props.hxx

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#ifndef __PROPS_HXX
#define __PROPS_HXX

#ifndef PROPS_STANDALONE
#define PROPS_STANDALONE 0
#endif

#include <vector>
#include <string>
#include <iostream>
#include <sstream>

#include <boost/utility.hpp>

#if PROPS_STANDALONE
#else
#include <simgear/compiler.h>
#include <simgear/debug/logstream.hxx>
#endif


#include <simgear/math/SGMathFwd.hxx>
#include <simgear/structure/SGReferenced.hxx>
#include <simgear/structure/SGSharedPtr.hxx>

// XXX This whole file should be in the simgear namespace, but I don't
// have the guts yet...

namespace simgear
{
template<typename T>
std::istream& readFrom(std::istream& stream, T& result)
{
    stream >> result;
    return stream;
}

template<typename T>
inline T parseString(const std::string& str)
{
    std::istringstream stream(str);
    T result;
    readFrom(stream, result);
    return result;
}

// Extended properties
template<>
std::istream& readFrom<SGVec3d>(std::istream& stream, SGVec3d& result);
template<>
std::istream& readFrom<SGVec4d>(std::istream& stream, SGVec4d& result);

    
#ifdef NONE
#pragma warn A sloppy coder has defined NONE as a macro!
#undef NONE
#endif

#ifdef ALIAS
#pragma warn A sloppy coder has defined ALIAS as a macro!
#undef ALIAS
#endif

#ifdef UNSPECIFIED
#pragma warn A sloppy coder has defined UNSPECIFIED as a macro!
#undef UNSPECIFIED
#endif

#ifdef BOOL
#pragma warn A sloppy coder has defined BOOL as a macro!
#undef BOOL
#endif

#ifdef INT
#pragma warn A sloppy coder has defined INT as a macro!
#undef INT
#endif

#ifdef LONG
#pragma warn A sloppy coder has defined LONG as a macro!
#undef LONG
#endif

#ifdef FLOAT
#pragma warn A sloppy coder has defined FLOAT as a macro!
#undef FLOAT
#endif

#ifdef DOUBLE
#pragma warn A sloppy coder has defined DOUBLE as a macro!
#undef DOUBLE
#endif

#ifdef STRING
#pragma warn A sloppy coder has defined STRING as a macro!
#undef STRING
#endif

namespace props
{
enum Type {
    NONE = 0, 
    ALIAS, 
    BOOL,
    INT,
    LONG,
    FLOAT,
    DOUBLE,
    STRING,
    UNSPECIFIED,
    EXTENDED, 
    // Extended properties
    VEC3D,
    VEC4D
};

template<typename T> struct PropertyTraits;

#define DEFINTERNALPROP(TYPE, PROP) \
template<> \
struct PropertyTraits<TYPE> \
{ \
    static const Type type_tag = PROP; \
    enum  { Internal = 1 }; \
}

DEFINTERNALPROP(bool, BOOL);
DEFINTERNALPROP(int, INT);
DEFINTERNALPROP(long, LONG);
DEFINTERNALPROP(float, FLOAT);
DEFINTERNALPROP(double, DOUBLE);
DEFINTERNALPROP(const char *, STRING);
DEFINTERNALPROP(const char[], STRING);
#undef DEFINTERNALPROP

template<>
struct PropertyTraits<SGVec3d>
{
    static const Type type_tag = VEC3D;
    enum  { Internal = 0 };
};

template<>
struct PropertyTraits<SGVec4d>
{
    static const Type type_tag = VEC4D;
    enum  { Internal = 0 };
};
}
}




// A raw value.
//
// This is the mechanism that information-providing routines can
// use to link their own values to the property manager.  Any
// SGValue can be tied to a raw value and then untied again.
//
// Note: we are forced to use inlined methods here to ensure
// that the templates will be instantiated.  We're probably taking
// a small performance hit for that.

class SGRaw
{
public:
    virtual simgear::props::Type getType() const = 0;
    virtual ~SGRaw() {}
    
    virtual SGRaw* clone() const = 0;

