function(s) {
return '<i>' + s + '</i>';
};
var marquee = function(s) {
return '<marquee>' + s + '</marquee>';
};
var blink = function(s) {
return '<blink>' + s + '</blink>';
};
//# sourceMappingURL=data:application/json;base64;...
In this example, the ``io.write`` function was provided with the pretty
unparser, an generator expression that will produce the two ASTs from
the two source files, and then both the target and sourcemap argument
are identical, which forces the source map generator to generate the
base64 encoding.
Do note that if multiple ASTs were supplied to a minifying printer with
globals being obfuscated, the resulting script will have the earlier
obfuscated global names mangled by later ones, as the unparsing is done
separately by the ``io.write`` function.
Extract an AST to a ``dict``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To assist with extracting values from an ast into a ``dict``, the
``calmjs.parse.unparsers.extractor`` module provides an ``ast_to_dict``
helper function to aid with that. This function will accept any valid
ast that was parsed as the argument,
.. code:: pycon
>>> from calmjs.parse.unparsers.extractor import ast_to_dict
>>> configuration = es5('''
... var config = module.exports = {};
...
... var name = "Morgan"
... msg = "Hello, " + name + "! " + "Welcome to the host.";
...
... config.server = {
... host: '0.0.0.0',
... port: process.env.PORT || 8000,
... threads: 4 + 4,
... columns: ['id', 'name', 'description'],
... memory: 1 << 15,
... msg: msg
... };
...
... // default proxy stub
... config.proxy = {
... host: 'localhost',
... port: 8080,
... options: {
... "https": !1,
... "threshold": -100
... }
... };
... ''')
>>> baseconf = ast_to_dict(configuration)
Accessing the values is simply done as a mapping:
.. code:: pycon
>>> print(baseconf['name'])
Morgan
Assignments are bound to the entire expression, i.e. not interpreted
down to individual existing assignments.
.. code:: pycon
>>> baseconf['config']
{}
>>> baseconf['config.server']['columns']
['id', 'name', 'description']
>>> baseconf['config.server']['msg']
'msg'
>>> baseconf['config.proxy']['options']['threshold']
-100
Note that the ``-100`` value involves folding the unary expression with
the ``-`` operator, and by default all other expressions of this type
are simply written back out as is.
.. code:: pycon
>>> baseconf['config.proxy']['options']['https']
'!1'
>>> baseconf['msg']
'"Hello, " + name + "! " + "Welcome to the host."'
>>> baseconf['config.server']['threads']
'4 + 4'
To assist with a more generalized usage, the ``ast_to_dict`` provides an
additional ``fold_ops`` argument. When set to ``True``, various
operators will be folded to assist with computing certain constants into
a single computed value. This is often useful for ensuring concatenated
strings are merged, and normalizing short-hand definition of boolean
values via ``!0`` or ``!1``, among other commonly seen expressions.
.. code:: pycon
>>> foldedconf = ast_to_dict(configuration, fold_ops=True)
>>> foldedconf['config.server']['threads']
8
>>> foldedconf['config.server']['memory']
32768
>>> foldedconf['config.server']['port']
8000
>>> foldedconf['config.proxy']['options']['https']
False
>>> # variables will remain as is
>>> foldedconf['config.server']['msg']
'msg'
>>> # however, in the context of a concatenated string, it will form
>>> # a format string instead.
>>> foldedconf['msg']
'Hello, {name}! Welcome to the host.'
As noted, any valid AST may serve as the input argument, with any
dangling expressions (i.e. those that are not assigned or bound to a
name) simply be appened to a list keyed under of its outermost asttype.
