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treewalker.h
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1 // © Copyright 2010 - 2014 BlackTopp Studios Inc.
2 /* This file is part of The Mezzanine Engine.
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40 /*
41  *
42  * Software, Files, Libraries and all other items referenced in this clause refers only
43  * to the contents of this file and associated documentation.
44  *
45  * Pugixml parser - version 1.0
46  * --------------------------------------------------------
47  * Copyright © 2006-2012, by Arseny Kapoulkine (arseny.kapoulkine@gmail.com)
48  * Report bugs and download new versions at http://pugixml.org/
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50  * This library is distributed under the MIT License. See notice at the end
51  * of this file.
52  *
53  * This work is based on the pugxml parser, which is:
54  * Copyright © 2003, by Kristen Wegner (kristen@tima.net)
55  */
56 #ifndef _xmltreewalker_h
57 #define _xmltreewalker_h
58 
59 /// @file
60 /// @brief This defines the TreeWalker Interface
61 
62 #include "datatypes.h"
63 #include "XML/node.h"
64 
65 
66 
67 namespace Mezzanine
68 {
69  namespace XML
70  {
71  //////////////////////////////////////////////////////////////////////////////
72  /// @brief Used to call a function OnEachNode member of the subtree of nodes descended from a specific node.
73  /// @details If you want to do a deep tree traversal, you'll either have to do it via a recursive function or some
74  /// equivalent method or use a TreeWalker. This provides a helper for depth-first traversal of a subtree. In order
75  /// to use it, you have to implement XML::TreeWalker interface and call XML::Node::Traverse() function. \n\n
76  /// * First, TreeWalker::OnTraversalBegin() is called with traversal root as its argument.\n
77  /// * Then, TreeWalker::OnEachNode() function is called for all nodes in the traversal subtree in depth first order, excluding the traversal root. Each Node is passed as an argument.\n
78  /// * Finally, TreeWalker::OnTraversalEnd() function is called with traversal root as its argument.\n\n
79  /// If TreeWalker::OnTraversalBegin(), TreeWalker::OnTraversalEnd() or any of the TreeWalker::OnEachNode() calls return false, the traversal
80  /// is terminated and false is returned as the traversal result; otherwise, the traversal results in true. Note that
81  /// you don't have to override begin or end functions; their default implementations return true.\n\n
82  /// You can get the node's depth relative to the traversal root at any point by calling TreeWalker::Depth() function.
83  class MEZZ_LIB TreeWalker
84  {
85  friend class Node;
86 
87  private:
88 
89  /// @internal
90  /// @brief Stores How deep in the tree we are
91  int TraversalDepth;
92 
93  protected:
94 
95  /// @brief How many descendants deep are we during traversal.
96  /// @return This returns -1 if called from TreeWalker::OnTraversalBegin() or TreeWalker::OnTraversalEnd(), and returns 0-based depth if called from OnEachNode - depth is 0 for all children of the traversal root, 1 for all grandchildren, 2 for great-grandchildren and so on.
97  int Depth() const;
98 
99  public:
100 
101  /// @brief Default constructor, initializes depth, and can do little else without a fully implemented treewalker.
102  TreeWalker();
103 
104  /// @brief Virtual deconstructor. Tears down a TreeWalker
105  virtual ~TreeWalker();
106 
107  /// @brief Called by the root Node of the xml subtree when traversal begins.
108  /// @param node The first node the Tree to traverse
109  /// @details By default this simply returns true, but is expected to be overridden with any desired behavior
110  /// @return True by default. If it returns false, then traversal ends and the Node::Traverse() that was called is expected to return false.
111  virtual bool OnTraversalBegin(Node& node);
112 
113  /// @brief A Pure Virtual function that is expected to be implemented to create the desired behavior.
114  /// @param node The curren node being trraversed.
115  /// @details This is called on every Node that is traversed except the root node of the traversed subtree. Can be used to perform sophisticated searches
116  /// of a portion of the xml document, alter the document on a large scale, gather statistics, or just about any other behavior that requires touching
117  /// many nodes.
118  /// @return if true Traversal is expected to continue, if false, then traversal ends and the Node::Traverse() that was called is expected to return false.
119  virtual bool OnEachNode(Node& node) = 0;
120 
121  /// @brief Called on the root Node of the xml subtree when traversal ends.
122  /// @param node The last node the Tree to traverse
123  /// @details By default this simply returns true, but is expected to be overridden with any desired behavior
124  /// @return True by default. If it returns false, then traversal ends and the Node::Traverse() that was called is expected to return false.
125  virtual bool OnTraversalEnd(Node& node);
126  };
127  }
128 }// /namespace Mezzanine
129 
130 
131 
132 #endif // Include guard
133 
134 /*
135  *
136  * Software, Files, Libraries and all other items referenced in this clause refers only
137  * to the contents of this file and associated documentation.
138  *
139  * Copyright © 2006-2012 Arseny Kapoulkine
140  *
141  * Permission is hereby granted, free of charge, to any person
142  * obtaining a copy of this software and associated documentation
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149  *
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