};

class SGRawExtended : public SGRaw
{
public:
    virtual SGRawExtended* makeContainer() const = 0;
    virtual std::ostream& printOn(std::ostream& stream) const = 0;
    virtual std::istream& readFrom(std::istream& stream) = 0;
};

// Choose between different base classes based on whether the value is
// stored internal to the property node. This frees us from defining
// the virtual functions in the SGRawExtended interface where they
// don't make sense, e.g. readFrom for the const char* type.
template<typename T, int internal = simgear::props::PropertyTraits<T>::Internal>
class SGRawBase;

template<typename T>
class SGRawBase<T, 1> : public SGRaw
{
};

template<typename T>
class SGRawBase<T, 0> : public SGRawExtended
{
    virtual SGRawExtended* makeContainer() const;
    virtual std::ostream& printOn(std::ostream& stream) const;
    virtual std::istream& readFrom(std::istream& stream);
};

template <class T>
class SGRawValue : public SGRawBase<T>
{
public:

  static T DefaultValue()
  {
    return T();
  }


  SGRawValue () {}


  virtual ~SGRawValue () {}


  virtual T getValue () const = 0;


  virtual bool setValue (T value) = 0;


  virtual simgear::props::Type getType() const
  {
    return simgear::props::PropertyTraits<T>::type_tag;
  }
};



// Default values for every type.

template<> inline bool SGRawValue<bool>::DefaultValue()
{
  return false;
}

template<> inline const char * SGRawValue<const char *>::DefaultValue()
{
  return "";
}

template <class T>
class SGRawValuePointer : public SGRawValue<T>
{
public:

  SGRawValuePointer (T * ptr) : _ptr(ptr) {}

  virtual ~SGRawValuePointer () {}

  virtual T getValue () const { return *_ptr; }

  virtual bool setValue (T value) { *_ptr = value; return true; }

  virtual SGRaw* clone () const {
    return new SGRawValuePointer(_ptr);
  }

private:
  T * _ptr;
};


template <class T>
class SGRawValueFunctions : public SGRawValue<T>
{
public:

  typedef T (*getter_t)();

  typedef void (*setter_t)(T);

  SGRawValueFunctions (getter_t getter = 0, setter_t setter = 0)
    : _getter(getter), _setter(setter) {}

  virtual ~SGRawValueFunctions () {}

  virtual T getValue () const {
    if (_getter) return (*_getter)();
    else return SGRawValue<T>::DefaultValue();
  }

  virtual bool setValue (T value) {
    if (_setter) { (*_setter)(value); return true; }
    else return false;
  }

  virtual SGRaw* clone () const {
    return new SGRawValueFunctions(_getter,_setter);
  }

private:
  getter_t _getter;
  setter_t _setter;
};


template <class T>
class SGRawValueFunctionsIndexed : public SGRawValue<T>
{
public:
  typedef T (*getter_t)(int);
  typedef void (*setter_t)(int,T);
  SGRawValueFunctionsIndexed (int index, getter_t getter = 0, setter_t setter = 0)
    : _index(index), _getter(getter), _setter(setter) {}
  virtual ~SGRawValueFunctionsIndexed () {}
  virtual T getValue () const {
    if (_getter) return (*_getter)(_index);
    else return SGRawValue<T>::DefaultValue();
  }
  virtual bool setValue (T value) {
    if (_setter) { (*_setter)(_index, value); return true; }
    else return false;
  }
  virtual SGRaw* clone () const {
    return new SGRawValueFunctionsIndexed(_index, _getter, _setter);
  }
private:
  int _index;
  getter_t _getter;
  setter_t _setter;
};


template <class C, class T>
class SGRawValueMethods : public SGRawValue<T>
{
public:
  typedef T (C::*getter_t)() const;
  typedef void (C::*setter_t)(T);
  SGRawValueMethods (C &obj, getter_t getter = 0, setter_t setter = 0)
    : _obj(obj), _getter(getter), _setter(setter) {}
  virtual ~SGRawValueMethods () {}
  virtual T getValue () const {
    if (_getter) { return (_obj.*_getter)(); }
    else { return SGRawValue<T>::DefaultValue(); }
  }
  virtual bool setValue (T value) {
    if (_setter) { (_obj.*_setter)(value); return true; }
    else return false;
  }
  virtual SGRaw* clone () const {
    return new SGRawValueMethods(_obj, _getter, _setter);
  }
private:
  C &_obj;
  getter_t _getter;
  setter_t _setter;
};


