HTMLPurifier_Config::getDefinition PHP Method

    public function getDefinition($type, $raw = false, $optimized = false)
    {
        if ($optimized && !$raw) {
            throw new HTMLPurifier_Exception("Cannot set optimized = true when raw = false");
        }
        if (!$this->finalized) {
            $this->autoFinalize();
        }
        // temporarily suspend locks, so we can handle recursive definition calls
        $lock = $this->lock;
        $this->lock = null;
        $factory = HTMLPurifier_DefinitionCacheFactory::instance();
        $cache = $factory->create($type, $this);
        $this->lock = $lock;
        if (!$raw) {
            // full definition
            // ---------------
            // check if definition is in memory
            if (!empty($this->definitions[$type])) {
                $def = $this->definitions[$type];
                // check if the definition is setup
                if ($def->setup) {
                    return $def;
                } else {
                    $def->setup($this);
                    if ($def->optimized) {
                        $cache->add($def, $this);
                    }
                    return $def;
                }
            }
            // check if definition is in cache
            $def = $cache->get($this);
            if ($def) {
                // definition in cache, save to memory and return it
                $this->definitions[$type] = $def;
                return $def;
            }
            // initialize it
            $def = $this->initDefinition($type);
            // set it up
            $this->lock = $type;
            $def->setup($this);
            $this->lock = null;
            // save in cache
            $cache->add($def, $this);
            // return it
            return $def;
        } else {
            // raw definition
            // --------------
            // check preconditions
            $def = null;
            if ($optimized) {
                if (is_null($this->get($type . '.DefinitionID'))) {
                    // fatally error out if definition ID not set
                    throw new HTMLPurifier_Exception("Cannot retrieve raw version without specifying %{$type}.DefinitionID");
                }
            }
            if (!empty($this->definitions[$type])) {
                $def = $this->definitions[$type];
                if ($def->setup && !$optimized) {
                    $extra = $this->chatty ? " (try moving this code block earlier in your initialization)" : "";
                    throw new HTMLPurifier_Exception("Cannot retrieve raw definition after it has already been setup" . $extra);
                }
                if ($def->optimized === null) {
                    $extra = $this->chatty ? " (try flushing your cache)" : "";
                    throw new HTMLPurifier_Exception("Optimization status of definition is unknown" . $extra);
                }
                if ($def->optimized !== $optimized) {
                    $msg = $optimized ? "optimized" : "unoptimized";
                    $extra = $this->chatty ? " (this backtrace is for the first inconsistent call, which was for a {$msg} raw definition)" : "";
                    throw new HTMLPurifier_Exception("Inconsistent use of optimized and unoptimized raw definition retrievals" . $extra);
                }
            }
            // check if definition was in memory
            if ($def) {
                if ($def->setup) {
                    // invariant: $optimized === true (checked above)
                    return null;
                } else {
                    return $def;
                }
            }
            // if optimized, check if definition was in cache
            // (because we do the memory check first, this formulation
            // is prone to cache slamming, but I think
            // guaranteeing that either /all/ of the raw
            // setup code or /none/ of it is run is more important.)
            if ($optimized) {
                // This code path only gets run once; once we put
                // something in $definitions (which is guaranteed by the
                // trailing code), we always short-circuit above.
                $def = $cache->get($this);
                if ($def) {
                    // save the full definition for later, but don't
                    // return it yet
                    $this->definitions[$type] = $def;
                    return null;
                }
            }
            // check invariants for creation
            if (!$optimized) {
                if (!is_null($this->get($type . '.DefinitionID'))) {
                    if ($this->chatty) {
                        $this->triggerError('Due to a documentation error in previous version of HTML Purifier, your ' . 'definitions are not being cached.  If this is OK, you can remove the ' . '%$type.DefinitionRev and %$type.DefinitionID declaration.  Otherwise, ' . 'modify your code to use maybeGetRawDefinition, and test if the returned ' . 'value is null before making any edits (if it is null, that means that a ' . 'cached version is available, and no raw operations are necessary).  See ' . '<a href="http://htmlpurifier.org/docs/enduser-customize.html#optimized">' . 'Customize</a> for more details', E_USER_WARNING);
                    } else {
                        $this->triggerError("Useless DefinitionID declaration", E_USER_WARNING);
                    }
                }
            }
            // initialize it
            $def = $this->initDefinition($type);
            $def->optimized = $optimized;
            return $def;
        }
        throw new HTMLPurifier_Exception("The impossible happened!");
    }

 /**
  * @param HTMLPurifier_Config $config
  * @return void
  */
 public function prepare($config)
 {
     $our_host = $config->getDefinition('URI')->host;
     if ($our_host !== null) {
         $this->ourHostParts = array_reverse(explode('.', $our_host));
     }
 }