text: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   * 
   *   http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  
  #ifndef NET_INSTAWEB_REWRITER_PUBLIC_FILE_LOAD_POLICY_H_
  #define NET_INSTAWEB_REWRITER_PUBLIC_FILE_LOAD_POLICY_H_
  
  #include <list>
  #include "pagespeed/kernel/base/basictypes.h"
  #include "pagespeed/kernel/base/gtest_prod.h"
  #include "pagespeed/kernel/base/string.h"
  #include "pagespeed/kernel/base/string_util.h"
  
  namespace net_instaweb {
  
  class GoogleUrl;
  class FileLoadMapping;
  class FileLoadRule;
  
  // Class for deciding which URLs get loaded from which files.
  //
  // Currently, you must explicitly set which directories to load directly
  // from filesystem.
  //
  // Files with unknown extensions are never loaded from file because we wouldn't
  // be able to set a content type.
  class FileLoadPolicy {
   public:
    FileLoadPolicy() {}
    virtual ~FileLoadPolicy();
  
    // Note: This is O(N+M) for N calls to Associate and M calls to AddRule.
    // TODO(sligocki): Set up a more efficient mapper.
    virtual bool ShouldLoadFromFile(const GoogleUrl& url,
                                    GoogleString* filename) const;
  
    // Tells us to load all URLs with this prefix from filename_prefix directory.
    // Both prefixes must specify directories, if they do not end in slashes,
    // we add them.
    //
    // Tests against youngest association first in case of overlapping prefixes.
    // Because we support regular expressions, checking for overlapping prefixes
    // isn't practical.
    virtual void Associate(StringPiece url_prefix, StringPiece filename_prefix);
  
    // A version of Associate supporting RE2-format regular expressions.
    // Backreferences are supported, as in:
    //
    //   AssociateRegexp("^https?://example.com/~([^/]*)/static/",
    //                   "/var/static/\\1", &error);
    //
    // Which will map urls as:
    //
    //   http://example.com/~pat/static/cat.jpg -> /var/static/pat/cat.jpg
    //   http://example.com/~sam/static/dog.jpg -> /var/static/sam/dog.jpg
    //   https://example.com/~al/static/css/ie -> /var/static/al/css/ie
    //
    // If the regular expression and substitution validate, returns true.
    // Otherwise it writes a message to error and returns false.
    virtual bool AssociateRegexp(StringPiece url_regexp,
                                 StringPiece filename_prefix,
                                 GoogleString* error);
  
    // By default Associate permits directly loading anything under the specified
    // filesystem path prefix.  So if we were given:
    //
    //   Associate("http://example.com/", "/var/www/")
    //
    // we would use load-from-file for everything on the site. If some of those
    // files actually need to be loaded through HTTP, for example because they
    // need to be interpreted, we might need:
    //
    //   AddRule("/var/www/cgi-bin/", false, false);  // literal blacklist.
    //
    // or:
    //
    //   // blacklist regexp
    //   AddRule("\\.php$", true, false);  // regexp blacklist.
    //
    // In cases where it's easier to list what's allowed than what's prohibited,
    // you can whitelist:
    //
    //   GoogleString e;  // For regexp errors.
    //   Associate("http://example.com/", "/var/www/")
    //   AddRule(".*", true, false, &e)  // regexp blacklist.
    //   AddRule("\\.html$", true, true, &e)  // regexp whitelist.
    //   AddRule("/var/www/static/", false, true, &e)  // literal whitelist.
    //   // regexp blacklist.
    //   AddRule("^/var/www/static/legacy/.*\\.php$", true, false, &e)
    //
    // AddRule will fail if RE2 can't compile the regular expression, and will
    // write an error message to it's error string and return false if that
    // happens.
    virtual bool AddRule(const GoogleString& rule, bool is_regexp, bool allowed,
                         GoogleString* error);
  
    // Merge in other policies (needed for rewrite_options).
    virtual void Merge(const FileLoadPolicy& other);
  
   protected:
    virtual bool ShouldLoadFromFileHelper(const GoogleUrl& url,
                                          GoogleString* filename) const;
  
   private:
    typedef std::list<FileLoadMapping*> FileLoadMappings;
    FileLoadMappings file_load_mappings_;
    typedef std::list<FileLoadRule*> FileLoadRules;
    FileLoadRules file_load_rules_;
  
    DISALLOW_COPY_AND_ASSIGN(FileLoadPolicy);
  };
  
  }  // namespace net_instaweb
  
  #endif  // NET_INSTAWEB_REWRITER_PUBLIC_FILE_LOAD_POLICY_H_
  
  