1 files changed, 59 insertions, 16 deletions

diff --git a/eval.c b/eval.c
index c8388e6..b5f78bc 100644
--- a/eval.c
+++ b/eval.c
@@ -14,19 +14,20 @@ int
 evalquery(Term *query)
 {
 	Binding *replbindings = nil;
-	goalstack = addgoals(goalstack, query, getmodule(L"user"));
+	goalstack = addgoals(goalstack, query, getmodule(L"user"), 0);
 
 	while(goalstack->goal != nil){
 		Term *goal = goalstack->goal;
 		Term *catcher = goalstack->catcher;
 		Module *module = goalstack->module;
+		uvlong goalnr = goalstack->goalnr;
 		goalstack = goalstack->next;
 
 		if(catcher)
 			continue;
 
 		if(flagdebug)
-			print("Working goal: %S:%S\n", module->name, prettyprint(goal, 0, 0, 0, nil));
+			print("Working goal %ulld: %S:%S\n", goalnr, module->name, prettyprint(goal, 0, 1, 0, nil));
 
 		if(goal->tag == VariableTerm)
 			goal = instantiationerror();
@@ -35,7 +36,46 @@ evalquery(Term *query)
 
 		Binding *bindings = nil;
 		Clause *clause = nil;
-		
+
+		/* handle special cases which need to cut: !/0, throw/1 */
+		if(goal->tag == AtomTerm && runestrcmp(goal->text, L"!") == 0){
+			Choicepoint *cp = choicestack;
+			/* Cut all choicepoints with an id larger or equal to the goal clause number,
+			   since they must have been introduced
+	   		   after this goal's parent.
+			*/
+			while(cp != nil && cp->id >= goalnr)
+				cp = cp->next;
+			choicestack = cp;
+			continue;
+		}else if(goal->tag == CompoundTerm && runestrcmp(goal->text, L"throw") == 0 && goal->arity == 1){
+			Term *ball = goal->children;
+			Goal *g;
+			int caught = 0;
+			for(g = goalstack; g != nil && !caught; g = g->next){
+				if(g->catcher == nil)
+					continue;
+
+				if(unify(g->catcher, ball, &bindings)){
+					goalstack = g->next;
+					Goal *newgoal = gmalloc(sizeof(Goal));
+					newgoal->goal = copyterm(g->goal);
+					newgoal->module = g->module;
+					newgoal->catcher = nil;
+					newgoal->next = goalstack;
+					goalstack = newgoal;
+					applybinding(newgoal->goal, bindings);
+
+					Choicepoint *cp = choicestack;
+					while(cp != nil && cp->id >= goalnr)
+						cp = cp->next;
+					choicestack = cp;
+					caught = 1;
+				}
+			}
+			continue;
+		}
+
 		/* Try to see if the goal can be solved using a builtin first */
 		Builtin builtin = findbuiltin(goal);
 		if(builtin != nil){
@@ -79,7 +119,7 @@ evalquery(Term *query)
 				case UnknownFail:
 					replacement = mkatom(L"fail");
 				}
-				goalstack = addgoals(goalstack, replacement, module);
+				goalstack = addgoals(goalstack, replacement, module, goalnr);
 				continue;
 			}
 
@@ -111,9 +151,9 @@ Backtrack:
 
 		/* Add clause body as goals, with bindings applied */
 		if(clause != nil && clause->body != nil){
-			Term *subgoal = copyterm(clause->body, nil);
+			Term *subgoal = copyterm(clause->body);
 			applybinding(subgoal, bindings);
-			goalstack = addgoals(goalstack, subgoal, module);
+			goalstack = addgoals(goalstack, subgoal, module, clause->clausenr);
 		}
 	}
 	goalstack = goalstack->next;
@@ -122,11 +162,11 @@ Backtrack:
 }
 
 Goal *
-addgoals(Goal *goals, Term *t, Module *module)
+addgoals(Goal *goals, Term *t, Module *module, uvlong goalnr)
 {
 	if(t->tag == CompoundTerm && runestrcmp(t->text, L",") == 0 && t->arity == 2){
-		goals = addgoals(goals, t->children->next, module);
-		goals = addgoals(goals, t->children, module);
+		goals = addgoals(goals, t->children->next, module, goalnr);
+		goals = addgoals(goals, t->children, module, goalnr);
 	}else{
 		if(t->tag == CompoundTerm && runestrcmp(t->text, L":") == 0 && t->arity == 2){
 			Term *moduleterm = t->children;
@@ -143,6 +183,7 @@ addgoals(Goal *goals, Term *t, Module *module)
 		}
 		Goal *g = gmalloc(sizeof(Goal));
 		g->goal = t;
+		g->goalnr = goalnr;
 		g->module = module;
 		g->catcher = nil;
 		g->next = goals;
@@ -194,8 +235,8 @@ unify(Term *a, Term *b, Binding **bindings)
 	Term *left;
 	Term *right;
 
-	leftstack = copyterm(a, nil);
-	rightstack = copyterm(b, nil);
+	leftstack = copyterm(a);
+	rightstack = copyterm(b);
 
 	while(leftstack != nil && rightstack != nil){
 		left = leftstack;
@@ -211,7 +252,7 @@ unify(Term *a, Term *b, Binding **bindings)
 				left = right;
 				right = tmp;
 			}
-			if(left->tag == VariableTerm && right->tag == VariableTerm && right->clausenr > left->clausenr){
+			if(left->tag == VariableTerm && right->tag == VariableTerm && right->varnr > left->varnr){
 				Term *tmp = left;
 				left = right;
 				right = tmp;
@@ -235,12 +276,12 @@ unify(Term *a, Term *b, Binding **bindings)
 			Term *leftchild = left->children;
 			Term *rightchild = right->children;
 			while(leftchild != nil && rightchild != nil){
-				Term *t1 = copyterm(leftchild, nil);
+				Term *t1 = copyterm(leftchild);
 				t1->next = leftstack;
 				leftstack = t1;
 				leftchild = leftchild->next;
 
-				Term *t2 = copyterm(rightchild, nil);
+				Term *t2 = copyterm(rightchild);
 				t2->next = rightstack;
 				rightstack = t2;
 				rightchild = rightchild->next;
@@ -300,12 +341,13 @@ copygoals(Goal *goals)
 	if(goals != nil){
 		Goal *g = gmalloc(sizeof(Goal));
 		g->module = goals->module;
+		g->goalnr = goals->goalnr;
 		if(goals->goal)
-			g->goal = copyterm(goals->goal, nil);
+			g->goal = copyterm(goals->goal);
 		else
 			g->goal = nil;
 		if(goals->catcher)
-			g->catcher = copyterm(goals->catcher, nil);
+			g->catcher = copyterm(goals->catcher);
 		else
 			g->catcher = nil;
 		g->next = copygoals(goals->next);
@@ -325,6 +367,7 @@ addchoicepoints(Clause *clause, Term *goal, Goal *goals, Module *mod){
 		Binding *altbindings = nil;
 		clause = findclause(alt, goal, &altbindings);
 		if(clause){
+			print("Created choicepoint for %S with id %ulld\n", prettyprint(goal, 0, 1, 0, nil), clause->clausenr);
 			/* Add choicepoint here */
 			Choicepoint *cp = gmalloc(sizeof(Choicepoint));
 			cp->goalstack = copygoals(goals);