ExpressionParser

This is my custom expression parser (as my programming exercise). The functions are similar to eval() in Python. In other words, this is my attempt to reimplement the eval() by myself without any guidance, so please don't expect the blazingly fast performance on this lib.

Let's get started

Import my lib

from expression_parser import SimpleParser

Create the SimpleParser object
```
exprs = SimpleParser()
```

You can declare some custom variable inside your expression via callback function. Lambda function also accepted.

def randomness():
    r = random.randint(0, 10)
    return math.sin(r * 0.01 * math.pi)

exprs.define(var_name="random_var", callback=randomness)
exprs.define(var_name="กะเพราไข่ดาว", callback=lambda: 60)

Let's rock! with your expression

exprs.eval("(กะเพราไข่ดาว*2)*50/100")
exprs.eval("random_var/(-2.00)")

Differences from Python's `eval()`

I have introduced some weird operation which is %. This operation basically does the multiplication with 0.01
- For example: 50% equals to 0.5
Compared to Python's eval(), my expression parser has no too many nested parentheses error when the expression is too long
The callback function is tied to my method define. Therefore, it will perform the callback function multiple times if you put your variable in more than one occurrence in your expression.
- In my opinion, this is good in some cases, such as random variables..? maybe
- Also, it may be worse in case that you let your callback perform some time-consuming task.
Of course, it is slower than Python's eval() in many cases.

markulox/ExpressionParser

ExpressionParser

Let's get started

Differences from Python's eval()

Differences from Python's `eval()`