.. code:: pycon
>>> from calmjs.parse.asttypes import (
... Identifier, FuncExpr, UnaryExpr)
>>> dict_of_ast = ast_to_dict(es5(u"""
... var i;
... i;
... !'ok';
... function foo(bar) {
... baz = true;
... }
... (function(y) {
... x = 1;
... });
... """), fold_ops=True)
>>> dict_of_ast['i']
>>> dict_of_ast[Identifier]
['i']
>>> dict_of_ast[UnaryExpr] # not simply string or boolean
[False]
>>> dict_of_ast['foo'] # named function resolved
[['bar'], {'baz': True}]
>>> dict_of_ast[FuncExpr]
[[['y'], {'x': 1}]]
Advanced usage
--------------
Lower level unparsing API
~~~~~~~~~~~~~~~~~~~~~~~~~
Naturally, the printers demonstrated previously are constructed using
the underlying Unparser class, which in turn bridges together the walk
function and the Dispatcher class found in the walker module. The walk
function walks through the AST node with an instance of the Dispatcher
class, which provides a description of all node types for the particular
type of AST node provided, along with the relevant handlers. These
handlers can be set up using existing rule provider functions. For
instance, a printer for obfuscating identifier names while maintaining
indentation for the output of an ES5 AST can be constructed like so:
.. code:: pycon
>>> from calmjs.parse.unparsers.es5 import Unparser
>>> from calmjs.parse.rules import indent
>>> from calmjs.parse.rules import obfuscate
>>> pretty_obfuscate = Unparser(rules=(
... # note that indent must come after, so that the whitespace
... # handling rules by indent will shadow over the minimum set
... # provided by obfuscate.
... obfuscate(obfuscate_globals=False),
... indent(indent_str=' '),
... ))
>>> math_module = es5('''
... (function(root) {
... var fibonacci = function(count) {
... if (count < 2)
... return count;
... else
... return fibonacci(count - 1) + fibonacci(count - 2);
... };
...
... var factorial = function(n) {
... if (n < 1)
... throw new Error('factorial where n < 1 not supported');
... else if (n == 1)
... return 1;
... else
... return n * factorial(n - 1);
... }
...
... root.fibonacci = fibonacci;
... root.factorial = factorial;
... })(window);
...
... var value = window.factorial(5) / window.fibonacci(5);
... console.log('the value is ' + value);
... ''')
>>> print(''.join(c.text for c in pretty_obfuscate(math_module)))
(function(b) {
var a = function(b) {
if (b < 2) return b;
else return a(b - 1) + a(b - 2);
};
var c = function(a) {
if (a < 1) throw new Error('factorial where n < 1 not supported');
else if (a == 1) return 1;
else return a * c(a - 1);
};
b.fibonacci = a;
b.factorial = c;
})(window);
var value = window.factorial(5) / window.fibonacci(5);
console.log('the value is ' + value);
Each of the rules (functions) have specific options that are set using
specific keyword arguments, details are documented in their respective
docstrings.
At an even lower level, the ``ruletypes`` submodule contains the
primitives that form the underlying definitions that each Dispatcher
implementations currently available. For an example on how this might
be extended beyond simply unparsing back to text, see the source for
the extractor unparser module.
Tree walking
~~~~~~~~~~~~
AST (Abstract Syntax Tree) generic walker classes are defined under the
appropriate named modules ``calmjs.parse.walkers``. Two default walker
classes are supplied. One of them is the ``ReprWalker`` class which was
previously demonstrated. The other is the ``Walker`` class, which
supplies a collection of generic tree walking methods for a tree of AST
nodes. The following is an example usage on how one might extract all
Object assignments from a given script file:
.. code:: pycon
>>> from calmjs.parse import es5
>>> from calmjs.parse.asttypes import Object, VarDecl, FunctionCall
>>> from calmjs.parse.walkers import Walker
>>> walker = Walker()
>>> declarations = es5('''
... var i = 1;
... var s = {
... a: "test",
... o: {
... v: "value"
... }
... };
... foo({foo: "bar"});
... function bar() {
... var t = {
... foo: "bar",
... };
... return t;
... }
... foo.bar = bar;
... foo.bar();
... ''')
>>> # print out the object nodes that were part of some assignments
>>> for node in walker.filter(declarations, lambda node: (
... isinstance(node, VarDecl) and
... isinstance(node.initializer, Object))):
... print(node.initializer)
...
{
a: "test",
o: {
v: "value"
}
}
{
foo: "bar"
}
>>> # print out all function calls
>>> for node in walker.filter(declarations, lambda node: (
... isinstance(node, FunctionCall))):
... print(node.identifier)
...
foo
foo.bar
Further details and example usage can be consulted from the various
docstrings found within the module.
Limitations
-----------
Comments currently may be incomplete
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Due to the implementation of the lexer/parser along with how the ast
node types have been implemented, there are restrictions on where the
comments may be exposed if enabled. Currently, such limitations exists
for nodes that are created by production rules that consume multiple
lexer tokens at once - only comments preceding the first token will be
captured, with all remaining comments discarded.
