Implement HCL2-style maps/key-value pairs.

Author: goncalo-rodrigues

_tests/maps.hcl

@@ -0,0 +1,5 @@
+Foo {
+  KeyVals =  {
+    baz = "buzz"
+  }
+}

_tests/nested-slices.hcl

@@ -1,10 +1,12 @@
-bar = [
-  ["bar"],
-  ["baz"],
-  ["buzz"],
-]
+ {
+  bar = [
+    ["bar"],
+    ["baz"],
+    ["buzz"],
+  ]
 
-foo = [
-  "bar",
-  "baz",
-]
+  foo = [
+    "bar",
+    "baz",
+  ]
+}

hclencoder_test.go

@@ -152,6 +152,23 @@ func TestEncoder(t *testing.T) {
 			},
 			Output: "nested-struct-slice-no-key",
 		},
+		{
+			ID: "maps",
+			Input: struct {
+				Foo struct {
+					KeyVals map[string]string
+				}
+			}{
+				struct {
+					KeyVals map[string]string
+				}{
+					KeyVals: map[string]string{
+						"baz": "buzz",
+					},
+				},
+			},
+			Output: "maps",
+		},
 		{
 			ID: "nested slices",
 			Input: map[string]interface{}{

nodes.go

@@ -225,7 +225,18 @@ func encodeMap(in reflect.Value) (ast.Node, []*ast.ObjectKey, error) {
 	}
 
 	sort.Sort(l)
-	return &ast.ObjectType{List: &ast.ObjectList{Items: []*ast.ObjectItem(l)}}, nil, nil
+
+	// here we wrap the map into an object with an empty key, just so that the map is not treated as an HCL object and
+	// is instead viewed an opaque node that can be used in an assignment. this is what happens when we try to write
+	// HCL2 with a HCL1 framework :)
+	return &ast.ObjectItem{
+		Keys: []*ast.ObjectKey{
+			{Token: token.Token{
+				Type: token.STRING,
+				Text: "",
+			}},
+		}, Val: &ast.ObjectType{List: &ast.ObjectList{Items: l}},
+	}, nil, nil
 }
 
 // encodeStruct converts a struct type into an ast.ObjectType. An ast.ObjectKey