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.