A formula interpreter for php using BC-Math
This library is a fork of the mormat/php-formula-interpreter adapted to use BC-Math. If you are looking for a similar library without the need for arbitrary precision mathematics, please use that one.
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.
The recommended way to install this library is through composer.
Run the Composer command to install the formula interpreter:
composer require ibthedatacompany/bcmath-formula-interpreter
First, create an instance of
$compiler = new \IB\FormulaInterpreter\Compiler();
Then use the
compile()method to parse the formula you want to interpret. It will return an instance of
$executable = $compiler->compile('2 + 2');
Finally run the formula from the executable :
$result = $executable->run(); // $result equals 4
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)'
Others operators like modulo, power, etc. will be implemented in the future as functions.
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);
Note that all variables should be numeric string representations.
Here is an example of expression using a function :
Available functions :
You can embed functions as much as you like
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 (  => foo  => bar )
The MIT License (MIT). Please see License File for more information.