libSyntax: when printing syntax tree with kind, optionally give syntax kind a visual highlight.

include/swift/Syntax/RawSyntax.h

@@ -186,6 +186,7 @@ enum class SourcePresence {
 
 /// The print option to specify when printing a raw syntax node.
 struct SyntaxPrintOptions {
+  bool Visual = false;
   bool PrintSyntaxKind = false;
 };
 

lib/Syntax/RawSyntax.cpp

@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "swift/Basic/ColorUtils.h"
 #include "swift/Syntax/RawSyntax.h"
 #include "swift/Syntax/TokenSyntax.h"
 #include "llvm/Support/Casting.h"
@@ -33,14 +34,26 @@ static bool isTrivialSyntaxKind(SyntaxKind Kind) {
     return false;
   }
 }
+
+static void printSyntaxKind(SyntaxKind Kind, llvm::raw_ostream &OS,
+                            SyntaxPrintOptions Opts, bool Open) {
+  std::unique_ptr<swift::OSColor> Color;
+  if (Opts.Visual) {
+    Color.reset(new swift::OSColor(OS, llvm::raw_ostream::GREEN));
+  }
+  OS << "<";
+  if (!Open)
+    OS << "/";
+  dumpSyntaxKind(OS, Kind);
+  OS << ">";
+}
+
 } // end of anonymous namespace
 void RawSyntax::print(llvm::raw_ostream &OS, SyntaxPrintOptions Opts) const {
   const bool PrintKind = Opts.PrintSyntaxKind && !isToken() &&
     !isTrivialSyntaxKind(Kind);
   if (PrintKind) {
-    OS << "<";
+    printSyntaxKind(Kind, OS, Opts, true);
-    dumpSyntaxKind(OS, Kind);
-    OS << ">";
   }
 
   if (const auto Tok = dyn_cast<RawTokenSyntax>(this)) {
@@ -51,9 +64,7 @@ void RawSyntax::print(llvm::raw_ostream &OS, SyntaxPrintOptions Opts) const {
     LE->print(OS, Opts);
   }
   if (PrintKind) {
-    OS << "</";
+    printSyntaxKind(Kind, OS, Opts, false);
-    dumpSyntaxKind(OS, Kind);
-    OS << ">";
   }
 }
 

tools/swift-syntax-test/swift-syntax-test.cpp

@@ -84,6 +84,11 @@ PrintNodeKind("print-node-kind",
               llvm::cl::desc("To print syntax node kind"),
               llvm::cl::cat(Category),
               llvm::cl::init(false));
+static llvm::cl::opt<bool>
+Visual("v",
+       llvm::cl::desc("Print visually"),
+       llvm::cl::cat(Category),
+       llvm::cl::init(false));
 } // end namespace options
 
 namespace {
@@ -283,6 +288,7 @@ int dumpParserGen(const char *MainExecutablePath,
   SourceFile *SF = getSourceFile(Instance, InputFileName, MainExecutablePath);
   SyntaxPrintOptions Opts;
   Opts.PrintSyntaxKind = options::PrintNodeKind;
+  Opts.Visual = options::Visual;
   SF->getSyntaxRoot().print(llvm::outs(), Opts);
   return 0;
 }