1 //===--- FormatToken.cpp - Format C++ code --------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 /// 9 /// \file 10 /// This file implements specific functions of \c FormatTokens and their 11 /// roles. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #include "FormatToken.h" 16 #include "ContinuationIndenter.h" 17 #include "llvm/ADT/SmallVector.h" 18 #include "llvm/Support/Debug.h" 19 #include <climits> 20 21 namespace clang { 22 namespace format { 23 24 const char *getTokenTypeName(TokenType Type) { 25 static const char *const TokNames[] = { 26 #define TYPE(X) #X, 27 LIST_TOKEN_TYPES 28 #undef TYPE 29 nullptr}; 30 31 if (Type < NUM_TOKEN_TYPES) 32 return TokNames[Type]; 33 llvm_unreachable("unknown TokenType"); 34 return nullptr; 35 } 36 37 // FIXME: This is copy&pasted from Sema. Put it in a common place and remove 38 // duplication. 39 bool FormatToken::isSimpleTypeSpecifier() const { 40 switch (Tok.getKind()) { 41 case tok::kw_short: 42 case tok::kw_long: 43 case tok::kw___int64: 44 case tok::kw___int128: 45 case tok::kw_signed: 46 case tok::kw_unsigned: 47 case tok::kw_void: 48 case tok::kw_char: 49 case tok::kw_int: 50 case tok::kw_half: 51 case tok::kw_float: 52 case tok::kw_double: 53 case tok::kw___bf16: 54 case tok::kw__Float16: 55 case tok::kw___float128: 56 case tok::kw___ibm128: 57 case tok::kw_wchar_t: 58 case tok::kw_bool: 59 #define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) case tok::kw___##Trait: 60 #include "clang/Basic/TransformTypeTraits.def" 61 case tok::annot_typename: 62 case tok::kw_char8_t: 63 case tok::kw_char16_t: 64 case tok::kw_char32_t: 65 case tok::kw_typeof: 66 case tok::kw_decltype: 67 case tok::kw__Atomic: 68 return true; 69 default: 70 return false; 71 } 72 } 73 74 bool FormatToken::isTypeOrIdentifier() const { 75 return isSimpleTypeSpecifier() || Tok.isOneOf(tok::kw_auto, tok::identifier); 76 } 77 78 bool FormatToken::isBlockIndentedInitRBrace(const FormatStyle &Style) const { 79 assert(is(tok::r_brace)); 80 if (!Style.Cpp11BracedListStyle || 81 Style.AlignAfterOpenBracket != FormatStyle::BAS_BlockIndent) { 82 return false; 83 } 84 const auto *LBrace = MatchingParen; 85 assert(LBrace && LBrace->is(tok::l_brace)); 86 if (LBrace->is(BK_BracedInit)) 87 return true; 88 if (LBrace->Previous && LBrace->Previous->is(tok::equal)) 89 return true; 90 return false; 91 } 92 93 bool FormatToken::opensBlockOrBlockTypeList(const FormatStyle &Style) const { 94 // C# Does not indent object initialisers as continuations. 95 if (is(tok::l_brace) && getBlockKind() == BK_BracedInit && Style.isCSharp()) 96 return true; 97 if (is(TT_TemplateString) && opensScope()) 98 return true; 99 return is(TT_ArrayInitializerLSquare) || is(TT_ProtoExtensionLSquare) || 100 (is(tok::l_brace) && 101 (getBlockKind() == BK_Block || is(TT_DictLiteral) || 102 (!Style.Cpp11BracedListStyle && NestingLevel == 0))) || 103 (is(tok::less) && Style.isProto()); 104 } 105 106 TokenRole::~TokenRole() {} 107 108 void TokenRole::precomputeFormattingInfos(const FormatToken *Token) {} 109 110 unsigned CommaSeparatedList::formatAfterToken(LineState &State, 111 ContinuationIndenter *Indenter, 112 bool DryRun) { 113 if (!State.NextToken || !State.NextToken->Previous) 114 return 0; 115 116 if (Formats.size() <= 1) 117 return 0; // Handled by formatFromToken (1) or avoid severe penalty (0). 118 119 // Ensure that we start on the opening brace. 120 const FormatToken *LBrace = 121 State.NextToken->Previous->getPreviousNonComment(); 122 if (!LBrace || !LBrace->isOneOf(tok::l_brace, TT_ArrayInitializerLSquare) || 123 LBrace->is(BK_Block) || LBrace->is(TT_DictLiteral) || 124 LBrace->Next->is(TT_DesignatedInitializerPeriod)) { 125 return 0; 126 } 127 128 // Calculate the number of code points we have to format this list. As the 129 // first token is already placed, we have to subtract it. 130 unsigned RemainingCodePoints = 131 Style.ColumnLimit - State.Column + State.NextToken->Previous->ColumnWidth; 132 133 // Find the best ColumnFormat, i.e. the best number of columns to use. 134 const ColumnFormat *Format = getColumnFormat(RemainingCodePoints); 135 136 // If no ColumnFormat can be used, the braced list would generally be 137 // bin-packed. Add a severe penalty to this so that column layouts are 138 // preferred if possible. 