[Jason-developers] SF.net SVN: jason:[1675] trunk/src

[<jom...@us...>]

Revision: 1675
          http://jason.svn.sourceforge.net/jason/?rev=1675&view=rev
Author:   jomifred
Date:     2012-03-05 21:23:12 +0000 (Mon, 05 Mar 2012)
Log Message:
-----------
improvements in cycled terms

Modified Paths:
--------------
    trunk/src/jason/asSemantics/Unifier.java
    trunk/src/jason/asSyntax/Structure.java
    trunk/src/jason/asSyntax/VarTerm.java
    trunk/src/test/TermTest.java

Modified: trunk/src/jason/asSemantics/Unifier.java
===================================================================
--- trunk/src/jason/asSemantics/Unifier.java	2012-03-01 18:16:35 UTC (rev 1674)
+++ trunk/src/jason/asSemantics/Unifier.java	2012-03-05 21:23:12 UTC (rev 1675)
@@ -28,6 +28,7 @@
 import jason.asSyntax.ListTerm;
 import jason.asSyntax.ListTermImpl;
 import jason.asSyntax.Literal;
+import jason.asSyntax.LiteralImpl;
 import jason.asSyntax.Pred;
 import jason.asSyntax.Structure;
 import jason.asSyntax.Term;
@@ -137,10 +138,26 @@
             }
         }
         
-        if (t1g.isCyclicTerm()) // reintroduce cycles in the unifier
-            bind(t1g.getCyclicVar(), t1g);
-        if (t2g.isCyclicTerm()) 
-            bind(t2g.getCyclicVar(), t2g);
+        if (t1g.isCyclicTerm() && t2g.isCyclicTerm()) { // both are cycled terms
+            // unification of cyclic terms:
+            // remove the vars (to avoid loops) and test just the structure, then reintroduce the vars
+            VarTerm v1 = t1g.getCyclicVar();
+            VarTerm v2 = t2g.getCyclicVar();
+            remove(v1);
+            remove(v2);
+            try {
+                return unifiesNoUndo(new LiteralImpl((Literal)t1g), new LiteralImpl((Literal)t2g));
+            } finally {
+                function.put(v1, t1g);
+                function.put(v2, t1g);
+            }
+            
+        } else {
+            if (t1g.isCyclicTerm() && get(t1g.getCyclicVar()) == null) // reintroduce cycles in the unifier
+                function.put(t1g.getCyclicVar(), t1g);
+            if (t2g.isCyclicTerm() && get(t2g.getCyclicVar()) == null) 
+                function.put(t2g.getCyclicVar(), t2g);            
+        }
         
         // unify as Term
         boolean ok = unifyTerms(t1g, t2g);
@@ -291,6 +308,10 @@
     }
     
     public void bind(VarTerm vt, Term vl) {
+        if (!vl.isCyclicTerm() && vl.hasVar(vt, this)) { 
+            vl = new CyclicTerm((Literal)vl, (VarTerm)vt.clone());
+            //System.out.println("changing "+vt+" <- "+vl+" in "+this);
+        }
         function.put((VarTerm) vt.clone(), vl);
     }
         

Modified: trunk/src/jason/asSyntax/Structure.java
===================================================================
--- trunk/src/jason/asSyntax/Structure.java	2012-03-01 18:16:35 UTC (rev 1674)
+++ trunk/src/jason/asSyntax/Structure.java	2012-03-05 21:23:12 UTC (rev 1675)
@@ -295,7 +295,7 @@
         // if the variable hasn't been renamed given the input unifier, then rename it.
         if (deref.equals(vt)) {
             // forget the name
-            VarTerm var = new UnnamedVar("_" + UnnamedVar.getUniqueId() + t);
+            VarTerm var = new UnnamedVar(); //("_" + UnnamedVar.getUniqueId() + t);
             // if deref has annotations then we need to replicate these in the new variable
             if (deref.hasAnnot()) {
                 var.setAnnots(deref.getAnnots().cloneLT());

Modified: trunk/src/jason/asSyntax/VarTerm.java
===================================================================
--- trunk/src/jason/asSyntax/VarTerm.java	2012-03-01 18:16:35 UTC (rev 1674)
+++ trunk/src/jason/asSyntax/VarTerm.java	2012-03-05 21:23:12 UTC (rev 1675)
@@ -151,10 +151,10 @@
             Term vl = u.get(this);
             //System.out.println("applying "+this+"="+vl+" un="+u);
             if (vl != null) {
-                if (vl.hasVar(this, u)) {
+                if (!vl.isCyclicTerm() && vl.hasVar(this, u)) {
                     //logger.warning("The value of a variable contains itself, variable "+super.getFunctor()+" "+super.getSrcInfo()+", value="+vl+", unifier="+u);
                     
-                    u.remove(this); // remove this var to avoid loops
+                    u.remove(this); // remove this var to avoid loops in the apply below
                     Term tempVl = vl.clone(); 
                     tempVl.apply(u);
                     u.bind(this, vl);

Modified: trunk/src/test/TermTest.java
===================================================================
--- trunk/src/test/TermTest.java	2012-03-01 18:16:35 UTC (rev 1674)
+++ trunk/src/test/TermTest.java	2012-03-05 21:23:12 UTC (rev 1675)
@@ -1065,4 +1065,19 @@
         assertTrue(y.isCyclicTerm());
     }
 
+    public void testCyclicTerm5() throws ParseException {
+        Term t1 = parseTerm("f(f(g(X)))");
+        VarTerm v1 = new VarTerm("X");
+
+        Term t2 = parseTerm("f(f(g(Y)))");
+        VarTerm v2 = new VarTerm("Y");
+        
+        Unifier u = new Unifier();
+        
+        assertTrue(u.unifies(t1, v1));
+        assertTrue(u.get(v1).isCyclicTerm());
+        assertTrue(u.unifies(t2, v2));
+        assertTrue(new Unifier().unifies(t1, t2));
+        assertTrue(u.unifies(v1, v2));
+    }
 }

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