docs/examples/simple-math.md
# Simple Math Expression
A more complex example of an addition and subtraction expressions, like:
```php
2 + 2 - 42
```
## Grammar
```pp2
%token T_NUMBER \d+
%token T_PLUS \+
%token T_MINUS \-
%skip T_WHITESPACE \s+
%pragma root Expression
Expression
: <T_NUMBER> Operation() (Expression() | <T_NUMBER>)
;
Operation
: <T_PLUS>
| <T_MINUS>
;
```