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
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