libbanshee/engine/term-var.c

   1 /*
   2  * Copyright (c) 2000-2001
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  */
  30
  31 #include <stdio.h>
  32 #include <regions.h>
  33 #include <assert.h>
  34 #include "ufind.h"
  35 #include "term-var.h"
  36
  37 DECLARE_UFIND(tv_elt,gen_e)
  38
  39 DEFINE_UFIND(tv_elt,gen_e)
  40
  41 DEFINE_LIST(term_var_list,term_var)
  42
  43 struct term_var
  44 {
  45 #ifdef NONSPEC
  46   sort_kind sort;
  47 #endif
  48   int type;
  49   stamp st;
  50   gen_e_list pending;
  51   const char *name;
  52   tv_elt elt;
  53 };
  54
  55 static term_var make_var(region r, const char *name, stamp st)
  56 {
  57   term_var result = ralloc(r, struct term_var);
  58   gen_e info = (gen_e) result;
  59
  60   result->type = VAR_TYPE;
  61   result->st = st;
  62   result->pending = new_gen_e_list(r);
  63   result->name = name ? rstrdup(r,name) : "fv";
  64   result->elt = new_tv_elt(r,info);
  65
  66   return result;
  67 }
  68
  69 term_var tv_fresh(region r, const char *name)
  70 {
  71   return make_var(r,name,stamp_fresh());
  72 }
  73
  74 term_var tv_fresh_small(region r, const char *name)
  75 {
  76   return make_var(r,name,stamp_fresh_small());
  77 }
  78
  79 term_var tv_fresh_large(region r, const char *name)
  80 {
  81   return make_var(r,name,stamp_fresh_large());
  82 }
  83
  84 static term_var tv_get_v_ecr(term_var v)
  85 {
  86   term_var ecr = (term_var)tv_get_ecr(v);
  87   assert (ecr->type == VAR_TYPE); /* this is a hack, but should be ok */
  88
  89   return ecr;
  90 }
  91
  92 const char *tv_get_name(term_var v)
  93 {
  94   return tv_get_v_ecr(v)->name;
  95 }
  96
  97 gen_e_list tv_get_pending(term_var v)
  98 {
  99   return tv_get_v_ecr(v)->pending;
 100 }
 101
 102 void tv_add_pending(term_var v,gen_e e)
 103 {
 104   gen_e_list_cons(e,tv_get_v_ecr(v)->pending);
 105 }
 106
 107 void tv_unify(term_var v, gen_e e)
 108 {
 109   tv_elt_update(v->elt,e);
 110
 111   assert(tv_get_ecr(v) == e);
 112 }
 113
 114 static gen_e tv_combine(gen_e e1, gen_e e2)
 115 {
 116   term_var v1 = (term_var)e1,
 117     v2 = (term_var)e2;
 118
 119   if (! (v1 == v2) )
 120     gen_e_list_append(tv_get_pending(v1), tv_get_pending(v2));
 121
 122   return e1;
 123 }
 124
 125 void tv_unify_vars(term_var v1, term_var v2)
 126 {
 127   tv_elt_unify(tv_combine,v1->elt, v2->elt);
 128 }
 129
 130 gen_e tv_get_ecr(term_var v)
 131 {
 132   return tv_elt_get_info(v->elt);
 133 }