X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=simgear%2Fprops%2Fprops.cxx;h=acbcc92dfb7ba8a1bdda4aba870c111af24c36db;hb=fc4009aa505702241a1b79c710c4358e686245b9;hp=c6f5145b1e20bd1cbe5d1afff0d496d1100b191b;hpb=3c08eae85b77e329d34245fa6f9200c08e52e3bb;p=simgear.git

diff --git a/simgear/props/props.cxx b/simgear/props/props.cxx
index c6f5145b..acbcc92d 100644
--- a/simgear/props/props.cxx
+++ b/simgear/props/props.cxx
@@ -6,39 +6,55 @@
 //
 // $Id$
 
+#ifdef HAVE_CONFIG_H
+#  include <simgear_config.h>
+#endif
+
 #include "props.hxx"
 
 #include <algorithm>
+
+#include <sstream>
+#include <iomanip>
+#include <iterator>
 #include <stdio.h>
 #include <string.h>
 
-#if PROPS_STANDALONE
+#include <boost/algorithm/string/find_iterator.hpp>
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/bind.hpp>
+#include <boost/functional/hash.hpp>
+#include <boost/range.hpp>
 
-#include <iostream>
-using std::cerr;
-using std::endl;
-using std::find;
-using std::sort;
-using std::vector;
+#include <simgear/math/SGMath.hxx>
 
+#if PROPS_STANDALONE
+#include <iostream>
 #else
 
 #include <simgear/compiler.h>
 #include <simgear/debug/logstream.hxx>
 
-SG_USING_STD(sort);
-SG_USING_STD(find);
-SG_USING_STD(vector);
-
-#ifdef _MSC_VER
-// MSVC is buggy, and needs something strange here
-SG_USING_STD(vector<SGPropertyNode_ptr>);
-SG_USING_STD(vector<SGPropertyChangeListener *>);
-SG_USING_STD(vector<SGPropertyNode *>);
+#if ( _MSC_VER == 1200 )
+// MSVC 6 is buggy, and needs something strange here
+using std::vector<SGPropertyNode_ptr>;
+using std::vector<SGPropertyChangeListener *>;
+using std::vector<SGPropertyNode *>;
+#endif
 #endif
 
+#if PROPS_STANDALONE
+using std::cerr;
 #endif
+using std::endl;
+using std::find;
+using std::sort;
+using std::string;
+using std::vector;
+using std::stringstream;
 
+using namespace simgear;
 
 
 ////////////////////////////////////////////////////////////////////////
@@ -64,69 +80,42 @@ public:
 
 #define TEST_READ(dflt) if (!getAttribute(READ)) return dflt
 #define TEST_WRITE if (!getAttribute(WRITE)) return false
-
-
 
-////////////////////////////////////////////////////////////////////////
-// Default values for every type.
-////////////////////////////////////////////////////////////////////////
-
-const bool SGRawValue<bool>::DefaultValue = false;
-const int SGRawValue<int>::DefaultValue = 0;
-const long SGRawValue<long>::DefaultValue = 0L;
-const float SGRawValue<float>::DefaultValue = 0.0;
-const double SGRawValue<double>::DefaultValue = 0.0L;
-const char * const SGRawValue<const char *>::DefaultValue = "";
 
-
-
 ////////////////////////////////////////////////////////////////////////
 // Local path normalization code.
 ////////////////////////////////////////////////////////////////////////
 
-/**
- * A component in a path.
- */
-struct PathComponent
-{
-  string name;
-  int index;
-};
-
 /**
  * Parse the name for a path component.
  *
  * Name: [_a-zA-Z][-._a-zA-Z0-9]*
  */
-static inline const string
-parse_name (const string &path, int &i)
+
+template<typename Range>
+inline Range
+parse_name (const Range &path)
 {
-  string name = "";
-  int max = path.size();
+  typename Range::iterator i = path.begin();
+  typename Range::iterator max = path.end();
 
-  if (path[i] == '.') {
+  if (*i == '.') {
     i++;
-    if (i < max && path[i] == '.') {
+    if (i != path.end() && *i == '.') {
       i++;
-      name = "..";
-    } else {
-      name = ".";
     }
-    if (i < max && path[i] != '/')
-      throw string("Illegal character after " + name);
-  }
-
-  else if (isalpha(path[i]) || path[i] == '_') {
-    name += path[i];
+    if (i != max && *i != '/')
+      throw string("illegal character after . or ..");
+  } else if (isalpha(*i) || *i == '_') {
     i++;
 
 				// The rules inside a name are a little
 				// less restrictive.
-    while (i < max) {
-      if (isalpha(path[i]) || isdigit(path[i]) || path[i] == '_' ||
-	  path[i] == '-' || path[i] == '.') {
-	name += path[i];
-      } else if (path[i] == '[' || path[i] == '/') {
+    while (i != max) {
+      if (isalpha(*i) || isdigit(*i) || *i == '_' ||
+	  *i == '-' || *i == '.') {
+	// name += path[i];
+      } else if (*i == '[' || *i == '/') {
 	break;
       } else {
 	throw string("name may contain only ._- and alphanumeric characters");
@@ -136,90 +125,24 @@ parse_name (const string &path, int &i)
   }
 
   else {
-    if (name.size() == 0)
+    if (path.begin() == i)
       throw string("name must begin with alpha or '_'");
   }
-
-  return name;
-}
-
-
-/**
- * Parse the optional integer index for a path component.
- *
- * Index: "[" [0-9]+ "]"
- */
-static inline int
-parse_index (const string &path, int &i)
-{
-  int index = 0;
-
-  if (path[i] != '[')
-    return 0;
-  else
-    i++;
-
-  for (int max = path.size(); i < max; i++) {
-    if (isdigit(path[i])) {
-      index = (index * 10) + (path[i] - '0');
-    } else if (path[i] == ']') {
-      i++;
-      return index;
-    } else {
-      break;
-    }
-  }
-
-  throw string("unterminated index (looking for ']')");
-}
-
-
-/**
- * Parse a single path component.
- *
- * Component: Name Index?
- */
-static inline PathComponent
-parse_component (const string &path, int &i)
-{
-  PathComponent component;
-  component.name = parse_name(path, i);
-  if (component.name[0] != '.')
-    component.index = parse_index(path, i);
-  else
-    component.index = -1;
-  return component;
+  return Range(path.begin(), i);
 }
 
-
-/**
- * Parse a path into its components.
- */
-static void
-parse_path (const string &path, vector<PathComponent> &components)
+// Validate the name of a single node
+inline bool validateName(const string& name)
 {
-  int pos = 0;
-  int max = path.size();
-
-				// Check for initial '/'
-  if (path[pos] == '/') {
-    PathComponent root;
-    root.name = "";
-    root.index = -1;
-    components.push_back(root);
-    pos++;
-    while (pos < max && path[pos] == '/')
-      pos++;
-  }
-
-  while (pos < max) {
-    components.push_back(parse_component(path, pos));
-    while (pos < max && path[pos] == '/')
-      pos++;
-  }
+  using namespace boost;
+  if (name.empty())
+    return false;
+  if (!isalpha(name[0]) && name[0] != '_')
+    return false;
+  return all(make_iterator_range(name.begin(), name.end()),
+             is_alnum() || is_any_of("_-."));
 }
 
-
 
 ////////////////////////////////////////////////////////////////////////
 // Other static utility functions.
@@ -229,11 +152,13 @@ parse_path (const string &path, vector<PathComponent> &components)
 static char *
 copy_string (const char * s)
 {
-				// FIXME: potential buffer overflow.
-				// For some reason, strnlen and
-				// strncpy cause all kinds of crashes.
-  char * copy = new char[strlen(s) + 1];
-  strcpy(copy, s);
+  unsigned long int slen = strlen(s);
+  char * copy = new char[slen + 1];
+
+  // the source string length is known so no need to check for '\0'
+  // when copying every single character
+  memcpy(copy, s, slen);
+  *(copy + slen) = '\0';
   return copy;
 }
 
@@ -246,67 +171,174 @@ compare_strings (const char * s1, const char * s2)
 /**
  * Locate a child node by name and index.
  */
+template<typename Itr>
 static int
-find_child (const char * name, int index, vector<SGPropertyNode_ptr> nodes)
+find_child (Itr begin, Itr end, int index, const PropertyList& nodes)
 {
   int nNodes = nodes.size();
+  boost::iterator_range<Itr> name(begin, end);
   for (int i = 0; i < nNodes; i++) {
     SGPropertyNode * node = nodes[i];
-    if (compare_strings(node->getName(), name) && node->getIndex() == index)
+
+    // searching for a mathing index is a lot less time consuming than
+    // comparing two strings so do that first.
+    if (node->getIndex() == index && boost::equals(node->getName(), name))
       return i;
   }
   return -1;
 }
 
-
 /**
- * Locate another node, given a relative path.
+ * Locate the child node with the highest index of the same name
  */
-static SGPropertyNode *
-find_node (SGPropertyNode * current,
-	   const vector<PathComponent> &components,
-	   int position,
-	   bool create)
+static int
+find_last_child (const char * name, const PropertyList& nodes)
 {
-				// Run off the end of the list
-  if (current == 0) {
-    return 0;
-  }
+  int nNodes = nodes.size();
+  int index = 0;
 
-				// Success! This is the one we want.
-  else if (position >= (int)components.size()) {
-    return current;
+  for (int i = 0; i < nNodes; i++) {
+    SGPropertyNode * node = nodes[i];
+    if (compare_strings(node->getName(), name))
+    {
+      int idx = node->getIndex();
+      if (idx > index) index = idx;
+    }
   }
+  return index;
+}
 