For example, this limitation means that any comments before the ``else``
token will be omitted (as the comment will be provided by the ``if``
token), as the production rule for an ``If`` node consumes both these
tokens and the node as implemented only provides a single slot for
comments. Likewise, any comments before the ``:`` token in a ternary
statement will also be discarded as that is the second token consumed
by the production rule that produces a ``Conditional`` node.
Troubleshooting
---------------
Instantiation of parser classes fails with ``UnicodeEncodeError``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For platforms or systems that do not have utf8 configured as the default
encoding, the automatic table generation may fail when constructing a
parser instance. An example:
.. code:: pycon
>>> from calmjs.parse.parsers import es5
>>> parser = es5.Parser()
Traceback (most recent call last):
...
File "c:\python35\....\ply\lex.py", line 1043, in lex
lexobj.writetab(lextab, outputdir)
File "c:\python35\....\ply\lex.py", line 195, in writetab
tf.write('_lexstatere = %s\n' % repr(tabre))
File "c:\python35\lib\encodings\cp1252.py", line 19, in encode
return codecs.charmap_encode(input,self.errors,encoding_table)[0]
UnicodeEncodeError: 'charmap' codec can't encode character '\u02c1' ...
A workaround helper script is provided, it may be executed like so:
.. code:: console
$ python -m calmjs.parse.parsers.optimize
Further details on this topic may be found in the `manual optimization`_
section of this document.
Slow performance
~~~~~~~~~~~~~~~~
As this program is basically fully decomposed into very small functions,
this result in massive performance penalties as compared to other
implementations due to function calls being one of the most expensive
operations in Python. It may be possible to further optimize the
definitions within the description in the Dispatcher by combining all
the resolved generator functions for each asttype Node type, however
this will may require both the token and layout functions not having
arguments with name collisions, and the new function will take in all
of those arguments in one go.
Contribute
----------
- Issue Tracker: https://github.com/calmjs/calmjs.parse/issues
- Source Code: https://github.com/calmjs/calmjs.parse
Legal
-----
The |calmjs.parse| package is copyright (c) 2017 Auckland Bioengineering
Institute, University of Auckland. The |calmjs.parse| package is
licensed under the MIT license (specifically, the Expat License), which
is also the same license that the package |slimit| was released under.
The lexer, parser and the other types definitions portions were
originally imported from the |slimit| package; |slimit| is copyright (c)
Ruslan Spivak.
The Calmjs project is copyright (c) 2017 Auckland Bioengineering
Institute, University of Auckland.
Changelog
=========
1.3.0 - 2021-10-08
------------------
- Introduce the extractor unparser - an unparser that will unparse a
valid AST into a ``dict``. [
`#35 <https://github.com/calmjs/calmjs.parse/issues/35>`_
`#38 <https://github.com/calmjs/calmjs.parse/issues/38>`_
]
- Correct the JoinAttr ruletype such that the intended empty definition
value is passed to walk if it was defined as such to avoid an
unintended infinite recursion. [
`#36 <https://github.com/calmjs/calmjs.parse/issues/36>`_
]
1.2.5 - 2020-07-03
------------------
- Will now import Iterable from the Python 3.3+ location as the previous
location is marked for removal in Python 3.9. The import will still
have a fallback to the previous location in order to maintain support
for Python 2.7. [
`#31 <https://github.com/calmjs/calmjs.parse/issues/31>`_
]
- Provide a test case helper to ensure that the generic ``Program`` repr
signature is provided to assist with test case portability. [
`#33 <https://github.com/calmjs/calmjs.parse/issues/33>`_
]
- In the ``calmjs.parse.vlq`` module, implemented the ``decode_vlq``
helper for completeness/symmetry to the ``encode_vlq`` helper. [
`#33 <https://github.com/calmjs/calmjs.parse/issues/33>`_
]
1.2.4 - 2020-03-17
------------------
- Correct usage of ``__doc__`` to support level 2 optimized mode. [
`#29 <https://github.com/calmjs/calmjs.parse/issues/29>`_
`#30 <https://github.com/calmjs/calmjs.parse/issues/30>`_
]
- Corrected some minor string definition syntax, where raw string prefix
should be used but was not previously.
