MathExecutor

A simple and extensible math expressions calculator

Features:

Built in support for +, -, *, / and power (^) operators plus ()
Logical operators (==, !=, <, <, >=, <=, &&, ||)
Built in support for most PHP math functions
Conditional If logic
Support for user defined operators
Support for user defined functions
Support for math on user defined objects
Dynamic variable resolution (delayed computation)
Unlimited variable name lengths
String support, as function parameters or as evaluated as a number by PHP
Exceptions on divide by zero, or treat as zero
Unary Plus and Minus (e.g. +3 or -sin(12))
Pi ($pi) and Euler's number ($e) support to 11 decimal places
Easily extensible

Install via Composer:

composer require nxp/math-executor

Sample usage:

use NXP\MathExecutor;

$executor = new MathExecutor();

echo $executor->execute('1 + 2 * (2 - (4+10))^2 + sin(10)');

Functions:

Default functions:

abs
acos (arccos)
acosh
arcctg (arccot, arccotan)
arcsec
arccsc (arccosec)
asin (arcsin)
atan (atn, arctan, arctg)
atan2
atanh
avg
bindec
ceil
cos
cosec (csc)
cosh
ctg (cot, cotan, cotg, ctn)
decbin
dechex
decoct
deg2rad
exp
expm1
floor
fmod
hexdec
hypot
if
intdiv
log (ln)
log10 (lg)
log1p
max
min
octdec
pi
pow
rad2deg
round
sec
sin
sinh
sqrt
tan (tn, tg)
tanh

Add custom function to executor:

$executor->addFunction('abs', function($arg) {return abs($arg);});

Function default parameters are not supported at this time.

Operators:

Default operators: + - * / ^

Add custom operator to executor:

use NXP\Classes\Operator;

$executor->addOperator(new Operator(
    '%', // Operator sign
    false, // Is right associated operator
    170, // Operator priority
    function (&$stack)
    {
       $op2 = array_pop($stack);
       $op1 = array_pop($stack);
       $result = $op1->getValue() % $op2->getValue();

       return $result;
    }
));

Logical operators:

Logical operators (==, !=, <, <, >=, <=, &&, ||) are supported, but logically they can only return true (1) or false (0). In order to leverage them, use the built in if function:

if($a > $b, $a - $b, $b - $a)

You can think of the if function as prototyped like:

function if($condition, $returnIfTrue, $returnIfFalse)

Variables:

Variables can be prefixed with the dollar sign ($) for PHP compatibility, but is not required.

Default variables:

$pi = 3.14159265359
$e  = 2.71828182846

You can add your own variables to executor:

$executor->setVar('var1', 0.15)->setVar('var2', 0.22);

echo $executor->execute("$var1 + var2");

By default, variables must be scalar values (int, float, bool or string). If you would like to support another type, use setVarValidationHandler

$executor->setVarValidationHandler(function (string $name, $variable) {
		// allow all scalars and null
		if (is_scalar($variable) || $variable === null) {
				return;
		}
		// Allow variables of type DateTime, but not others
		if (! $variable instanceof \DateTime) {
				throw new MathExecutorException("Invalid variable type");
		}
});

You can dynamically define variables at run time. If a variable has a high computation cost, but might not be used, then you can define an undefined variable handler. It will only get called when the variable is used, rather than having to always set it initially.

$calculator = new MathExecutor();
$calculator->setVarNotFoundHandler(
    function ($varName) {
        if ($varName == 'trans') {
            return transmogrify();
        }
        return null;
    }
);

Division By Zero Support:

Division by zero throws a \NXP\Exception\DivisionByZeroException by default

try {
    echo $executor->execute('1/0');
} catch (DivisionByZeroException $e) {
    echo $e->getMessage();
}

Or call setDivisionByZeroIsZero

echo $executor->setDivisionByZeroIsZero()->execute('1/0');

If you want another behavior, you can override division operator:

$executor->addOperator("/", false, 180, function($a, $b) {
    if ($b == 0) {
        return null;
    }
    return $a / $b;
});
echo $executor->execute('1/0');

String Support:

Expressions can contain double or single quoted strings that are evaluated the same way as PHP evalutes strings as numbers. You can also pass strings to functions.

echo $executor->execute("1 + '2.5' * '.5' + myFunction('category')");

Extending MathExecutor

You can add operators, functions and variables with the public methods in MathExecutor, but if you need to do more serious modifications to base behaviours, the easiest way to extend MathExecutor is to redefine the following methods in your derived class:

defaultOperators
defaultFunctions
defaultVars

This will allow you to remove functions and operators if needed, or implement different types more simply.

Also note that you can replace an existing default operator by adding a new operator with the same regular expression string. For example if you just need to redefine TokenPlus, you can just add a new operator with the same regex string, in this case '\+'.

Documentation

Full class documentation via PHPFUI/InstaDoc

Future Enhancements

This package will continue to track currently supported versions of PHP.

dacodmagagula/MathExecutor