From 8785108e66d55a04a8bc520ef9a7ded9f965abc1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADtor=20Santos=20Costa?= <vsc@dcc.fc.up.pt>
Date: Thu, 27 Oct 2011 12:35:40 +0200
Subject: [PATCH] Yap_unifiable and TagOfTerm

---
 C/c_interface.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 58 insertions(+), 1 deletion(-)

diff --git a/C/c_interface.c b/C/c_interface.c
index c648f78b3..a60bad24b 100644
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -425,6 +425,7 @@ X_API Int     STD_PROTO(YAP_ArityOfFunctor,(Functor));
 X_API void   *STD_PROTO(YAP_ExtraSpace,(void));
 X_API void    STD_PROTO(YAP_cut_up,(void));
 X_API Int     STD_PROTO(YAP_Unify,(Term,Term));
+X_API int     STD_PROTO(YAP_Unifiable,(Term,Term));
 X_API int     STD_PROTO(YAP_Reset,(void));
 X_API Int     STD_PROTO(YAP_Init,(YAP_init_args *));
 X_API Int     STD_PROTO(YAP_FastInit,(char *));
@@ -545,6 +546,7 @@ X_API int      STD_PROTO(YAP_NewOpaqueType,(void *));
 X_API Term     STD_PROTO(YAP_NewOpaqueObject,(int, size_t));
 X_API void    *STD_PROTO(YAP_OpaqueObjectFromTerm,(Term));
 X_API int      STD_PROTO(YAP_Argv,(char *** argvp));
+X_API YAP_tag_t    STD_PROTO(YAP_TagOfTerm,(Term));
 
 static int
 dogc( USES_REGS1 )
@@ -1180,6 +1182,18 @@ YAP_Unify(Term t1, Term t2)
   return out;
 }
 
+X_API int
+YAP_Unifiable(Term t1, Term t2)
+{
+  int out;
+  BACKUP_MACHINE_REGS();
+
+  out = Yap_unifiable(t1, t2);
+
+  RECOVER_MACHINE_REGS();
+  return out;
+}
+
 /* == */
 X_API int
 YAP_ExactlyEqual(Term t1, Term t2)
@@ -3788,7 +3802,6 @@ YAP_OpInfo(Atom at, Term module, int opkind, int *yap_type, int *prio)
   return 1;
 }
 
-
 int
 YAP_Argv(char ***argvp)
 {
@@ -3797,3 +3810,47 @@ YAP_Argv(char ***argvp)
   }
   return GLOBAL_argc;
 }
+
+YAP_tag_t
+YAP_TagOfTerm(Term t)
+{
+  if (IsVarTerm(t)) {
+    CELL *pt = VarOfTerm(t);
+    if (IsUnboundVar(pt)) {
+      if (IsAttVar(pt))
+	return YAP_TAG_ATT;
+      return YAP_TAG_UNBOUND;
+    }
+    return YAP_TAG_REF;
+  }
+  if (IsPairTerm(t))
+    return YAP_TAG_PAIR;
+  if (IsAtomOrIntTerm(t)) {
+    if (IsAtomTerm(t))
+      return YAP_TAG_ATOM;
+    return YAP_TAG_INT;
+  } else {
+    Functor f = FunctorOfTerm(t);
+    
+    if (IsExtensionFunctor(f)) {
+      if (f == FunctorDBRef) {
+	return YAP_TAG_DBREF;
+      }
+      if (f == FunctorLongInt) {
+	return YAP_TAG_LONG_INT;
+      }
+      if (f == FunctorBigInt) {
+	big_blob_type bt = RepAppl(t)[1];
+	switch (bt) {
+	case BIG_INT:
+	  return YAP_TAG_BIG_INT;
+	case BIG_RATIONAL:
+	  return YAP_TAG_RATIONAL;
+	default:
+	  return YAP_TAG_OPAQUE;
+	}
+      }
+    }
+    return YAP_TAG_APPL;
+  }
+}