CLDRPluralRuleEvaluator.php

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<?php

class CLDRPluralRuleEvaluator {
    public static function evaluate( $number, array $rules ) {
        $rules = self::compile( $rules );

        return self::evaluateCompiled( $number, $rules );
    }

    public static function compile( array $rules ) {
        // We can't use array_map() for this because it generates a warning if
        // there is an exception.
        foreach ( $rules as &$rule ) {
            $rule = CLDRPluralRuleConverter::convert( $rule );
        }

        return $rules;
    }

    public static function evaluateCompiled( $number, array $rules ) {
        // Calculate the values of the operand symbols
        $number = strval( $number );
        if ( !preg_match( '/^ -? ( ([0-9]+) (?: \. ([0-9]+) )? )$/x', $number, $m ) ) {
            wfDebug( __METHOD__ . ": invalid number input, returning 'other'\n" );

            return count( $rules );
        }
        if ( !isset( $m[3] ) ) {
            $operandSymbols = array(
                'n' => intval( $m[1] ),
                'i' => intval( $m[1] ),
                'v' => 0,
                'w' => 0,
                'f' => 0,
                't' => 0
            );
        } else {
            $absValStr = $m[1];
            $intStr = $m[2];
            $fracStr = $m[3];
            $operandSymbols = array(
                'n' => floatval( $absValStr ),
                'i' => intval( $intStr ),
                'v' => strlen( $fracStr ),
                'w' => strlen( rtrim( $fracStr, '0' ) ),
                'f' => intval( $fracStr ),
                't' => intval( rtrim( $fracStr, '0' ) ),
            );
        }

        // The compiled form is RPN, with tokens strictly delimited by
        // spaces, so this is a simple RPN evaluator.
        foreach ( $rules as $i => $rule ) {
            $stack = array();
            $zero = ord( '0' );
            $nine = ord( '9' );
            foreach ( StringUtils::explode( ' ', $rule ) as $token ) {
                $ord = ord( $token );
                if ( isset( $operandSymbols[$token] ) ) {
                    $stack[] = $operandSymbols[$token];
                } elseif ( $ord >= $zero && $ord <= $nine ) {
                    $stack[] = intval( $token );
                } else {
                    $right = array_pop( $stack );
                    $left = array_pop( $stack );
                    $result = self::doOperation( $token, $left, $right );
                    $stack[] = $result;
                }
            }
            if ( $stack[0] ) {
                return $i;
            }
        }
        // None of the provided rules match. The number belongs to category
        // 'other', which comes last.
        return count( $rules );
    }

    private static function doOperation( $token, $left, $right ) {
        if ( in_array( $token, array( 'in', 'not-in', 'within', 'not-within' ) ) ) {
            if ( !( $right instanceof CLDRPluralRuleEvaluatorRange ) ) {
                $right = new CLDRPluralRuleEvaluatorRange( $right );
            }
        }
        switch ( $token ) {
            case 'or':
                return $left || $right;
            case 'and':
                return $left && $right;
            case 'is':
                return $left == $right;
            case 'is-not':
                return $left != $right;
            case 'in':
                return $right->isNumberIn( $left );
            case 'not-in':
                return !$right->isNumberIn( $left );
            case 'within':
                return $right->isNumberWithin( $left );
            case 'not-within':
                return !$right->isNumberWithin( $left );
            case 'mod':
                if ( is_int( $left ) ) {
                    return (int)fmod( $left, $right );
                }

                return fmod( $left, $right );
            case ',':
                if ( $left instanceof CLDRPluralRuleEvaluatorRange ) {
                    $range = $left;
                } else {
                    $range = new CLDRPluralRuleEvaluatorRange( $left );
                }
                $range->add( $right );

                return $range;
            case '..':
                return new CLDRPluralRuleEvaluatorRange( $left, $right );
            default:
                throw new CLDRPluralRuleError( "Invalid RPN token" );
        }
    }
}