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Evaluate expressions in dict/json objects

Project description


dicteval
========

Library to evaluate expressions in dict/json objects.


Requirements
------------

* Python 3.6+


Basic Usage
-----------

Module ``dicteval`` will evaluate basic types with no modifications but it will
evaluate dicts (or json objects) containing keys started with ``=`` (equal)
symbol as an expression:

>>> from dicteval import dicteval
>>> dicteval(3)
3
>>> dicteval([3, 5])
[3, 5]
>>> dicteval((5, 3))
[5, 3]
>>> dicteval({"=sum": [3, 5]})
8
>>> dicteval({"=": 5}) # = symbol alone is a 'nop' function
5

You can provide a dictionary with context to be used during evaluation process.
Context will be used, eg, to evaluate string objects:

>>> dicteval({"=": "var = {var}"}, context={"var": 1})
'var = 1'

You can also wrap your string content with ``@{}`` to force a Python ``eval()``
with the context provided:

>>> dicteval({"=sum": [3, "@{var + 2}"]}, context={"var": 3})
8


Functions
---------

You can use the following builtin functions in your expressions:


Function ``=eq``
''''''''''''''''

Returns ``True`` if all elements of sequence are equals:

>>> dicteval({"=eq": [1, 1, 1, 1]})
True


Function ``=neq``
''''''''''''''''

Returns ``True`` if elements of sequence are different:

>>> dicteval({"=neq": [1, 1, 1, 5]})
True


Function ``=`` (or ``nop``)
'''''''''''''''''''''''''''

Returns the same values passed as arguments:

>>> dicteval({"=": [1, 2, 3, 4]})
[1, 2, 3, 4]
>>> dicteval({"=nop": "spam"})
'spam'


Function ``=not``
''''''''''''''''

Returns the boolean inverse of argument:

>>> dicteval({"=not": False})
True
>>> dicteval({"=not": True})
False
>>> dicteval({"=not": None})
True
>>> dicteval({"=not": "XYZ"})
False


Function ``=sum``
'''''''''''''''''

Returns a number with the sum of arguments:

>>> dicteval({"=sum": [3, 5]})
8

To Do
-----

- Add more functions to the builtin language


License
-------

This software is licensed under MIT license.

Project details


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