dicteval 0.0.5

Evaluate expressions in dict/json objects

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.

>>> dicteval({"=": "!{var}"}, context={"var": 1.0})
1.0

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

.. warning::
This functionality will be removed (or changed) in future releases for
security reasons.


Functions
---------

You can use the following builtin functions in your expressions:


Function ``=any``
'''''''''''''''''

Returns ``True`` if any element of sequence is true.

>>> dicteval({"=any": [1, 2, 3]})
True
>>> dicteval({"=any": [0, 0]})
False


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

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

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


Function ``=if``
''''''''''''''''

Evaluates condition and returns first value if true, otherwise, returns second value.
If no false value is supplied, it is assumed to be ``None``.

>>> dicteval({"=if": [{"=": "@{var > 5}"}, "yes", "no"]}, context={"var": 6})
'yes'
>>> dicteval({"=if": [{"=": "@{var > 5}"}, "yes", "no"]}, context={"var": 4})
'no'
>>> dicteval({"=if": [{"=": "@{var > 5}"}, "yes"]}, context={"var": 4})


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


Function ``=mul``
'''''''''''''''''

Returns a number with the product of arguments:

>>> dicteval({"=mul": [3, 5]})
15


Function ``=all``
'''''''''''''''''

Return True if all elements of the iterable are true (or if the iterable is empty)

>>> dicteval({"=all": (True, False)})
False
>>> dicteval({"=all": (True, True)})
True


Function ``=divmod``
'''''''''''''''''

Returns a tuple containing the quotient and remainder after division:

>>> dicteval({"=divmod": [8,3]})
(2, 2)
>>> dicteval({"=divmod": [7.5,2.5]})
(3.0, 0.0)


Function ``=zip``
'''''''''''''''''

Return list of aggregate tuples constructed from elements of multiple iterables.

>>> dicteval({"=zip": [[1, 2, 3], [4, 5], [6, 7, 8, 9]]})
[(1, 4, 6), (2, 5, 7)]


To Do
-----

- Add more functions to the builtin language


Contribute
----------

To contribute to `dicteval`:

1. Clone this repository and `cd` into it
2. Install dev dependencies with [pipenv](https://github.com/pypa/pipenv)
```bash
pipenv install --dev
```
3. Create a branch, like `git checkout -b [feature_name]`
4. Git commit changes
5. Pull request


License
-------

This software is licensed under MIT license.