PathRouter.php

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<?php
class PathRouter {

    private $patterns = array();

    protected function doAdd( $path, $params, $options, $key = null ) {
        // Make sure all paths start with a /
        if ( $path[0] !== '/' ) {
            $path = '/' . $path;
        }

        if ( !isset( $options['strict'] ) || !$options['strict'] ) {
            // Unless this is a strict path make sure that the path has a $1
            if ( strpos( $path, '$1' ) === false ) {
                if ( substr( $path, -1 ) !== '/' ) {
                    $path .= '/';
                }
                $path .= '$1';
            }
        }

        // If 'title' is not specified and our path pattern contains a $1
        // Add a default 'title' => '$1' rule to the parameters.
        if ( !isset( $params['title'] ) && strpos( $path, '$1' ) !== false ) {
            $params['title'] = '$1';
        }
        // If the user explicitly marked 'title' as false then omit it from the matches
        if ( isset( $params['title'] ) && $params['title'] === false ) {
            unset( $params['title'] );
        }

        // Loop over our parameters and convert basic key => string
        // patterns into fully descriptive array form
        foreach ( $params as $paramName => $paramData ) {
            if ( is_string( $paramData ) ) {
                if ( preg_match( '/\$(\d+|key)/u', $paramData ) ) {
                    $paramArrKey = 'pattern';
                } else {
                    // If there's no replacement use a value instead
                    // of a pattern for a little more efficiency
                    $paramArrKey = 'value';
                }
                $params[$paramName] = array(
                    $paramArrKey => $paramData
                );
            }
        }

        // Loop over our options and convert any single value $# restrictions
        // into an array so we only have to do in_array tests.
        foreach ( $options as $optionName => $optionData ) {
            if ( preg_match( '/^\$\d+$/u', $optionName ) ) {
                if ( !is_array( $optionData ) ) {
                    $options[$optionName] = array( $optionData );
                }
            }
        }

        $pattern = (object)array(
            'path' => $path,
            'params' => $params,
            'options' => $options,
            'key' => $key,
        );
        $pattern->weight = self::makeWeight( $pattern );
        $this->patterns[] = $pattern;
    }

    public function add( $path, $params = array(), $options = array() ) {
        if ( is_array( $path ) ) {
            foreach ( $path as $key => $onePath ) {
                $this->doAdd( $onePath, $params, $options, $key );
            }
        } else {
            $this->doAdd( $path, $params, $options );
        }
    }

    public function addStrict( $path, $params = array(), $options = array() ) {
        $options['strict'] = true;
        $this->add( $path, $params, $options );
    }

    protected function sortByWeight() {
        $weights = array();
        foreach ( $this->patterns as $key => $pattern ) {
            $weights[$key] = $pattern->weight;
        }
        array_multisort( $weights, SORT_DESC, SORT_NUMERIC, $this->patterns );
    }

    protected static function makeWeight( $pattern ) {
        # Start with a weight of 0
        $weight = 0;

        // Explode the path to work with
        $path = explode( '/', $pattern->path );

        # For each level of the path
        foreach ( $path as $piece ) {
            if ( preg_match( '/^\$(\d+|key)$/u', $piece ) ) {
                # For a piece that is only a $1 variable add 1 points of weight
                $weight += 1;
            } elseif ( preg_match( '/\$(\d+|key)/u', $piece ) ) {
                # For a piece that simply contains a $1 variable add 2 points of weight
                $weight += 2;
            } else {
                # For a solid piece add a full 3 points of weight
                $weight += 3;
            }
        }

        foreach ( $pattern->options as $key => $option ) {
            if ( preg_match( '/^\$\d+$/u', $key ) ) {
                # Add 0.5 for restrictions to values
                # This way given two separate "/$2/$1" patterns the
                # one with a limited set of $2 values will dominate
                # the one that'll match more loosely
                $weight += 0.5;
            }
        }

        return $weight;
    }

    public function parse( $path ) {
        // Make sure our patterns are sorted by weight so the most specific
        // matches are tested first
        $this->sortByWeight();

        $matches = null;

        foreach ( $this->patterns as $pattern ) {
            $matches = self::extractTitle( $path, $pattern );
            if ( !is_null( $matches ) ) {
                break;
            }
        }