template <class C, class T>
class SGRawValueMethodsIndexed : public SGRawValue<T>
{
public:
  typedef T (C::*getter_t)(int) const;
  typedef void (C::*setter_t)(int, T);
  SGRawValueMethodsIndexed (C &obj, int index,
                     getter_t getter = 0, setter_t setter = 0)
    : _obj(obj), _index(index), _getter(getter), _setter(setter) {}
  virtual ~SGRawValueMethodsIndexed () {}
  virtual T getValue () const {
    if (_getter) { return (_obj.*_getter)(_index); }
    else { return SGRawValue<T>::DefaultValue(); }
  }
  virtual bool setValue (T value) {
    if (_setter) { (_obj.*_setter)(_index, value); return true; }
    else return false;
  }
  virtual SGRaw* clone () const {
    return new SGRawValueMethodsIndexed(_obj, _index, _getter, _setter);
  }
private:
  C &_obj;
  int _index;
  getter_t _getter;
  setter_t _setter;
};

template <class T>
class SGRawValueContainer : public SGRawValue<T>
{
public:

    SGRawValueContainer(const T& obj) : _obj(obj) {}

    virtual ~SGRawValueContainer() {}

    virtual T getValue() const { return _obj; }

    virtual bool setValue (T value) { _obj = value; return true; }

    virtual SGRaw* clone () const {
        return new SGRawValueContainer(_obj);
    }

private:
    T _obj;
};

template<typename T>
SGRawExtended* SGRawBase<T, 0>::makeContainer() const
{
    return new SGRawValueContainer<T>(static_cast<const SGRawValue<T>*>(this)
                                      ->getValue());
}

template<typename T>
std::ostream& SGRawBase<T, 0>::printOn(std::ostream& stream) const
{
    return stream << static_cast<SGRawValue<T>*>(this)->getValue();
}

template<typename T>
std::istream& SGRawBase<T, 0>::readFrom(std::istream& stream)
{
    T value;
    simgear::readFrom(stream, value);
    static_cast<SGRawValue<T>*>(this)->setValue(value);
    return stream;
}

template<>
std::ostream& SGRawBase<SGVec3d>::printOn(std::ostream& stream) const;
template<>
std::ostream& SGRawBase<SGVec4d>::printOn(std::ostream& stream) const;


class SGPropertyNode;
typedef SGSharedPtr<SGPropertyNode> SGPropertyNode_ptr;
typedef SGSharedPtr<const SGPropertyNode> SGConstPropertyNode_ptr;

namespace simgear
{
typedef std::vector<SGPropertyNode_ptr> PropertyList;
}


class SGPropertyChangeListener
{
public:
  virtual ~SGPropertyChangeListener ();
  virtual void valueChanged (SGPropertyNode * node);
  virtual void childAdded (SGPropertyNode * parent, SGPropertyNode * child);
  virtual void childRemoved (SGPropertyNode * parent, SGPropertyNode * child);

protected:
  friend class SGPropertyNode;
  virtual void register_property (SGPropertyNode * node);
  virtual void unregister_property (SGPropertyNode * node);

private:
  std::vector<SGPropertyNode *> _properties;
};



class SGPropertyNode : public SGReferenced
{
public:

  enum {
    MAX_STRING_LEN = 1024
  };

  enum Attribute {
    READ = 1,
    WRITE = 2,
    ARCHIVE = 4,
    REMOVED = 8,
    TRACE_READ = 16,
    TRACE_WRITE = 32,
    USERARCHIVE = 64
  };


  static const int LAST_USED_ATTRIBUTE;


  SGPropertyNode ();


  SGPropertyNode (const SGPropertyNode &node);


  virtual ~SGPropertyNode ();



