khumbal / php-formula-interpreter
Formula interpreter for PHP
Requires
- php: ^8.1
Requires (Dev)
- friendsofphp/php-cs-fixer: ^v2
- phing/phing: ~2.16.1
- phpunit/phpunit: ^9
- symfony/class-loader: 2.1.*
This package is auto-updated.
Last update: 2024-05-13 15:38:50 UTC
README
A formula interpreter for php
Why this library ?
Some user could wants to perform a simple calculation and being able to change it as much as he can. Before using a library, you could use the eval
function. But this method has two major drawbacks :
-
Security. A php script is being evaluated by the eval function. Php is a very powerful language, perhaps too powerful for a user especially when the user wants to inject malicious code.
-
Complexity. Php is also complex for someone who doesn't understand programming language. It could be nice to interpret an excel-like formula instead.
Installing
Use Composer to install it:
composer require khumbal/php-formula-interpreter
How does it work ?
First, create an instance of FormulaInterpreter\Compiler
$compiler = new FormulaInterpreter\Compiler();
Then use the compile()
method to parse the formula you want to interpret. It will return an instance of FormulaInterpreter\Executable
:
$executable = $compiler->compile('2 + 2');
Finally run the formula from the executable :
$result = $executable->run(); // $result equals 4
Using operators
Operator multiplication (*) and division () are being evaluted first, then addition (+) and subtraction (-)
You can also force the prioriry of an expression by using parentheses like this
'2 * (3 + 2)'
You can use as many parentheses as you like.
'2 * (2 * (3 + 2 * (3 + 2)) + 2)'
Comparison operators
Supported comparison operators are =
, !=
, <>
, >=
, >
, <=
, '<'.
'1 = 1' //true '1 != 1' //false '1 != 2' //true '1 < 2' //true
Boolean operators
Supported boolean operators are AND
and OR
.
'(4 > 0) AND (3 > 2)' //true '(4 > 0) AND (3 < 2)' //false '(4 > 0) OR (3 < 2)' //true '(4 < 0) AND (3 < 2)' //false
Future operators
Others operators like modulo, power, etc. will be implemented in the future as functions.
Using variables
A variable is just a word inside your formula like this :
'price * rate / 100'
Just before executing a formula, make sure to inject all the required variables in an array
$variables = [
'price' => 40.2,
'rate' => 12.8
];
$executable->run($variables);
Variables now supports dot .
as the name.
$variables = [ 'user.name' => 'John Doe' 'user.age' => '23' ]; $executable->run($variables);
String support
Variables can contain string. Use double quote ("
) for denote a string.
'a = "Hello world"'
Using functions
Here is an example of expression using a function :
'cos(0)'
Available functions : pi
, pow
, cos
, sin
, sqrt
& modulo
You can embed functions as much as you like
'pow(sqrt(4), 2)'
Custom functions
Now function can be added before compiling should you want to add more variables.
$compiler = new Compiler(); $compiler->registerFunction('foobar', function ($a, $b) { return $a + $b; }); $executable = $compiler->compile("foobar(foo, bar)"); $params = [ 'foo' => 1, 'bar' => 2 ]; $executable->run($params);
Listing parameters
You can get a list of all variables that must be provided to the run()
method in order to run the executable:
$executable = $compiler->compile('foo + bar'); print_r($executable->getParameters());
This will output:
Array ( [0] => foo [0] => bar )