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"] );
                }
        }

}