[clang-format] Add comment manipulation header

[krasimir]

Summary

Introduces a separate target for comment manipulation.
Currently, comment manipulation is in BreakableComment.cpp.
Towards implementing comment reflowing, we want to factor out the
comment-related functionality, so it can be reused.
Start simple by just moving out getLineCommentIndentPrefix.

[djasper]

Looks good.

[krasimir]

Please land. I have no commit rights yet.

cfe/trunk/lib/Format/BreakableToken.cpp

 //===--- BreakableToken.cpp - Format C++ code -----------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// \brief Contains implementation of BreakableToken class and classes derived
 /// from it.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "BreakableToken.h"
+#include "Comments.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Format/Format.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Debug.h"
 #include <algorithm>
 
 #define DEBUG_TYPE "format-token-breaker"
 
void BreakableStringLiteral::insertBreak(unsigned LineIndex,
   // precomputation step.
   if (Prefix.startswith("@"))
     --LeadingSpaces;
   Whitespaces.replaceWhitespaceInToken(
       Tok, Prefix.size() + TailOffset + Split.first, Split.second, Postfix,
       Prefix, InPPDirective, 1, IndentLevel, LeadingSpaces);
 }
 
-static StringRef getLineCommentIndentPrefix(StringRef Comment) {
-  static const char *const KnownPrefixes[] = {"///", "//", "//!"};
-  StringRef LongestPrefix;
-  for (StringRef KnownPrefix : KnownPrefixes) {
-    if (Comment.startswith(KnownPrefix)) {
-      size_t PrefixLength = KnownPrefix.size();
-      while (PrefixLength < Comment.size() && Comment[PrefixLength] == ' ')
-        ++PrefixLength;
-      if (PrefixLength > LongestPrefix.size())
-        LongestPrefix = Comment.substr(0, PrefixLength);
-    }
-  }
-  return LongestPrefix;
-}
-
 BreakableLineComment::BreakableLineComment(
     const FormatToken &Token, unsigned IndentLevel, unsigned StartColumn,
     bool InPPDirective, encoding::Encoding Encoding, const FormatStyle &Style)
     : BreakableSingleLineToken(Token, IndentLevel, StartColumn,
                                getLineCommentIndentPrefix(Token.TokenText), "",
                                InPPDirective, Encoding, Style) {
   OriginalPrefix = Prefix;
   if (Token.TokenText.size() > Prefix.size() &&

cfe/trunk/lib/Format/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS support)
 
 add_clang_library(clangFormat
   AffectedRangeManager.cpp
   BreakableToken.cpp
+  Comments.cpp
   ContinuationIndenter.cpp
   Format.cpp
   FormatToken.cpp
   FormatTokenLexer.cpp
   SortJavaScriptImports.cpp
   TokenAnalyzer.cpp
   TokenAnnotator.cpp
   UnwrappedLineFormatter.cpp
   UnwrappedLineParser.cpp
   WhitespaceManager.cpp
 
   LINK_LIBS
   clangBasic
   clangLex
   clangToolingCore
   )

cfe/trunk/lib/Format/Comments.h

+//===--- Comments.cpp - Comment manipulation  -----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Declares comment manipulation functionality.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_FORMAT_COMMENTS_H
+#define LLVM_CLANG_LIB_FORMAT_COMMENTS_H
+
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace clang {
+namespace format {
+
+/// \brief Returns the comment prefix of the line comment \p Comment.
+///
+/// The comment prefix consists of a leading known prefix, like "//" or "///",
+/// together with the following whitespace.
+StringRef getLineCommentIndentPrefix(StringRef Comment);
+
+} // namespace format
+} // namespace clang
+
+#endif

cfe/trunk/lib/Format/Comments.cpp

+//===--- Comments.cpp - Comment Manipulation  -------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Implements comment manipulation.
+///
+//===----------------------------------------------------------------------===//
+
+#include "Comments.h"
+
+namespace clang {
+namespace format {
+
+StringRef getLineCommentIndentPrefix(StringRef Comment) {
+  static const char *const KnownPrefixes[] = {"///", "//", "//!"};
+  StringRef LongestPrefix;
+  for (StringRef KnownPrefix : KnownPrefixes) {
+    if (Comment.startswith(KnownPrefix)) {
+      size_t PrefixLength = KnownPrefix.size();
+      while (PrefixLength < Comment.size() && Comment[PrefixLength] == ' ')
+        ++PrefixLength;
+      if (PrefixLength > LongestPrefix.size())
+        LongestPrefix = Comment.substr(0, PrefixLength);
+    }
+  }
+  return LongestPrefix;
+}
+
+} // namespace format
+} // namespace clang