# Logic formula checker
Script for checking is formula is correct

### Installation
You can run this script without downloading any other libraries. 

### Usage
There are several ways of usage.
+ You can use is as a library in your project:
```
    from logic_formula_checker import is_formula_correct
```
+ With run.py for interactive console
+ From bash
```
    $ python -m logic_formula_checker -f (a∧b)
```

### Testing
Some tests is written in tests.py file. They check if formula single tests work properly.


## Script logic explaination
It takes two test of formula for checking formula's correctness.
Firstly check if all brackets are properly opened and closed.  
```
    ( { } ) - Good
    ( { ) } - Wrong
    ( { } - Wrong
```
Next script checks if signs are rightly put. Brackets are bypassed. Steps:
1. Read sign, check what kind it is (Types are in logic_formula_checker/types.py).
2. Check if it is in expected_sign list. 
3. Update expected_sign list base on current sign
```
    a ^ ¬ b // take a, write to expected_sign conjuction symbols and negation symbols 
    ^ ¬ b // take ^, check is it in expected_sign, update expected_sign with asci lowercase sings (formula variables) and negation signs
    
```