# r183750 - Insert a space at the start of a line comment in case it starts with an alphanumeric character.

Tue Jun 11 09:01:50 PDT 2013

```Author: alexfh
Date: Tue Jun 11 11:01:49 2013
New Revision: 183750

URL: http://llvm.org/viewvc/llvm-project?rev=183750&view=rev
Log:
Insert a space at the start of a line comment in case it starts with an alphanumeric character.

Summary:
"//Test" becomes "// Test". This change is aimed to improve code
readability and conformance to certain coding styles. If a comment starts with a
non-alphanumeric character, the space isn't added, e.g. "//-*-c++-*-" stays
unchanged.

Reviewers: klimek

Reviewed By: klimek

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D949

Modified:
cfe/trunk/lib/Format/BreakableToken.cpp
cfe/trunk/lib/Format/BreakableToken.h
cfe/trunk/lib/Format/WhitespaceManager.cpp
cfe/trunk/lib/Format/WhitespaceManager.h
cfe/trunk/unittests/Format/FormatTest.cpp

Modified: cfe/trunk/lib/Format/BreakableToken.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/BreakableToken.cpp?rev=183750&r1=183749&r2=183750&view=diff
==============================================================================
--- cfe/trunk/lib/Format/BreakableToken.cpp (original)
+++ cfe/trunk/lib/Format/BreakableToken.cpp Tue Jun 11 11:01:49 2013
@@ -16,6 +16,7 @@
#define DEBUG_TYPE "format-token-breaker"

#include "BreakableToken.h"
+#include "clang/Basic/CharInfo.h"
#include "clang/Format/Format.h"
#include "llvm/Support/Debug.h"
@@ -118,15 +119,6 @@ unsigned BreakableSingleLineToken::getLi
encoding::getCodePointCount(Line.substr(Offset, Length), Encoding);
}

-void BreakableSingleLineToken::insertBreak(unsigned LineIndex,
-                                           unsigned TailOffset, Split Split,
-                                           bool InPPDirective,
-                                           WhitespaceManager &Whitespaces) {
-  Whitespaces.breakToken(Tok, Prefix.size() + TailOffset + Split.first,
-                         Split.second, Postfix, Prefix, InPPDirective,
-                         StartColumn);
-}
-
BreakableSingleLineToken::BreakableSingleLineToken(const FormatToken &Tok,
unsigned StartColumn,
StringRef Prefix,
@@ -151,6 +143,15 @@ BreakableStringLiteral::getSplit(unsigne
Encoding);
}

+void BreakableStringLiteral::insertBreak(unsigned LineIndex,
+                                         unsigned TailOffset, Split Split,
+                                         bool InPPDirective,
+                                         WhitespaceManager &Whitespaces) {
+  Whitespaces.replaceWhitespaceInToken(
+      Tok, Prefix.size() + TailOffset + Split.first, Split.second, Postfix,
+      Prefix, InPPDirective, 1, StartColumn);
+}
+
static StringRef getLineCommentPrefix(StringRef Comment) {
const char *KnownPrefixes[] = { "/// ", "///", "// ", "//" };
for (size_t i = 0, e = llvm::array_lengthof(KnownPrefixes); i != e; ++i)
@@ -164,7 +165,16 @@ BreakableLineComment::BreakableLineComme
encoding::Encoding Encoding)
: BreakableSingleLineToken(Token, StartColumn,
getLineCommentPrefix(Token.TokenText), "",
-                               Encoding) {}
+                               Encoding) {
+  OriginalPrefix = Prefix;
+  if (Token.TokenText.size() > Prefix.size() &&
+      isAlphanumeric(Token.TokenText[Prefix.size()])) {
+    if (Prefix == "//")
+      Prefix = "// ";
+    else if (Prefix == "///")
+      Prefix = "/// ";
+  }
+}

BreakableToken::Split
BreakableLineComment::getSplit(unsigned LineIndex, unsigned TailOffset,
@@ -173,6 +183,24 @@ BreakableLineComment::getSplit(unsigned
ColumnLimit, Encoding);
}