1.2.2 - 2020-01-18
------------------
- Correctly include LICENSE file in sdist. [
`#27 <https://github.com/calmjs/calmjs.parse/issues/27>`_
`#28 <https://github.com/calmjs/calmjs.parse/issues/28>`_
]
- Include the correct test data general form for some previously added
test cases to better accommodate already planned future features.
1.2.1 - 2019-11-21
------------------
- Fix the issue of failures with regex statement that occur due to lexer
being in a state where the disambiguation between REGEX or DIV token
types is not immediately possible, as tokens such as RBRACE, PLUSPLUS
or MINUSMINUS must be consumed by parser in order to be disambiguated,
but due to the lookahead nature done by yacc, the DIV token will be
prematurely produced and the only way to achieve this is during the
error handling stage. [
`#25 <https://github.com/calmjs/calmjs.parse/issues/25>`_
`#26 <https://github.com/calmjs/calmjs.parse/issues/26>`_
]
- Part of the previous fix also removed newline or comment tokens from
being reported as part of parsing error messages.
1.2.0 - 2019-08-15
------------------
- Partial support for parsing of comments. Currently not all comments
will be captured during parsing, due to the desire to simplify access
of them through the ``asttypes.Node`` instances with the generic
``comments`` attribute provided by it. [
`#24 <https://github.com/calmjs/calmjs.parse/issues/24>`_
]
- Enabled by passing ``with_comments=True`` to the parser..
- The limitation lies in the fact that if a node has multiple token
slots (e.g. ``if...else``), the comments that lie immediate before
the first will be captured, while the comments that lie immediate to
the subsequent ones will be omitted. The fix would involve
providing a full syntax tree node types, and that the parser rules
would need to be implemented in a more amenable manner such that the
generation of such could be done.
- All comments that lie immediately before the node are accessible
using the ``comments`` attribute.
- These comments nodes will not be yielded via the children() method.
- Various features and methods have been updated to account for
comments. Notably, sourcemap generation will be able to deal with
source fragments that contain newlines provided that both colno and
lineno are provided.
- Correctly fail on incorrect hexadecimal/unicode escape sequences while
reporting the specific character location; also report on the starting
position of an unterminated string literal. [
`#23 <https://github.com/calmjs/calmjs.parse/issues/23>`_
]
1.1.3 - 2018-11-08
------------------
- Correct issues with certain non-optional spaces being omitted for the
minify print cases, which caused malformed outputs. [
`#22 <https://github.com/calmjs/calmjs.parse/issues/22>`_
]
1.1.2 - 2018-08-20
------------------
- Default repr on synthetic nodes or nodes without column or row number
assigned should no longer error. [
`#20 <https://github.com/calmjs/calmjs.parse/issues/20>`_
]
- The same line terminator regex introduced in 1.1.0 used for line
continuation in strings now applied to the line terminator pattern to
the lexer, such that the line numbering is corrected for the Windows
specific <CR><LF> sequence. [
`#21 <https://github.com/calmjs/calmjs.parse/issues/21>`_
]
1.1.1 - 2018-08-11
------------------
- Ensure that the accounting of layout rule chunks is done correctly in
the case where layout handlers specified a tuple of layout rules for
combined handling. [
`#19 <https://github.com/calmjs/calmjs.parse/issues/19>`_
]
- The issue caused by this error manifest severely in the case where
multiple layout rule tokens are produced in a manner that repeats
a pattern that also have a layout handler rule for them, which
does not typically happen for normal code with the standard printers
(as layout chunks are many and they generally do not result in a
repeated pattern that gets consumed). However this is severely
manifested in the case of minified output with semicolons dropped,
as that basically guarantee that any series of closing blocks that
fit the pattern to be simply dropped.
