external/bsd/llvm/dist/clang/lib/Format/BreakableToken.cpp

   1 //===--- BreakableToken.cpp - Format C++ code -----------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 ///
  10 /// \file
  11 /// \brief Contains implementation of BreakableToken class and classes derived
  12 /// from it.
  13 ///
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "BreakableToken.h"
  17 #include "clang/Basic/CharInfo.h"
  18 #include "clang/Format/Format.h"
  19 #include "llvm/ADT/STLExtras.h"
  20 #include "llvm/Support/Debug.h"
  21 #include <algorithm>
  22
  23 #define DEBUG_TYPE "format-token-breaker"
  24
  25 namespace clang {
  26 namespace format {
  27
  28 static const char *const Blanks = " \t\v\f\r";
  29 static bool IsBlank(char C) {
  30   switch (C) {
  31   case ' ':
  32   case '\t':
  33   case '\v':
  34   case '\f':
  35   case '\r':
  36     return true;
  37   default:
  38     return false;
  39   }
  40 }
  41
  42 static BreakableToken::Split getCommentSplit(StringRef Text,
  43                                              unsigned ContentStartColumn,
  44                                              unsigned ColumnLimit,
  45                                              unsigned TabWidth,
  46                                              encoding::Encoding Encoding) {
  47   if (ColumnLimit <= ContentStartColumn + 1)
  48     return BreakableToken::Split(StringRef::npos, 0);
  49
  50   unsigned MaxSplit = ColumnLimit - ContentStartColumn + 1;
  51   unsigned MaxSplitBytes = 0;
  52
  53   for (unsigned NumChars = 0;
  54        NumChars < MaxSplit && MaxSplitBytes < Text.size();) {
  55     unsigned BytesInChar =
  56         encoding::getCodePointNumBytes(Text[MaxSplitBytes], Encoding);
  57     NumChars +=
  58         encoding::columnWidthWithTabs(Text.substr(MaxSplitBytes, BytesInChar),
  59                                       ContentStartColumn, TabWidth, Encoding);
  60     MaxSplitBytes += BytesInChar;
  61   }
  62
  63   StringRef::size_type SpaceOffset = Text.find_last_of(Blanks, MaxSplitBytes);
  64   if (SpaceOffset == StringRef::npos ||
  65       // Don't break at leading whitespace.
  66       Text.find_last_not_of(Blanks, SpaceOffset) == StringRef::npos) {
  67     // Make sure that we don't break at leading whitespace that
  68     // reaches past MaxSplit.
  69     StringRef::size_type FirstNonWhitespace = Text.find_first_not_of(Blanks);
  70     if (FirstNonWhitespace == StringRef::npos)
  71       // If the comment is only whitespace, we cannot split.
  72       return BreakableToken::Split(StringRef::npos, 0);
  73     SpaceOffset = Text.find_first_of(
  74         Blanks, std::max<unsigned>(MaxSplitBytes, FirstNonWhitespace));
  75   }
  76   if (SpaceOffset != StringRef::npos && SpaceOffset != 0) {
  77     StringRef BeforeCut = Text.substr(0, SpaceOffset).rtrim(Blanks);
  78     StringRef AfterCut = Text.substr(SpaceOffset).ltrim(Blanks);
  79     return BreakableToken::Split(BeforeCut.size(),
  80                                  AfterCut.begin() - BeforeCut.end());
  81   }
  82   return BreakableToken::Split(StringRef::npos, 0);
  83 }
  84
  85 static BreakableToken::Split
  86 getStringSplit(StringRef Text, unsigned UsedColumns, unsigned ColumnLimit,
  87                unsigned TabWidth, encoding::Encoding Encoding) {
  88   // FIXME: Reduce unit test case.