-				// Empty component means root.
-  else if (components[position].name == "") {
-    return find_node(current->getRootNode(), components, position + 1, create);
+template<typename Itr>
+inline SGPropertyNode*
+SGPropertyNode::getExistingChild (Itr begin, Itr end, int index, bool create)
+{
+  int pos = find_child(begin, end, index, _children);
+  if (pos >= 0) {
+    return _children[pos];
+  } else if (create) {
+    SGPropertyNode_ptr node;
+    pos = find_child(begin, end, index, _removedChildren);
+    if (pos >= 0) {
+      PropertyList::iterator it = _removedChildren.begin();
+      it += pos;
+      node = _removedChildren[pos];
+      _removedChildren.erase(it);
+      node->setAttribute(REMOVED, false);
+      _children.push_back(node);
+      fireChildAdded(node);
+      return node;      
+    }
   }
+  return 0;
+}
+    
+template<typename Itr>
+SGPropertyNode *
+SGPropertyNode::getChildImpl (Itr begin, Itr end, int index, bool create)
+{
+    SGPropertyNode* node = getExistingChild(begin, end, index, create);
 
-				// . means current directory
-  else if (components[position].name == ".") {
-    return find_node(current, components, position + 1, create);
+    if (node) {
+      return node;
+    } else if (create) {
+      node = new SGPropertyNode(begin, end, index, this);
+      _children.push_back(node);
+      fireChildAdded(node);
+      return node;
+    } else {
+      return 0;
+    }
+}
+
+template<typename SplitItr>
+SGPropertyNode*
+find_node_aux(SGPropertyNode * current, SplitItr& itr, bool create,
+              int last_index)
+{
+  typedef typename SplitItr::value_type Range;
+  // Run off the end of the list
+  if (current == 0) {
+    return 0;
   }
 
-				// .. means parent directory
-  else if (components[position].name == "..") {
+  // Success! This is the one we want.
+  if (itr.eof())
+    return current;
+  Range token = *itr;
+  // Empty name at this point is empty, not root.
+  if (token.empty())
+    return find_node_aux(current, ++itr, create, last_index);
+  Range name = parse_name(token);
+  if (equals(name, "."))
+    return find_node_aux(current, ++itr, create, last_index);
+  if (equals(name, "..")) {
     SGPropertyNode * parent = current->getParent();
     if (parent == 0)
-      throw string("Attempt to move past root with '..'");
-    else
-      return find_node(parent, components, position + 1, create);
-  }
-
-				// Otherwise, a child name
-  else {
-    SGPropertyNode * child =
-      current->getChild(components[position].name.c_str(),
-			components[position].index,
-			create);
-    return find_node(child, components, position + 1, create);
+      throw string("attempt to move past root with '..'");
+    return find_node_aux(parent, ++itr, create, last_index);
+  }
+  int index = -1;
+  if (last_index >= 0) {
+    // If we are at the last token and last_index is valid, use
+    // last_index as the index value
+    bool lastTok = true;
+    while (!(++itr).eof()) {
+      if (!itr->empty()) {
+        lastTok = false;
+        break;
+      }
+    }
+    if (lastTok)
+      index = last_index;
+  } else {
+    ++itr;
+  }
+
+  if (index < 0) {
+    index = 0;
+    if (name.end() != token.end()) {
+      if (*name.end() == '[') {
+        typename Range::iterator i = name.end() + 1, end = token.end();
+        for (;i != end; ++i) {
+          if (isdigit(*i)) {
+            index = (index * 10) + (*i - '0');
+          } else {
+            break;
+          }
+        }
+        if (i == token.end() || *i != ']')
+          throw string("unterminated index (looking for ']')");
+      } else {
+        throw string("illegal characters in token: ")
+          + string(name.begin(), name.end());
+      }
+    }
   }
+  return find_node_aux(current->getChildImpl(name.begin(), name.end(),
+                                             index, create), itr, create,
+                       last_index);
 }
 
+// Internal function for parsing property paths. last_index provides
+// and index value for the last node name token, if supplied.
+template<typename Range>
+SGPropertyNode*
+find_node (SGPropertyNode * current,
+           const Range& path,
+	   bool create,
+           int last_index = -1)
+{
+  using namespace boost;
+  typedef split_iterator<typename range_result_iterator<Range>::type>
+    PathSplitIterator;
+  
+  PathSplitIterator itr
+    = make_split_iterator(path, first_finder("/", is_equal()));
+  if (*path.begin() == '/')
+    return find_node_aux(current->getRootNode(), itr, create, last_index);
+   else
+     return find_node_aux(current, itr, create, last_index);
+}
 
 
 ////////////////////////////////////////////////////////////////////////
@@ -317,7 +349,7 @@ inline bool
 SGPropertyNode::get_bool () const
 {
   if (_tied)
-    return _value.bool_val->getValue();
+    return static_cast<SGRawValue<bool>*>(_value.val)->getValue();
   else
     return _local_val.bool_val;
 }
@@ -326,7 +358,7 @@ inline int
 SGPropertyNode::get_int () const
 {
   if (_tied)
-    return _value.int_val->getValue();
+      return (static_cast<SGRawValue<int>*>(_value.val))->getValue();
   else
     return _local_val.int_val;
 }
@@ -335,7 +367,7 @@ inline long
 SGPropertyNode::get_long () const
 {
   if (_tied)
-    return _value.long_val->getValue();
+    return static_cast<SGRawValue<long>*>(_value.val)->getValue();
   else
     return _local_val.long_val;
 }
@@ -344,7 +376,7 @@ inline float
 SGPropertyNode::get_float () const
 {
   if (_tied)
-    return _value.float_val->getValue();
+    return static_cast<SGRawValue<float>*>(_value.val)->getValue();
   else
     return _local_val.float_val;
 }
@@ -353,7 +385,7 @@ inline double
 SGPropertyNode::get_double () const
 {
   if (_tied)
-    return _value.double_val->getValue();
+    return static_cast<SGRawValue<double>*>(_value.val)->getValue();
   else
     return _local_val.double_val;
 }
@@ -362,7 +394,7 @@ inline const char *
 SGPropertyNode::get_string () const
 {
   if (_tied)
-    return _value.string_val->getValue();
+      return static_cast<SGRawValue<const char*>*>(_value.val)->getValue();
   else
     return _local_val.string_val;
 }
@@ -371,7 +403,7 @@ inline bool
 SGPropertyNode::set_bool (bool val)
 {
   if (_tied) {
-    if (_value.bool_val->setValue(val)) {
+    if (static_cast<SGRawValue<bool>*>(_value.val)->setValue(val)) {
       fireValueChanged();
       return true;
     } else {
@@ -388,7 +420,7 @@ inline bool
 SGPropertyNode::set_int (int val)
 {
   if (_tied) {
-    if (_value.int_val->setValue(val)) {
+    if (static_cast<SGRawValue<int>*>(_value.val)->setValue(val)) {
       fireValueChanged();
       return true;
     } else {
@@ -405,7 +437,7 @@ inline bool
 SGPropertyNode::set_long (long val)
 {
   if (_tied) {
-    if (_value.long_val->setValue(val)) {
+    if (static_cast<SGRawValue<long>*>(_value.val)->setValue(val)) {
       fireValueChanged();
       return true;
     } else {
@@ -422,7 +454,7 @@ inline bool
 SGPropertyNode::set_float (float val)
 {
   if (_tied) {
-    if (_value.float_val->setValue(val)) {
+    if (static_cast<SGRawValue<float>*>(_value.val)->setValue(val)) {
       fireValueChanged();
       return true;
     } else {
@@ -439,7 +471,7 @@ inline bool
 SGPropertyNode::set_double (double val)
 {
   if (_tied) {
-    if (_value.double_val->setValue(val)) {
+    if (static_cast<SGRawValue<double>*>(_value.val)->setValue(val)) {
       fireValueChanged();
       return true;
     } else {
@@ -456,7 +488,7 @@ inline bool
 SGPropertyNode::set_string (const char * val)
 {
   if (_tied) {
-    if (_value.string_val->setValue(val)) {
+      if (static_cast<SGRawValue<const char*>*>(_value.val)->setValue(val)) {
       fireValueChanged();
       return true;
     } else {
@@ -471,62 +503,43 @@ SGPropertyNode::set_string (const char * val)
 }
 
