1 //===--- FormatToken.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 This file implements specific functions of \c FormatTokens and their
12 /// roles.
13 ///
14 //===----------------------------------------------------------------------===//
15
16 #include "ContinuationIndenter.h"
17 #include "FormatToken.h"
18 #include "clang/Format/Format.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/Support/Debug.h"
21 #include <climits>
22
23 namespace clang {
24 namespace format {
25
getTokenTypeName(TokenType Type)26 const char *getTokenTypeName(TokenType Type) {
27 static const char *const TokNames[] = {
28 #define TYPE(X) #X,
29 LIST_TOKEN_TYPES
30 #undef TYPE
31 nullptr
32 };
33
34 if (Type < NUM_TOKEN_TYPES)
35 return TokNames[Type];
36 llvm_unreachable("unknown TokenType");
37 return nullptr;
38 }
39
40 // FIXME: This is copy&pasted from Sema. Put it in a common place and remove
41 // duplication.
isSimpleTypeSpecifier() const42 bool FormatToken::isSimpleTypeSpecifier() const {
43 switch (Tok.getKind()) {
44 case tok::kw_short:
45 case tok::kw_long:
46 case tok::kw___int64:
47 case tok::kw___int128:
48 case tok::kw_signed:
49 case tok::kw_unsigned:
50 case tok::kw_void:
51 case tok::kw_char:
52 case tok::kw_int:
53 case tok::kw_half:
54 case tok::kw_float:
55 case tok::kw_double:
56 case tok::kw___float128:
57 case tok::kw_wchar_t:
58 case tok::kw_bool:
59 case tok::kw___underlying_type:
60 case tok::annot_typename:
61 case tok::kw_char16_t:
62 case tok::kw_char32_t:
63 case tok::kw_typeof:
64 case tok::kw_decltype:
65 return true;
66 default:
67 return false;
68 }
69 }
70
~TokenRole()71 TokenRole::~TokenRole() {}
72
precomputeFormattingInfos(const FormatToken * Token)73 void TokenRole::precomputeFormattingInfos(const FormatToken *Token) {}
74
formatAfterToken(LineState & State,ContinuationIndenter * Indenter,bool DryRun)75 unsigned CommaSeparatedList::formatAfterToken(LineState &State,
76 ContinuationIndenter *Indenter,
77 bool DryRun) {
78 if (State.NextToken == nullptr || !State.NextToken->Previous)
79 return 0;
80
81 // Ensure that we start on the opening brace.
82 const FormatToken *LBrace =
83 State.NextToken->Previous->getPreviousNonComment();
84 if (!LBrace || !LBrace->isOneOf(tok::l_brace, TT_ArrayInitializerLSquare) ||
85 LBrace->BlockKind == BK_Block || LBrace->Type == TT_DictLiteral ||
86 LBrace->Next->Type == TT_DesignatedInitializerPeriod)
87 return 0;
88
89 // Calculate the number of code points we have to format this list. As the
90 // first token is already placed, we have to subtract it.
91 unsigned RemainingCodePoints =
92 Style.ColumnLimit - State.Column + State.NextToken->Previous->ColumnWidth;
93
94 // Find the best ColumnFormat, i.e. the best number of columns to use.
95 const ColumnFormat *Format = getColumnFormat(RemainingCodePoints);
96 // If no ColumnFormat can be used, the braced list would generally be
97 // bin-packed. Add a severe penalty to this so that column layouts are
98 // preferred if possible.
99 if (!Format)
100 return 10000;
101
102 // Format the entire list.
103 unsigned Penalty = 0;
104 unsigned Column = 0;
105 unsigned Item = 0;
106 while (State.NextToken != LBrace->MatchingParen) {
107 bool NewLine = false;
108 unsigned ExtraSpaces = 0;
109
110 // If the previous token was one of our commas, we are now on the next item.
111 if (Item < Commas.size() && State.NextToken->Previous == Commas[Item]) {
112 if (!State.NextToken->isTrailingComment()) {
113 ExtraSpaces += Format->ColumnSizes[Column] - ItemLengths[Item];
114 ++Column;
115 }
116 ++Item;
117 }
118
119 if (Column == Format->Columns || State.NextToken->MustBreakBefore) {
120 Column = 0;
121 NewLine = true;
122 }
123
124 // Place token using the continuation indenter and store the penalty.
