xref: /freebsd/contrib/llvm-project/clang/lib/Format/WhitespaceManager.h (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3)
1 //===--- WhitespaceManager.h - Format C++ code ------------------*- C++ -*-===//
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 /// WhitespaceManager class manages whitespace around tokens and their
11 /// replacements.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_LIB_FORMAT_WHITESPACEMANAGER_H
16 #define LLVM_CLANG_LIB_FORMAT_WHITESPACEMANAGER_H
17 
18 #include "TokenAnnotator.h"
19 #include "clang/Basic/SourceManager.h"
20 #include "clang/Format/Format.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include <algorithm>
23 #include <string>
24 #include <tuple>
25 
26 namespace clang {
27 namespace format {
28 
29 /// Manages the whitespaces around tokens and their replacements.
30 ///
31 /// This includes special handling for certain constructs, e.g. the alignment of
32 /// trailing line comments.
33 ///
34 /// To guarantee correctness of alignment operations, the \c WhitespaceManager
35 /// must be informed about every token in the source file; for each token, there
36 /// must be exactly one call to either \c replaceWhitespace or
37 /// \c addUntouchableToken.
38 ///
39 /// There may be multiple calls to \c breakToken for a given token.
40 class WhitespaceManager {
41 public:
42   WhitespaceManager(const SourceManager &SourceMgr, const FormatStyle &Style,
43                     bool UseCRLF)
44       : SourceMgr(SourceMgr), Style(Style), UseCRLF(UseCRLF) {}
45 
46   bool useCRLF() const { return UseCRLF; }
47 
48   /// Replaces the whitespace in front of \p Tok. Only call once for
49   /// each \c AnnotatedToken.
50   ///
51   /// \p StartOfTokenColumn is the column at which the token will start after
52   /// this replacement. It is needed for determining how \p Spaces is turned
53   /// into tabs and spaces for some format styles.
54   void replaceWhitespace(FormatToken &Tok, unsigned Newlines, unsigned Spaces,
55                          unsigned StartOfTokenColumn, bool isAligned = false,
56                          bool InPPDirective = false);
57 
58   /// Adds information about an unchangeable token's whitespace.
59   ///
60   /// Needs to be called for every token for which \c replaceWhitespace
61   /// was not called.
62   void addUntouchableToken(const FormatToken &Tok, bool InPPDirective);
63 
64   llvm::Error addReplacement(const tooling::Replacement &Replacement);
65 
66   /// Inserts or replaces whitespace in the middle of a token.
67   ///
68   /// Inserts \p PreviousPostfix, \p Newlines, \p Spaces and \p CurrentPrefix
69   /// (in this order) at \p Offset inside \p Tok, replacing \p ReplaceChars
70   /// characters.
71   ///
72   /// Note: \p Spaces can be negative to retain information about initial
73   /// relative column offset between a line of a block comment and the start of
74   /// the comment. This negative offset may be compensated by trailing comment
75   /// alignment here. In all other cases negative \p Spaces will be truncated to
76   /// 0.
77   ///
78   /// When \p InPPDirective is true, escaped newlines are inserted. \p Spaces is
79   /// used to align backslashes correctly.
80   void replaceWhitespaceInToken(const FormatToken &Tok, unsigned Offset,
81                                 unsigned ReplaceChars,
82                                 StringRef PreviousPostfix,
83                                 StringRef CurrentPrefix, bool InPPDirective,
84                                 unsigned Newlines, int Spaces);
85 
86   /// Returns all the \c Replacements created during formatting.
87   const tooling::Replacements &generateReplacements();
88 
89   /// Represents a change before a token, a break inside a token,
90   /// or the layout of an unchanged token (or whitespace within).
91   struct Change {
92     /// Functor to sort changes in original source order.
93     class IsBeforeInFile {
94     public:
95       IsBeforeInFile(const SourceManager &SourceMgr) : SourceMgr(SourceMgr) {}
96       bool operator()(const Change &C1, const Change &C2) const;
97 
98     private:
99       const SourceManager &SourceMgr;
100     };
101 
102     /// Creates a \c Change.
103     ///
104     /// The generated \c Change will replace the characters at
105     /// \p OriginalWhitespaceRange with a concatenation of
106     /// \p PreviousLinePostfix, \p NewlinesBefore line breaks, \p Spaces spaces
107     /// and \p CurrentLinePrefix.
108     ///
109     /// \p StartOfTokenColumn and \p InPPDirective will be used to lay out
110     /// trailing comments and escaped newlines.
111     Change(const FormatToken &Tok, bool CreateReplacement,
112            SourceRange OriginalWhitespaceRange, int Spaces,
113            unsigned StartOfTokenColumn, unsigned NewlinesBefore,
114            StringRef PreviousLinePostfix, StringRef CurrentLinePrefix,
115            bool IsAligned, bool ContinuesPPDirective, bool IsInsideToken);
116 
117     // The kind of the token whose whitespace this change replaces, or in which
118     // this change inserts whitespace.