 void
-SGPropertyNode::clear_value ()
-{
-  switch (_type) {
-  case NONE:
-    break;
-  case ALIAS:
-    _value.alias = 0;
-    break;
-  case BOOL:
-    if (_tied) {
-      delete _value.bool_val;
-      _value.bool_val = 0;
-    }
-    _local_val.bool_val = SGRawValue<bool>::DefaultValue;
-    break;
-  case INT:
-    if (_tied) {
-      delete _value.int_val;
-      _value.int_val = 0;
-    }
-    _local_val.int_val = SGRawValue<int>::DefaultValue;
-    break;
-  case LONG:
-    if (_tied) {
-      delete _value.long_val;
-      _value.long_val = 0L;
-    }
-    _local_val.long_val = SGRawValue<long>::DefaultValue;
-    break;
-  case FLOAT:
-    if (_tied) {
-      delete _value.float_val;
-      _value.float_val = 0;
-    }
-    _local_val.float_val = SGRawValue<float>::DefaultValue;
-    break;
-  case DOUBLE:
-    if (_tied) {
-      delete _value.double_val;
-      _value.double_val = 0;
+SGPropertyNode::clearValue ()
+{
+    if (_type == props::ALIAS) {
+        put(_value.alias);
+        _value.alias = 0;
+    } else if (_type != props::NONE) {
+        switch (_type) {
+        case props::BOOL:
+            _local_val.bool_val = SGRawValue<bool>::DefaultValue();
+            break;
+        case props::INT:
+            _local_val.int_val = SGRawValue<int>::DefaultValue();
+            break;
+        case props::LONG:
+            _local_val.long_val = SGRawValue<long>::DefaultValue();
+            break;
+        case props::FLOAT:
+            _local_val.float_val = SGRawValue<float>::DefaultValue();
+            break;
+        case props::DOUBLE:
+            _local_val.double_val = SGRawValue<double>::DefaultValue();
+            break;
+        case props::STRING:
+        case props::UNSPECIFIED:
+            if (!_tied) {
+                delete [] _local_val.string_val;
+            }
+            _local_val.string_val = 0;
+            break;
+        default: // avoid compiler warning
+            break;
+        }
+        delete _value.val;
+        _value.val = 0;
     }
-    _local_val.double_val = SGRawValue<double>::DefaultValue;
-    break;
-  case STRING:
-  case UNSPECIFIED:
-    if (_tied) {
-      delete _value.string_val;
-      _value.string_val = 0;
-    } else {
-      delete [] _local_val.string_val;
-    }
-    _local_val.string_val = 0;
-    break;
-  }
-  _tied = false;
-  _type = NONE;
+    _tied = false;
+    _type = props::NONE;
 }
 
 
@@ -536,36 +549,49 @@ SGPropertyNode::clear_value ()
 const char *
 SGPropertyNode::make_string () const
 {
-  if (!getAttribute(READ))
-    return "";
-
-  switch (_type) {
-  case ALIAS:
-    return _value.alias->getStringValue();
-  case BOOL:
-    if (get_bool())
-      return "true";
-    else
-      return "false";
-  case INT:
-    sprintf(_buffer, "%d", get_int());
-    return _buffer;
-  case LONG:
-    sprintf(_buffer, "%ld", get_long());
-    return _buffer;
-  case FLOAT:
-    sprintf(_buffer, "%f", get_float());
-    return _buffer;
-  case DOUBLE:
-    sprintf(_buffer, "%f", get_double());
-    return _buffer;
-  case STRING:
-  case UNSPECIFIED:
-    return get_string();
-  case NONE:
-  default:
-    return "";
-  }
+    if (!getAttribute(READ))
+        return "";
+    switch (_type) {
+    case props::ALIAS:
+        return _value.alias->getStringValue();
+    case props::BOOL:
+        return get_bool() ? "true" : "false";
+    case props::STRING:
+    case props::UNSPECIFIED:
+        return get_string();
+    case props::NONE:
+        return "";
+    default:
+        break;
+    }
+    stringstream sstr;
+    switch (_type) {
+    case props::INT:
+        sstr << get_int();
+        break;
+    case props::LONG:
+        sstr << get_long();
+        break;
+    case props::FLOAT:
+        sstr << get_float();
+        break;
+    case props::DOUBLE:
+        sstr << std::setprecision(10) << get_double();
+        break;
+    case props::EXTENDED:
+    {
+        props::Type realType = _value.val->getType();
+        // Perhaps this should be done for all types?
+        if (realType == props::VEC3D || realType == props::VEC4D)
+            sstr.precision(10);
+        static_cast<SGRawExtended*>(_value.val)->printOn(sstr);
+    }
+        break;
+    default:
+        return "";
+    }
+    _buffer = sstr.str();
+    return _buffer.c_str();
 }
 
 /**
@@ -575,11 +601,11 @@ void
 SGPropertyNode::trace_write () const
 {
 #if PROPS_STANDALONE
-  cerr << "TRACE: Write node " << getPath () << ", value\""
+  cerr << "TRACE: Write node " << getPath () << ", value \""
        << make_string() << '"' << endl;
 #else
-  SG_LOG(SG_GENERAL, SG_INFO, "TRACE: Write node " << getPath()
-	 << ", value\"" << make_string() << '"');
+  SG_LOG(SG_GENERAL, SG_ALERT, "TRACE: Write node " << getPath()
+	 << ", value \"" << make_string() << '"');
 #endif
 }
 
@@ -593,30 +619,11 @@ SGPropertyNode::trace_read () const
   cerr << "TRACE: Write node " << getPath () << ", value \""
        << make_string() << '"' << endl;
 #else
-  SG_LOG(SG_GENERAL, SG_INFO, "TRACE: Read node " << getPath()
+  SG_LOG(SG_GENERAL, SG_ALERT, "TRACE: Read node " << getPath()
 	 << ", value \"" << make_string() << '"');
 #endif
 }
 
-/**
- * Increment reference counter
- */
-void
-SGPropertyNode::incrementRef()
-{
-  ++_count;
-}
-
-/**
- * Decrement reference counter
- */
-int
-SGPropertyNode::decrementRef()
-{
-  return --_count;
-}
-
-
 
 ////////////////////////////////////////////////////////////////////////
 // Public methods from SGPropertyNode.
@@ -626,25 +633,22 @@ SGPropertyNode::decrementRef()
  * Last used attribute
  * Update as needed when enum Attribute is changed
  */
-const int SGPropertyNode::LAST_USED_ATTRIBUTE = TRACE_WRITE;
+const int SGPropertyNode::LAST_USED_ATTRIBUTE = USERARCHIVE;
 
 /**
  * Default constructor: always creates a root node.
  */
 SGPropertyNode::SGPropertyNode ()
-  : _name(copy_string("")),
-    _display_name(0),
-    _index(0),
+  : _index(0),
     _parent(0),
-    _path(0),
     _path_cache(0),
-    _type(NONE),
+    _type(props::NONE),
     _tied(false),
     _attr(READ|WRITE),
-    _count(0),
     _listeners(0)
 {
   _local_val.string_val = 0;
+  _value.val = 0;
 }
 
 
@@ -652,80 +656,50 @@ SGPropertyNode::SGPropertyNode ()
  * Copy constructor.
  */
 SGPropertyNode::SGPropertyNode (const SGPropertyNode &node)
-  : _display_name(0),
-    _index(node._index),
+  : _index(node._index),
+    _name(node._name),
     _parent(0),			// don't copy the parent
-    _path(0),
     _path_cache(0),
     _type(node._type),
     _tied(node._tied),
     _attr(node._attr),
-    _count(0),
     _listeners(0)		// CHECK!!
 {
-  _name = copy_string(node._name);
   _local_val.string_val = 0;
-  switch (_type) {
-  case NONE:
-    break;
-  case ALIAS:
+  _value.val = 0;
+  if (_type == props::NONE)
+    return;
+  if (_type == props::ALIAS) {
     _value.alias = node._value.alias;
+    get(_value.alias);
     _tied = false;
+    return;
+  }
+  if (_tied || _type == props::EXTENDED) {
+    _value.val = node._value.val->clone();
+    return;
+  }
+  switch (_type) {
+  case props::BOOL:
+    set_bool(node.get_bool());    
     break;
-  case BOOL:
-    if (_tied) {
-      _tied = true;
-      _value.bool_val = node._value.bool_val->clone();
-    } else {
-      _tied = false;
-      set_bool(node.get_bool());
-    }
+  case props::INT:
+    set_int(node.get_int());
     break;
-  case INT:
-    if (_tied) {
-      _tied = true;
-      _value.int_val = node._value.int_val->clone();
-    } else {
-      _tied = false;
-      set_int(node.get_int());
-    }
+  case props::LONG:
+    set_long(node.get_long());
     break;
-  case LONG:
-    if (_tied) {
-      _tied = true;
-      _value.long_val = node._value.long_val->clone();
-    } else {
-      _tied = false;
-      set_long(node.get_long());
-    }
+  case props::FLOAT:
+    set_float(node.get_float());
     break;
-  case FLOAT:
-    if (_tied) {
-      _tied = true;
-      _value.float_val = node._value.float_val->clone();
-    } else {
-      _tied = false;
-      set_float(node.get_float());
-    }
+  case props::DOUBLE:
+    set_double(node.get_double());
     break;
-  case DOUBLE:
-    if (_tied) {
-      _tied = true;
-      _value.double_val = node._value.double_val->clone();
-    } else {
-      _tied = false;
-      set_double(node.get_double());
-    }
+  case props::STRING:
+  case props::UNSPECIFIED:
+    set_string(node.get_string());
     break;
-  case STRING:
-  case UNSPECIFIED:
-    if (_tied) {
-      _tied = true;
-      _value.string_val = node._value.string_val->clone();
-    } else {
-      _tied = false;
-      set_string(node.get_string());
-    }
+  default:
     break;
   }
 }
@@ -734,36 +708,62 @@ SGPropertyNode::SGPropertyNode (const SGPropertyNode &node)
 /**
  * Convenience constructor.
  */
-SGPropertyNode::SGPropertyNode (const char * name,
+template<typename Itr>
+SGPropertyNode::SGPropertyNode (Itr begin, Itr end,
 				int index,
 				SGPropertyNode * parent)
-  : _display_name(0),
-    _index(index),
+  : _index(index),
+    _name(begin, end),
     _parent(parent),
-    _path(0),
     _path_cache(0),
-    _type(NONE),
+    _type(props::NONE),
     _tied(false),
     _attr(READ|WRITE),
-    _count(0),
     _listeners(0)
 {
-  _name = copy_string(name);
   _local_val.string_val = 0;
+  _value.val = 0;
+  if (!validateName(_name))
+    throw string("plain name expected instead of '") + _name + '\'';
 }
 