125 Penalty += Indenter->addTokenToState(State, NewLine, DryRun, ExtraSpaces);
126 }
127 return Penalty;
128 }
129
formatFromToken(LineState & State,ContinuationIndenter * Indenter,bool DryRun)130 unsigned CommaSeparatedList::formatFromToken(LineState &State,
131 ContinuationIndenter *Indenter,
132 bool DryRun) {
133 if (HasNestedBracedList)
134 State.Stack.back().AvoidBinPacking = true;
135 return 0;
136 }
137
138 // Returns the lengths in code points between Begin and End (both included),
139 // assuming that the entire sequence is put on a single line.
CodePointsBetween(const FormatToken * Begin,const FormatToken * End)140 static unsigned CodePointsBetween(const FormatToken *Begin,
141 const FormatToken *End) {
142 assert(End->TotalLength >= Begin->TotalLength);
143 return End->TotalLength - Begin->TotalLength + Begin->ColumnWidth;
144 }
145
precomputeFormattingInfos(const FormatToken * Token)146 void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
147 // FIXME: At some point we might want to do this for other lists, too.
148 if (!Token->MatchingParen ||
149 !Token->isOneOf(tok::l_brace, TT_ArrayInitializerLSquare))
150 return;
151
152 // In C++11 braced list style, we should not format in columns unless they
153 // have many items (20 or more) or we allow bin-packing of function call
154 // arguments.
155 if (Style.Cpp11BracedListStyle && !Style.BinPackArguments &&
156 Commas.size() < 19)
157 return;
158
159 // Limit column layout for JavaScript array initializers to 20 or more items
160 // for now to introduce it carefully. We can become more aggressive if this
161 // necessary.
162 if (Token->is(TT_ArrayInitializerLSquare) && Commas.size() < 19)
163 return;
164
165 // Column format doesn't really make sense if we don't align after brackets.
166 if (Style.AlignAfterOpenBracket == FormatStyle::BAS_DontAlign)
167 return;
168
169 FormatToken *ItemBegin = Token->Next;
170 while (ItemBegin->isTrailingComment())
171 ItemBegin = ItemBegin->Next;
172 SmallVector<bool, 8> MustBreakBeforeItem;
173
174 // The lengths of an item if it is put at the end of the line. This includes
175 // trailing comments which are otherwise ignored for column alignment.
176 SmallVector<unsigned, 8> EndOfLineItemLength;
177
178 bool HasSeparatingComment = false;
179 for (unsigned i = 0, e = Commas.size() + 1; i != e; ++i) {
180 // Skip comments on their own line.
181 while (ItemBegin->HasUnescapedNewline && ItemBegin->isTrailingComment()) {
182 ItemBegin = ItemBegin->Next;
183 HasSeparatingComment = i > 0;
184 }
185
186 MustBreakBeforeItem.push_back(ItemBegin->MustBreakBefore);
187 if (ItemBegin->is(tok::l_brace))
188 HasNestedBracedList = true;
189 const FormatToken *ItemEnd = nullptr;
190 if (i == Commas.size()) {
191 ItemEnd = Token->MatchingParen;
192 const FormatToken *NonCommentEnd = ItemEnd->getPreviousNonComment();
193 ItemLengths.push_back(CodePointsBetween(ItemBegin, NonCommentEnd));
194 if (Style.Cpp11BracedListStyle &&
195 !ItemEnd->Previous->isTrailingComment()) {
196 // In Cpp11 braced list style, the } and possibly other subsequent
197 // tokens will need to stay on a line with the last element.
198 while (ItemEnd->Next && !ItemEnd->Next->CanBreakBefore)
199 ItemEnd = ItemEnd->Next;
200 } else {
201 // In other braced lists styles, the "}" can be wrapped to the new line.
202 ItemEnd = Token->MatchingParen->Previous;
203 }
204 } else {
205 ItemEnd = Commas[i];
206 // The comma is counted as part of the item when calculating the length.