  89   if (Text.empty())
  90     return BreakableToken::Split(StringRef::npos, 0);
  91   if (ColumnLimit <= UsedColumns)
  92     return BreakableToken::Split(StringRef::npos, 0);
  93   unsigned MaxSplit = ColumnLimit - UsedColumns;
  94   StringRef::size_type SpaceOffset = 0;
  95   StringRef::size_type SlashOffset = 0;
  96   StringRef::size_type WordStartOffset = 0;
  97   StringRef::size_type SplitPoint = 0;
  98   for (unsigned Chars = 0;;) {
  99     unsigned Advance;
 100     if (Text[0] == '\\') {
 101       Advance = encoding::getEscapeSequenceLength(Text);
 102       Chars += Advance;
 103     } else {
 104       Advance = encoding::getCodePointNumBytes(Text[0], Encoding);
 105       Chars += encoding::columnWidthWithTabs(
 106           Text.substr(0, Advance), UsedColumns + Chars, TabWidth, Encoding);
 107     }
 108
 109     if (Chars > MaxSplit || Text.size() == Advance)
 110       break;
 111
 112     if (IsBlank(Text[0]))
 113       SpaceOffset = SplitPoint;
 114     if (Text[0] == '/')
 115       SlashOffset = SplitPoint;
 116     if (Advance == 1 && !isAlphanumeric(Text[0]))
 117       WordStartOffset = SplitPoint;
 118
 119     SplitPoint += Advance;
 120     Text = Text.substr(Advance);
 121   }
 122
 123   if (SpaceOffset != 0)
 124     return BreakableToken::Split(SpaceOffset + 1, 0);
 125   if (SlashOffset != 0)
 126     return BreakableToken::Split(SlashOffset + 1, 0);
 127   if (WordStartOffset != 0)
 128     return BreakableToken::Split(WordStartOffset + 1, 0);
 129   if (SplitPoint != 0)
 130     return BreakableToken::Split(SplitPoint, 0);
 131   return BreakableToken::Split(StringRef::npos, 0);
 132 }
 133
 134 unsigned BreakableSingleLineToken::getLineCount() const { return 1; }
 135
 136 unsigned BreakableSingleLineToken::getLineLengthAfterSplit(
 137     unsigned LineIndex, unsigned Offset, StringRef::size_type Length) const {
 138   return StartColumn + Prefix.size() + Postfix.size() +
 139          encoding::columnWidthWithTabs(Line.substr(Offset, Length),
 140                                        StartColumn + Prefix.size(),
 141                                        Style.TabWidth, Encoding);
 142 }
 143
 144 BreakableSingleLineToken::BreakableSingleLineToken(
 145     const FormatToken &Tok, unsigned IndentLevel, unsigned StartColumn,
 146     StringRef Prefix, StringRef Postfix, bool InPPDirective,
 147     encoding::Encoding Encoding, const FormatStyle &Style)
 148     : BreakableToken(Tok, IndentLevel, InPPDirective, Encoding, Style),
 149       StartColumn(StartColumn), Prefix(Prefix), Postfix(Postfix) {
 150   assert(Tok.TokenText.endswith(Postfix));
 151   Line = Tok.TokenText.substr(
 152       Prefix.size(), Tok.TokenText.size() - Prefix.size() - Postfix.size());
 153 }
 154
 155 BreakableStringLiteral::BreakableStringLiteral(
 156     const FormatToken &Tok, unsigned IndentLevel, unsigned StartColumn,
 157     StringRef Prefix, StringRef Postfix, bool InPPDirective,
 158     encoding::Encoding Encoding, const FormatStyle &Style)
 159     : BreakableSingleLineToken(Tok, IndentLevel, StartColumn, Prefix, Postfix,
 160                                InPPDirective, Encoding, Style) {}
 161
 162 BreakableToken::Split
 163 BreakableStringLiteral::getSplit(unsigned LineIndex, unsigned TailOffset,
 164                                  unsigned ColumnLimit) const {
 165   return getStringSplit(Line.substr(TailOffset),
 166                         StartColumn + Prefix.size() + Postfix.size(),
 167                         ColumnLimit, Style.TabWidth, Encoding);
 168 }
 169
 170 void BreakableStringLiteral::insertBreak(unsigned LineIndex,
 171                                          unsigned TailOffset, Split Split,
 172                                          WhitespaceManager &Whitespaces) {
 173   unsigned LeadingSpaces = StartColumn;
 174   // The '@' of an ObjC string literal (@"Test") does not become part of the
 175   // string token.
 176   // FIXME: It might be a cleaner solution to merge the tokens as a
 177   // precomputation step.