  //
  // Basic properties.
  //

    bool hasValue () const { return (_type != simgear::props::NONE); }


  const char * getName () const { return _name.c_str(); }

  const std::string& getNameString () const { return _name; }

    std::string getDisplayName (bool simplify = false) const;


  int getIndex () const { return _index; }


  SGPropertyNode * getParent () { return _parent; }


  const SGPropertyNode * getParent () const { return _parent; }


  //
  // Children.
  //


  int nChildren () const { return (int)_children.size(); }


  SGPropertyNode * getChild (int position);


  const SGPropertyNode * getChild (int position) const;


  bool hasChild (const char * name, int index = 0) const
  {
    return (getChild(name, index) != 0);
  }

  bool hasChild (const std::string& name, int index = 0) const
  {
    return (getChild(name, index) != 0);
  }

  SGPropertyNode * addChild (const char * name);

  SGPropertyNode * getChild (const char* name, int index = 0,
                             bool create = false);
  SGPropertyNode * getChild (const std::string& name, int index = 0,
                             bool create = false);
  const SGPropertyNode * getChild (const char * name, int index = 0) const;

  const SGPropertyNode * getChild (const std::string& name, int index = 0) const
  { return getChild(name.c_str(), index); }


  simgear::PropertyList getChildren (const char * name) const;

  simgear::PropertyList getChildren (const std::string& name) const
  { return getChildren(name.c_str()); }

  SGPropertyNode_ptr removeChild (int pos, bool keep = true);


  SGPropertyNode_ptr removeChild (const char * name, int index = 0,
                                  bool keep = true);

  SGPropertyNode_ptr removeChild (const std::string& name, int index = 0,
                                  bool keep = true)
  { return removeChild(name.c_str(), index, keep); }

  simgear::PropertyList removeChildren (const char * name, bool keep = true);

  simgear::PropertyList removeChildren (const std::string& name,
                                        bool keep = true)
  { return removeChildren(name.c_str(), keep); }

  //
  // Alias support.
  //


  bool alias (SGPropertyNode * target);


  bool alias (const char * path);

  bool alias (const std::string& path)
  { return alias(path.c_str()); }


  bool unalias ();


  bool isAlias () const { return (_type == simgear::props::ALIAS); }


  SGPropertyNode * getAliasTarget ();


  const SGPropertyNode * getAliasTarget () const;


  //
  // Path information.
  //


  const char * getPath (bool simplify = false) const;


  SGPropertyNode * getRootNode ();


  const SGPropertyNode * getRootNode () const;


  SGPropertyNode * getNode (const char * relative_path, bool create = false);

  SGPropertyNode * getNode (const std::string& relative_path, bool create = false)
  { return getNode(relative_path.c_str(), create); }

  SGPropertyNode * getNode (const char * relative_path, int index,
                            bool create = false);

  SGPropertyNode * getNode (const std::string& relative_path, int index,
                            bool create = false)
  { return getNode(relative_path.c_str(), index, create); }

  const SGPropertyNode * getNode (const char * relative_path) const;

  const SGPropertyNode * getNode (const std::string& relative_path) const
  { return getNode(relative_path.c_str()); }


  const SGPropertyNode * getNode (const char * relative_path,
                                  int index) const;

  const SGPropertyNode * getNode (const std::string& relative_path,
                                  int index) const
  { return getNode(relative_path.c_str(), index); }

  //
  // Access Mode.
  //

  bool getAttribute (Attribute attr) const { return ((_attr & attr) != 0); }


  void setAttribute (Attribute attr, bool state) {
    (state ? _attr |= attr : _attr &= ~attr);
  }


  int getAttributes () const { return _attr; }


  void setAttributes (int attr) { _attr = attr; }
  

  //
  // Leaf Value (primitive).
  //


  simgear::props::Type getType () const;


  bool getBoolValue () const;


  int getIntValue () const;


  long getLongValue () const;


  float getFloatValue () const;


  double getDoubleValue () const;


  const char * getStringValue () const;

  template<typename T>
  T getValue(typename boost::enable_if_c<simgear::props::PropertyTraits<T>::Internal>
             ::type* dummy = 0) const;
  // Getter for extended property
  template<typename T>
  T getValue(typename boost::disable_if_c<simgear::props::PropertyTraits<T>::Internal>
             ::type* dummy = 0) const;

