https://github.com/timofurrer/tag-expressions

Python implementation of Shunting-yard Algorithm to evaluate logical tag expressions
https://github.com/timofurrer/tag-expressions

bdd bool cucumber evaluate expression logic parse radish shunting-yard-algorithm tags tree

Last synced: 25 days ago
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Python implementation of Shunting-yard Algorithm to evaluate logical tag expressions

• Host: GitHub
• URL: https://github.com/timofurrer/tag-expressions
• Owner: timofurrer
• License: mit
• Created: 2017-02-25T13:22:00.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2024-11-23T15:47:31.000Z (about 2 months ago)
• Last Synced: 2024-12-15T08:04:03.527Z (29 days ago)
• Topics: bdd, bool, cucumber, evaluate, expression, logic, parse, radish, shunting-yard-algorithm, tags, tree
• Language: Python
• Size: 39.1 KB
• Stars: 3
• Watchers: 4
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

        
tag-expressions

===============

Package to evaluate logical tag expressions by using a modified version of the `Shunting Yard algorithm `_.

This package is a Python port of cucumbers tag expression.

It's also used by `radish `_.

|Build Status| |PyPI package version| |PyPI python versions|

Installing

----------

.. code:: bash

    $ pip install tag-expressions

Here is a tease

---------------

.. code:: python

    >>> from tagexpressions import parse

    >>>

    >>> expression = '( a and b ) or ( c and d )'

    >>> compiled_expression = parse(expression)

    >>> print(compiled_expression)

    ( ( a and b ) or ( c and d ) )

    >>>

    >>> data = ['a', 'b', 'c', 'd']

    >>> assert compiled_expression.evaluate(data) == True

    >>>

    >>> data = ['a', 'c']

    >>> assert compiled_expression.evaluate(data) == False

    >>>

    >>>

    >>> expression = 'not a or b and not c or not d or e and f'

    >>> compiled_expression = parse(expression)

    >>> print(compiled_expression)

    ( ( ( not ( a ) or ( b and not ( c ) ) ) or not ( d ) ) or ( e and f ) )

    >>>

    >>> data = ['b', 'e', 'f']

    >>> assert compiled_expression.evaluate(data) == True

    >>>

    >>> data = ['a', 'c', 'd']

    >>> assert compiled_expression.evaluate(data) == False

Usage

-----

Available operators

~~~~~~~~~~~~~~~~~~~

* **or** - "or" conjunction of two given variables

* **and** - "and" conjunction of two given variables

* **not** - negation of a single variable

Every other token given in an *infix* is considered a variable.

Operator precedence

~~~~~~~~~~~~~~~~~~~

From high to low:

* ()

* or

* and

* not

.. |Build Status| image:: https://github.com/timofurrer/tag-expressions/actions/workflows/build.yml/badge.svg

   :target: https://github.com/timofurrer/tag-expressions/actions/workflows/build.yml

.. |PyPI package version| image:: https://badge.fury.io/py/tag-expressions.svg

   :target: https://badge.fury.io/py/tag-expressions

.. |PyPI python versions| image:: https://img.shields.io/pypi/pyversions/tag-expressions.svg

   :target: https://pypi.python.org/pypi/tag-expressions