1.1.0 - 2018-08-07
------------------
- Correct the implementation of line continuation in strings. This also
meant a change in the minify unparser so that it will continue to
remove the line continuation sequences. [
`#16 <https://github.com/calmjs/calmjs.parse/issues/16>`_
]
- Correct the implementation of ASI (automatic semicolon insertion) by
introducing a dedicated token type, such that the production of
empty statement can no longer happen and that distinguishes it from
production of statements that should not have ASI applied, such that
incorrectly successful parsing due to this issue will no longer
result. [
`#18 <https://github.com/calmjs/calmjs.parse/issues/18>`_
`rspivak/slimit#29 <https://github.com/rspivak/slimit/issues/29>`_
`rspivak/slimit#101 <https://github.com/rspivak/slimit/issues/101>`_
]
1.0.1 - 2018-04-19
------------------
- Ensure that the es5 Unparser pass on the prewalk_hooks argument in
its constructor.
- Minor packaging fixes; also include optimization modules for ply-3.11.
1.0.0 - 2017-09-26
------------------
Full support for sourcemaps; changes that make it possible follows:
- High level read/write functionality provided by a new ``io`` module.
- There is now a ``Deferrable`` rule type for marking certain Tokens
that need extra handling. The support for this has changed the
various API that deals with setting up of this.
- For support of the sourcemap generation, a number of new ruletypes
have been added.
- The sourcemap write function had its argument order modified to
better support the sourcepath tracking feature of input Nodes. Its
return value also now match the ordering of the encode_sourcemap
function.
- The chunk types in ruletypes have been renamed, and also a new type
called StreamFragment is introduced, so that multiple sources output
to a single stream can be properly tracked by the source mapping
processes.
- `rspivak/slimit#66 <https://github.com/rspivak/slimit/issues/66>`_
should be fully supported now.
Minify printer now has ability to shorten/obfuscate identifiers:
- Provide a name obfuscation function for shortening identifiers, to
further achieve minified output. Note that this does not yet fully
achieve the level of minification ``slimit`` had; future versions
may implement this functionality as various AST transformations.
- Also provided ability to drop unneeded semicolons.
Other significant changes:
- Various changes to internal class and function names for the 1.0.0
release. A non exhaustive listing of changes to modules relative to
the root of this package name as compared to previous major release
follows:
``asttypes``
- All ``slimit`` compatibility features removed.
- ``Switch`` (the incorrect version) removed.
- ``SwitchStatement`` -> ``Switch``
- ``SetPropAssign`` constructor: ``parameters`` -> ``parameter``
- ``UnaryOp`` -> ``UnaryExpr``
- Other general deprecated features also removed.
``factory``
- ``Factory`` -> ``SRFactory``
``visitors``
- Removed (details follow).
``walkers``
- ``visitors.generic.ReprVisitor`` -> ``walkers.ReprWalker``
``layouts``
- Module was split and reorganised; the simple base ones can be
found in ``handlers.core``, the indentation related features are
now in ``handlers.indentation``.
``unparsers.base``
- ``.default_layout_handlers`` -> ``handlers.core.default_rules``
- ``.minimum_layout_handlers`` -> ``handlers.core.minimum_rules``
``unparsers.prettyprint``
- Renamed to ``unparsers.walker``.
- The implementation was actually standard tree walking, no
correctly implemented visitor functions/classes were ever present.
``vlq``
- ``.create_sourcemap`` -> ``sourcemap.create_sourcemap``
- Broke up the visitors class as they weren't really visitors as
described. The new implementations (calmjs.parse-0.9.0) were really
walkers, so move them to that name and leave it at that. Methods
were also renamed to better reflect their implementation and purpose.
- Many slimit compatibility modules, classes and incorrectly implemented
functionalities removed.
- The usage of the Python 3 ``str`` type (``unicode`` in Python 2) is
now enforced for the parser, to avoid various failure cases where
mismatch types occur.
- The base Node asttype has a sourcepath attribute which is to be used
for tracking the original source of the node; if assigned, all its
subnodes without sourcepath defined should be treated as from that
source.
- Also provide an even higher level function for usage with streams
through the ``calmjs.parse.io`` module.
- Semicolons and braces added as structures to be rendered.
Bug fixes:
- Functions starting with a non-word character will now always have a
whitespace rendered before it to avoid syntax error.
- Correct an incorrect iterator usage in the walk function.
- Ensure List separators don't use the rowcol positions of a subsequent
Elision node.
- Lexer will only report real lexer tokens on errors (ASI generated
tokens are now dropped as they don't exist in the original source
which results in confusing rowcol reporting).