  bool setBoolValue (bool value);


  bool setIntValue (int value);


  bool setLongValue (long value);


  bool setFloatValue (float value);


  bool setDoubleValue (double value);


  bool setStringValue (const char * value);

  bool setStringValue (const std::string& value)
  { return setStringValue(value.c_str()); }


  bool setUnspecifiedValue (const char * value);

  template<typename T>
  bool setValue(const T& val,
                typename boost::enable_if_c<simgear::props::PropertyTraits<T>::Internal>
                ::type* dummy = 0);

  template<typename T>
  bool setValue(const T& val,
                typename boost::disable_if_c<simgear::props::PropertyTraits<T>::Internal>
                ::type* dummy = 0);

  template<int N>
  bool setValue(const char (&val)[N])
  {
    return setValue(&val[0]);
  }
  
  std::ostream& printOn(std::ostream& stream) const;
  
  //
  // Data binding.
  //


  bool isTied () const { return _tied; }

    template<typename T>
    bool tie(const SGRawValue<T> &rawValue, bool useDefault = true);

  bool untie ();


  //
  // Convenience methods using paths.
  // TODO: add attribute methods
  //


  simgear::props::Type getType (const char * relative_path) const;

  simgear::props::Type getType (const std::string& relative_path) const
  { return getType(relative_path.c_str()); }

  bool hasValue (const char * relative_path) const;

  bool hasValue (const std::string& relative_path) const
  { return hasValue(relative_path.c_str()); }

  bool getBoolValue (const char * relative_path,
                     bool defaultValue = false) const;

  bool getBoolValue (const std::string& relative_path,
                     bool defaultValue = false) const
  { return getBoolValue(relative_path.c_str(), defaultValue); }

  int getIntValue (const char * relative_path,
                   int defaultValue = 0) const;

  int getIntValue (const std::string& relative_path,
                   int defaultValue = 0) const
  { return getIntValue(relative_path.c_str(), defaultValue); }


  long getLongValue (const char * relative_path,
                     long defaultValue = 0L) const;

  long getLongValue (const std::string& relative_path,
                     long defaultValue = 0L) const
  { return getLongValue(relative_path.c_str(), defaultValue); }

  float getFloatValue (const char * relative_path,
                       float defaultValue = 0.0f) const;

  float getFloatValue (const std::string& relative_path,
                       float defaultValue = 0.0f) const
  { return getFloatValue(relative_path.c_str(), defaultValue); }


  double getDoubleValue (const char * relative_path,
                         double defaultValue = 0.0) const;

  double getDoubleValue (const std::string& relative_path,
                         double defaultValue = 0.0) const
  { return getDoubleValue(relative_path.c_str(), defaultValue); }

  const char * getStringValue (const char * relative_path,
                               const char * defaultValue = "") const;


  const char * getStringValue (const std::string& relative_path,
                               const char * defaultValue = "") const
  { return getStringValue(relative_path.c_str(), defaultValue); }


  bool setBoolValue (const char * relative_path, bool value);

  bool setBoolValue (const std::string& relative_path, bool value)
  { return setBoolValue(relative_path.c_str(), value); }


  bool setIntValue (const char * relative_path, int value);

  bool setIntValue (const std::string& relative_path, int value)
  { return setIntValue(relative_path.c_str(), value); }


  bool setLongValue (const char * relative_path, long value);

  bool setLongValue (const std::string& relative_path, long value)
  { return setLongValue(relative_path.c_str(), value); }


  bool setFloatValue (const char * relative_path, float value);

  bool setFloatValue (const std::string& relative_path, float value)
  { return setFloatValue(relative_path.c_str(), value); }


  bool setDoubleValue (const char * relative_path, double value);

  bool setDoubleValue (const std::string& relative_path, double value)
  { return setDoubleValue(relative_path.c_str(), value); }


  bool setStringValue (const char * relative_path, const char * value);

  bool setStringValue(const char * relative_path, const std::string& value)
  { return setStringValue(relative_path, value.c_str()); }
  bool setStringValue (const std::string& relative_path, const char * value)
  { return setStringValue(relative_path.c_str(), value); }