+SGPropertyNode::SGPropertyNode (const string& name,
+				int index,
+				SGPropertyNode * parent)
+  : _index(index),
+    _name(name),
+    _parent(parent),
+    _path_cache(0),
+    _type(props::NONE),
+    _tied(false),
+    _attr(READ|WRITE),
+    _listeners(0)
+{
+  _local_val.string_val = 0;
+  _value.val = 0;
+  if (!validateName(name))
+    throw string("plain name expected instead of '") + _name + '\'';
+}
 
 /**
  * Destructor.
  */
 SGPropertyNode::~SGPropertyNode ()
 {
-  delete [] _name;
-  delete [] _display_name;
-  delete [] _path;
+  // zero out all parent pointers, else they might be dangling
+  for (unsigned i = 0; i < _children.size(); ++i)
+    _children[i]->_parent = 0;
+  for (unsigned i = 0; i < _removedChildren.size(); ++i)
+    _removedChildren[i]->_parent = 0;
   delete _path_cache;
-  clear_value();
-  delete _listeners;
+  clearValue();
+
+  if (_listeners) {
+    vector<SGPropertyChangeListener*>::iterator it;
+    for (it = _listeners->begin(); it != _listeners->end(); ++it)
+      (*it)->unregister_property(this);
+    delete _listeners;
+  }
 }
 
 
@@ -773,11 +773,12 @@ SGPropertyNode::~SGPropertyNode ()
 bool
 SGPropertyNode::alias (SGPropertyNode * target)
 {
-  if (target == 0 || _type == ALIAS || _tied)
+  if (target == 0 || _type == props::ALIAS || _tied)
     return false;
-  clear_value();
+  clearValue();
+  get(target);
   _value.alias = target;
-  _type = ALIAS;
+  _type = props::ALIAS;
   return true;
 }
 
@@ -798,10 +799,9 @@ SGPropertyNode::alias (const char * path)
 bool
 SGPropertyNode::unalias ()
 {
-  if (_type != ALIAS)
+  if (_type != props::ALIAS)
     return false;
-  _type = NONE;
-  _value.alias = 0;
+  clearValue();
   return true;
 }
 
@@ -812,14 +812,29 @@ SGPropertyNode::unalias ()
 SGPropertyNode *
 SGPropertyNode::getAliasTarget ()
 {
-  return (_type == ALIAS ? _value.alias : 0);
+  return (_type == props::ALIAS ? _value.alias : 0);
 }
 
 
 const SGPropertyNode *
 SGPropertyNode::getAliasTarget () const
 {
-  return (_type == ALIAS ? _value.alias : 0);
+  return (_type == props::ALIAS ? _value.alias : 0);
+}
+
+/**
+ * create a non-const child by name after the last node with the same name.
+ */
+SGPropertyNode *
+SGPropertyNode::addChild (const char * name)
+{
+  int pos = find_last_child(name, _children)+1;
+
+  SGPropertyNode_ptr node;
+  node = new SGPropertyNode(name, name + strlen(name), pos, this);
+  _children.push_back(node);
+  fireChildAdded(node);
+  return node;
 }
 
 
@@ -852,40 +867,37 @@ SGPropertyNode::getChild (int position) const
 /**
  * Get a non-const child by name and index, creating if necessary.
  */
+
 SGPropertyNode *
 SGPropertyNode::getChild (const char * name, int index, bool create)
 {
-  int pos = find_child(name, index, _children);
-  if (pos >= 0) {
-    return _children[pos];
-  } else if (create) {
-    SGPropertyNode_ptr node;
-    pos = find_child(name, index, _removedChildren);
-    if (pos >= 0) {
-      vector<SGPropertyNode_ptr>::iterator it = _removedChildren.begin();
-      it += pos;
-      node = _removedChildren[pos];
-      _removedChildren.erase(it);
-      node->setAttribute(REMOVED, false);
-    } else {
+  return getChildImpl(name, name + strlen(name), index, create);
+}
+
+SGPropertyNode *
+SGPropertyNode::getChild (const string& name, int index, bool create)
+{
+  SGPropertyNode* node = getExistingChild(name.begin(), name.end(), index,
+                                          create);
+  if (node) {
+      return node;
+    } else if (create) {
       node = new SGPropertyNode(name, index, this);
+      _children.push_back(node);
+      fireChildAdded(node);
+      return node;
+    } else {
+      return 0;
     }
-    _children.push_back(node);
-    fireChildAdded(node);
-    return node;
-  } else {
-    return 0;
-  }
 }
 
-
 /**
  * Get a const child by name and index.
  */
 const SGPropertyNode *
 SGPropertyNode::getChild (const char * name, int index) const
 {
-  int pos = find_child(name, index, _children);
+  int pos = find_child(name, name + strlen(name), index, _children);
   if (pos >= 0)
     return _children[pos];
   else
@@ -896,10 +908,10 @@ SGPropertyNode::getChild (const char * name, int index) const
 /**
  * Get all children with the same name (but different indices).
  */
-vector<SGPropertyNode_ptr>
+PropertyList
 SGPropertyNode::getChildren (const char * name) const
 {
-  vector<SGPropertyNode_ptr> children;
+  PropertyList children;
   int max = _children.size();
 
   for (int i = 0; i < max; i++)
@@ -911,68 +923,135 @@ SGPropertyNode::getChildren (const char * name) const
 }
 
 
+/**
+ * Remove this node and all children from nodes that link to them
+ * in their path cache.
+ */
+void
+SGPropertyNode::remove_from_path_caches ()
+{
+  for (unsigned int i = 0; i < _children.size(); ++i)
+    _children[i]->remove_from_path_caches();
+
+  for (unsigned int i = 0; i < _linkedNodes.size(); i++)
+    _linkedNodes[i]->erase(this);
+  _linkedNodes.clear();
+}
+
+
+/**
+ * Remove child by position.
+ */
+SGPropertyNode_ptr
+SGPropertyNode::removeChild (int pos, bool keep)
+{
+  SGPropertyNode_ptr node;
+  if (pos < 0 || pos >= (int)_children.size())
+    return node;
+
+  PropertyList::iterator it = _children.begin();
+  it += pos;
+  node = _children[pos];
+  _children.erase(it);
+  if (keep) {
+    _removedChildren.push_back(node);
+  }
+
+  node->remove_from_path_caches();
+  node->setAttribute(REMOVED, true);
+  node->clearValue();
+  fireChildRemoved(node);
+  return node;
+}
+
+
 /**
  * Remove a child node
  */
-SGPropertyNode_ptr 
+SGPropertyNode_ptr
 SGPropertyNode::removeChild (const char * name, int index, bool keep)
 {
   SGPropertyNode_ptr ret;
-  int pos = find_child(name, index, _children);
-  if (pos >= 0) {
-    vector<SGPropertyNode_ptr>::iterator it = _children.begin();
-    it += pos;
-    SGPropertyNode_ptr node = _children[pos];
-    _children.erase(it);
-    if (keep) {
-      _removedChildren.push_back(node);
+  int pos = find_child(name, name + strlen(name), index, _children);
+  if (pos >= 0)
+    ret = removeChild(pos, keep);
+  return ret;
+}
+
+
+/**
+  * Remove all children with the specified name.
+  */
+PropertyList
+SGPropertyNode::removeChildren (const char * name, bool keep)
+{
+  PropertyList children;
+
+  for (int pos = _children.size() - 1; pos >= 0; pos--)
+    if (compare_strings(_children[pos]->getName(), name))
+      children.push_back(removeChild(pos, keep));
+
+  sort(children.begin(), children.end(), CompareIndices());
+  return children;
+}
+
+
+/**
+  * Remove a linked node.
+  */
+bool
+SGPropertyNode::remove_linked_node (hash_table * node)
+{
+  for (unsigned int i = 0; i < _linkedNodes.size(); i++) {
+    if (_linkedNodes[i] == node) {
+      vector<hash_table *>::iterator it = _linkedNodes.begin();
+      it += i;
+      _linkedNodes.erase(it);
+      return true;
     }
-    node->setAttribute(REMOVED, true);
-    ret = node;
-    fireChildRemoved(node);
   }
-  return ret;
+  return false;
 }
 
 
-const char *
+string
 SGPropertyNode::getDisplayName (bool simplify) const
 {
-  string display = _name;
+  string display_name = _name;
   if (_index != 0 || !simplify) {
-    char buffer[64];
-    sprintf(buffer, "[%d]", _index);
-    display += buffer;
+    stringstream sstr;
+    sstr << '[' << _index << ']';
+    display_name += sstr.str();
   }
-  _display_name = copy_string(display.c_str());
-  return _display_name;
+  return display_name;
 }
 
 
-const char *
+string
 SGPropertyNode::getPath (bool simplify) const
 {
-				// Calculate the complete path only once.
-  if (_path == 0) {
-    string path;
-    if (_parent == 0) {
-      path = "";
-    } else {
-      path = _parent->getPath(simplify);
-      path += '/';
-      path += getDisplayName(simplify);
-    }
-    _path = copy_string(path.c_str());
+  typedef std::vector<SGConstPropertyNode_ptr> PList;
+  PList pathList;
+  for (const SGPropertyNode* node = this; node->_parent; node = node->_parent)
+    pathList.push_back(node);
+  string result;
+  for (PList::reverse_iterator itr = pathList.rbegin(),
+         rend = pathList.rend();
+       itr != rend;
+       ++itr) {
+    result += '/';
+    result += (*itr)->getDisplayName(simplify);
   }
-
-  return _path;
+  return result;
 }
 