 178   if (Prefix.startswith("@"))
 179     --LeadingSpaces;
 180   Whitespaces.replaceWhitespaceInToken(
 181       Tok, Prefix.size() + TailOffset + Split.first, Split.second, Postfix,
 182       Prefix, InPPDirective, 1, IndentLevel, LeadingSpaces);
 183 }
 184
 185 static StringRef getLineCommentIndentPrefix(StringRef Comment) {
 186   static const char *const KnownPrefixes[] = { "///", "//" };
 187   StringRef LongestPrefix;
 188   for (StringRef KnownPrefix : KnownPrefixes) {
 189     if (Comment.startswith(KnownPrefix)) {
 190       size_t PrefixLength = KnownPrefix.size();
 191       while (PrefixLength < Comment.size() && Comment[PrefixLength] == ' ')
 192         ++PrefixLength;
 193       if (PrefixLength > LongestPrefix.size())
 194         LongestPrefix = Comment.substr(0, PrefixLength);
 195     }
 196   }
 197   return LongestPrefix;
 198 }
 199
 200 BreakableLineComment::BreakableLineComment(
 201     const FormatToken &Token, unsigned IndentLevel, unsigned StartColumn,
 202     bool InPPDirective, encoding::Encoding Encoding, const FormatStyle &Style)
 203     : BreakableSingleLineToken(Token, IndentLevel, StartColumn,
 204                                getLineCommentIndentPrefix(Token.TokenText), "",
 205                                InPPDirective, Encoding, Style) {
 206   OriginalPrefix = Prefix;
 207   if (Token.TokenText.size() > Prefix.size() &&
 208       isAlphanumeric(Token.TokenText[Prefix.size()])) {
 209     if (Prefix == "//")
 210       Prefix = "// ";
 211     else if (Prefix == "///")
 212       Prefix = "/// ";
 213   }
 214 }
 215
 216 BreakableToken::Split
 217 BreakableLineComment::getSplit(unsigned LineIndex, unsigned TailOffset,
 218                                unsigned ColumnLimit) const {
 219   return getCommentSplit(Line.substr(TailOffset), StartColumn + Prefix.size(),
 220                          ColumnLimit, Style.TabWidth, Encoding);
 221 }
 222
 223 void BreakableLineComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
 224                                        Split Split,
 225                                        WhitespaceManager &Whitespaces) {
 226   Whitespaces.replaceWhitespaceInToken(
 227       Tok, OriginalPrefix.size() + TailOffset + Split.first, Split.second,
 228       Postfix, Prefix, InPPDirective, /*Newlines=*/1, IndentLevel, StartColumn);
 229 }
 230
 231 void BreakableLineComment::replaceWhitespace(unsigned LineIndex,
 232                                              unsigned TailOffset, Split Split,
 233                                              WhitespaceManager &Whitespaces) {
 234   Whitespaces.replaceWhitespaceInToken(
 235       Tok, OriginalPrefix.size() + TailOffset + Split.first, Split.second, "",
 236       "", /*InPPDirective=*/false, /*Newlines=*/0, /*IndentLevel=*/0,
 237       /*Spaces=*/1);
 238 }
 239
 240 void
 241 BreakableLineComment::replaceWhitespaceBefore(unsigned LineIndex,
 242                                               WhitespaceManager &Whitespaces) {
 243   if (OriginalPrefix != Prefix) {
 244     Whitespaces.replaceWhitespaceInToken(Tok, OriginalPrefix.size(), 0, "", "",
 245                                          /*InPPDirective=*/false,
 246                                          /*Newlines=*/0, /*IndentLevel=*/0,
 247                                          /*Spaces=*/1);
 248   }
 249 }
 250
 251 BreakableBlockComment::BreakableBlockComment(
 252     const FormatToken &Token, unsigned IndentLevel, unsigned StartColumn,
 253     unsigned OriginalStartColumn, bool FirstInLine, bool InPPDirective,
 254     encoding::Encoding Encoding, const FormatStyle &Style)
 255     : BreakableToken(Token, IndentLevel, InPPDirective, Encoding, Style) {
 256   StringRef TokenText(Token.TokenText);
 257   assert(TokenText.startswith("/*") && TokenText.endswith("*/"));
 258   TokenText.substr(2, TokenText.size() - 4).split(Lines, "\n");
 259
 260   int IndentDelta = StartColumn - OriginalStartColumn;
 261   LeadingWhitespace.resize(Lines.size());
 262   StartOfLineColumn.resize(Lines.size());
 263   StartOfLineColumn[0] = StartColumn + 2;
 264   for (size_t i = 1; i < Lines.size(); ++i)
 265     adjustWhitespace(i, IndentDelta);
 266
 267   Decoration = "* ";
 268   if (Lines.size() == 1 && !FirstInLine) {
 269     // Comments for which FirstInLine is false can start on arbitrary column,
 270     // and available horizontal space can be too small to align consecutive
 271     // lines with the first one.
 272     // FIXME: We could, probably, align them to current indentation level, but
 273     // now we just wrap them without stars.