  bool setStringValue (const std::string& relative_path,
                       const std::string& value)
  { return setStringValue(relative_path.c_str(), value.c_str()); }

  bool setUnspecifiedValue (const char * relative_path, const char * value);


  bool isTied (const char * relative_path) const;

  bool isTied (const std::string& relative_path) const
  { return isTied(relative_path.c_str()); }

  bool tie (const char * relative_path, const SGRawValue<bool> &rawValue,
            bool useDefault = true);

  bool tie (const std::string& relative_path, const SGRawValue<bool> &rawValue,
            bool useDefault = true)
  { return tie(relative_path.c_str(), rawValue, useDefault); }


  bool tie (const char * relative_path, const SGRawValue<int> &rawValue,
            bool useDefault = true);

  bool tie (const std::string& relative_path, const SGRawValue<int> &rawValue,
            bool useDefault = true)
  { return tie(relative_path.c_str(), rawValue, useDefault); }


  bool tie (const char * relative_path, const SGRawValue<long> &rawValue,
            bool useDefault = true);

  bool tie (const std::string& relative_path, const SGRawValue<long> &rawValue,
            bool useDefault = true)
  { return tie(relative_path.c_str(), rawValue, useDefault); }


  bool tie (const char * relative_path, const SGRawValue<float> &rawValue,
            bool useDefault = true);

  bool tie (const std::string& relative_path, const SGRawValue<float> &rawValue,
            bool useDefault = true)
  { return tie(relative_path.c_str(), rawValue, useDefault); }


  bool tie (const char * relative_path, const SGRawValue<double> &rawValue,
            bool useDefault = true);

  bool tie (const std::string& relative_path, const SGRawValue<double> &rawValue,
            bool useDefault = true)
  { return tie(relative_path.c_str(), rawValue, useDefault); }


  bool tie (const char * relative_path, const SGRawValue<const char *> &rawValue,
            bool useDefault = true);

  bool tie (const std::string& relative_path, const SGRawValue<const char*> &rawValue,
            bool useDefault = true)
  { return tie(relative_path.c_str(), rawValue, useDefault); }


  bool untie (const char * relative_path);

  bool untie (const std::string& relative_path)
  { return untie(relative_path.c_str()); }


  void addChangeListener (SGPropertyChangeListener * listener,
                          bool initial = false);


  void removeChangeListener (SGPropertyChangeListener * listener);


  int nListeners () const { return _listeners ? (int)_listeners->size() : 0; }


  void fireValueChanged ();


  void fireChildAdded (SGPropertyNode * child);


  void fireChildRemoved (SGPropertyNode * child);


  void clearValue ();

  static bool compare (const SGPropertyNode& lhs, const SGPropertyNode& rhs);

protected:

  void fireValueChanged (SGPropertyNode * node);
  void fireChildAdded (SGPropertyNode * parent, SGPropertyNode * child);
  void fireChildRemoved (SGPropertyNode * parent, SGPropertyNode * child);

  SGPropertyNode (const std::string& name, int index, SGPropertyNode * parent);
  template<typename Itr>
  SGPropertyNode (Itr begin, Itr end, int index, SGPropertyNode * parent);

private:

  // Get the raw value
  bool get_bool () const;
  int get_int () const;
  long get_long () const;
  float get_float () const;
  double get_double () const;
  const char * get_string () const;

  // Set the raw value
  bool set_bool (bool value);
  bool set_int (int value);
  bool set_long (long value);
  bool set_float (float value);
  bool set_double (double value);
  bool set_string (const char * value);


  const char * make_string () const;

  void trace_read () const;


  void trace_write () const;


  void remove_from_path_caches();


  class hash_table;

  int _index;
  std::string _name;
  SGPropertyNode * _parent;
  simgear::PropertyList _children;
  simgear::PropertyList _removedChildren;
  std::vector<hash_table *> _linkedNodes;
  mutable std::string _path;
  mutable std::string _buffer;
  hash_table * _path_cache;
  simgear::props::Type _type;
  bool _tied;
  int _attr;