        // We know the difference between null (no matches) and
        // array() (a match with no data) but our WebRequest caller
        // expects array() even when we have no matches so return
        // a array() when we have null
        return is_null( $matches ) ? array() : $matches;
    }

    protected static function extractTitle( $path, $pattern ) {
        // Convert the path pattern into a regexp we can match with
        $regexp = preg_quote( $pattern->path, '#' );
        // .* for the $1
        $regexp = preg_replace( '#\\\\\$1#u', '(?P<par1>.*)', $regexp );
        // .+ for the rest of the parameter numbers
        $regexp = preg_replace( '#\\\\\$(\d+)#u', '(?P<par$1>.+?)', $regexp );
        $regexp = "#^{$regexp}$#";

        $matches = array();
        $data = array();

        // Try to match the path we were asked to parse with our regexp
        if ( preg_match( $regexp, $path, $m ) ) {
            // Ensure that any $# restriction we have set in our {$option}s
            // matches properly here.
            foreach ( $pattern->options as $key => $option ) {
                if ( preg_match( '/^\$\d+$/u', $key ) ) {
                    $n = intval( substr( $key, 1 ) );
                    $value = rawurldecode( $m["par{$n}"] );
                    if ( !in_array( $value, $option ) ) {
                        // If any restriction does not match return null
                        // to signify that this rule did not match.
                        return null;
                    }
                }
            }

            // Give our $data array a copy of every $# that was matched
            foreach ( $m as $matchKey => $matchValue ) {
                if ( preg_match( '/^par\d+$/u', $matchKey ) ) {
                    $n = intval( substr( $matchKey, 3 ) );
                    $data['$' . $n] = rawurldecode( $matchValue );
                }
            }
            // If present give our $data array a $key as well
            if ( isset( $pattern->key ) ) {
                $data['$key'] = $pattern->key;
            }

            // Go through our parameters for this match and add data to our matches and data arrays
            foreach ( $pattern->params as $paramName => $paramData ) {
                $value = null;
                // Differentiate data: from normal parameters and keep the correct
                // array key around (ie: foo for data:foo)
                if ( preg_match( '/^data:/u', $paramName ) ) {
                    $isData = true;
                    $key = substr( $paramName, 5 );
                } else {
                    $isData = false;
                    $key = $paramName;
                }

                if ( isset( $paramData['value'] ) ) {
                    // For basic values just set the raw data as the value
                    $value = $paramData['value'];
                } elseif ( isset( $paramData['pattern'] ) ) {
                    // For patterns we have to make value replacements on the string
                    $value = $paramData['pattern'];
                    $replacer = new PathRouterPatternReplacer;
                    $replacer->params = $m;
                    if ( isset( $pattern->key ) ) {
                        $replacer->key = $pattern->key;
                    }
                    $value = $replacer->replace( $value );
                    if ( $value === false ) {
                        // Pattern required data that wasn't available, abort
                        return null;
                    }
                }

                // Send things that start with data: to $data, the rest to $matches
                if ( $isData ) {
                    $data[$key] = $value;
                } else {
                    $matches[$key] = $value;
                }
            }

            // If this match includes a callback, execute it
            if ( isset( $pattern->options['callback'] ) ) {
                call_user_func_array( $pattern->options['callback'], array( &$matches, $data ) );
            }
        } else {
            // Our regexp didn't match, return null to signify no match.
            return null;
        }
        // Fall through, everything went ok, return our matches array
        return $matches;
    }

}

class PathRouterPatternReplacer {

    public $key, $params, $error;

    public function replace( $value ) {
        $this->error = false;
        $value = preg_replace_callback( '/\$(\d+|key)/u', array( $this, 'callback' ), $value );
        if ( $this->error ) {
            return false;
        }
        return $value;
    }

    protected function callback( $m ) {
        if ( $m[1] == "key" ) {
            if ( is_null( $this->key ) ) {
                $this->error = true;
                return '';
            }
            return $this->key;
        } else {
            $d = $m[1];
            if ( !isset( $this->params["par$d"] ) ) {
                $this->error = true;
                return '';
            }
            return rawurldecode( $this->params["par$d"] );
        }
    }

}