gn format: penalty-based scheme for line breaking

tools/gn/parse_tree.h

 // Copyright 2014 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"
@@ skipping 360 matching lines @@
 
   void set_begin_token(const Token& t) { begin_token_ = t; }
   void set_end(scoped_ptr<EndNode> e) { end_ = e.Pass(); }
   const EndNode* End() const { return end_.get(); }
 
   void append_item(scoped_ptr<ParseNode> s) {
     contents_.push_back(s.release());
   }
   const std::vector<const ParseNode*>& contents() const { return contents_; }
 
+  // During formatting, do we want this list to always be multliline? This is
+  // used to make assignments to deps, sources, etc. always be multiline lists,
+  // rather than collapsed to a single line when they're one element.
+  bool prefer_multiline() const { return prefer_multiline_; }
+  void set_prefer_multiline(bool prefer_multiline) {
+    prefer_multiline_ = prefer_multiline;
+  }
+
  private:
   // Tokens corresponding to the [ and ]. The end token is stored in inside an
   // custom parse node so that it can have comments hung off of it.
   Token begin_token_;
   scoped_ptr<EndNode> end_;
+  bool prefer_multiline_;
 
   // Owning pointers, use unique_ptr when we can use C++11.
   std::vector<const ParseNode*> contents_;
 
   DISALLOW_COPY_AND_ASSIGN(ListNode);
 };
 
 // LiteralNode -----------------------------------------------------------------
 
 class LiteralNode : public ParseNode {
@@ skipping 100 matching lines @@
   const Token& value() const { return value_; }
   void set_value(const Token& t) { value_ = t; }
 
  private:
   Token value_;
 
   DISALLOW_COPY_AND_ASSIGN(EndNode);
 };
 
 #endif  // TOOLS_GN_PARSE_TREE_H_