-SGPropertyNode::Type
+props::Type
 SGPropertyNode::getType () const
 {
-  if (_type == ALIAS)
+  if (_type == props::ALIAS)
     return _value.alias->getType();
+  else if (_type == props::EXTENDED)
+      return _value.val->getType();
   else
     return _type;
 }
@@ -982,32 +1061,32 @@ bool
 SGPropertyNode::getBoolValue () const
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == BOOL)
+  if (_attr == (READ|WRITE) && _type == props::BOOL)
     return get_bool();
 
   if (getAttribute(TRACE_READ))
     trace_read();
   if (!getAttribute(READ))
-    return SGRawValue<bool>::DefaultValue;
+    return SGRawValue<bool>::DefaultValue();
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     return _value.alias->getBoolValue();
-  case BOOL:
+  case props::BOOL:
     return get_bool();
-  case INT:
+  case props::INT:
     return get_int() == 0 ? false : true;
-  case LONG:
+  case props::LONG:
     return get_long() == 0L ? false : true;
-  case FLOAT:
+  case props::FLOAT:
     return get_float() == 0.0 ? false : true;
-  case DOUBLE:
+  case props::DOUBLE:
     return get_double() == 0.0L ? false : true;
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     return (compare_strings(get_string(), "true") || getDoubleValue() != 0.0L);
-  case NONE:
+  case props::NONE:
   default:
-    return SGRawValue<bool>::DefaultValue;
+    return SGRawValue<bool>::DefaultValue();
   }
 }
 
@@ -1015,32 +1094,32 @@ int
 SGPropertyNode::getIntValue () const
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == INT)
+  if (_attr == (READ|WRITE) && _type == props::INT)
     return get_int();
 
   if (getAttribute(TRACE_READ))
     trace_read();
   if (!getAttribute(READ))
-    return SGRawValue<int>::DefaultValue;
+    return SGRawValue<int>::DefaultValue();
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     return _value.alias->getIntValue();
-  case BOOL:
+  case props::BOOL:
     return int(get_bool());
-  case INT:
+  case props::INT:
     return get_int();
-  case LONG:
+  case props::LONG:
     return int(get_long());
-  case FLOAT:
+  case props::FLOAT:
     return int(get_float());
-  case DOUBLE:
+  case props::DOUBLE:
     return int(get_double());
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     return atoi(get_string());
-  case NONE:
+  case props::NONE:
   default:
-    return SGRawValue<int>::DefaultValue;
+    return SGRawValue<int>::DefaultValue();
   }
 }
 
@@ -1048,32 +1127,32 @@ long
 SGPropertyNode::getLongValue () const
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == LONG)
+  if (_attr == (READ|WRITE) && _type == props::LONG)
     return get_long();
 
   if (getAttribute(TRACE_READ))
     trace_read();
   if (!getAttribute(READ))
-    return SGRawValue<long>::DefaultValue;
+    return SGRawValue<long>::DefaultValue();
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     return _value.alias->getLongValue();
-  case BOOL:
+  case props::BOOL:
     return long(get_bool());
-  case INT:
+  case props::INT:
     return long(get_int());
-  case LONG:
+  case props::LONG:
     return get_long();
-  case FLOAT:
+  case props::FLOAT:
     return long(get_float());
-  case DOUBLE:
+  case props::DOUBLE:
     return long(get_double());
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     return strtol(get_string(), 0, 0);
-  case NONE:
+  case props::NONE:
   default:
-    return SGRawValue<long>::DefaultValue;
+    return SGRawValue<long>::DefaultValue();
   }
 }
 
@@ -1081,32 +1160,32 @@ float
 SGPropertyNode::getFloatValue () const
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == FLOAT)
+  if (_attr == (READ|WRITE) && _type == props::FLOAT)
     return get_float();
 
   if (getAttribute(TRACE_READ))
     trace_read();
   if (!getAttribute(READ))
-    return SGRawValue<float>::DefaultValue;
+    return SGRawValue<float>::DefaultValue();
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     return _value.alias->getFloatValue();
-  case BOOL:
+  case props::BOOL:
     return float(get_bool());
-  case INT:
+  case props::INT:
     return float(get_int());
-  case LONG:
+  case props::LONG:
     return float(get_long());
-  case FLOAT:
+  case props::FLOAT:
     return get_float();
-  case DOUBLE:
+  case props::DOUBLE:
     return float(get_double());
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     return atof(get_string());
-  case NONE:
+  case props::NONE:
   default:
-    return SGRawValue<float>::DefaultValue;
+    return SGRawValue<float>::DefaultValue();
   }
 }
 
@@ -1114,33 +1193,33 @@ double
 SGPropertyNode::getDoubleValue () const
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == DOUBLE)
+  if (_attr == (READ|WRITE) && _type == props::DOUBLE)
     return get_double();
 
   if (getAttribute(TRACE_READ))
     trace_read();
   if (!getAttribute(READ))
-    return SGRawValue<double>::DefaultValue;
+    return SGRawValue<double>::DefaultValue();
 
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     return _value.alias->getDoubleValue();
-  case BOOL:
+  case props::BOOL:
     return double(get_bool());
-  case INT:
+  case props::INT:
     return double(get_int());
-  case LONG:
+  case props::LONG:
     return double(get_long());
-  case FLOAT:
+  case props::FLOAT:
     return double(get_float());
-  case DOUBLE:
+  case props::DOUBLE:
     return get_double();
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     return strtod(get_string(), 0);
-  case NONE:
+  case props::NONE:
   default:
-    return SGRawValue<double>::DefaultValue;
+    return SGRawValue<double>::DefaultValue();
   }
 }
 
@@ -1148,13 +1227,13 @@ const char *
 SGPropertyNode::getStringValue () const
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == STRING)
+  if (_attr == (READ|WRITE) && _type == props::STRING)
     return get_string();
 
   if (getAttribute(TRACE_READ))
     trace_read();
   if (!getAttribute(READ))
-    return SGRawValue<const char *>::DefaultValue;
+    return SGRawValue<const char *>::DefaultValue();
   return make_string();
 }
 
@@ -1162,41 +1241,41 @@ bool
 SGPropertyNode::setBoolValue (bool value)
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == BOOL)
+  if (_attr == (READ|WRITE) && _type == props::BOOL)
     return set_bool(value);
 
   bool result = false;
   TEST_WRITE;
-  if (_type == NONE || _type == UNSPECIFIED) {
-    clear_value();
+  if (_type == props::NONE || _type == props::UNSPECIFIED) {
+    clearValue();
     _tied = false;
-    _type = BOOL;
+    _type = props::BOOL;
   }
 
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     result = _value.alias->setBoolValue(value);
     break;
-  case BOOL:
+  case props::BOOL:
     result = set_bool(value);
     break;
-  case INT:
+  case props::INT:
     result = set_int(int(value));
     break;
-  case LONG:
+  case props::LONG:
     result = set_long(long(value));
     break;
-  case FLOAT:
+  case props::FLOAT:
     result = set_float(float(value));
     break;
-  case DOUBLE:
+  case props::DOUBLE:
     result = set_double(double(value));
     break;
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     result = set_string(value ? "true" : "false");
     break;
-  case NONE:
+  case props::NONE:
   default:
     break;
   }
@@ -1210,44 +1289,44 @@ bool
 SGPropertyNode::setIntValue (int value)
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == INT)
+  if (_attr == (READ|WRITE) && _type == props::INT)
     return set_int(value);
 
   bool result = false;
   TEST_WRITE;
-  if (_type == NONE || _type == UNSPECIFIED) {
-    clear_value();
-    _type = INT;
+  if (_type == props::NONE || _type == props::UNSPECIFIED) {
+    clearValue();
+    _type = props::INT;
     _local_val.int_val = 0;
   }
 
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     result = _value.alias->setIntValue(value);
     break;
-  case BOOL:
+  case props::BOOL:
     result = set_bool(value == 0 ? false : true);
     break;
-  case INT:
+  case props::INT:
     result = set_int(value);
     break;
-  case LONG:
+  case props::LONG:
     result = set_long(long(value));
     break;
-  case FLOAT:
+  case props::FLOAT:
     result = set_float(float(value));
     break;
-  case DOUBLE:
+  case props::DOUBLE:
     result = set_double(double(value));
     break;
-  case STRING:
-  case UNSPECIFIED: {
+  case props::STRING:
+  case props::UNSPECIFIED: {
     char buf[128];
     sprintf(buf, "%d", value);
     result = set_string(buf);
     break;
   }
-  case NONE:
+  case props::NONE:
   default:
     break;
   }
@@ -1261,44 +1340,44 @@ bool
 SGPropertyNode::setLongValue (long value)
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == LONG)
+  if (_attr == (READ|WRITE) && _type == props::LONG)
     return set_long(value);
 
   bool result = false;
   TEST_WRITE;
-  if (_type == NONE || _type == UNSPECIFIED) {
-    clear_value();
-    _type = LONG;
+  if (_type == props::NONE || _type == props::UNSPECIFIED) {
+    clearValue();
+    _type = props::LONG;
     _local_val.long_val = 0L;
   }
 
