Add SQL either function for simplified IF ELSE clauses

sql/funcs.go

@@ -103,6 +103,7 @@ var funcs = map[string]map[int]interface{}{
 	"binary":     {1: nil},
 	"difference": {-1: nil},
 	"distinct":   {1: nil},
+	"either":     {-1: nil},
 	"get":        {2: nil},
 	"if":         {3: nil},
 	"intersect":  {-1: nil},

util/fncs/either.go

@@ -0,0 +1,51 @@
+// Copyright © 2016 Abcum Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fncs
+
+import (
+	"context"
+)
+
+func either(ctx context.Context, args ...interface{}) (interface{}, error) {
+	for _, a := range args {
+		switch v := a.(type) {
+		case nil:
+			continue
+		default:
+			return v, nil
+		case string:
+			if v != "" {
+				return v, nil
+			}
+		case int64:
+			if v != 0 {
+				return v, nil
+			}
+		case float64:
+			if v != 0 {
+				return v, nil
+			}
+		case []interface{}:
+			if len(v) != 0 {
+				return v, nil
+			}
+		case map[string]interface{}:
+			if len(v) != 0 {
+				return v, nil
+			}
+		}
+	}
+	return nil, nil
+}

util/fncs/either_test.go

@@ -0,0 +1,64 @@
+// Copyright © 2016 Abcum Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fncs
+
+import (
+	"context"
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestEither(t *testing.T) {
+
+	var res interface{}
+
+	Convey("either() works properly", t, func() {
+
+		res, _ = Run(context.Background(), "either", nil, true)
+		So(res, ShouldResemble, true)
+
+		res, _ = Run(context.Background(), "either", int64(0), "two")
+		So(res, ShouldResemble, "two")
+		res, _ = Run(context.Background(), "either", int64(1), "two")
+		So(res, ShouldResemble, int64(1))
+		res, _ = Run(context.Background(), "either", int64(-1), "two")
+		So(res, ShouldResemble, int64(-1))
+
+		res, _ = Run(context.Background(), "either", float64(0), "two")
+		So(res, ShouldResemble, "two")
+		res, _ = Run(context.Background(), "either", float64(1), "two")
+		So(res, ShouldResemble, float64(1))
+		res, _ = Run(context.Background(), "either", float64(-1), "two")
+		So(res, ShouldResemble, float64(-1))
+
+		res, _ = Run(context.Background(), "either", "", "two")
+		So(res, ShouldResemble, "two")
+		res, _ = Run(context.Background(), "either", "one", "two")
+		So(res, ShouldResemble, "one")
+
+		res, _ = Run(context.Background(), "either", []interface{}{}, []interface{}{"two"})
+		So(res, ShouldResemble, []interface{}{"two"})
+		res, _ = Run(context.Background(), "either", []interface{}{"one"}, []interface{}{"two"})
+		So(res, ShouldResemble, []interface{}{"one"})
+
+		res, _ = Run(context.Background(), "either", map[string]interface{}{}, map[string]interface{}{"two": true})
+		So(res, ShouldResemble, map[string]interface{}{"two": true})
+		res, _ = Run(context.Background(), "either", map[string]interface{}{"one": true}, map[string]interface{}{"two": true})
+		So(res, ShouldResemble, map[string]interface{}{"one": true})
+
+	})
+
+}

util/fncs/fnc.go

@@ -28,6 +28,8 @@ func Run(ctx context.Context, name string, args ...interface{}) (interface{}, er
 		return difference(ctx, args...)
 	case "distinct":
 		return distinct(ctx, args...)
+	case "either":
+		return either(ctx, args...)
 	case "get":
 		return get(ctx, args...)
 	case "if":