Minify Python 2 source code
Project description
a Python 2 minifier by Gareth Rees <http://garethrees.org/>
Introduction
minipy is a minifier for Python 2. It rewrites Python 2 source code in a way that preserves the meaning of the code while reducing it in size. For example:
$ cat fib.py
cache = {0: 0, 1: 1, 2: 1, 3: 2}
def fibonacci(n):
"""Return the nth Fibonacci number."""
if n not in cache:
a = n // 2
r = n % 2
m = (r * 2) - 1
cache[n] = fibonacci(a + 1) ** 2 + m * fibonacci(a + r - 1) ** 2
return cache[n]
$ minipy --rename --docstrings fib.py
b={0:0,1:1,2:1,3:2}
def c(a):
if a not in b:d=a//2;e=a%2;f=e*2-1;b[a]=c(d+1)**2+f*c(d+e-1)**2
return b[a]
Command line
Usage: minipy [options] [-o OUTPUT] FILE
Options:
--version show program's version number and exit
-h, --help show this help message and exit
-o OUTPUT, --output=OUTPUT
output file (default: stdout)
-D, --docstrings remove docstrings and other statements with no side
effects (implies --noselftest)
-R, --rename aggressively rename non-preserved variables
-i INDENT, --indent=INDENT
number of spaces per indentation level
-p PRESERVE, --preserve=PRESERVE
preserve words from renaming (separate by commas)
--nojoinlines put each statement on its own line
--noselftest skip the self-test
--debug dump the parse tree
The self-test
Generating minified source code without accidentally changing the meaning is tricky: see the list of issues for many awkward cases that had to be fixed. Therefore, in its default operating mode, minipy performs a “self-test”: it takes the minified code, re-parses it, and asserts that the parse tree for the minified code is identical to the parse tree for the original code. If the self-test passes, then you can be highly confident that minipy has not changed the meaning of your code.
In order to pass the self-test, minipy must eschew a few changes to the code that result in harmless changes to the parse tree. These changes are:
Replacing pass with 0.
Replacing -(1) with -1.
You can use the --noselftest option to enable these changes, but by disabling the self-test you accept a small risk of a bug in minipy changing the meaning of your code.
The optional transformations --rename and --docstrings can’t be combined with the self-test, so these options imply --noselftest.
Please report all self-test failures, attaching the code that causes the failure.
Renaming
Python’s use of introspection and duck typing means that it is not possible to change names in a program without risk of changing the meaning. The --rename option to minipy therefore makes a “best attempt” to discover names that need to be preserved, but does not guarantee anything. Use at your own risk!
The following names are preserved when renaming:
Names specified on the command-line via the --preserve option (write --preserve=name1,name2,name3 to preserve more than one name).
Built-in names (abs, all, any, apply, …).
Any name used as an attribute (.join, .index, .copy, .sort, …).
Any name starting and ending with two underscores.
The names of all imported modules.
Any name exported by a module in a from module import * statement.
Any name in the list assigned to the __all__ global variable.
License
minipy is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
