Move code into src directory.

git-svn-id: http://svn.drobilla.net/resp/tuplr@160 ad02d1e2-f140-0410-9f75-f8b11f17cedd

1 files changed, 94 insertions, 0 deletions

diff --git a/src/unify.cpp b/src/unify.cpp
new file mode 100644
index 0000000..2a8e6a0
--- /dev/null
+++ b/src/unify.cpp
@@ -0,0 +1,94 @@
+/* Tuplr Unification
+ * Copyright (C) 2008-2009 David Robillard <dave@drobilla.net>
+ *
+ * Tuplr is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Tuplr is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Tuplr.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <set>
+#include "tuplr.hpp"
+
+/***************************************************************************
+ * Type Inference/Substitution                                             *
+ ***************************************************************************/
+
+static void
+substitute(ATuple* tup, const AST* from, AST* to)
+{
+	if (!tup) return;
+	for (size_t i = 0; i < tup->size(); ++i)
+		if (*tup->at(i) == *from)
+			tup->at(i) = to;
+		else if (tup->at(i) != to)
+			substitute(tup->at(i)->to<ATuple*>(), from, to);
+}
+
+Subst
+Subst::compose(const Subst& delta, const Subst& gamma) // TAPL 22.1.1
+{
+	Subst r;
+	for (Subst::const_iterator g = gamma.begin(); g != gamma.end(); ++g) {
+		Subst::const_iterator d = delta.find(g->second);
+		r.add(g->first, ((d != delta.end()) ? d : g)->second);
+	}
+	for (Subst::const_iterator d = delta.begin(); d != delta.end(); ++d) {
+		if (gamma.find(d->first) == gamma.end())
+			r.add(d->first, d->second);
+	}
+	return r;
+}
+
+void
+substConstraints(Constraints& constraints, AType* s, AType* t)
+{
+	for (Constraints::iterator c = constraints.begin(); c != constraints.end();) {
+		Constraints::iterator next = c; ++next;
+		if (*c->first  == *s) c->first  = t;
+		if (*c->second == *s) c->second = t;
+		substitute(c->first, s, t);
+		substitute(c->second, s, t);
+		c = next;
+	}
+}
+
+Subst
+TEnv::unify(const Constraints& constraints) // TAPL 22.4
+{
+	if (constraints.empty()) return Subst();
+	AType*      s  = constraints.begin()->first;
+	AType*      t  = constraints.begin()->second;
+	Constraints cp = constraints;
+	cp.erase(cp.begin());
+
+	if (*s == *t) {
+		return unify(cp);
+	} else if (s->var() && !t->contains(s)) {
+		substConstraints(cp, s, t);
+		return Subst::compose(unify(cp), Subst(s, t));
+	} else if (t->var() && !s->contains(t)) {
+		substConstraints(cp, t, s);
+		return Subst::compose(unify(cp), Subst(t, s));
+	} else if (s->kind == AType::EXPR && s->kind == t->kind && s->size() == t->size()) {
+		for (size_t i = 0; i < s->size(); ++i) {
+			AType* si = s->at(i)->to<AType*>();
+			AType* ti = t->at(i)->to<AType*>();
+			if (si && ti)
+				cp.push_back(Constraint(si, ti, si->loc));
+		}
+		return unify(cp);
+	} else {
+		throw Error(s->loc ? s->loc : t->loc,
+				(format("type is `%1%' but should be `%2%'") % s->str() % t->str()).str());
+	}
+}
+