gn: attach comments to parse tree

tools/gn/parse_tree.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TOOLS_GN_PARSE_TREE_H_
 #define TOOLS_GN_PARSE_TREE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "tools/gn/err.h"
 #include "tools/gn/token.h"
 #include "tools/gn/value.h"
 
 class AccessorNode;
 class BinaryOpNode;
 class BlockNode;
 class ConditionNode;
 class FunctionCallNode;
 class IdentifierNode;
 class ListNode;
 class LiteralNode;
 class Scope;
 class UnaryOpNode;
 
+class Comments {
+ public:
+  Comments();
+  virtual ~Comments();
+
+  const std::vector<Token>& before() const { return before_; }
+  void append_before(Token c) {
+    before_.push_back(c);
+  }
+
+  const std::vector<Token>& suffix() const { return suffix_; }
+  void append_suffix(Token c) {
+    suffix_.push_back(c);
+  }
+
+  const std::vector<Token>& after() const { return after_; }
+  void append_after(Token c) {
+    after_.push_back(c);
+  }
+
+ private:
+  // Whole line comments before the expression.
+  std::vector<Token> before_;
+
+  // End-of-line comments after this expression.
+  std::vector<Token> suffix_;
+
+  // For top-level expressions only, after_ lists whole-line comments
+  // following the expression.
+  std::vector<Token> after_;
+
+  DISALLOW_COPY_AND_ASSIGN(Comments);
+};
+
 // ParseNode -------------------------------------------------------------------
 
 // A node in the AST.
 class ParseNode {
  public:
   ParseNode();
   virtual ~ParseNode();
 
   virtual const AccessorNode* AsAccessor() const;
   virtual const BinaryOpNode* AsBinaryOp() const;
@@ skipping 12 matching lines @@
   // Returns an error with the given messages and the range set to something
   // that indicates this node.
   virtual Err MakeErrorDescribing(
       const std::string& msg,
       const std::string& help = std::string()) const = 0;
 
   // Prints a representation of this node to the given string, indenting
   // by the given number of spaces.
   virtual void Print(std::ostream& out, int indent) const = 0;
 
+  const Comments* comments() const { return comments_.get(); }
+  Comments* comments_mutable();
+  void PrintComments(std::ostream& out, int indent) const;
+
  private:
+  scoped_ptr<Comments> comments_;
+
   DISALLOW_COPY_AND_ASSIGN(ParseNode);
 };
 
 // AccessorNode ----------------------------------------------------------------
 
 // Access an array or scope element.
 //
 // Currently, such values are only read-only. In that you can do:
 //   a = obj1.a
 //   b = obj2[0]
@@ skipping 317 matching lines @@
   }
 
  private:
   Token op_;
   scoped_ptr<ParseNode> operand_;
 
   DISALLOW_COPY_AND_ASSIGN(UnaryOpNode);
 };
 
 #endif  // TOOLS_GN_PARSE_TREE_H_