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wagon_interp.cc

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/*                Centre for Speech Technology Research                  */
/*                     University of Edinburgh, UK                       */
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/*************************************************************************/
/*                     Author :  Alan W Black                            */
/*                     Date   :  May 1996                                */
/*-----------------------------------------------------------------------*/
/*                                                                       */
/* A simple interpreter for CART trees as produced by Wagon              */
/*                                                                       */
/*=======================================================================*/
#include <stdio.h>
#include "EST_unix.h"
#include <stdlib.h>
#include "festival.h"

#define ques_oper_str(X) (get_c_string(car(cdr(X))))
#define ques_operand(X) (car(cdr(cdr(X))))
static int wagon_ask(EST_Item *s, LISP tree,
                 EST_TKVL <EST_String,EST_Val> *fcache);
static LISP l_wagon_predict(EST_Item *s, LISP tree,
                      EST_TKVL <EST_String,EST_Val> *fcache);

/* It seems to be worth building a feature cache */

EST_Val wagon_predict(EST_Item *s, LISP tree)
{
    LISP answer,val;
    EST_TKVL <EST_String,EST_Val> *fcache;

    fcache = new EST_TKVL<EST_String,EST_Val>;  // feature cache saves some calls
    answer = l_wagon_predict(s,tree,fcache);
    delete fcache;
    
    // Decide if this is a number of a string
    val = car(siod_last(answer));
    if (!FLONUMP(val))  // just in case 
      return EST_Val(get_c_string(val));
    else if (!CONSP(car(answer)))
      return EST_Val(get_c_float(val));
    else
      return EST_Val(get_c_string(val));

}

LISP wagon_pd(EST_Item *s, LISP tree)
{
    // return probability distribution 
    LISP answer;
    EST_TKVL <EST_String,EST_Val> *fcache;

    fcache = new EST_TKVL<EST_String,EST_Val>;  // feature cache saves some calls
    answer = l_wagon_predict(s,tree,fcache);
    delete fcache;

    return answer;

}

static LISP l_wagon_predict(EST_Item *s, LISP tree,
                      EST_TKVL <EST_String,EST_Val> *fcache)
{
    // Use the tree to predict

    if (cdr(tree) == NIL)
      return car(tree);
    else if (wagon_ask(s,car(tree),fcache) == TRUE)
      return l_wagon_predict(s,car(cdr(tree)),fcache);
    else
      return l_wagon_predict(s,car(cdr(cdr(tree))),fcache);
}

static int wagon_ask(EST_Item *s, LISP question,
                 EST_TKVL <EST_String,EST_Val> *fcache)
{
    // Ask a question of this stream item
    EST_Val answer;
    const char *str_oper;
    const EST_String fname = get_c_string(car(question));
    LISP operand;

    if (!fcache->present(fname))
    {
      answer = ffeature(s,fname);
      fcache->add_item(fname,answer,0);
    }
    else
      answer = fcache->val(fname);

    str_oper = ques_oper_str(question);
    operand = ques_operand(question);
    // So that you can use LISP variables in the operand (or any LISP)
    // check if we've got a , if so eval it.
    if ((consp(operand)) && (!consp(car(operand))) &&
      (streq("+internal-comma",get_c_string(car(operand)))))
      operand = leval(cdr(operand),NIL);
    
    if (streq("is",str_oper))
      if (answer.string() == get_c_string(operand))
          return TRUE;
      else
          return FALSE;
    else if (streq("=",str_oper))
      if (answer == get_c_float(operand))
          return TRUE;
      else
          return FALSE;
    else if (streq("<",str_oper))
      if ((float)answer < get_c_float(operand))
          return TRUE;
      else
          return FALSE;
    else if (streq(">",str_oper))
      if ((float)answer > get_c_float(operand))
          return TRUE;
      else
          return FALSE;
    else if (streq("matches",str_oper))
      if (answer.string().matches(make_regex(get_c_string(operand))))
          return TRUE;
      else
          return FALSE;
    else if (streq("in",str_oper))
      if (siod_member_str(answer.string(),operand) != NIL)
          return TRUE;
      else
          return FALSE;
    else 
    {
      cerr << "Decision tree: unknown question operator: \"" << 
          str_oper << "\"\n";
      festival_error();
    }
    return 0;
}

LISP l_wagon(LISP si, LISP tree)
{
    // Lisp level binding for tree prediction 
    EST_Item *s = item(si);
    LISP answer;
    EST_TKVL <EST_String,EST_Val> *fcache;
    
    fcache = new EST_TKVL<EST_String,EST_Val>;  // feature cache saves some calls
    answer = l_wagon_predict(s,tree,fcache);
    delete fcache;
    return answer;
}
    

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