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     result = _value.alias->setLongValue(value);
     break;
-  case BOOL:
+  case props::BOOL:
     result = set_bool(value == 0L ? false : true);
     break;
-  case INT:
+  case props::INT:
     result = set_int(int(value));
     break;
-  case LONG:
+  case props::LONG:
     result = set_long(value);
     break;
-  case FLOAT:
+  case props::FLOAT:
     result = set_float(float(value));
     break;
-  case DOUBLE:
+  case props::DOUBLE:
     result = set_double(double(value));
     break;
-  case STRING:
-  case UNSPECIFIED: {
+  case props::STRING:
+  case props::UNSPECIFIED: {
     char buf[128];
     sprintf(buf, "%ld", value);
     result = set_string(buf);
     break;
   }
-  case NONE:
+  case props::NONE:
   default:
     break;
   }
@@ -1312,44 +1391,44 @@ bool
 SGPropertyNode::setFloatValue (float value)
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == FLOAT)
+  if (_attr == (READ|WRITE) && _type == props::FLOAT)
     return set_float(value);
 
   bool result = false;
   TEST_WRITE;
-  if (_type == NONE || _type == UNSPECIFIED) {
-    clear_value();
-    _type = FLOAT;
+  if (_type == props::NONE || _type == props::UNSPECIFIED) {
+    clearValue();
+    _type = props::FLOAT;
     _local_val.float_val = 0;
   }
 
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     result = _value.alias->setFloatValue(value);
     break;
-  case BOOL:
+  case props::BOOL:
     result = set_bool(value == 0.0 ? false : true);
     break;
-  case INT:
+  case props::INT:
     result = set_int(int(value));
     break;
-  case LONG:
+  case props::LONG:
     result = set_long(long(value));
     break;
-  case FLOAT:
+  case props::FLOAT:
     result = set_float(value);
     break;
-  case DOUBLE:
+  case props::DOUBLE:
     result = set_double(double(value));
     break;
-  case STRING:
-  case UNSPECIFIED: {
+  case props::STRING:
+  case props::UNSPECIFIED: {
     char buf[128];
     sprintf(buf, "%f", value);
     result = set_string(buf);
     break;
   }
-  case NONE:
+  case props::NONE:
   default:
     break;
   }
@@ -1363,44 +1442,44 @@ bool
 SGPropertyNode::setDoubleValue (double value)
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == DOUBLE)
+  if (_attr == (READ|WRITE) && _type == props::DOUBLE)
     return set_double(value);
 
   bool result = false;
   TEST_WRITE;
-  if (_type == NONE || _type == UNSPECIFIED) {
-    clear_value();
+  if (_type == props::NONE || _type == props::UNSPECIFIED) {
+    clearValue();
     _local_val.double_val = value;
-    _type = DOUBLE;
+    _type = props::DOUBLE;
   }
 
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     result = _value.alias->setDoubleValue(value);
     break;
-  case BOOL:
+  case props::BOOL:
     result = set_bool(value == 0.0L ? false : true);
     break;
-  case INT:
+  case props::INT:
     result = set_int(int(value));
     break;
-  case LONG:
+  case props::LONG:
     result = set_long(long(value));
     break;
-  case FLOAT:
+  case props::FLOAT:
     result = set_float(float(value));
     break;
-  case DOUBLE:
+  case props::DOUBLE:
     result = set_double(value);
     break;
-  case STRING:
-  case UNSPECIFIED: {
+  case props::STRING:
+  case props::UNSPECIFIED: {
     char buf[128];
     sprintf(buf, "%f", value);
     result = set_string(buf);
     break;
   }
-  case NONE:
+  case props::NONE:
   default:
     break;
   }
@@ -1414,41 +1493,47 @@ bool
 SGPropertyNode::setStringValue (const char * value)
 {
 				// Shortcut for common case
-  if (_attr == (READ|WRITE) && _type == STRING)
+  if (_attr == (READ|WRITE) && _type == props::STRING)
     return set_string(value);
 
   bool result = false;
   TEST_WRITE;
-  if (_type == NONE || _type == UNSPECIFIED) {
-    clear_value();
-    _type = STRING;
+  if (_type == props::NONE || _type == props::UNSPECIFIED) {
+    clearValue();
+    _type = props::STRING;
   }
 
   switch (_type) {
-  case ALIAS:
+  case props::ALIAS:
     result = _value.alias->setStringValue(value);
     break;
-  case BOOL:
+  case props::BOOL:
     result = set_bool((compare_strings(value, "true")
 		       || atoi(value)) ? true : false);
     break;
-  case INT:
+  case props::INT:
     result = set_int(atoi(value));
     break;
-  case LONG:
+  case props::LONG:
     result = set_long(strtol(value, 0, 0));
     break;
-  case FLOAT:
+  case props::FLOAT:
     result = set_float(atof(value));
     break;
-  case DOUBLE:
+  case props::DOUBLE:
     result = set_double(strtod(value, 0));
     break;
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     result = set_string(value);
     break;
-  case NONE:
+  case props::EXTENDED:
+  {
+    stringstream sstr(value);
+    static_cast<SGRawExtended*>(_value.val)->readFrom(sstr);
+  }
+  break;
+  case props::NONE:
   default:
     break;
   }
@@ -1463,36 +1548,44 @@ SGPropertyNode::setUnspecifiedValue (const char * value)
 {
   bool result = false;
   TEST_WRITE;
-  if (_type == NONE) {
-    clear_value();
-    _type = UNSPECIFIED;
-  }
-
-  switch (_type) {
-  case ALIAS:
+  if (_type == props::NONE) {
+    clearValue();
+    _type = props::UNSPECIFIED;
+  }
+  props::Type type = _type;
+  if (type == props::EXTENDED)
+      type = _value.val->getType();
+  switch (type) {
+  case props::ALIAS:
     result = _value.alias->setUnspecifiedValue(value);
     break;
-  case BOOL:
+  case props::BOOL:
     result = set_bool((compare_strings(value, "true")
 		       || atoi(value)) ? true : false);
     break;
-  case INT:
+  case props::INT:
     result = set_int(atoi(value));
     break;
-  case LONG:
+  case props::LONG:
     result = set_long(strtol(value, 0, 0));
     break;
-  case FLOAT:
+  case props::FLOAT:
     result = set_float(atof(value));
     break;
-  case DOUBLE:
+  case props::DOUBLE:
     result = set_double(strtod(value, 0));
     break;
-  case STRING:
-  case UNSPECIFIED:
+  case props::STRING:
+  case props::UNSPECIFIED:
     result = set_string(value);
     break;
-  case NONE:
+  case props::VEC3D:
+      result = static_cast<SGRawValue<SGVec3d>*>(_value.val)->setValue(parseString<SGVec3d>(value));
+      break;
+  case props::VEC4D:
+      result = static_cast<SGRawValue<SGVec4d>*>(_value.val)->setValue(parseString<SGVec4d>(value));
+      break;
+  case props::NONE:
   default:
     break;
   }
@@ -1502,139 +1595,64 @@ SGPropertyNode::setUnspecifiedValue (const char * value)
   return result;
 }
 
-bool
-SGPropertyNode::tie (const SGRawValue<bool> &rawValue, bool useDefault)
-{
-  if (_type == ALIAS || _tied)
-    return false;
-
-  useDefault = useDefault && hasValue();
-  bool old_val = false;
-  if (useDefault)
-    old_val = getBoolValue();
-
-  clear_value();
-  _type = BOOL;
-  _tied = true;
-  _value.bool_val = rawValue.clone();
-
-  if (useDefault)
-    setBoolValue(old_val);
-
-  return true;
-}
-
-bool
-SGPropertyNode::tie (const SGRawValue<int> &rawValue, bool useDefault)
-{
-  if (_type == ALIAS || _tied)
-    return false;
-
-  useDefault = useDefault && hasValue();
-  int old_val = 0;
-  if (useDefault)
-    old_val = getIntValue();
-
-  clear_value();
-  _type = INT;
-  _tied = true;
-  _value.int_val = rawValue.clone();
-
-  if (useDefault)
-    setIntValue(old_val);
-
-  return true;
-}
-
-bool
-SGPropertyNode::tie (const SGRawValue<long> &rawValue, bool useDefault)
-{
-  if (_type == ALIAS || _tied)
-    return false;
-
-  useDefault = useDefault && hasValue();
-  long old_val = 0;
-  if (useDefault)
-    old_val = getLongValue();
-
-  clear_value();
-  _type = LONG;
-  _tied = true;
-  _value.long_val = rawValue.clone();
-
-  if (useDefault)
-    setLongValue(old_val);
-
-  return true;
-}
-
-bool
-SGPropertyNode::tie (const SGRawValue<float> &rawValue, bool useDefault)
-{
-  if (_type == ALIAS || _tied)
-    return false;
-
-  useDefault = useDefault && hasValue();
-  float old_val = 0.0;
-  if (useDefault)
-    old_val = getFloatValue();
-
-  clear_value();
-  _type = FLOAT;
-  _tied = true;
-  _value.float_val = rawValue.clone();
-
-  if (useDefault)
-    setFloatValue(old_val);
-
-  return true;
-}
-
-bool
-SGPropertyNode::tie (const SGRawValue<double> &rawValue, bool useDefault)
-{
-  if (_type == ALIAS || _tied)
-    return false;
-
-  useDefault = useDefault && hasValue();
-  double old_val = 0.0;
-  if (useDefault)
-    old_val = getDoubleValue();
-
-  clear_value();
-  _type = DOUBLE;
-  _tied = true;
-  _value.double_val = rawValue.clone();
-
-  if (useDefault)
-    setDoubleValue(old_val);
-
-  return true;
-
+std::ostream& SGPropertyNode::printOn(std::ostream& stream) const
+{
+    if (!getAttribute(READ))
+        return stream;
+    switch (_type) {
+    case props::ALIAS:
+        return _value.alias->printOn(stream);
+    case props::BOOL:
+        stream << (get_bool() ? "true" : "false");
+        break;
+    case props::INT:
+        stream << get_int();
+        break;
+    case props::LONG:
+        stream << get_long();
+        break;
+    case props::FLOAT:
+        stream << get_float();
+        break;
+    case props::DOUBLE:
+        stream << get_double();
+        break;
+    case props::STRING:
+    case props::UNSPECIFIED:
+        stream << get_string();
+        break;
+    case props::EXTENDED:
+        static_cast<SGRawExtended*>(_value.val)->printOn(stream);
+        break;
+    case props::NONE:
+        break;
+    default: // avoid compiler warning
+        break;
+    }
+    return stream;
 }
 
