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.