139 if (!Format) 140 return 10000; 141 142 // Format the entire list. 143 unsigned Penalty = 0; 144 unsigned Column = 0; 145 unsigned Item = 0; 146 while (State.NextToken != LBrace->MatchingParen) { 147 bool NewLine = false; 148 unsigned ExtraSpaces = 0; 149 150 // If the previous token was one of our commas, we are now on the next item. 151 if (Item < Commas.size() && State.NextToken->Previous == Commas[Item]) { 152 if (!State.NextToken->isTrailingComment()) { 153 ExtraSpaces += Format->ColumnSizes[Column] - ItemLengths[Item]; 154 ++Column; 155 } 156 ++Item; 157 } 158 159 if (Column == Format->Columns || State.NextToken->MustBreakBefore) { 160 Column = 0; 161 NewLine = true; 162 } 163 164 // Place token using the continuation indenter and store the penalty. 165 Penalty += Indenter->addTokenToState(State, NewLine, DryRun, ExtraSpaces); 166 } 167 return Penalty; 168 } 169 170 unsigned CommaSeparatedList::formatFromToken(LineState &State, 171 ContinuationIndenter *Indenter, 172 bool DryRun) { 173 // Formatting with 1 Column isn't really a column layout, so we don't need the 174 // special logic here. We can just avoid bin packing any of the parameters. 175 if (Formats.size() == 1 || HasNestedBracedList) 176 State.Stack.back().AvoidBinPacking = true; 177 return 0; 178 } 179 180 // Returns the lengths in code points between Begin and End (both included), 181 // assuming that the entire sequence is put on a single line. 182 static unsigned CodePointsBetween(const FormatToken *Begin, 183 const FormatToken *End) { 184 assert(End->TotalLength >= Begin->TotalLength); 185 return End->TotalLength - Begin->TotalLength + Begin->ColumnWidth; 186 } 187 188 void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) { 189 // FIXME: At some point we might want to do this for other lists, too. 190 if (!Token->MatchingParen || 191 !Token->isOneOf(tok::l_brace, TT_ArrayInitializerLSquare)) { 192 return; 193 } 194 195 // In C++11 braced list style, we should not format in columns unless they 196 // have many items (20 or more) or we allow bin-packing of function call 197 // arguments. 198 if (Style.Cpp11BracedListStyle && !Style.BinPackArguments && 199 Commas.size() < 19) { 200 return; 201 } 202 203 // Limit column layout for JavaScript array initializers to 20 or more items 204 // for now to introduce it carefully. We can become more aggressive if this 205 // necessary. 206 if (Token->is(TT_ArrayInitializerLSquare) && Commas.size() < 19) 207 return; 208 209 // Column format doesn't really make sense if we don't align after brackets. 210 if (Style.AlignAfterOpenBracket == FormatStyle::BAS_DontAlign) 211 return; 212 213 FormatToken *ItemBegin = Token->Next; 214 while (ItemBegin->isTrailingComment()) 215 ItemBegin = ItemBegin->Next; 216 SmallVector<bool, 8> MustBreakBeforeItem; 217 218 // The lengths of an item if it is put at the end of the line. This includes 219 // trailing comments which are otherwise ignored for column alignment. 220 SmallVector<unsigned, 8> EndOfLineItemLength; 221 MustBreakBeforeItem.reserve(Commas.size() + 1); 222 EndOfLineItemLength.reserve(Commas.size() + 1); 223 ItemLengths.reserve(Commas.size() + 1); 224 225 bool HasSeparatingComment = false; 226 for (unsigned i = 0, e = Commas.size() + 1; i != e; ++i) { 227 assert(ItemBegin); 228 // Skip comments on their own line. 229 while (ItemBegin->HasUnescapedNewline && ItemBegin->isTrailingComment()) { 230 ItemBegin = ItemBegin->Next; 231 HasSeparatingComment = i > 0; 232 } 233 234 MustBreakBeforeItem.push_back(ItemBegin->MustBreakBefore); 235 if (ItemBegin->is(tok::l_brace)) 236 HasNestedBracedList = true; 237 const FormatToken *ItemEnd = nullptr; 238 if (i == Commas.size()) { 239 ItemEnd = Token->MatchingParen; 240 const FormatToken *NonCommentEnd = ItemEnd->getPreviousNonComment(); 241 ItemLengths.push_back(CodePointsBetween(ItemBegin, NonCommentEnd)); 242 if (Style.Cpp11BracedListStyle && 243 !ItemEnd->Previous->isTrailingComment()) { 244 // In Cpp11 braced list style, the } and possibly other subsequent 245 // tokens will need to stay on a line with the last element. 