Boolexp provides "safe" evaluation of boolean expressions for use cases where eval might be dangerous. Boolexp expressions are context-free and mimic Python sytax. Only basic math opearations and data structures are provided.
To install Boolexp, change to the directory where setup.py is located and type:
python setup.py install
- Python 2.7
- pyparsing 1.5.0 or later
Expression Syntax Overview
Basic math operators *,/,+,- have highest priority
>>> from boolexp import Expression >>> Expression("4 + 4 / 2").evaluate() >>> 6 >>> Expression("( 4 + 4 ) / 2 ").evaluate() >>> 4
Comparsion operators !=, ==, <, >, <=, >=, in are next in priority. All comparsion operators have return type of boolean, which can be used as input for boolean operators and, or, not with lowest priority.
>>> from boolexp import Expression >>> Expression(2 == 1).evaluate() >>> False >>> Expression("2 * - 2 == - 4").evaluate() >>> True >>> Expression("not 2 == 3").evaluate() >>> True >>> Expression("3 <= 8 and 2 == 5").evaluate() >>> False
Expresions with with variables
This all would not be much of a fun without posibility to use variables. Allowed types for variables are bool,int,float,str,list,dict
>>> from boolexp import Expression >>> Expression("1 in v").evaluate(dict(v=[1,2])) >>> True >>> Expression("one.part == 2").evaluate(dict(one=[1, dict(part=2)], two=1)) >>> True
This project is now in a state of proof of concept only, thus far from suitable for production enviroment.
Copyright (C) 2013, Peter Facka, Lukas Lamper
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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