gn format: Have format sort sources

tools/gn/command_format.cc

 // 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.
 
 #include <sstream>
 
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/strings/string_split.h"
 #include "tools/gn/commands.h"
@@ skipping 111 matching lines @@
 
   // Remove trailing spaces from the current line.
   void Trim();
 
   // Whether there's a blank separator line at the current position.
   bool HaveBlankLine();
 
   // Flag assignments to sources, deps, etc. to make their RHSs multiline.
   void AnnotatePreferredMultilineAssignment(const BinaryOpNode* binop);
 
+  // Alphabetically a list on the RHS if the LHS is 'sources'.
+  void SortIfSources(const BinaryOpNode* binop);
+
   // Heuristics to decide if there should be a blank line added between two
   // items. For various "small" items, it doesn't look nice if there's too much
   // vertical whitespace added.
   bool ShouldAddBlankLineInBetween(const ParseNode* a, const ParseNode* b);
 
   // Get the 0-based x position on the current line.
   int CurrentColumn() const;
 
   // Get the current line in the output;
   int CurrentLine() const;
@@ skipping 156 matching lines @@
   if (binop->op().value() == "=" && ident && list) {
     const base::StringPiece lhs = ident->value().value();
     if (lhs == "data" || lhs == "datadeps" || lhs == "deps" ||
         lhs == "inputs" || lhs == "outputs" || lhs == "public" ||
         lhs == "public_deps" || lhs == "sources") {
       const_cast<ListNode*>(list)->set_prefer_multiline(true);
     }
   }
 }
 
+void Printer::SortIfSources(const BinaryOpNode* binop) {
+  const IdentifierNode* ident = binop->left()->AsIdentifier();
+  const ListNode* list = binop->right()->AsList();
+  // TODO(scottmg): Sort more than 'sources'?
+  if ((binop->op().value() == "=" || binop->op().value() == "+=" ||
+       binop->op().value() == "-=") &&
+      ident && list) {
+    const base::StringPiece lhs = ident->value().value();
+    if (lhs == "sources")
+      const_cast<ListNode*>(list)->SortAsStringsList();
+  }
+}
+
+
 bool Printer::ShouldAddBlankLineInBetween(const ParseNode* a,
                                           const ParseNode* b) {
   LocationRange a_range = a->GetRange();
   LocationRange b_range = b->GetRange();
   // If they're already separated by 1 or more lines, then we want to keep a
   // blank line.
-  return b_range.begin().line_number() > a_range.end().line_number() + 1;
+  return (b_range.begin().line_number() > a_range.end().line_number() + 1) ||
+         // Always put a blank line before a block comment.
+         b->AsBlockComment();
 }
 
 int Printer::CurrentColumn() const {
   int n = 0;
   while (n < static_cast<int>(output_.size()) &&
          output_[output_.size() - 1 - n] != '\n') {
     ++n;
   }
   return n;
 }
@@ skipping 109 matching lines @@
       Expr(accessor->member(), kPrecedenceLowest, std::string());
     } else {
       CHECK(accessor->index());
       Print("[");
       Expr(accessor->index(), kPrecedenceLowest, "]");
     }
   } else if (const BinaryOpNode* binop = root->AsBinaryOp()) {
     CHECK(precedence_.find(binop->op().value()) != precedence_.end());
     AnnotatePreferredMultilineAssignment(binop);
 
+    SortIfSources(binop);
+
     Precedence prec = precedence_[binop->op().value()];
 
     // Since binary operators format left-to-right, it is ok for the left side
     // use the same operator without parentheses, so the left uses prec. For the
     // same reason, the right side cannot reuse the same operator, or else "x +
     // (y + z)" would format as "x + y + z" which means "(x + y) + z". So, treat
     // the right expression as appearing one precedence level higher.
     // However, because the source parens are not in the parse tree, as a
     // special case for && and || we insert strictly-redundant-but-helpful-for-
     // human-readers parentheses.
@@ skipping 187 matching lines @@
       if (i != 0 && x->comments() && !x->comments()->before().empty() &&
           !HaveBlankLine()) {
         Newline();
       }
       bool body_of_list = i < list.size() - 1 || style == kSequenceStyleList;
       bool want_comma =
           body_of_list && (style == kSequenceStyleList && !x->AsBlockComment());
       Expr(x, kPrecedenceLowest, want_comma ? "," : std::string());
       CHECK(!x->comments() || x->comments()->after().empty());
       if (body_of_list) {
-        if (!want_comma) {
-          if (i < list.size() - 1 &&
-              ShouldAddBlankLineInBetween(list[i], list[i + 1]))
-            Newline();
-        }
+        if (i < list.size() - 1 &&
+            ShouldAddBlankLineInBetween(list[i], list[i + 1]))
+          Newline();
       }
       ++i;
     }
 
     // Trailing comments.
     if (end->comments() && !end->comments()->before().empty()) {
       if (list.size() >= 2)
         Newline();
       for (const auto& c : end->comments()->before()) {
         Newline();
@@ skipping 355 matching lines @@
       }
     } else {
       printf("%s", output_string.c_str());
     }
   }
 
   return 0;
 }
 
 }  // namespace commands