Exception specifiers.

More efficient constraints construction (c') in unify().


git-svn-id: http://svn.drobilla.net/resp/resp@253 ad02d1e2-f140-0410-9f75-f8b11f17cedd

1 files changed, 8 insertions, 9 deletions

diff --git a/src/unify.cpp b/src/unify.cpp
index 3f06868..93dd78b 100644
--- a/src/unify.cpp
+++ b/src/unify.cpp
@@ -92,7 +92,7 @@ Subst::compose(const Subst& delta, const Subst& gamma)
 }
 
 /// Replace all occurrences of @a s with @a t
-void
+Constraints&
 Constraints::replace(AType* s, AType* t)
 {
 	for (Constraints::iterator c = begin(); c != end();) {
@@ -103,6 +103,7 @@ Constraints::replace(AType* s, AType* t)
 		substitute(c->second, s, t);
 		c = next;
 	}
+	return *this;
 }
 
 /// Unify a type constraint set (TAPL 22.4)
@@ -112,19 +113,17 @@ unify(const Constraints& constraints)
 	if (constraints.empty())
 		return Subst();
 
-	AType*      s  = constraints.begin()->first;
-	AType*      t  = constraints.begin()->second;
-	Constraints cp = constraints;
-	cp.erase(cp.begin());
+	Constraints::const_iterator i  = constraints.begin();
+	AType*                      s  = i->first;
+	AType*                      t  = i->second;
+	Constraints                 cp(++i, constraints.end());
 
 	if (*s == *t) {
 		return unify(cp);
 	} else if (s->kind == AType::VAR && !t->contains(s)) {
-		cp.replace(s, t);
-		return Subst::compose(unify(cp), Subst(s, t));
+		return Subst::compose(unify(cp.replace(s, t)), Subst(s, t));
 	} else if (t->kind == AType::VAR && !s->contains(t)) {
-		cp.replace(t, s);
-		return Subst::compose(unify(cp), Subst(t, s));
+		return Subst::compose(unify(cp.replace(t, s)), Subst(t, s));
 	} else if (s->kind == AType::EXPR && t->kind == AType::EXPR) {
 		AType::iterator si = s->begin() + 1;
 		AType::iterator ti = t->begin() + 1;