  // The right kind of pointer...
  union {
    SGPropertyNode * alias;
    SGRaw* val;
  } _value;

  union {
    bool bool_val;
    int int_val;
    long long_val;
    float float_val;
    double double_val;
    char * string_val;
  } _local_val;

  std::vector<SGPropertyChangeListener *> * _listeners;


  void add_linked_node (hash_table * node) { _linkedNodes.push_back(node); }
  bool remove_linked_node (hash_table * node);



  class hash_table {
  public:

    class entry {
    public:
      entry ();
      ~entry ();
      const char * get_key () { return _key.c_str(); }
      void set_key (const char * key);
      SGPropertyNode * get_value () { return _value; }
      void set_value (SGPropertyNode * value);
    private:
      std::string _key;
      SGSharedPtr<SGPropertyNode> _value;
    };


    class bucket {
    public:
      bucket ();
      ~bucket ();
      entry * get_entry (const char * key, bool create = false);
      bool erase (SGPropertyNode * node);
      void clear (hash_table * owner);
    private:
      int _length;
      entry ** _entries;
    };

    friend class bucket;

    hash_table ();
    ~hash_table ();
    SGPropertyNode * get (const char * key);
    void put (const char * key, SGPropertyNode * value);
    bool erase (SGPropertyNode * node);

  private:
    unsigned int hashcode (const char * key);
    unsigned int _data_length;
    bucket ** _data;
  };
  // Pass name as a pair of iterators
  template<typename Itr>
  SGPropertyNode * getChildImpl (Itr begin, Itr end, int index = 0, bool create = false);
  // very internal method
  template<typename Itr>
  SGPropertyNode* getExistingChild (Itr begin, Itr end, int index, bool create);
  // very internal path parsing function
  template<typename SplitItr>
  friend SGPropertyNode* find_node_aux(SGPropertyNode * current, SplitItr& itr,
                                       bool create, int last_index);
  // For boost
  friend size_t hash_value(const SGPropertyNode& node);
};

// Convenience functions for use in templates
template<typename T>
T getValue(const SGPropertyNode*);

template<>
inline bool getValue<bool>(const SGPropertyNode* node) { return node->getBoolValue(); }

template<>
inline int getValue<int>(const SGPropertyNode* node) { return node->getIntValue(); }

template<>
inline long getValue<long>(const SGPropertyNode* node) { return node->getLongValue(); }

template<>
inline float getValue<float>(const SGPropertyNode* node)
{
    return node->getFloatValue();
}

template<>
inline double getValue<double>(const SGPropertyNode* node)
{
    return node->getDoubleValue();
}

template<>
inline const char * getValue<const char*>(const SGPropertyNode* node)
{
    return node->getStringValue ();
}

inline bool setValue(SGPropertyNode* node, bool value)
{
    return node->setBoolValue(value);
}

inline bool setValue(SGPropertyNode* node, int value)
{
    return node->setIntValue(value);
}

inline bool setValue(SGPropertyNode* node, long value)
{
    return node->setLongValue(value);
}

inline bool setValue(SGPropertyNode* node, float value)
{
    return node->setFloatValue(value);
}

inline bool setValue(SGPropertyNode* node, double value)
{
    return node->setDoubleValue(value);
}

inline bool setValue(SGPropertyNode* node, const char* value)
{
    return node->setStringValue(value);
}

inline bool setValue (SGPropertyNode* node, const std::string& value)
{
    return node->setStringValue(value.c_str());
}

template<typename T>
bool SGPropertyNode::tie(const SGRawValue<T> &rawValue, bool useDefault)
{
    using namespace simgear::props;
    if (_type == ALIAS || _tied)
        return false;

    useDefault = useDefault && hasValue();
    T old_val = SGRawValue<T>::DefaultValue();
    if (useDefault)
        old_val = getValue<T>(this);
    clearValue();
    if (PropertyTraits<T>::Internal)
        _type = PropertyTraits<T>::type_tag;
    else
        _type = EXTENDED;
    _tied = true;
    _value.val = rawValue.clone();
    if (useDefault)
        setValue(old_val);
    return true;
}