207 ItemLengths.push_back(CodePointsBetween(ItemBegin, ItemEnd));
208
209 // Consume trailing comments so the are included in EndOfLineItemLength.
210 if (ItemEnd->Next && !ItemEnd->Next->HasUnescapedNewline &&
211 ItemEnd->Next->isTrailingComment())
212 ItemEnd = ItemEnd->Next;
213 }
214 EndOfLineItemLength.push_back(CodePointsBetween(ItemBegin, ItemEnd));
215 // If there is a trailing comma in the list, the next item will start at the
216 // closing brace. Don't create an extra item for this.
217 if (ItemEnd->getNextNonComment() == Token->MatchingParen)
218 break;
219 ItemBegin = ItemEnd->Next;
220 }
221
222 // Don't use column layout for lists with few elements and in presence of
223 // separating comments.
224 if (Commas.size() < 5 || HasSeparatingComment)
225 return;
226
227 if (Token->NestingLevel != 0 && Token->is(tok::l_brace) && Commas.size() < 19)
228 return;
229
230 // We can never place more than ColumnLimit / 3 items in a row (because of the
231 // spaces and the comma).
232 unsigned MaxItems = Style.ColumnLimit / 3;
233 std::vector<unsigned> MinSizeInColumn;
234 MinSizeInColumn.reserve(MaxItems);
235 for (unsigned Columns = 1; Columns <= MaxItems; ++Columns) {
236 ColumnFormat Format;
237 Format.Columns = Columns;
238 Format.ColumnSizes.resize(Columns);
239 MinSizeInColumn.assign(Columns, UINT_MAX);
240 Format.LineCount = 1;
241 bool HasRowWithSufficientColumns = false;
242 unsigned Column = 0;
243 for (unsigned i = 0, e = ItemLengths.size(); i != e; ++i) {
244 assert(i < MustBreakBeforeItem.size());
245 if (MustBreakBeforeItem[i] || Column == Columns) {
246 ++Format.LineCount;
247 Column = 0;
248 }
249 if (Column == Columns - 1)
250 HasRowWithSufficientColumns = true;
251 unsigned Length =
252 (Column == Columns - 1) ? EndOfLineItemLength[i] : ItemLengths[i];
253 Format.ColumnSizes[Column] = std::max(Format.ColumnSizes[Column], Length);
254 MinSizeInColumn[Column] = std::min(MinSizeInColumn[Column], Length);
255 ++Column;
256 }
257 // If all rows are terminated early (e.g. by trailing comments), we don't
258 // need to look further.
259 if (!HasRowWithSufficientColumns)
260 break;
261 Format.TotalWidth = Columns - 1; // Width of the N-1 spaces.
262
263 for (unsigned i = 0; i < Columns; ++i)
264 Format.TotalWidth += Format.ColumnSizes[i];
265
266 // Don't use this Format, if the difference between the longest and shortest
267 // element in a column exceeds a threshold to avoid excessive spaces.
268 if ([&] {
269 for (unsigned i = 0; i < Columns - 1; ++i)
270 if (Format.ColumnSizes[i] - MinSizeInColumn[i] > 10)
271 return true;
272 return false;
273 }())
274 continue;
275
276 // Ignore layouts that are bound to violate the column limit.
277 if (Format.TotalWidth > Style.ColumnLimit)
278 continue;
279
280 Formats.push_back(Format);
281 }
282 }
283
284 const CommaSeparatedList::ColumnFormat *
getColumnFormat(unsigned RemainingCharacters) const285 CommaSeparatedList::getColumnFormat(unsigned RemainingCharacters) const {
286 const ColumnFormat *BestFormat = nullptr;
287 for (SmallVector<ColumnFormat, 4>::const_reverse_iterator
288 I = Formats.rbegin(),
289 E = Formats.rend();
290 I != E; ++I) {
291 if (I->TotalWidth <= RemainingCharacters) {
292 if (BestFormat && I->LineCount > BestFormat->LineCount)
293 break;
294 BestFormat = &*I;
295 }
296 }
297 return BestFormat;
298 }
299
300 } // namespace format
301 } // namespace clang
302