 274     Decoration = "";
 275   }
 276   for (size_t i = 1, e = Lines.size(); i < e && !Decoration.empty(); ++i) {
 277     // If the last line is empty, the closing "*/" will have a star.
 278     if (i + 1 == e && Lines[i].empty())
 279       break;
 280     while (!Lines[i].startswith(Decoration))
 281       Decoration = Decoration.substr(0, Decoration.size() - 1);
 282   }
 283
 284   LastLineNeedsDecoration = true;
 285   IndentAtLineBreak = StartOfLineColumn[0] + 1;
 286   for (size_t i = 1; i < Lines.size(); ++i) {
 287     if (Lines[i].empty()) {
 288       if (i + 1 == Lines.size()) {
 289         // Empty last line means that we already have a star as a part of the
 290         // trailing */. We also need to preserve whitespace, so that */ is
 291         // correctly indented.
 292         LastLineNeedsDecoration = false;
 293       } else if (Decoration.empty()) {
 294         // For all other lines, set the start column to 0 if they're empty, so
 295         // we do not insert trailing whitespace anywhere.
 296         StartOfLineColumn[i] = 0;
 297       }
 298       continue;
 299     }
 300     // The first line already excludes the star.
 301     // For all other lines, adjust the line to exclude the star and
 302     // (optionally) the first whitespace.
 303     StartOfLineColumn[i] += Decoration.size();
 304     Lines[i] = Lines[i].substr(Decoration.size());
 305     LeadingWhitespace[i] += Decoration.size();
 306     IndentAtLineBreak =
 307         std::min<int>(IndentAtLineBreak, std::max(0, StartOfLineColumn[i]));
 308   }
 309   IndentAtLineBreak = std::max<unsigned>(IndentAtLineBreak, Decoration.size());
 310   DEBUG({
 311     llvm::dbgs() << "IndentAtLineBreak " << IndentAtLineBreak << "\n";
 312     for (size_t i = 0; i < Lines.size(); ++i) {
 313       llvm::dbgs() << i << " |" << Lines[i] << "| " << LeadingWhitespace[i]
 314                    << "\n";
 315     }
 316   });
 317 }
 318
 319 void BreakableBlockComment::adjustWhitespace(unsigned LineIndex,
 320                                              int IndentDelta) {
 321   // When in a preprocessor directive, the trailing backslash in a block comment
 322   // is not needed, but can serve a purpose of uniformity with necessary escaped
 323   // newlines outside the comment. In this case we remove it here before
 324   // trimming the trailing whitespace. The backslash will be re-added later when
 325   // inserting a line break.
 326   size_t EndOfPreviousLine = Lines[LineIndex - 1].size();
 327   if (InPPDirective && Lines[LineIndex - 1].endswith("\\"))
 328     --EndOfPreviousLine;
 329
 330   // Calculate the end of the non-whitespace text in the previous line.
 331   EndOfPreviousLine =
 332       Lines[LineIndex - 1].find_last_not_of(Blanks, EndOfPreviousLine);
 333   if (EndOfPreviousLine == StringRef::npos)
 334     EndOfPreviousLine = 0;
 335   else
 336     ++EndOfPreviousLine;
 337   // Calculate the start of the non-whitespace text in the current line.
 338   size_t StartOfLine = Lines[LineIndex].find_first_not_of(Blanks);
 339   if (StartOfLine == StringRef::npos)
 340     StartOfLine = Lines[LineIndex].size();
 341
 342   StringRef Whitespace = Lines[LineIndex].substr(0, StartOfLine);
 343   // Adjust Lines to only contain relevant text.
 344   Lines[LineIndex - 1] = Lines[LineIndex - 1].substr(0, EndOfPreviousLine);
 345   Lines[LineIndex] = Lines[LineIndex].substr(StartOfLine);
 346   // Adjust LeadingWhitespace to account all whitespace between the lines
 347   // to the current line.
 348   LeadingWhitespace[LineIndex] =
 349       Lines[LineIndex].begin() - Lines[LineIndex - 1].end();
 350
 351   // Adjust the start column uniformly across all lines.
 352   StartOfLineColumn[LineIndex] =
 353       encoding::columnWidthWithTabs(Whitespace, 0, Style.TabWidth, Encoding) +
 354       IndentDelta;
 355 }
 356
 357 unsigned BreakableBlockComment::getLineCount() const { return Lines.size(); }
 358
 359 unsigned BreakableBlockComment::getLineLengthAfterSplit(
 360     unsigned LineIndex, unsigned Offset, StringRef::size_type Length) const {
 361   unsigned ContentStartColumn = getContentStartColumn(LineIndex, Offset);
 362   return ContentStartColumn +
 363          encoding::columnWidthWithTabs(Lines[LineIndex].substr(Offset, Length),
 364                                        ContentStartColumn, Style.TabWidth,
 365                                        Encoding) +
 366          // The last line gets a "*/" postfix.
