Make ListScope and DictScope support empty labels

[zturner]

Summary

You might want to label a scope with nothing at all, for example so that you can print out a list of records as:

{
   Field1,
   Field2
}
{
   FieldA,
   FieldB
}

This wasn't possible though, because a space was always being inserted after the label name, even if the label was empty. Rather than duplicate this ugly code in both ListScope and DictScope, I noticed that they were essentially identical except for the scope delimeters. So I made DelimitedScope<Open,Close> and then turned DictScope and ListScope into template aliases

[rnk]

lgtm

[Eugene.Zelenko]

Committed in r268472.

include/llvm/Support/ScopedPrinter.h

   startLine() << Label << ": " << hex(Value) << "\n";
 }
 
-struct DictScope {
-  DictScope(ScopedPrinter &W, StringRef N) : W(W) {
-    W.startLine() << N << " {\n";
+template<char Open, char Close>
+struct DelimitedScope {
+  DelimitedScope(ScopedPrinter &W, StringRef N) : W(W) {
+    W.startLine() << N;
+    if (!N.empty())
+      W.getOStream() << ' ';
+    W.getOStream() << Open << '\n';
     W.indent();
   }
 
-  ~DictScope() {
+  ~DelimitedScope() {
     W.unindent();
-    W.startLine() << "}\n";
+    W.startLine() << Close << '\n';
   }
 
   ScopedPrinter &W;
 };
 
-struct ListScope {
-  ListScope(ScopedPrinter &W, StringRef N) : W(W) {
-    W.startLine() << N << " [\n";
-    W.indent();
-  }
-
-  ~ListScope() {
-    W.unindent();
-    W.startLine() << "]\n";
-  }
-
-  ScopedPrinter &W;
-};
+using DictScope = DelimitedScope<'{', '}'>;
+using ListScope = DelimitedScope<'[', ']'>;
 
 } // namespace llvm