Add newlines around list of structs

Since a struct(parser.Map) occupies multiple lines, adding newlines
around brackets([]) looks better even the list has only a single value.

  prop: [ {
    name: "foo",
  }],

vs

  prop: [
    {
      name: "foo",
    },
  ],

Bug: n/a
Test: go test ./parser
Change-Id: I1a574aa038a26235848b6c9b5b4f01a0ab2c8c00

parser/printer.go

@@ -139,7 +139,7 @@ func (p *printer) printExpression(value Expression) {
 func (p *printer) printList(list []Expression, pos, endPos scanner.Position) {
 	p.requestSpace()
 	p.printToken("[", pos)
-	if len(list) > 1 || pos.Line != endPos.Line {
+	if len(list) > 1 || pos.Line != endPos.Line || listHasMap(list) {
 		p.requestNewline()
 		p.indent(p.curIndent() + 4)
 		for _, value := range list {
@@ -392,3 +392,12 @@ func max(a, b int) int {
 		return b
 	}
 }
+
+func listHasMap(list []Expression) bool {
+	for _, value := range list {
+		if _, ok := value.(*Map); ok {
+			return true
+		}
+	}
+	return false
+}

parser/printer_test.go

@@ -426,6 +426,27 @@ stuff {
         ],
     ],
 }
+`,
+	},
+	{
+		input: `
+// test
+stuff {
+    namespace: "google",
+    list_of_structs: [{ key1: "a", key2: "b" }],
+}
+`,
+		output: `
+// test
+stuff {
+    namespace: "google",
+    list_of_structs: [
+        {
+            key1: "a",
+            key2: "b",
+        },
+    ],
+}
 `,
 	},
 }