119     // FIXME: Currently this is not set correctly for breaks inside comments, as
120     // the \c BreakableToken is still doing its own alignment.
121     const FormatToken *Tok;
122 
123     bool CreateReplacement;
124     // Changes might be in the middle of a token, so we cannot just keep the
125     // FormatToken around to query its information.
126     SourceRange OriginalWhitespaceRange;
127     unsigned StartOfTokenColumn;
128     unsigned NewlinesBefore;
129     std::string PreviousLinePostfix;
130     std::string CurrentLinePrefix;
131     bool IsAligned;
132     bool ContinuesPPDirective;
133 
134     // The number of spaces in front of the token or broken part of the token.
135     // This will be adapted when aligning tokens.
136     // Can be negative to retain information about the initial relative offset
137     // of the lines in a block comment. This is used when aligning trailing
138     // comments. Uncompensated negative offset is truncated to 0.
139     int Spaces;
140 
141     // If this change is inside of a token but not at the start of the token or
142     // directly after a newline.
143     bool IsInsideToken;
144 
145     // \c IsTrailingComment, \c TokenLength, \c PreviousEndOfTokenColumn and
146     // \c EscapedNewlineColumn will be calculated in
147     // \c calculateLineBreakInformation.
148     bool IsTrailingComment;
149     unsigned TokenLength;
150     unsigned PreviousEndOfTokenColumn;
151     unsigned EscapedNewlineColumn;
152 
153     // These fields are used to retain correct relative line indentation in a
154     // block comment when aligning trailing comments.
155     //
156     // If this Change represents a continuation of a block comment,
157     // \c StartOfBlockComment is pointer to the first Change in the block
158     // comment. \c IndentationOffset is a relative column offset to this
159     // change, so that the correct column can be reconstructed at the end of
160     // the alignment process.
161     const Change *StartOfBlockComment;
162     int IndentationOffset;
163 
164     // Depth of conditionals. Computed from tracking fake parenthesis, except
165     // it does not increase the indent for "chained" conditionals.
166     int ConditionalsLevel;
167 
168     // A combination of indent, nesting and conditionals levels, which are used
169     // in tandem to compute lexical scope, for the purposes of deciding
170     // when to stop consecutive alignment runs.
171     std::tuple<unsigned, unsigned, unsigned> indentAndNestingLevel() const {
172       return std::make_tuple(Tok->IndentLevel, Tok->NestingLevel,
173                              ConditionalsLevel);
174     }
175   };
176 
177 private:
178   struct CellDescription {
179     unsigned Index = 0;
180     unsigned Cell = 0;
181     unsigned EndIndex = 0;
182     bool HasSplit = false;
183     CellDescription *NextColumnElement = nullptr;
184 
185     constexpr bool operator==(const CellDescription &Other) const {
186       return Index == Other.Index && Cell == Other.Cell &&
187              EndIndex == Other.EndIndex;
188     }
189     constexpr bool operator!=(const CellDescription &Other) const {
190       return !(*this == Other);
191     }
192   };
193 
194   struct CellDescriptions {
195     SmallVector<CellDescription> Cells;
196     unsigned CellCount = 0;
197     unsigned InitialSpaces = 0;
198   };
199 
200   /// Calculate \c IsTrailingComment, \c TokenLength for the last tokens
201   /// or token parts in a line and \c PreviousEndOfTokenColumn and
202   /// \c EscapedNewlineColumn for the first tokens or token parts in a line.
203   void calculateLineBreakInformation();
204 
205   /// \brief Align consecutive C/C++ preprocessor macros over all \c Changes.
206   void alignConsecutiveMacros();
207 
208   /// Align consecutive assignments over all \c Changes.
209   void alignConsecutiveAssignments();
210 
211   /// Align consecutive bitfields over all \c Changes.
212   void alignConsecutiveBitFields();
213 
214   /// Align consecutive declarations over all \c Changes.
215   void alignConsecutiveDeclarations();
216 
217   /// Align consecutive declarations over all \c Changes.
218   void alignChainedConditionals();
219 
220   /// Align trailing comments over all \c Changes.
221   void alignTrailingComments();
222 
223   /// Align trailing comments from change \p Start to change \p End at
224   /// the specified \p Column.
225   void alignTrailingComments(unsigned Start, unsigned End, unsigned Column);
226 
227   /// Align escaped newlines over all \c Changes.
228   void alignEscapedNewlines();
229 
230   /// Align escaped newlines from change \p Start to change \p End at
231   /// the specified \p Column.
232   void alignEscapedNewlines(unsigned Start, unsigned End, unsigned Column);
233 
234   /// Align Array Initializers over all \c Changes.
