Namespaces

• ICanBoogie
  • CLDR
    • Plurals
    • Units

Classes

• Operands
• Relation
• Rule
• Samples

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<?php

/*
 * This file is part of the ICanBoogie package.
 *
 * (c) Olivier Laviale <olivier.laviale@gmail.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace ICanBoogie\CLDR\Plurals;

use ICanBoogie\CLDR\Number;

/**
 * Representation of a plural rule relation.
 *
 * @see http://unicode.org/reports/tr35/tr35-numbers.html#Relations
 */
final class Relation
{
    const RANGE_SEPARATOR = '..';
    const MODULUS_SIGN = '%';

    /**
     * @var array
     */
    static private $instances = [];

    /**
     * @param string $relation
     *
     * @return Relation
     */
    static public function from($relation)
    {
        $instance = &self::$instances[$relation];

        if ($instance)
        {
            return $instance;
        }

        list($x_expression, $range) = self::parse_relation($relation);

        return $instance = new static($x_expression, $range);
    }

    /**
     * @param $relation
     *
     * @return array
     */
    static private function parse_relation($relation)
    {
        list($x_expression, $range_list) = explode('= ', $relation) + [ 1 => null ];
        list($x_expression, $negative) = self::parse_x_expression($x_expression);

        $range = self::parse_range_list($range_list);

        if ($negative)
        {
            $range = "!($range)";
        }

        return [ $x_expression, $range ];
    }

    /**
     * @param string $x_expression
     *
     * @return array [ $x_expression, $negative ]
     */
    static private function parse_x_expression($x_expression)
    {
        if (!$x_expression)
        {
            return [ null, false ];
        }

        $negative = false;

        if ($x_expression{strlen($x_expression) - 1} === '!')
        {
            $negative = true;

            $x_expression = substr($x_expression, 0, -1);
        }

        $x_expression = '$' . rtrim($x_expression);

        if (strpos($x_expression, self::MODULUS_SIGN) !== false)
        {
            list($operand, $modulus) = explode(self::MODULUS_SIGN, $x_expression);

            $operand = trim($operand);

            $x_expression = "fmod($operand, $modulus)";
        }

        return [ $x_expression, $negative ];
    }

    /**
     * Parse a range list into a PHP statement.
     *
     * @param string $range_list
     *
     * @return string A PHP statement.
     */
    static private function parse_range_list($range_list)
    {
        $ranges = [];

        foreach (explode(',', $range_list) as $range)
        {
            if (strpos($range, self::RANGE_SEPARATOR))
            {
                $ranges = array_merge($ranges, self::unwind_range($range));

                continue;
            }

            $ranges[] = "(\$x == $range)";
        }

        return implode(' || ', $ranges);
    }

    /**
     * @param string $range
     *
     * @return array
     */
    static private function unwind_range($range)
    {
        list($start, $end) = explode(self::RANGE_SEPARATOR, $range);

        $precision = self::precision_from($start) ?: self::precision_from($end);
        $step = 1 / (int) ('1' . str_repeat('0', $precision));
        $end += $step;

        $ranges = [];

        for ( ; $start < $end ; $start += $step)
        {
            $ranges[] = "(\$x == $start)";
        }

        return $ranges;
    }

    /**
     * @param number $number
     *
     * @return int
     */
    static private function precision_from($number)
    {
        return Number::precision_from($number);
    }

    /**
     * @var string
     */
    private $x_expression;

    /**
     * @var string
     */
    private $conditions;

    /**
     * @param string $x_expression PHP code to evaluate `x`.
     * @param string $conditions PHP code to evaluate.
     */
    private function __construct($x_expression, $conditions)
    {
        $this->x_expression = $x_expression;
        $this->conditions = $conditions;
    }

    /**
     * Resolve `x`.
     *
     * @param Operands $operands
     *
     * @return number
     */
    public function resolve_x(Operands $operands)
    {
        extract($operands->to_array());

        return eval("return ($this->x_expression);");
    }

    /**
     * @param Operands $operands
     *
     * @return bool `true` if the operands satisfy the rule, `false` otherwise.
     */
    public function evaluate(Operands $operands)
    {
        if (!$this->x_expression)
        {
            return true;
        }

        // $x is typecasted as a string because `fmod(4.3, 3) != 1.3` BUT `(string) fmod(4.3, 3) == 1.3
        $x = (string) $this->resolve_x($operands);

        return eval("return $this->conditions;");
    }
}