gn: attach comments to parse tree

tools/gn/parse_tree.cc

Index: tools/gn/parse_tree.cc
diff --git a/tools/gn/parse_tree.cc b/tools/gn/parse_tree.cc
index c4f78b7ce0768f9f7e7d025d112e1e25c7c31930..a1d969a1089465827fe3061a40369dfb1b7929d0 100644
--- a/tools/gn/parse_tree.cc
+++ b/tools/gn/parse_tree.cc
@@ -16,14 +16,17 @@
 namespace {
 
 std::string IndentFor(int value) {
-  std::string ret;
-  for (int i = 0; i < value; i++)
-    ret.append(" ");
-  return ret;
+  return std::string(value, ' ');
 }
 
 }  // namespace
 
+Comments::Comments() {
+}
+
+Comments::~Comments() {
+}
+
 ParseNode::ParseNode() {
 }
 
@@ -40,6 +43,33 @@ const ListNode* ParseNode::AsList() const { return NULL; }
 const LiteralNode* ParseNode::AsLiteral() const { return NULL; }
 const UnaryOpNode* ParseNode::AsUnaryOp() const { return NULL; }
 
+Comments* ParseNode::comments_mutable() {
+  if (!comments_)
+    comments_.reset(new Comments);
+  return comments_.get();
+}
+
+void ParseNode::PrintComments(std::ostream& out, int indent) const {
+  if (comments_) {
+    std::string ind = IndentFor(indent + 1);
+    for (std::vector<Token>::const_iterator i(comments_->before().begin());
+         i != comments_->before().end();
+         ++i) {
+      out << ind << "+BEFORE_COMMENT(\"" << i->value() << "\")\n";
+    }
+    for (std::vector<Token>::const_iterator i(comments_->suffix().begin());
+         i != comments_->suffix().end();
+         ++i) {
+      out << ind << "+SUFFIX_COMMENT(\"" << i->value() << "\")\n";
+    }
+    for (std::vector<Token>::const_iterator i(comments_->after().begin());
+         i != comments_->after().end();
+         ++i) {
+      out << ind << "+AFTER_COMMENT(\"" << i->value() << "\")\n";
+    }
+  }
+}
+
 // AccessorNode ---------------------------------------------------------------
 
 AccessorNode::AccessorNode() {
@@ -77,6 +107,7 @@ Err AccessorNode::MakeErrorDescribing(const std::string& msg,
 
 void AccessorNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "ACCESSOR\n";
+  PrintComments(out, indent);
   out << IndentFor(indent + 1) << base_.value() << "\n";
   if (index_)
     index_->Print(out, indent + 1);
@@ -192,6 +223,7 @@ Err BinaryOpNode::MakeErrorDescribing(const std::string& msg,
 
 void BinaryOpNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "BINARY(" << op_.value() << ")\n";
+  PrintComments(out, indent);
   left_->Print(out, indent + 1);
   right_->Print(out, indent + 1);
 }
@@ -241,6 +273,7 @@ Err BlockNode::MakeErrorDescribing(const std::string& msg,
 
 void BlockNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "BLOCK\n";
+  PrintComments(out, indent);
   for (size_t i = 0; i < statements_.size(); i++)
     statements_[i]->Print(out, indent + 1);
 }
@@ -317,6 +350,7 @@ Err ConditionNode::MakeErrorDescribing(const std::string& msg,
 
 void ConditionNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "CONDITION\n";
+  PrintComments(out, indent);
   condition_->Print(out, indent + 1);
   if_true_->Print(out, indent + 1);
   if (if_false_)
@@ -354,6 +388,7 @@ Err FunctionCallNode::MakeErrorDescribing(const std::string& msg,
 
 void FunctionCallNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "FUNCTION(" << function_.value() << ")\n";
+  PrintComments(out, indent);
   args_->Print(out, indent + 1);
   if (block_)
     block_->Print(out, indent + 1);
@@ -398,6 +433,7 @@ Err IdentifierNode::MakeErrorDescribing(const std::string& msg,
 
 void IdentifierNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "IDENTIFIER(" << value_.value() << ")\n";
+  PrintComments(out, indent);
 }
 
 // ListNode -------------------------------------------------------------------
@@ -444,6 +480,7 @@ Err ListNode::MakeErrorDescribing(const std::string& msg,
 
 void ListNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "LIST\n";
+  PrintComments(out, indent);
   for (size_t i = 0; i < contents_.size(); i++)
     contents_[i]->Print(out, indent + 1);
 }
@@ -499,6 +536,7 @@ Err LiteralNode::MakeErrorDescribing(const std::string& msg,
 
 void LiteralNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "LITERAL(" << value_.value() << ")\n";
+  PrintComments(out, indent);
 }
 
 // UnaryOpNode ----------------------------------------------------------------
@@ -531,5 +569,6 @@ Err UnaryOpNode::MakeErrorDescribing(const std::string& msg,
 
 void UnaryOpNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "UNARY(" << op_.value() << ")\n";
+  PrintComments(out, indent);
   operand_->Print(out, indent + 1);
 }