coral-media/binary-rules-evaluator

Choose an option based on binary rules for a set of conditions

0.1 2023-02-28 17:02 UTC

Requires

• php: ^7.4|^8.1

Requires (Dev)

• phpunit/phpunit: ^10.0

MIT

• rernesto

README

Purpose

Evaluate set of conditions avoiding redundant if/else statements.

How it works

Having the following table:

	Condition1	Condition2	Condition2
Result1	true	false	false
Result2	false	true	true
Result3	null	true	false
Result3	true	null	false

We translate that table into an array

$rulesTable = [
    'Result1' => [
        [
            'Condition1' => true,
            'Condition2' => false,
            'Condition3' => false
        ],
    ],
    'Result2' => [
        [
            'Condition1' => false,
            'Condition2' => true,
            'Condition3' => true
        ],
    ],
    'Result3' => [
        [
            'Condition1' => null,
            'Condition2' => true,
            'Condition3' => false
        ],
        [
            'Condition1' => true,
            'Condition2' => null,
            'Condition3' => false
        ],
    ],
];

Having as example the following inputs:

$input1 = [true, null, false] //matches Result3
$input2 = [null, null, false] //matches none

The validator will return the condition label or false if none matches. The null was added to represent unknown values and will not be evaluated.

$binaryRulesEvaluator = (new BinaryRulesEvaluator())
    ->setRulesTable($rulesTable);

$binaryRulesEvaluator->evaluate($input1); // 'Result3'
$binaryRulesEvaluator->evaluate($input2); // false

If more than one result share rules set, the method validate will return the first matching result.

This utility class helps to keep code consistent, clean and maintainable. Trust me, code with a lot of if/elseif/else statements can be really messy and hard to understand. Keep in mind almost always you would be able to turn any set of evaluations into a true/false table.