/*************************************************************************/
/*                                                                       */
/*                Centre for Speech Technology Research                  */
/*                     University of Edinburgh, UK                       */
/*                         Copyright (c) 1996                            */
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/*************************************************************************/
/*                     Author :  Alan W Black                            */
/*                     Date   :  June 1996                               */
/*-----------------------------------------------------------------------*/
/*                                                                       */
/* A class for building EST_String (char-based) tries for indexing       */
/* arbitrary objects by Strings                                          */
/*                                                                       */
/*=======================================================================*/
#ifndef __EST_STRINGTRIE_H__
#define __EST_STRINGTRIE_H__

#include "EST_String.h"

class EST_StringTrie;

/** An internal class for \Ref{EST_StringTrie} used to hold represent the
    node in an string index tree.

    This basically represents a 128-branching node (on for each character)
    plus a contents field for strings ending at this point.

    @author Alan W Black (awb@cstr.ed.ac.uk): June 1996
*/
class EST_TrieNode {
  private:
    int w;
    EST_TrieNode **d;
    void *contents;
    // will use EST_TrieContents when I have a list of contents 
  public:
    ///
    EST_TrieNode() {w=0; d=0; contents=0;}
    ///
    EST_TrieNode(const int width);
    ///
    ~EST_TrieNode();
    /// Find the contents for given string, 0 if no current contents
    void *lookup(const unsigned char *key) const;
    /// add {\tt item} for {\tt key} overwriting previous contents
    void add(const unsigned char *key,void *item);
    /// copy all entries in trie node into trie
    void copy_into(EST_StringTrie &trie, const EST_String &path) const;
};

/** A string tree index class for indexing arbitrary objects by 
    strings of characters.

    Note this only deals with 7 but characters, and can only hold
    one item per index key.
*/
class EST_StringTrie {
  private:
    EST_TrieNode *tree;
  public:
    ///
    EST_StringTrie();
    ///
    EST_StringTrie(const EST_StringTrie &trie) { copy(trie); }
    ///
    ~EST_StringTrie();
    ///
    void copy(const EST_StringTrie &trie);
    /// Find contents index by {\tt key}, 0 if there is not contents
    void *lookup(const EST_String &key) const;
    /// Add {\tt item} indexed by {\tt key}, overwriting previous contents
    void add(const EST_String &key,void *item);
    /// Delete the tree
    void clear(void);
    /// Delete the tree, apply {\tt deletenote} function to each {\tt contents}
    void clear(void (*deletenode)(void *n));

    ///
    EST_StringTrie & operator = (const EST_StringTrie &a) 
       { copy(a); return *this; }

};

#endif // __EST_STRINGTRIE_H__