-bool
-SGPropertyNode::tie (const SGRawValue<const char *> &rawValue, bool useDefault)
+template<>
+bool SGPropertyNode::tie (const SGRawValue<const char *> &rawValue,
+                          bool useDefault)
 {
-  if (_type == ALIAS || _tied)
-    return false;
-
-  useDefault = useDefault && hasValue();
-  string old_val;
-  if (useDefault)
-    old_val = getStringValue();
+    if (_type == props::ALIAS || _tied)
+        return false;
 
-  clear_value();
-  _type = STRING;
-  _tied = true;
-  _value.string_val = rawValue.clone();
+    useDefault = useDefault && hasValue();
+    std::string old_val;
+    if (useDefault)
+        old_val = getStringValue();
+    clearValue();
+    _type = props::STRING;
+    _tied = true;
+    _value.val = rawValue.clone();
 
-  if (useDefault)
-    setStringValue(old_val.c_str());
+    if (useDefault)
+        setStringValue(old_val.c_str());
 
-  return true;
+    return true;
 }
-
 bool
 SGPropertyNode::untie ()
 {
@@ -1642,50 +1660,59 @@ SGPropertyNode::untie ()
     return false;
 
   switch (_type) {
-  case BOOL: {
+  case props::BOOL: {
     bool val = getBoolValue();
-    clear_value();
-    _type = BOOL;
+    clearValue();
+    _type = props::BOOL;
     _local_val.bool_val = val;
     break;
   }
-  case INT: {
+  case props::INT: {
     int val = getIntValue();
-    clear_value();
-    _type = INT;
+    clearValue();
+    _type = props::INT;
     _local_val.int_val = val;
     break;
   }
-  case LONG: {
+  case props::LONG: {
     long val = getLongValue();
-    clear_value();
-    _type = LONG;
+    clearValue();
+    _type = props::LONG;
     _local_val.long_val = val;
     break;
   }
-  case FLOAT: {
+  case props::FLOAT: {
     float val = getFloatValue();
-    clear_value();
-    _type = FLOAT;
+    clearValue();
+    _type = props::FLOAT;
     _local_val.float_val = val;
     break;
   }
-  case DOUBLE: {
+  case props::DOUBLE: {
     double val = getDoubleValue();
-    clear_value();
-    _type = DOUBLE;
+    clearValue();
+    _type = props::DOUBLE;
     _local_val.double_val = val;
     break;
   }
-  case STRING:
-  case UNSPECIFIED: {
+  case props::STRING:
+  case props::UNSPECIFIED: {
     string val = getStringValue();
-    clear_value();
-    _type = STRING;
+    clearValue();
+    _type = props::STRING;
     _local_val.string_val = copy_string(val.c_str());
     break;
   }
-  case NONE:
+  case props::EXTENDED: {
+    SGRawExtended* val = static_cast<SGRawExtended*>(_value.val);
+    _value.val = 0;             // Prevent clearValue() from deleting
+    clearValue();
+    _type = props::EXTENDED;
+    _value.val = val->makeContainer();
+    delete val;
+    break;
+  }
+  case props::NONE:
   default:
     break;
   }
@@ -1715,14 +1742,16 @@ SGPropertyNode::getRootNode () const
 SGPropertyNode *
 SGPropertyNode::getNode (const char * relative_path, bool create)
 {
+  using namespace boost;
   if (_path_cache == 0)
     _path_cache = new hash_table;
 
   SGPropertyNode * result = _path_cache->get(relative_path);
   if (result == 0) {
-    vector<PathComponent> components;
-    parse_path(relative_path, components);
-    result = find_node(this, components, 0, create);
+    result = find_node(this,
+                       make_iterator_range(relative_path, relative_path
+                                           + strlen(relative_path)),
+                       create);
     if (result != 0)
       _path_cache->put(relative_path, result);
   }
@@ -1733,11 +1762,10 @@ SGPropertyNode::getNode (const char * relative_path, bool create)
 SGPropertyNode *
 SGPropertyNode::getNode (const char * relative_path, int index, bool create)
 {
-  vector<PathComponent> components;
-  parse_path(relative_path, components);
-  if (components.size() > 0)
-    components[components.size()-1].index = index;
-  return find_node(this, components, 0, create);
+  using namespace boost;
+  return find_node(this, make_iterator_range(relative_path, relative_path
+                                             + strlen(relative_path)),
+                   create, index);
 }
 
 const SGPropertyNode *
@@ -1772,11 +1800,11 @@ SGPropertyNode::hasValue (const char * relative_path) const
 /**
  * Get the value type for another node.
  */
-SGPropertyNode::Type
+props::Type
 SGPropertyNode::getType (const char * relative_path) const
 {
   const SGPropertyNode * node = getNode(relative_path);
-  return (node == 0 ? UNSPECIFIED : (Type)(node->getType()));
+  return (node == 0 ? props::UNSPECIFIED : node->getType());
 }
 
 
@@ -2017,24 +2045,27 @@ SGPropertyNode::untie (const char * relative_path)
 }
 
 void
-SGPropertyNode::addChangeListener (SGPropertyChangeListener * listener)
+SGPropertyNode::addChangeListener (SGPropertyChangeListener * listener,
+                                   bool initial)
 {
   if (_listeners == 0)
-    _listeners = new vector<SGPropertyChangeListener *>;
+    _listeners = new vector<SGPropertyChangeListener*>;
   _listeners->push_back(listener);
   listener->register_property(this);
+  if (initial)
+    listener->valueChanged(this);
 }
 
 void
 SGPropertyNode::removeChangeListener (SGPropertyChangeListener * listener)
 {
-  vector<SGPropertyChangeListener *>::iterator it =
+  vector<SGPropertyChangeListener*>::iterator it =
     find(_listeners->begin(), _listeners->end(), listener);
   if (it != _listeners->end()) {
     _listeners->erase(it);
     listener->unregister_property(this);
     if (_listeners->empty()) {
-      vector<SGPropertyChangeListener *> * tmp = _listeners;
+      vector<SGPropertyChangeListener*>* tmp = _listeners;
       _listeners = 0;
       delete tmp;
     }
@@ -2106,8 +2137,7 @@ SGPropertyNode::fireChildRemoved (SGPropertyNode * parent,
 #define HASH_TABLE_SIZE 199
 
 SGPropertyNode::hash_table::entry::entry ()
-  : _key(0),
-    _value(0)
+  : _value(0)
 {
 }
 
@@ -2115,13 +2145,12 @@ SGPropertyNode::hash_table::entry::~entry ()
 {
 				// Don't delete the value; we don't own
 				// the pointer.
-  delete [] _key;
 }
 
 void
 SGPropertyNode::hash_table::entry::set_key (const char * key)
 {
-  _key = copy_string(key);
+  _key = key;
 }
 
 void
@@ -2140,6 +2169,7 @@ SGPropertyNode::hash_table::bucket::~bucket ()
 {
   for (int i = 0; i < _length; i++)
     delete _entries[i];
+  delete [] _entries;
 }
 
 SGPropertyNode::hash_table::entry *
@@ -2166,6 +2196,31 @@ SGPropertyNode::hash_table::bucket::get_entry (const char * key, bool create)
   }
 }
 
+bool
+SGPropertyNode::hash_table::bucket::erase (SGPropertyNode * node)
+{
+  for (int i = 0; i < _length; i++) {
+    if (_entries[i]->get_value() == node) {
+      delete _entries[i];
+      for (++i; i < _length; i++) {
+        _entries[i-1] = _entries[i];
+      }
+      _length--;
+      return true;
+    }
+  }
+  return false;
+}
+
+void
+SGPropertyNode::hash_table::bucket::clear (SGPropertyNode::hash_table * owner)
+{
+  for (int i = 0; i < _length; i++) {
+    SGPropertyNode * node = _entries[i]->get_value();
+    if (node)
+      node->remove_linked_node(owner);
+  }
+}
 
 SGPropertyNode::hash_table::hash_table ()
   : _data_length(0),
@@ -2175,8 +2230,13 @@ SGPropertyNode::hash_table::hash_table ()
 
 SGPropertyNode::hash_table::~hash_table ()
 {
-  for (unsigned int i = 0; i < _data_length; i++)
-    delete _data[i];
+  for (unsigned int i = 0; i < _data_length; i++) {
+    if (_data[i]) {
+      _data[i]->clear(this);
+      delete _data[i];
+    }
+  }
+  delete [] _data;
 }
 
