Configuration

Configuration#

Arokettu\ArithmeticParser\Config class is used to configure the calculator and the parser.

Config is mutable but it is cloned internally when passed to prevent external alterations.

Warning

Calling parser and calculator with different config objects is not supported unless only functions were added.

Config::default()#

The default preset used when no config is specified.

Functions#

Added in version 3.0: Lazy functions, see Lazy Calculations

Added in version 3.0: defined(), true(), false(), nan(), inf(), precision param for round()

Changed in version 3.0: setFunctions() and addFunctions() no longer accept callables, addFunctionsFromCallables() was added to handle them

The function must be a callable that accepts float arguments.

Default functions: abs, exp, log(num, base = e()), log10, sqrt, acos, asin, atan, cos, sin, tan, acosh, asinh, atanh, cosh, sinh, tanh, ceil, floor, round(num, precision = 0), deg2rad, rad2deg, pi, e, true, false, nan, inf.

Default lazy functions:

  • if(if, then, else). Regular if expression

  • defined(variable). Returns 1 if variable is defined and 0 if not

Warning

Lazy functions act like regular functions in the default calculator. For example, if (a = 0, 0, 1/a) will result in division by zero if a = 0.

You can:

  • Replace functions with your own list:

    <?php
$config->setFunctions(
    new Config\Func('myfunc2', fn (float $a) => $a ** 2)
)

  • Add new functions:

    <?php
// by object
$config->setFunctions(
    new Config\Func('myfunc3', fn (float $a) => $a ** 3)
)
// or by callable
$config->addFunctionsFromCallables(myfunc4: fn (float $a) => $a ** 4);

  • Remove functions:

    <?php
$config->removeFunctions('acos', 'asin');
$config->removeFunction('acos'); // semantic alias for removeFunctions('acos')
$config->clearFunctions(); // remove all functions

Callable must accept all floats for a regular function or all instances of LazyArgument for a lazy function. Lazy functions can be used with the default calculator, but they will act like regular functions in that case.

For example, function that returns its first nonzero argument:

<?php

declare(strict_types=1);

use Arokettu\ArithmeticParser\Argument\LazyArgument;
use Arokettu\ArithmeticParser\Config;
use Arokettu\ArithmeticParser\LazyCalculator;

$config = Config::default();

$config->addFunctionFromCallable('first_nonzero', function (LazyArgument ...$args) {
    foreach ($args as $a) {
        $value = $a->getValue();
        if ($value !== 0.0) {
            return $value;
        }
    }
    return 0;
}, true);

var_dump(LazyCalculator::evaluate(
    'first_nonzero(a, b, c, notafunc(d) / 0)', $config,
    a: 0, b: 0, c: 3
)); // 3

Operators#

Added in version 3.0: not (also NOT)

Added in version 3.0: Lazy operators, see Lazy Calculations

Operators can be unary and binary. Operator symbol can be any string without digits. Be wary when using latin character based operators, they are case-sensitive and may shadow variables and functions.

Default operators:

  • +, - in both unary and binary form. They are built-in and are not configurable.

  • *, /, <, >, <=, >=, = (also ==), <> (also !=), and (also AND), or (also OR), not (also NOT).

Note

and/AND and or/OR) are lazy like in most programming languages

You can:

  • Replace operators with your own list:

    <?php
$config->setOperators(
    new BinaryOperator('×', fn (float $a, float $b) => $a * $b, BinaryOperator::PRIORITY_MUL),
    new BinaryOperator('÷', fn (float $a, float $b) => $a / $b, BinaryOperator::PRIORITY_MUL),
);

  • Add new operators:

    <?php
// assuming you have factorial() defined
$config->addOperators(
    new BinaryOperator('^', pow(...), BinaryOperator::PRIORITY_POW, BinaryAssoc::RIGHT),
    new UnaryOperator('!', factorial(...), UnaryPos::POSTFIX),
);

  • Remove operators:

    <?php
// remove any custom or built-in operators except for + and -
$config->removeOperators('*', '/');
// you cannot divide by zero if you cannot divide
$config->removeOperator('/'); // semantic alias for removeOperators('/')
// leave only + and -
$config->clearOperators(); // + and - are handled specially and can't be removed

Like functions, operators can be lazy, in that case callables must accept instances of LazyArgument as arguments.

For example, OR operator that returns the actual value of the first truth-y argument:

<?php

declare(strict_types=1);

use Arokettu\ArithmeticParser\Argument\LazyArgument;
use Arokettu\ArithmeticParser\Config;
use Arokettu\ArithmeticParser\Config\BinaryPriority;
use Arokettu\ArithmeticParser\LazyCalculator;

$config = Config::default();

$config->addOperator(new Config\BinaryOperator(
    '||',
    fn (LazyArgument $a, LazyArgument $b)
        => $a->getValue() ?: $b->getValue(),
    BinaryPriority::OR,
    Config\BinaryAssoc::LEFT,
    true,
));

var_dump(LazyCalculator::evaluate('a || b', $config, a: 0, b: 12)); // 12
var_dump(LazyCalculator::evaluate('a || b / 0', $config, a: 123)); // 123
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