246 while (ItemEnd->Next && !ItemEnd->Next->CanBreakBefore) 247 ItemEnd = ItemEnd->Next; 248 } else { 249 // In other braced lists styles, the "}" can be wrapped to the new line. 250 ItemEnd = Token->MatchingParen->Previous; 251 } 252 } else { 253 ItemEnd = Commas[i]; 254 // The comma is counted as part of the item when calculating the length. 255 ItemLengths.push_back(CodePointsBetween(ItemBegin, ItemEnd)); 256 257 // Consume trailing comments so the are included in EndOfLineItemLength. 258 if (ItemEnd->Next && !ItemEnd->Next->HasUnescapedNewline && 259 ItemEnd->Next->isTrailingComment()) { 260 ItemEnd = ItemEnd->Next; 261 } 262 } 263 EndOfLineItemLength.push_back(CodePointsBetween(ItemBegin, ItemEnd)); 264 // If there is a trailing comma in the list, the next item will start at the 265 // closing brace. Don't create an extra item for this. 266 if (ItemEnd->getNextNonComment() == Token->MatchingParen) 267 break; 268 ItemBegin = ItemEnd->Next; 269 } 270 271 // Don't use column layout for lists with few elements and in presence of 272 // separating comments. 273 if (Commas.size() < 5 || HasSeparatingComment) 274 return; 275 276 if (Token->NestingLevel != 0 && Token->is(tok::l_brace) && Commas.size() < 19) 277 return; 278 279 // We can never place more than ColumnLimit / 3 items in a row (because of the 280 // spaces and the comma). 281 unsigned MaxItems = Style.ColumnLimit / 3; 282 SmallVector<unsigned> MinSizeInColumn; 283 MinSizeInColumn.reserve(MaxItems); 284 for (unsigned Columns = 1; Columns <= MaxItems; ++Columns) { 285 ColumnFormat Format; 286 Format.Columns = Columns; 287 Format.ColumnSizes.resize(Columns); 288 MinSizeInColumn.assign(Columns, UINT_MAX); 289 Format.LineCount = 1; 290 bool HasRowWithSufficientColumns = false; 291 unsigned Column = 0; 292 for (unsigned i = 0, e = ItemLengths.size(); i != e; ++i) { 293 assert(i < MustBreakBeforeItem.size()); 294 if (MustBreakBeforeItem[i] || Column == Columns) { 295 ++Format.LineCount; 296 Column = 0; 297 } 298 if (Column == Columns - 1) 299 HasRowWithSufficientColumns = true; 300 unsigned Length = 301 (Column == Columns - 1) ? EndOfLineItemLength[i] : ItemLengths[i]; 302 Format.ColumnSizes[Column] = std::max(Format.ColumnSizes[Column], Length); 303 MinSizeInColumn[Column] = std::min(MinSizeInColumn[Column], Length); 304 ++Column; 305 } 306 // If all rows are terminated early (e.g. by trailing comments), we don't 307 // need to look further. 308 if (!HasRowWithSufficientColumns) 309 break; 310 Format.TotalWidth = Columns - 1; // Width of the N-1 spaces. 311 312 for (unsigned i = 0; i < Columns; ++i) 313 Format.TotalWidth += Format.ColumnSizes[i]; 314 315 // Don't use this Format, if the difference between the longest and shortest 316 // element in a column exceeds a threshold to avoid excessive spaces. 317 if ([&] { 318 for (unsigned i = 0; i < Columns - 1; ++i) 319 if (Format.ColumnSizes[i] - MinSizeInColumn[i] > 10) 320 return true; 321 return false; 322 }()) { 323 continue; 324 } 325 326 // Ignore layouts that are bound to violate the column limit. 327 if (Format.TotalWidth > Style.ColumnLimit && Columns > 1) 328 continue; 329 330 Formats.push_back(Format); 331 } 332 } 333 334 const CommaSeparatedList::ColumnFormat * 335 CommaSeparatedList::getColumnFormat(unsigned RemainingCharacters) const { 336 const ColumnFormat *BestFormat = nullptr; 337 for (const ColumnFormat &Format : llvm::reverse(Formats)) { 338 if (Format.TotalWidth <= RemainingCharacters || Format.Columns == 1) { 339 if (BestFormat && Format.LineCount > BestFormat->LineCount) 340 break; 341 BestFormat = &Format; 342 } 343 } 344 return BestFormat; 345 } 346 347 } // namespace format 348 } // namespace clang 349