/*
SGPC: Simple Genetic Programming in C
(c) 1993 by Walter Alden Tackett and Aviram Carmi
 
 This code and documentation is copyrighted and is not in the public domain.
 All rights reserved. 
 
 - This notice may not be removed or altered.
 
 - You may not try to make money by distributing the package or by using the
   process that the code creates.
 
 - You may not distribute modified versions without clearly documenting your
   changes and notifying the principal author.
 
 - The origin of this software must not be misrepresented, either by
   explicit claim or by omission.  Since few users ever read sources,
   credits must appear in the documentation.
 
 - Altered versions must be plainly marked as such, and must not be
   misrepresented as being the original software.  Since few users ever read
   sources, credits must appear in the documentation.
 
 - The authors are not responsible for the consequences of use of this 
   software, no matter how awful, even if they arise from flaws in it.
 
If you make changes to the code, or have suggestions for changes,
let us know!  (gpc@ipld01.hac.com)
*/

#ifndef lint
static char crossover_c_rcsid[]="$Id: crossover.c,v 2.5 1993/04/14 05:07:57 gpc-avc Exp gpc-avc $";
#endif

/*
 *
 * $Log: crossover.c,v $
 * Revision 2.5  1993/04/14  05:07:57  gpc-avc
 * removed #ifdef TRACE code
 *
 *
 */

#include <stdio.h>
#include <malloc.h>
#include <errno.h>
#include "gpc.h"


/*
#define TRACEcaap
#define TRACEcafp
*/

#ifdef ANSI_FUNC

VOID crossover_at_any_pt(
  pop_struct 	*pop,
  tree 		*p1,
  tree 		*p2,
  tree 		**o1,
  tree 		**o2
  )
#else

VOID crossover_at_any_pt(pop,p1, p2, o1, o2)
  pop_struct	*pop;
  tree		*p1, *p2, **o1, **o2;
#endif
{
  tree	*st1, *st2, **st1ptr, **st2ptr;
  int	xpt1, xpt2;

  xpt1 = random_int(count_crossover_pts(p1));
  xpt2 = random_int(count_crossover_pts(p2));

  *o1 = copy_tree(p1);
  *o2 = copy_tree(p2);

  st1 = get_subtree(*o1, xpt1);
  st2 = get_subtree(*o2, xpt2);

  st1ptr = pointer_to_subtree(o1, st1);
  st2ptr = pointer_to_subtree(o2, st2);

  *st1ptr = st2;
  *st2ptr = st1;

  validate_crossover(pop, p1, p2, o1, o2);

}

#ifdef ANSI_FUNC

VOID crossover_at_func_pt(
  pop_struct 	*pop,
  tree 		*p1,
  tree 		*p2,
  tree 		**o1,
  tree 		**o2
  )
#else

VOID crossover_at_func_pt(pop, p1, p2, o1, o2)
  pop_struct 	*pop;
  tree		*p1, *p2, **o1, **o2;
#endif
{
  tree	*st1, *st2, **st1ptr, **st2ptr;
  int	xpt1, xpt2;

  xpt1 = random_int(count_function_pts(p1));
  xpt2 = random_int(count_function_pts(p2));

  *o1 = copy_tree(p1);
  *o2 = copy_tree(p2);

  st1 = get_function_subtree(*o1, xpt1);
  st2 = get_function_subtree(*o2, xpt2);

  st1ptr = pointer_to_subtree(o1, st1);
  st2ptr = pointer_to_subtree(o2, st2);

  *st1ptr = st2;
  *st2ptr = st1;

  validate_crossover(pop, p1, p2, o1, o2);
}


#ifdef ANSI_FUNC

VOID validate_crossover(
  pop_struct 	*pop,
  tree 		*p1,
  tree 		*p2,
  tree 		**o1,
  tree 		**o2
  )
#else

VOID validate_crossover(pop, p1, p2, o1, o2)
  pop_struct 	*pop;
  tree		*p1, *p2, **o1, **o2;
#endif
{
  int	d1, d2;

  d1 = depth_of_tree(*o1);
  d2 = depth_of_tree(*o2);

  if (d1 > pop[(*o1)->pop].max_depth_after_crossover) {
    free_tree(*o1);
    *o1 = copy_tree(p1);

