flatmap: add richer API to resulting flattened map

flatmap/flatten.go

@@ -12,14 +12,14 @@ import (
 // any combination of those together.
 //
 // See the tests for examples of what inputs are turned into.
-func Flatten(thing map[string]interface{}) map[string]string {
+func Flatten(thing map[string]interface{}) Map {
 	result := make(map[string]string)
 
 	for k, raw := range thing {
 		flatten(result, k, reflect.ValueOf(raw))
 	}
 
-	return result
+	return Map(result)
 }
 
 func flatten(result map[string]string, prefix string, v reflect.Value) {

flatmap/flatten_test.go

@@ -77,7 +77,7 @@ func TestFlatten(t *testing.T) {
 
 	for _, tc := range cases {
 		actual := Flatten(tc.Input)
-		if !reflect.DeepEqual(actual, tc.Output) {
+		if !reflect.DeepEqual(actual, Map(tc.Output)) {
 			t.Fatalf(
 				"Input:\n\n%#v\n\nOutput:\n\n%#v\n\nExpected:\n\n%#v\n",
 				tc.Input,

flatmap/map.go

@@ -0,0 +1,28 @@
+package flatmap
+
+import (
+	"strings"
+)
+
+// Map is a wrapper around map[string]string that provides some helpers
+// above it that assume the map is in the format that flatmap expects
+// (the result of Flatten).
+//
+// All modifying functions such as Delete are done in-place unless
+// otherwise noted.
+type Map map[string]string
+
+// Delete deletes a key out of the map with the given prefix.
+func (m Map) Delete(prefix string) {
+	for k, _ := range m {
+		match := k == prefix
+		if !match && !strings.HasPrefix(k, prefix) {
+			continue
+		}
+		if k[len(prefix):len(prefix)+1] != "." {
+			continue
+		}
+
+		delete(m, k)
+	}
+}

flatmap/map_test.go

@@ -0,0 +1,24 @@
+package flatmap
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestMapDelete(t *testing.T) {
+	m := Flatten(map[string]interface{}{
+		"foo": "bar",
+		"routes": []map[string]string{
+			map[string]string{
+				"foo": "bar",
+			},
+		},
+	})
+
+	m.Delete("routes")
+
+	expected := Map(map[string]string{"foo": "bar"})
+	if !reflect.DeepEqual(m, expected) {
+		t.Fatalf("bad: %#v", m)
+	}
+}