+void BreakableLineComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
+                                       Split Split, bool InPPDirective,
+                                       WhitespaceManager &Whitespaces) {
+  Whitespaces.replaceWhitespaceInToken(
+      Tok, OriginalPrefix.size() + TailOffset + Split.first, Split.second,
+      Postfix, Prefix, InPPDirective, 1, StartColumn);
+}
+
+void
+BreakableLineComment::replaceWhitespaceBefore(unsigned LineIndex,
+                                              unsigned InPPDirective,
+                                              WhitespaceManager &Whitespaces) {
+  if (OriginalPrefix != Prefix) {
+    Whitespaces.replaceWhitespaceInToken(Tok, OriginalPrefix.size(), 0, "", "",
+                                         false, 0, 1);
+  }
+}
+
BreakableBlockComment::BreakableBlockComment(
const FormatStyle &Style, const FormatToken &Token, unsigned StartColumn,
unsigned OriginalStartColumn, bool FirstInLine, encoding::Encoding Encoding)
@@ -299,8 +327,9 @@ void BreakableBlockComment::insertBreak(
Text.data() - Tok.TokenText.data() + Split.first;
unsigned CharsToRemove = Split.second;
assert(IndentAtLineBreak >= Decoration.size());
-  Whitespaces.breakToken(Tok, BreakOffsetInToken, CharsToRemove, "", Prefix,
-                         InPPDirective, IndentAtLineBreak - Decoration.size());
+  Whitespaces.replaceWhitespaceInToken(Tok, BreakOffsetInToken, CharsToRemove,
+                                       "", Prefix, InPPDirective, 1,
+                                       IndentAtLineBreak - Decoration.size());
}

void
@@ -331,9 +360,9 @@ BreakableBlockComment::replaceWhitespace
Lines[LineIndex].data() - Tok.TokenText.data() -
assert(StartOfLineColumn[LineIndex] >= Prefix.size());
-  Whitespaces.breakToken(
+  Whitespaces.replaceWhitespaceInToken(
-      InPPDirective, StartOfLineColumn[LineIndex] - Prefix.size());
+      InPPDirective, 1, StartOfLineColumn[LineIndex] - Prefix.size());
}

unsigned

Modified: cfe/trunk/lib/Format/BreakableToken.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/BreakableToken.h?rev=183750&r1=183749&r2=183750&view=diff
==============================================================================
--- cfe/trunk/lib/Format/BreakableToken.h (original)
+++ cfe/trunk/lib/Format/BreakableToken.h Tue Jun 11 11:01:49 2013
@@ -84,8 +84,6 @@ public:
virtual unsigned getLineLengthAfterSplit(unsigned LineIndex,
unsigned TailOffset,
StringRef::size_type Length) const;
-  virtual void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
-                           bool InPPDirective, WhitespaceManager &Whitespaces);

protected:
BreakableSingleLineToken(const FormatToken &Tok, unsigned StartColumn,
@@ -113,6 +111,9 @@ public:

virtual Split getSplit(unsigned LineIndex, unsigned TailOffset,
unsigned ColumnLimit) const;
+  virtual void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
+                           bool InPPDirective,
+                           WhitespaceManager &Whitespaces);
};

class BreakableLineComment : public BreakableSingleLineToken {
@@ -126,6 +127,15 @@ public:

virtual Split getSplit(unsigned LineIndex, unsigned TailOffset,
unsigned ColumnLimit) const;
+  virtual void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
+                           bool InPPDirective, WhitespaceManager &Whitespaces);
+  virtual void replaceWhitespaceBefore(unsigned LineIndex,
+                                       unsigned InPPDirective,
+                                       WhitespaceManager &Whitespaces);
+
+private:
+  // The prefix without an additional space if one was added.