  }	      
  if (d2 > pop[(*o2)->pop].max_depth_after_crossover) {
    free_tree(*o2);
    *o2 = copy_tree(p2);

  }	      
}

#ifdef ANSI_FUNC

int depth_of_tree(
	tree *t
	)
#else

int depth_of_tree(t)
tree	*t;
#endif
{
  int	i, n, maxn=0;
  pop_struct *pop = POP;

  if (t->nodetype == FUNCTION) {
    for (i=0; i<function_arity(t); i++) {
      n = depth_of_tree(t->type.func->arg[i]);
      maxn = max(maxn,n);
    }
    return 1+maxn;
  } else {
    return 0;
  }
}
  
#ifdef ANSI_FUNC

int count_crossover_pts(
	tree *t
	)
#else

int count_crossover_pts(t)
tree	*t;
#endif
{
  int	i, n=1;
  pop_struct *pop = POP;

  if (t->nodetype == FUNCTION) {
    for (i=0; i<function_arity(t); i++) {
      n += count_crossover_pts(t->type.func->arg[i]);
    }
  }
  return n;
}

#ifdef ANSI_FUNC

int count_function_pts(
	tree *t
	)
#else

int count_function_pts(t)
tree	*t;
#endif
{
  int	i, n=1;
  pop_struct *pop = POP;

  if (t->nodetype == FUNCTION) {
    for (i=0; i<function_arity(t); i++) {
      n += count_function_pts(t->type.func->arg[i]);
    }
    return n;
  } else {
    return 0;
  }
}

#ifdef ANSI_FUNC

tree *get_subtree(
	tree *t,
	int n
	)
#else

tree *get_subtree(t,n)
tree	*t;
int	n;
#endif
{
  int	m;

  m = n;
  return gs(t,&m);
}  

#ifdef ANSI_FUNC

tree *gs(
	tree *t,
	int *n
	)
#else

tree *gs(t,n)
tree	*t;
int	*n;
#endif
{
  tree	*st;
  int	i;
  pop_struct *pop = POP;

  if (!(*n)) return(t);
  else if (t->nodetype == FUNCTION) {
    for (i=0; i<function_arity(t); i++) {      
      --(*n);
      st = gs(t->type.func->arg[i],n);
      if (!(*n)) break;
    }
    return st;
  } else {
    return (tree *) NULL;
  }
}

#ifdef ANSI_FUNC

tree *get_function_subtree(
	tree *t,
	int n
	)
#else

tree *get_function_subtree(t,n)
tree	*t;
int	n;
#endif
{
  int	m;
  
  m = n;
  return gfs(t,&m);
}  

#ifdef ANSI_FUNC

tree *gfs(
	tree *t,
	int *n
	)
#else

tree *gfs(t,n)
tree	*t;
int	*n;
#endif
{
  tree	*st;
  int	i;
  pop_struct *pop = POP;

  if (!(*n)) return(t);
  for (i=0; i<function_arity(t); i++) {      
    if (t->type.func->arg[i]->nodetype == FUNCTION) {
      --(*n);
      st = gfs(t->type.func->arg[i],n);
      if (!(*n)) break;
    }
  }
  return st;
}

#ifdef ANSI_FUNC

tree **pointer_to_subtree(
	tree **pointer,
	tree *subt
	)
#else

tree 	**pointer_to_subtree(pointer, subt)
tree	**pointer, *subt;
#endif
{
  int	i;
  tree	**pos;
  pop_struct *pop = POP;

  if (*pointer == subt) {
    return pointer;
  }
  
  for (i=0; i<function_arity(*pointer); i++) {
    if ((*pointer)->type.func->arg[i]->nodetype == FUNCTION) {
      pos = pointer_to_subtree(&((*pointer)->type.func->arg[i]), subt);
      if ((pos != NULL) && ((*pos) == subt)) return pos;
    } else {
      if ((*pointer)->type.func->arg[i] == subt)
	return &((*pointer)->type.func->arg[i]);
    }
  }
  return ((tree **)NULL); /* make lint happy */
}