template<>
bool SGPropertyNode::tie (const SGRawValue<const char *> &rawValue,
                          bool useDefault);

template<typename T>
T SGPropertyNode::getValue(typename boost::disable_if_c<simgear::props
                           ::PropertyTraits<T>::Internal>::type* dummy) const
{
    using namespace simgear::props;
    if (_attr == (READ|WRITE) && _type == EXTENDED
        && _value.val->getType() == PropertyTraits<T>::type_tag) {
        return static_cast<SGRawValue<T>*>(_value.val)->getValue();
    }
    if (getAttribute(TRACE_READ))
        trace_read();
    if (!getAttribute(READ))
      return SGRawValue<T>::DefaultValue();
    switch (_type) {
    case EXTENDED:
        if (_value.val->getType() == PropertyTraits<T>::type_tag)
            return static_cast<SGRawValue<T>*>(_value.val)->getValue();
        break;
    case STRING:
    case UNSPECIFIED:
        return simgear::parseString<T>(make_string());
        break;
    default: // avoid compiler warning
        break;
    }
    return SGRawValue<T>::DefaultValue();
}

template<typename T>
inline T SGPropertyNode::getValue(typename boost::enable_if_c<simgear::props
                                  ::PropertyTraits<T>::Internal>::type* dummy) const
{
  return ::getValue<T>(this);
}

template<typename T>
bool SGPropertyNode::setValue(const T& val,
                              typename boost::disable_if_c<simgear::props
                              ::PropertyTraits<T>::Internal>::type* dummy)
{
    using namespace simgear::props;
    if (_attr == (READ|WRITE) && _type == EXTENDED
        && _value.val->getType() == PropertyTraits<T>::type_tag) {
        static_cast<SGRawValue<T>*>(_value.val)->setValue(val);
        return true;
    }
    if (getAttribute(WRITE)
        && ((_type == EXTENDED
            && _value.val->getType() == PropertyTraits<T>::type_tag)
            || _type == NONE || _type == UNSPECIFIED)) {
        if (_type == NONE || _type == UNSPECIFIED) {
            clearValue();
            _type = EXTENDED;
            _value.val = new SGRawValueContainer<T>(val);
        } else {
            static_cast<SGRawValue<T>*>(_value.val)->setValue(val);
        }
        if (getAttribute(TRACE_WRITE))
            trace_write();
        return true;
    }
    return false;
}

template<typename T>
inline bool SGPropertyNode::setValue(const T& val,
                                     typename boost::enable_if_c<simgear::props
                                     ::PropertyTraits<T>::Internal>::type* dummy)
{
  return ::setValue(this, val);
}

inline SGPropertyNode* makeChild(SGPropertyNode* parent, const char* name,
                                 int index = 0)
{
    return parent->getChild(name, index, true);
}

namespace simgear
{
template<typename StringType>
inline SGPropertyNode* makeNode(SGPropertyNode* parent, const StringType& name)
{
    return parent->getNode(name, true);
}
}

// For boost::hash
size_t hash_value(const SGPropertyNode& node);

// Helper comparison and hash functions for common cases

namespace simgear
{
namespace props
{
struct Compare
{
    bool operator()(const SGPropertyNode* lhs, const SGPropertyNode* rhs) const
    {
        return SGPropertyNode::compare(*lhs, *rhs);
    }
    bool operator()(SGPropertyNode_ptr lhs, const SGPropertyNode* rhs) const
    {
        return SGPropertyNode::compare(*lhs, *rhs);
    }
    bool operator()(const SGPropertyNode* lhs, SGPropertyNode_ptr rhs) const
    {
        return SGPropertyNode::compare(*lhs, *rhs);
    }
    bool operator()(SGPropertyNode_ptr lhs, SGPropertyNode_ptr rhs) const
    {
        return SGPropertyNode::compare(*lhs, *rhs);
    }
};

struct Hash
{
    size_t operator()(const SGPropertyNode* node) const
    {
        return hash_value(*node);
    }
    size_t operator()(SGPropertyNode_ptr node) const
    {
        return hash_value(*node);
    }
};
}
}
#endif // __PROPS_HXX

// end of props.hxx

---