Enable specifying a regex using a function

sql/funcs.go

@@ -106,6 +106,7 @@ var funcs = map[string]map[int]interface{}{
 	"if":         {3: nil},
 	"intersect":  {-1: nil},
 	"model":      {2: nil, 3: nil, 4: nil},
+	"regex":      {1: nil},
 	"table":      {1: nil},
 	"thing":      {2: nil},
 	"union":      {-1: nil},

util/fncs/fnc.go

@@ -34,6 +34,8 @@ func Run(ctx context.Context, name string, args ...interface{}) (interface{}, er
 		return intersect(ctx, args...)
 	case "model":
 		return model(ctx, args...)
+	case "regex":
+		return regex(ctx, args...)
 	case "table":
 		return table(ctx, args...)
 	case "thing":

util/fncs/regex.go

@@ -0,0 +1,25 @@
+// 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"
+	"regexp"
+)
+
+func regex(ctx context.Context, args ...interface{}) (*regexp.Regexp, error) {
+	reg, _ := ensureString(args[0])
+	return regexp.Compile(reg)
+}

util/fncs/regex_test.go

@@ -0,0 +1,36 @@
+// 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"
+	"regexp"
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestRegex(t *testing.T) {
+
+	var res interface{}
+
+	Convey("regex() works properly", t, func() {
+		res, _ = Run(context.Background(), "regex", "something")
+		So(res, ShouldResemble, regexp.MustCompile("something"))
+		res, _ = Run(context.Background(), "regex", `^[a-z]+\[[0-9]+\]$`)
+		So(res, ShouldResemble, regexp.MustCompile(`^[a-z]+\[[0-9]+\]$`))
+	})
+
+}