+  StringRef OriginalPrefix;
};

class BreakableBlockComment : public BreakableToken {

Modified: cfe/trunk/lib/Format/WhitespaceManager.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/WhitespaceManager.cpp?rev=183750&r1=183749&r2=183750&view=diff
==============================================================================
--- cfe/trunk/lib/Format/WhitespaceManager.cpp (original)
+++ cfe/trunk/lib/Format/WhitespaceManager.cpp Tue Jun 11 11:01:49 2013
@@ -56,16 +56,15 @@ void WhitespaceManager::addUntouchableTo
InPPDirective && !Tok.IsFirst));
}

-void WhitespaceManager::breakToken(const FormatToken &Tok, unsigned Offset,
-                                   unsigned ReplaceChars,
-                                   StringRef PreviousPostfix,
-                                   StringRef CurrentPrefix, bool InPPDirective,
-                                   unsigned Spaces) {
+void WhitespaceManager::replaceWhitespaceInToken(
+    const FormatToken &Tok, unsigned Offset, unsigned ReplaceChars,
+    StringRef PreviousPostfix, StringRef CurrentPrefix, bool InPPDirective,
+    unsigned Newlines, unsigned Spaces) {
Changes.push_back(Change(
true, SourceRange(Tok.getStartOfNonWhitespace().getLocWithOffset(Offset),
Tok.getStartOfNonWhitespace().getLocWithOffset(
Offset + ReplaceChars)),
-      Spaces, Spaces, 1, PreviousPostfix, CurrentPrefix,
+      Spaces, Spaces, Newlines, PreviousPostfix, CurrentPrefix,
// FIXME: Unify token adjustment, so we don't split it between
// BreakableToken and the WhitespaceManager. That would also allow us to
// correctly store a tok::TokenKind instead of rolling our own enum.
@@ -214,10 +213,10 @@ void WhitespaceManager::generateChanges(
std::string ReplacementText =
C.PreviousLinePostfix +
(C.ContinuesPPDirective
-               ? getNewLineText(C.NewlinesBefore, C.Spaces,
+               ? getNewlineText(C.NewlinesBefore, C.Spaces,
C.PreviousEndOfTokenColumn,
C.EscapedNewlineColumn)
-               : getNewLineText(C.NewlinesBefore, C.Spaces)) +
+               : getNewlineText(C.NewlinesBefore, C.Spaces)) +
C.CurrentLinePrefix;
storeReplacement(C.OriginalWhitespaceRange, ReplacementText);
}
@@ -237,26 +236,26 @@ void WhitespaceManager::storeReplacement
SourceMgr, CharSourceRange::getCharRange(Range), Text));
}

-std::string WhitespaceManager::getNewLineText(unsigned NewLines,
+std::string WhitespaceManager::getNewlineText(unsigned Newlines,
unsigned Spaces) {
-  return std::string(NewLines, '\n') + getIndentText(Spaces);
+  return std::string(Newlines, '\n') + getIndentText(Spaces);
}

-std::string WhitespaceManager::getNewLineText(unsigned NewLines,
+std::string WhitespaceManager::getNewlineText(unsigned Newlines,
unsigned Spaces,
unsigned PreviousEndOfTokenColumn,
unsigned EscapedNewlineColumn) {
-  std::string NewLineText;
-  if (NewLines > 0) {
+  std::string NewlineText;
+  if (Newlines > 0) {
unsigned Offset =
std::min<int>(EscapedNewlineColumn - 1, PreviousEndOfTokenColumn);
-    for (unsigned i = 0; i < NewLines; ++i) {
-      NewLineText += std::string(EscapedNewlineColumn - Offset - 1, ' ');
-      NewLineText += "\\\n";
+    for (unsigned i = 0; i < Newlines; ++i) {
+      NewlineText += std::string(EscapedNewlineColumn - Offset - 1, ' ');
+      NewlineText += "\\\n";
Offset = 0;
}
}
-  return NewLineText + getIndentText(Spaces);
+  return NewlineText + getIndentText(Spaces);
}

std::string WhitespaceManager::getIndentText(unsigned Spaces) {

Modified: cfe/trunk/lib/Format/WhitespaceManager.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/WhitespaceManager.h?rev=183750&r1=183749&r2=183750&view=diff
==============================================================================
--- cfe/trunk/lib/Format/WhitespaceManager.h (original)
+++ cfe/trunk/lib/Format/WhitespaceManager.h Tue Jun 11 11:01:49 2013
@@ -52,17 +52,19 @@ public:
/// was not called.
