/*

    These are the functions to manipulate logic expressions.

*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "glob.h"

lox *NewLox(int kind)
{
  lox *t;
  t = (lox *)malloc(sizeof(lox));
  if (t==NULL) eprintf("Allocation error in new-lox.",0,0,0);
  t->type = kind;
  t->id = 0;
  t->vc = 0;
  t->a = t->b = NULL;
  dprintf(" new lox %p",t);
  return t;
}

int FreeLox(lox *t)
{
  lox *u,*v;

  dprintf("free lox %p",t);
  if (t==NULL) return 1;
  u = t->a;
  v = t->b;
  t->a = t->b = NULL;       /* prevents infinite recursion */
  free(t);
  t = NULL;
  FreeLox(u);
  FreeLox(v);
  return 0;
}

lox *DeepCopyLox(lox *t)          /* returns a deep copy of t */
{
  lox *u;

  if (t == NULL) return NULL;

  u = NewLox(t->type);
  memcpy(u,t,sizeof(*u));
  u->a = DeepCopyLox(t->a);
  u->b = DeepCopyLox(t->b);
  return u;
}

/*---------------------------------------------------------------------------
  This returns a shallow copy of t.  All logical connectives and quantifiers
  are copied, but the predicates and below are not.
*/
lox *CopyLox(lox *t)
{
  lox *u;

  if (t == NULL) return NULL;
  if (t->type <= TERM) return t;

  u = NewLox(t->type);
  memcpy(u,t,sizeof(*u));
  u->a = CopyLox(t->a);
  u->b = CopyLox(t->b);
  return u;
}