lang: Move type duplicates checker into a separate package

lang/util/util.go

@@ -0,0 +1,40 @@
+// Mgmt
+// Copyright (C) 2013-2019+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package util
+
+import (
+	"fmt"
+
+	"github.com/purpleidea/mgmt/lang/types"
+)
+
+// HasDuplicateTypes returns an error if the list of types is not unique.
+func HasDuplicateTypes(typs []*types.Type) error {
+	// FIXME: do this comparison in < O(n^2) ?
+	for i, ti := range typs {
+		for j, tj := range typs {
+			if i == j {
+				continue // don't compare to self
+			}
+			if ti.Cmp(tj) == nil {
+				return fmt.Errorf("duplicate type of %+v found", ti)
+			}
+		}
+	}
+	return nil
+}