235   void alignArrayInitializers();
236 
237   /// Align Array Initializers from change \p Start to change \p End at
238   /// the specified \p Column.
239   void alignArrayInitializers(unsigned Start, unsigned End);
240 
241   /// Align Array Initializers being careful to right justify the columns
242   /// as described by \p CellDescs.
243   void alignArrayInitializersRightJustified(CellDescriptions &&CellDescs);
244 
245   /// Align Array Initializers being careful to leftt justify the columns
246   /// as described by \p CellDescs.
247   void alignArrayInitializersLeftJustified(CellDescriptions &&CellDescs);
248 
249   /// Calculate the cell width between two indexes.
250   unsigned calculateCellWidth(unsigned Start, unsigned End,
251                               bool WithSpaces = false) const;
252 
253   /// Get a set of fully specified CellDescriptions between \p Start and
254   /// \p End of the change list.
255   CellDescriptions getCells(unsigned Start, unsigned End);
256 
257   /// Does this \p Cell contain a split element?
258   static bool isSplitCell(const CellDescription &Cell);
259 
260   /// Get the width of the preceeding cells from \p Start to \p End.
261   template <typename I>
262   auto getNetWidth(const I &Start, const I &End, unsigned InitialSpaces) const {
263     auto NetWidth = InitialSpaces;
264     for (auto PrevIter = Start; PrevIter != End; ++PrevIter) {
265       // If we broke the line the initial spaces are already
266       // accounted for.
267       if (Changes[PrevIter->Index].NewlinesBefore > 0)
268         NetWidth = 0;
269       NetWidth +=
270           calculateCellWidth(PrevIter->Index, PrevIter->EndIndex, true) + 1;
271     }
272     return NetWidth;
273   }
274 
275   /// Get the maximum width of a cell in a sequence of columns.
276   template <typename I>
277   unsigned getMaximumCellWidth(I CellIter, unsigned NetWidth) const {
278     unsigned CellWidth =
279         calculateCellWidth(CellIter->Index, CellIter->EndIndex, true);
280     if (Changes[CellIter->Index].NewlinesBefore == 0)
281       CellWidth += NetWidth;
282     for (const auto *Next = CellIter->NextColumnElement; Next != nullptr;
283          Next = Next->NextColumnElement) {
284       auto ThisWidth = calculateCellWidth(Next->Index, Next->EndIndex, true);
285       if (Changes[Next->Index].NewlinesBefore == 0)
286         ThisWidth += NetWidth;
287       CellWidth = std::max(CellWidth, ThisWidth);
288     }
289     return CellWidth;
290   }
291 
292   /// Get The maximum width of all columns to a given cell.
293   template <typename I>
294   unsigned getMaximumNetWidth(const I &CellStart, const I &CellStop,
295                               unsigned InitialSpaces,
296                               unsigned CellCount) const {
297     auto MaxNetWidth = getNetWidth(CellStart, CellStop, InitialSpaces);
298     auto RowCount = 1U;
299     auto Offset = std::distance(CellStart, CellStop);
300     for (const auto *Next = CellStop->NextColumnElement; Next != nullptr;
301          Next = Next->NextColumnElement) {
302       auto Start = (CellStart + RowCount * CellCount);
303       auto End = Start + Offset;
304       MaxNetWidth =
305           std::max(MaxNetWidth, getNetWidth(Start, End, InitialSpaces));
306       ++RowCount;
307     }
308     return MaxNetWidth;
309   }
310 
311   /// Align a split cell with a newline to the first element in the cell.
312   void alignToStartOfCell(unsigned Start, unsigned End);
313 
314   /// Link the Cell pointers in the list of Cells.
315   static CellDescriptions linkCells(CellDescriptions &&CellDesc);
316 
317   /// Fill \c Replaces with the replacements for all effective changes.
318   void generateChanges();
319 
320   /// Stores \p Text as the replacement for the whitespace in \p Range.
321   void storeReplacement(SourceRange Range, StringRef Text);
322   void appendNewlineText(std::string &Text, unsigned Newlines);
323   void appendEscapedNewlineText(std::string &Text, unsigned Newlines,
324                                 unsigned PreviousEndOfTokenColumn,
325                                 unsigned EscapedNewlineColumn);
326   void appendIndentText(std::string &Text, unsigned IndentLevel,
327                         unsigned Spaces, unsigned WhitespaceStartColumn,
328                         bool IsAligned);
329   unsigned appendTabIndent(std::string &Text, unsigned Spaces,
330                            unsigned Indentation);
331 
332   SmallVector<Change, 16> Changes;
333   const SourceManager &SourceMgr;
334   tooling::Replacements Replaces;
335   const FormatStyle &Style;
336   bool UseCRLF;
337 };
338 
339 } // namespace format
340 } // namespace clang
341 
342 #endif
343