- `rspivak/slimit#57 <https://github.com/rspivak/slimit/issues/57>`_,
as it turns out ``'\0'`` is not considered to be octal, but is a <NUL>
character, which the rule to parse was not actually included in the
lexer patches that were pulled in previous to this version.
- `rspivak/slimit#75 <https://github.com/rspivak/slimit/issues/75>`_,
Option for shadowing of names of named closures, which is now disabled
by default (obfuscated named closures will not be shadowed by other
obfuscated names in children).
- Expressions can no longer contain an unnamed function.
0.10.1 - 2017-08-26
-------------------
- Corrected the line number reporting for the lexer, and correct the
propagation of that to the parser and the Node subclasses. Fixes the
incorrect implementation added by `moses-palmer/slimit@8f9a39c7769
<https://github.com/moses-palmer/slimit/commit/8f9a39c7769>`_ (where
the line numbers are tabulated incorrectly when comments are present,
and also the yacc tracking added by `moses-palmer/slimit@6aa92d68e0
<https://github.com/moses-palmer/slimit/commit/6aa92d68e0>`_ (where
the custom lexer class does not provide the position attributes
required by ply).
- Implemented bookkeeping of column numbers.
- Made other various changes to AST but for compatibility reasons (to
not force a major semver bump) they are only enabled with a flag to
the ES5 parser.
- Corrected a fault with how switch/case statements are handled in a way
that may break compatibility; fixes are only enabled when flagged.
`rspivak/slimit#94 <https://github.com/rspivak/slimit/issues/94>`_
- The repr form of Node now shows the line/col number info by default;
the visit method of the ReprVisitor class have not been changed, only
the invocation of it via the callable form has as that is the call
target for __repr__. This is a good time to mention that named
methods afford the most control for usage as documented already.
- Parsers now accept an asttypes module during its construction.
- Provide support for source map generation classes.
- Introduced a flexible visitor function/state class that accepts a
definition of rules for the generation of chunk tuples that are
compatible for the source map generation. A new way for pretty
printing and minification can be achieved using this module.
0.9.0 - 2017-06-09
------------------
- Initial release of the fork of ``slimit.parser`` and its parent
modules as ``calmjs.parse``.
- This release brings in a number of bug fixes that were available via
other forks of ``slimit``, with modifications or even a complete
revamp.
- Issues addressed includes:
- `rspivak/slimit#52 <https://github.com/rspivak/slimit/issues/52>`_,
`rspivak/slimit#59 <https://github.com/rspivak/slimit/issues/59>`_,
`rspivak/slimit#81 <https://github.com/rspivak/slimit/issues/81>`_,
`rspivak/slimit#90 <https://github.com/rspivak/slimit/issues/90>`_
(relating to conformance of ecma-262 7.6 identifier names)
- `rspivak/slimit#54 <https://github.com/rspivak/slimit/issues/54>`_
(fixed by tracking scope and executable current token in lexer)
- `rspivak/slimit#57 <https://github.com/rspivak/slimit/issues/57>`_,
`rspivak/slimit#70 <https://github.com/rspivak/slimit/issues/70>`_
(octal encoding (e.g \0), from `redapple/slimit@a93204577f
<https://github.com/redapple/slimit/commit/a93204577f>`_)
- `rspivak/slimit#62 <https://github.com/rspivak/slimit/issues/62>`_
(formalized into a unittest that passed)
- `rspivak/slimit#73 <https://github.com/rspivak/slimit/issues/73>`_
(specifically the desire for a better repr; the minifier bits are
not relevant to this package)
- `rspivak/slimit#79 <https://github.com/rspivak/slimit/pull/79>`_
(tab module handling was completely reimplemented)
- `rspivak/slimit#82 <https://github.com/rspivak/slimit/issues/82>`_
(formalized into a unittest that passed)
- Include various changes gathered by `rspivak/slimit#65
<https://github.com/rspivak/slimit/pull/65>`_, which may be the source
of some of the fixes listed above.
نیازمندی
| مقدار | نام |
|---|---|
| - | setuptools |
| >=3.6 | ply |
نحوه نصب
نصب پکیج whl calmjs.parse-1.3.0:
pip install calmjs.parse-1.3.0.whl
نصب پکیج tar.gz calmjs.parse-1.3.0:
pip install calmjs.parse-1.3.0.tar.gz