 367          (LineIndex + 1 == Lines.size() ? 2 : 0);
 368 }
 369
 370 BreakableToken::Split
 371 BreakableBlockComment::getSplit(unsigned LineIndex, unsigned TailOffset,
 372                                 unsigned ColumnLimit) const {
 373   return getCommentSplit(Lines[LineIndex].substr(TailOffset),
 374                          getContentStartColumn(LineIndex, TailOffset),
 375                          ColumnLimit, Style.TabWidth, Encoding);
 376 }
 377
 378 void BreakableBlockComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
 379                                         Split Split,
 380                                         WhitespaceManager &Whitespaces) {
 381   StringRef Text = Lines[LineIndex].substr(TailOffset);
 382   StringRef Prefix = Decoration;
 383   if (LineIndex + 1 == Lines.size() &&
 384       Text.size() == Split.first + Split.second) {
 385     // For the last line we need to break before "*/", but not to add "* ".
 386     Prefix = "";
 387   }
 388
 389   unsigned BreakOffsetInToken =
 390       Text.data() - Tok.TokenText.data() + Split.first;
 391   unsigned CharsToRemove = Split.second;
 392   assert(IndentAtLineBreak >= Decoration.size());
 393   Whitespaces.replaceWhitespaceInToken(
 394       Tok, BreakOffsetInToken, CharsToRemove, "", Prefix, InPPDirective, 1,
 395       IndentLevel, IndentAtLineBreak - Decoration.size());
 396 }
 397
 398 void BreakableBlockComment::replaceWhitespace(unsigned LineIndex,
 399                                               unsigned TailOffset, Split Split,
 400                                               WhitespaceManager &Whitespaces) {
 401   StringRef Text = Lines[LineIndex].substr(TailOffset);
 402   unsigned BreakOffsetInToken =
 403       Text.data() - Tok.TokenText.data() + Split.first;
 404   unsigned CharsToRemove = Split.second;
 405   Whitespaces.replaceWhitespaceInToken(
 406       Tok, BreakOffsetInToken, CharsToRemove, "", "", /*InPPDirective=*/false,
 407       /*Newlines=*/0, /*IndentLevel=*/0, /*Spaces=*/1);
 408 }
 409
 410 void
 411 BreakableBlockComment::replaceWhitespaceBefore(unsigned LineIndex,
 412                                                WhitespaceManager &Whitespaces) {
 413   if (LineIndex == 0)
 414     return;
 415   StringRef Prefix = Decoration;
 416   if (Lines[LineIndex].empty()) {
 417     if (LineIndex + 1 == Lines.size()) {
 418       if (!LastLineNeedsDecoration) {
 419         // If the last line was empty, we don't need a prefix, as the */ will
 420         // line up with the decoration (if it exists).
 421         Prefix = "";
 422       }
 423     } else if (!Decoration.empty()) {
 424       // For other empty lines, if we do have a decoration, adapt it to not
 425       // contain a trailing whitespace.
 426       Prefix = Prefix.substr(0, 1);
 427     }
 428   } else {
 429     if (StartOfLineColumn[LineIndex] == 1) {
 430       // This line starts immediately after the decorating *.
 431       Prefix = Prefix.substr(0, 1);
 432     }
 433   }
 434
 435   unsigned WhitespaceOffsetInToken = Lines[LineIndex].data() -
 436                                      Tok.TokenText.data() -
 437                                      LeadingWhitespace[LineIndex];
 438   Whitespaces.replaceWhitespaceInToken(
 439       Tok, WhitespaceOffsetInToken, LeadingWhitespace[LineIndex], "", Prefix,
 440       InPPDirective, 1, IndentLevel,
 441       StartOfLineColumn[LineIndex] - Prefix.size());
 442 }
 443
 444 unsigned
 445 BreakableBlockComment::getContentStartColumn(unsigned LineIndex,
 446                                              unsigned TailOffset) const {
 447   // If we break, we always break at the predefined indent.
 448   if (TailOffset != 0)
 449     return IndentAtLineBreak;
 450   return std::max(0, StartOfLineColumn[LineIndex]);
 451 }
 452
 453 } // namespace format
 454 } // namespace clang