void addUntouchableToken(const FormatToken &Tok, bool InPPDirective);

-  /// \brief Inserts a line break into the middle of a token.
+  /// \brief Inserts or replaces whitespace in the middle of a token.
///
-  /// Will break at \p Offset inside \p Tok, putting \p PreviousPostfix before
-  /// the line break and \p CurrentPrefix before the rest of the token starts in
-  /// the next line.
+  /// Inserts \p PreviousPostfix, \p Newlines, \p Spaces and \p CurrentPrefix
+  /// (in this order) at \p Offset inside \p Tok, replacing \p ReplaceChars
+  /// characters.
///
-  /// \p InPPDirective and \p Spaces are used to generate the correct line
-  /// break.
-  void breakToken(const FormatToken &Tok, unsigned Offset,
-                  unsigned ReplaceChars, StringRef PreviousPostfix,
-                  StringRef CurrentPrefix, bool InPPDirective, unsigned Spaces);
+  /// When \p InPPDirective is true, escaped newlines are inserted. \p Spaces is
+  /// used to align backslashes correctly.
+  void replaceWhitespaceInToken(const FormatToken &Tok, unsigned Offset,
+                                unsigned ReplaceChars,
+                                StringRef PreviousPostfix,
+                                StringRef CurrentPrefix, bool InPPDirective,
+                                unsigned Newlines, unsigned Spaces);

/// \brief Returns all the \c Replacements created during formatting.
const tooling::Replacements &generateReplacements();
@@ -151,8 +153,8 @@ private:

/// \brief Stores \p Text as the replacement for the whitespace in \p Range.
void storeReplacement(const SourceRange &Range, StringRef Text);
-  std::string getNewLineText(unsigned NewLines, unsigned Spaces);
-  std::string getNewLineText(unsigned NewLines, unsigned Spaces,
+  std::string getNewlineText(unsigned Newlines, unsigned Spaces);
+  std::string getNewlineText(unsigned Newlines, unsigned Spaces,
unsigned PreviousEndOfTokenColumn,
unsigned EscapedNewlineColumn);
std::string getIndentText(unsigned Spaces);

Modified: cfe/trunk/unittests/Format/FormatTest.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/Format/FormatTest.cpp?rev=183750&r1=183749&r2=183750&view=diff
==============================================================================
--- cfe/trunk/unittests/Format/FormatTest.cpp (original)
+++ cfe/trunk/unittests/Format/FormatTest.cpp Tue Jun 11 11:01:49 2013
@@ -860,10 +860,15 @@ TEST_F(FormatTest, SplitsLongCxxComments
getLLVMStyleWithColumns(20)));
-  EXPECT_EQ(
-      "//whitespace",
+            "// whitespace",
+  EXPECT_EQ("// whitespace", format("//whitespace", getLLVMStyle()));
+  EXPECT_EQ("// Even if it makes the line exceed the column\n"
+            "// limit",
+            format("//Even if it makes the line exceed the column limit",
+                   getLLVMStyleWithColumns(51)));
+  EXPECT_EQ("//--But not here", format("//--But not here", getLLVMStyle()));
EXPECT_EQ("// A comment before\n"
"// a macro\n"
"// definition\n"

```