PHPFunctional\PatternMatching\Matcher

Complexity

Total Complexity

36

Size/Duplication

Total Lines	151
Duplicated Lines	0 %

Coupling/Cohesion

Components	2
Dependencies	0

Test Coverage

Coverage

100%

Importance

Changes

0

9 Methods

Rating	Name	Duplication	Size	Complexity
A	_parseBooleanConstant()	0	5	4
A	_parseStringConstant()	0	5	3
A	_parseIdentifier()	0	4	2
A	_parseWildcard()	0	4	1
C	_parseArray()	0	31	7
B	_parseCons()	0	28	6
A	_parseAs()	0	7	2
B	parse()	0	20	7
A	match()	0	14	4

<?php

namespace PHPFunctional\PatternMatching;

class Matcher
{
    private static $reserved = ['true', 'false'];

    private static $rules = [
        '/^(true|false)$/i' => '_parseBooleanConstant',
        '/^([\'"])(?:(?!\\1).)*\\1$/' => '_parseStringConstant',
        '/^[a-zA-Z]+$/' => '_parseIdentifier',
        '/^_$/' => '_parseWildcard',
        '/^\\[.*\\]$/' => '_parseArray',
        '/^\\([^:]+:.+\\)$/' => '_parseCons',
        '/^[a-zA-Z]+@.+$/' => '_parseAs',
    ];

    private static function _parseBooleanConstant($value, $pattern)
    {
        $pattern_value = strtoupper($pattern) === 'TRUE' ? true : false;
        return is_bool($value) && $value === $pattern_value ? [] : false;
    }

    private static function _parseStringConstant($value, $pattern)
    {
        $string_pattern = substr($pattern, 1, -1);
        return is_string($value) && $string_pattern == $value ? [] : false;
    }

    private static function _parseIdentifier($value, $pattern)
    {
        return in_array(strtolower($pattern), self::$reserved) ? false : [$value];
    }

    private static function _parseWildcard($value, $pattern)
    {
        return [];
    }

    private static function _parseArray($value, $pattern)
    {
        if(! is_array($value)) {
            return false;
        }

        $patterns = array_filter(array_map('trim', split_enclosed(',', '[', ']', substr($pattern, 1, -1))));

        if(count($patterns) === 0) {
            return count($value) === 0 ? [] : false;
        }

        if(count($patterns) > count($value)) {
            return false;
        }

        $index = 0;
        $results = [];
        foreach($value as $v) {
            $new = self::parse($v, $patterns[$index]);

            if($new === false) {
                return false;
            }

            $results = array_merge($results, $new);
            ++$index;
        }

        return $results;
    }

    private static function _parseCons($value, $pattern)
    {
        if(! is_array($value)) {
            return false;
        }

        $patterns = array_filter(array_map('trim', split_enclosed(':', '(', ')', substr($pattern, 1, -1))));
        $last = array_pop($patterns);

        $results = [];
        foreach($patterns as $p) {
            if(count($value) == 0) {
                return false;
            }

            $new = self::parse(array_shift($value), $p);

            if($new === false) {
                return false;
            }

            $results = array_merge($results, $new);
        }

        $new = self::parse($value, $last);

        return $new === false ? false : array_merge($results, $new);
    }

    private static function _parseAs($value, $pattern)
    {
        $patterns = explode('@', $pattern, 2);

        $rest = self::parse($value, $patterns[1]);
        return $rest === false ? false : array_merge([$value], $rest);
    }

    /**
     * @param mixed $value
     * @param string $pattern
     * @return bool|array
     */
    private static function parse($value, $pattern)
    {
        $pattern = trim($pattern);

        if(is_numeric($pattern) && is_numeric($value)) {
            return $pattern == $value ? [] : false;
        }

        foreach(self::$rules as $regex => $method) {
            if(preg_match($regex, $pattern)) {
                $arguments = call_user_func_array(['static', $method], [$value, $pattern]);

                if($arguments !== false) {
                    return $arguments;
                }
            }
        }

        return false;
    }

    /**
     * @param mixed $value
     * @param array $patterns
     * @return mixed
     */
    public static function match($value, array $patterns)
    {
        foreach($patterns as $pattern => $callback) {
            $match = self::parse($value, $pattern);

            if($match !== false) {
                return is_callable($callback) ?
                    call_user_func_array($callback, $match) :
                    $callback;
            }
        }

        throw new \RuntimeException('Non-exhaustive patterns.');
    }
}