Created helper class for parsing Apple style XML dictionaries.

chrome/utility/media_galleries/iapps_xml_utils.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_UTILITY_MEDIA_GALLERIES_IAPPS_XML_UTILS_H_
 #define CHROME_UTILITY_MEDIA_GALLERIES_IAPPS_XML_UTILS_H_
 
+#include <set>
 #include <string>
 
 #include "base/files/file.h"
+#include "base/stl_util.h"
 
 class XmlReader;
 
 namespace iapps {
 
 // Like XmlReader::SkipToElement, but will advance to the next open tag if the
 // cursor is on a close tag.
 bool SkipToNextElement(XmlReader* reader);
 
 // Traverse |reader| looking for a node named |name| at the current depth
 // of |reader|.
 bool SeekToNodeAtCurrentDepth(XmlReader* reader, const std::string& name);
 
 // Search within a "dict" node for |key|. The cursor must be on the starting
 // "dict" node when entering this function.
 bool SeekInDict(XmlReader* reader, const std::string& key);
 
 // Get the value out of a string node.
 bool ReadString(XmlReader* reader, std::string* result);
 
 // Get the value out of an integer node.
 bool ReadInteger(XmlReader* reader, uint64* result);
 
 // Read in the contents of the given library xml |file| and return as a string.
 std::string ReadFileAsString(base::File file);
 
+// Contains the common code and main loop for reading the key/values
+// of an XML dict. The derived class must implement |HandleKeyImpl()|
+// which is called with each key, and may re-implement |ShouldLoop()|,
+// |FinishedOk()| and/or |AllowRepeats()|.
+class XmlDictReader {
+ public:
+  explicit XmlDictReader(XmlReader* reader);
+  virtual ~XmlDictReader();
+
+  // The main loop of this class. Reads all the keys in the
+  // current element and calls |HandleKey()| with each.
+  bool Read();
+
+  // Re-implemented by derived class if it should bail from the
+  // loop earlier, such as if it encountered all required fields.
+  virtual bool ShouldLoop();
+
+  // Called by |Read()| with each key. Calls derived |HandleKeyImpl()|.
+  bool HandleKey(const std::string& key);
+
+  virtual bool HandleKeyImpl(const std::string& key) = 0;
+
+  // Re-implemented by the derived class (to return true) if
+  // it should allow fields to be repeated, but skipped.
+  virtual bool AllowRepeats();
+
+  // Re-implemented by derived class if it should test for required
+  // fields instead of just returning true.
+  virtual bool FinishedOk();
+
+  // A convenience function for the derived classes.
+  // Skips to next element.
+  bool SkipToNext();
+
+  // A convenience function for the derived classes.
+  // Used to test if all required keys have been encountered.
+  bool Found(const std::string& key) const;
+
+ protected:
+  XmlReader* reader_;
+
+ private:
+  // The keys that the reader has run into in this element.
+  std::set<std::string> found_;
+
+  DISALLOW_COPY_AND_ASSIGN(XmlDictReader);
+};
+
 }  // namespace iapps
 
 #endif  // CHROME_UTILITY_MEDIA_GALLERIES_IAPPS_XML_UTILS_H_