 SGPropertyNode *
@@ -2209,6 +2269,17 @@ SGPropertyNode::hash_table::put (const char * key, SGPropertyNode * value)
   }
   entry * e = _data[index]->get_entry(key, true);
   e->set_value(value);
+  value->add_linked_node(this);
+}
+
+bool
+SGPropertyNode::hash_table::erase (SGPropertyNode * node)
+{
+  for (unsigned int i = 0; i < _data_length; i++)
+    if (_data[i] && _data[i]->erase(node))
+      return true;
+
+  return false;
 }
 
 unsigned int
@@ -2223,103 +2294,6 @@ SGPropertyNode::hash_table::hashcode (const char * key)
 }
 
 
-
-/**
- * Default constructor
- */
-SGPropertyNode_ptr::SGPropertyNode_ptr()
-{
-  _ptr = 0;
-}
-
-/**
- * Copy constructor
- */
-SGPropertyNode_ptr::SGPropertyNode_ptr( const SGPropertyNode_ptr &r )
-{
-  _ptr = r._ptr;
-  if (_ptr)
-     _ptr->incrementRef();
-}
-
-/**
- * Constructor from a pointer to a node
- */
-SGPropertyNode_ptr::SGPropertyNode_ptr( SGPropertyNode *p )
-{
-  _ptr = p;
-  if (_ptr)
-     _ptr->incrementRef();
-}
-
-/**
- * Destructor
- */
-SGPropertyNode_ptr::~SGPropertyNode_ptr()
-{
-  if (_ptr && _ptr->decrementRef() == 0)
-    delete _ptr;
-}
-
-/**
- * Assignement operator
- */
-SGPropertyNode_ptr &
-SGPropertyNode_ptr::operator=( const SGPropertyNode_ptr &r )
-{
-  if (_ptr && _ptr->decrementRef() == 0)
-    delete _ptr;
-  _ptr = r._ptr;
-  if (_ptr)
-     _ptr->incrementRef();
-
-  return *this;
-}
-
-/**
- * Pointer access operator
- */
-SGPropertyNode *
-SGPropertyNode_ptr::operator->()
-{
-  return _ptr;
-}
-
-/**
- * Pointer access operator (const)
- */
-const SGPropertyNode *
-SGPropertyNode_ptr::operator->() const
-{
-  return _ptr;
-}
-
-/**
- * Conversion to SGPropertyNode * operator
- */
-SGPropertyNode_ptr::operator SGPropertyNode *()
-{
-  return _ptr;
-}
-
-/**
- * Conversion to const SGPropertyNode * operator
- */
-SGPropertyNode_ptr::operator const SGPropertyNode *() const
-{
-  return _ptr;
-}
-
-/**
- * Validity test
- */
-bool 
-SGPropertyNode_ptr::valid() const
-{
-  return _ptr != 0;
-}
-
-
 
 ////////////////////////////////////////////////////////////////////////
 // Implementation of SGPropertyChangeListener.
@@ -2327,12 +2301,8 @@ SGPropertyNode_ptr::valid() const
 
 SGPropertyChangeListener::~SGPropertyChangeListener ()
 {
-				// This will come back and remove
-				// the current item each time.  Is
-				// that OK?
-  vector<SGPropertyNode *>::iterator it;
-  for (it = _properties.begin(); it != _properties.end(); it++)
-    (*it)->removeChangeListener(this);
+  for (int i = _properties.size() - 1; i >= 0; i--)
+    _properties[i]->removeChangeListener(this);
 }
 
 void
@@ -2370,5 +2340,193 @@ SGPropertyChangeListener::unregister_property (SGPropertyNode * node)
     _properties.erase(it);
 }
 
+template<>
+std::ostream& SGRawBase<SGVec3d>::printOn(std::ostream& stream) const
+{
+    const SGVec3d vec
+        = static_cast<const SGRawValue<SGVec3d>*>(this)->getValue();
+    for (int i = 0; i < 3; ++i) {
+        stream << vec[i];
+        if (i < 2)
+            stream << ' ';
+    }
+    return stream;
+}
+
+namespace simgear
+{
+template<>
+std::istream& readFrom<SGVec3d>(std::istream& stream, SGVec3d& result)
+{
+    for (int i = 0; i < 3; ++i) {
+        stream >> result[i];
+    }
+    return stream;
+}
+}
+template<>
+std::ostream& SGRawBase<SGVec4d>::printOn(std::ostream& stream) const
+{
+    const SGVec4d vec
+        = static_cast<const SGRawValue<SGVec4d>*>(this)->getValue();    
+    for (int i = 0; i < 4; ++i) {
+        stream << vec[i];
+        if (i < 3)
+            stream << ' ';
+    }
+    return stream;
+}
+
+namespace simgear
+{
+template<>
+std::istream& readFrom<SGVec4d>(std::istream& stream, SGVec4d& result)
+{
+    for (int i = 0; i < 4; ++i) {
+        stream >> result[i];
+    }
+    return stream;
+}
+
+namespace
+{
+bool compareNodeValue(const SGPropertyNode& lhs, const SGPropertyNode& rhs)
+{
+    props::Type ltype = lhs.getType();
+    props::Type rtype = rhs.getType();
+    if (ltype != rtype)
+        return false;
+    switch (ltype) {
+    case props::NONE:
+        return true;
+    case props::ALIAS:
+        return false;           // XXX Should we look in aliases?
+    case props::BOOL:
+        return lhs.getValue<bool>() == rhs.getValue<bool>();
+    case props::INT:
+        return lhs.getValue<int>() == rhs.getValue<int>();
+    case props::LONG:
+        return lhs.getValue<long>() == rhs.getValue<long>();
+    case props::FLOAT:
+        return lhs.getValue<float>() == rhs.getValue<float>();
+    case props::DOUBLE:
+        return lhs.getValue<double>() == rhs.getValue<double>();
+    case props::STRING:
+    case props::UNSPECIFIED:
+        return !strcmp(lhs.getStringValue(), rhs.getStringValue());
+    case props::VEC3D:
+        return lhs.getValue<SGVec3d>() == rhs.getValue<SGVec3d>();
+    case props::VEC4D:
+        return lhs.getValue<SGVec4d>() == rhs.getValue<SGVec4d>();
+    default:
+        return false;
+    }
+}
+}
+}
+
+bool SGPropertyNode::compare(const SGPropertyNode& lhs,
+                             const SGPropertyNode& rhs)
+{
+    if (&lhs == &rhs)
+        return true;
+    int lhsChildren = lhs.nChildren();
+    int rhsChildren = rhs.nChildren();
+    if (lhsChildren != rhsChildren)
+        return false;
+    if (lhsChildren == 0)
+        return compareNodeValue(lhs, rhs);
+    for (size_t i = 0; i < lhs._children.size(); ++i) {
+        const SGPropertyNode* lchild = lhs._children[i];
+        const SGPropertyNode* rchild = rhs._children[i];
+        // I'm guessing that the nodes will usually be in the same
+        // order.
+        if (lchild->getIndex() != rchild->getIndex()
+            || lchild->getNameString() != rchild->getNameString()) {
+            rchild = 0;
+            for (PropertyList::const_iterator itr = rhs._children.begin(),
+                     end = rhs._children.end();
+                 itr != end;
+                ++itr)
+                if (lchild->getIndex() == (*itr)->getIndex()
+                    && lchild->getNameString() == (*itr)->getNameString()) {
+                    rchild = *itr;
+                    break;
+                }
+            if (!rchild)
+                return false;
+        }
+        if (!compare(*lchild, *rchild))
+            return false;
+    }
+    return true;
+}
+
+struct PropertyPlaceLess {
+    typedef bool result_type;
+    bool operator()(SGPropertyNode_ptr lhs, SGPropertyNode_ptr rhs) const
+    {
+        int comp = lhs->getNameString().compare(rhs->getNameString());
+        if (comp == 0)
+            return lhs->getIndex() < rhs->getIndex();
+        else
+            return comp < 0;
+    }
+};
+
+size_t hash_value(const SGPropertyNode& node)
+{
+    using namespace boost;
+
+    if (node.nChildren() == 0) {
+        switch (node.getType()) {
+        case props::NONE:
+            return 0;
+
+        case props::BOOL:
+            return hash_value(node.getValue<bool>());
+        case props::INT:
+            return hash_value(node.getValue<int>());
+        case props::LONG:
+            return hash_value(node.getValue<long>());
+        case props::FLOAT:
+            return hash_value(node.getValue<float>());
+        case props::DOUBLE:
+            return hash_value(node.getValue<double>());
+        case props::STRING:
+        case props::UNSPECIFIED:
+        {
+            const char *val = node.getStringValue();
+            return hash_range(val, val + strlen(val));
+        }
+        case props::VEC3D:
+        {
+            const SGVec3d val = node.getValue<SGVec3d>();
+            return hash_range(&val[0], &val[3]);
+        }
+        case props::VEC4D:
+        {
+            const SGVec4d val = node.getValue<SGVec4d>();
+            return hash_range(&val[0], &val[4]);
+        }
+        case props::ALIAS:      // XXX Should we look in aliases?
+        default:
+            return 0;
+        }
+    } else {
+        size_t seed = 0;
+        PropertyList children(node._children.begin(), node._children.end());
+        sort(children.begin(), children.end(), PropertyPlaceLess());
+        for (PropertyList::const_iterator itr  = children.begin(),
+                 end = children.end();
+             itr != end;
+             ++itr) {
+            hash_combine(seed, (*itr)->_name);
+            hash_combine(seed, (*itr)->_index);
+            hash_combine(seed, hash_value(**itr));
+        }
+        return seed;
+    }
+}
 
 // end of props.cxx