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 <string>
22#include <tuple>
23
24namespace clang {
25namespace format {
26
27/// Manages the whitespaces around tokens and their replacements.
28///
29/// This includes special handling for certain constructs, e.g. the alignment of
30/// trailing line comments.
31///
32/// To guarantee correctness of alignment operations, the \c WhitespaceManager
33/// must be informed about every token in the source file; for each token, there
34/// must be exactly one call to either \c replaceWhitespace or
35/// \c addUntouchableToken.
36///
37/// There may be multiple calls to \c breakToken for a given token.
38class WhitespaceManager {
39public:
40  WhitespaceManager(const SourceManager &SourceMgr, const FormatStyle &Style,
41                    bool UseCRLF)
42      : SourceMgr(SourceMgr), Style(Style), UseCRLF(UseCRLF) {}
43
44  bool useCRLF() const { return UseCRLF; }
45
46  /// Replaces the whitespace in front of \p Tok. Only call once for
47  /// each \c AnnotatedToken.
48  ///
49  /// \p StartOfTokenColumn is the column at which the token will start after
50  /// this replacement. It is needed for determining how \p Spaces is turned
51  /// into tabs and spaces for some format styles.
52  void replaceWhitespace(FormatToken &Tok, unsigned Newlines, unsigned Spaces,
53                         unsigned StartOfTokenColumn, bool isAligned = false,
54                         bool InPPDirective = false);
55
56  /// Adds information about an unchangeable token's whitespace.
57  ///
58  /// Needs to be called for every token for which \c replaceWhitespace
59  /// was not called.
60  void addUntouchableToken(const FormatToken &Tok, bool InPPDirective);
61
62  llvm::Error addReplacement(const tooling::Replacement &Replacement);
63
64  /// Inserts or replaces whitespace in the middle of a token.
65  ///
66  /// Inserts \p PreviousPostfix, \p Newlines, \p Spaces and \p CurrentPrefix
67  /// (in this order) at \p Offset inside \p Tok, replacing \p ReplaceChars
68  /// characters.
69  ///
70  /// Note: \p Spaces can be negative to retain information about initial
71  /// relative column offset between a line of a block comment and the start of
72  /// the comment. This negative offset may be compensated by trailing comment
73  /// alignment here. In all other cases negative \p Spaces will be truncated to
74  /// 0.
75  ///
76  /// When \p InPPDirective is true, escaped newlines are inserted. \p Spaces is
77  /// used to align backslashes correctly.
78  void replaceWhitespaceInToken(const FormatToken &Tok, unsigned Offset,
79                                unsigned ReplaceChars,
80                                StringRef PreviousPostfix,
81                                StringRef CurrentPrefix, bool InPPDirective,
82                                unsigned Newlines, int Spaces);
83
84  /// Returns all the \c Replacements created during formatting.
85  const tooling::Replacements &generateReplacements();
86
87  /// Represents a change before a token, a break inside a token,
88  /// or the layout of an unchanged token (or whitespace within).
89  struct Change {
90    /// Functor to sort changes in original source order.
91    class IsBeforeInFile {
92    public:
93      IsBeforeInFile(const SourceManager &SourceMgr) : SourceMgr(SourceMgr) {}
94      bool operator()(const Change &C1, const Change &C2) const;
95
96    private:
97      const SourceManager &SourceMgr;
98    };
99
100    /// Creates a \c Change.
101    ///
102    /// The generated \c Change will replace the characters at
103    /// \p OriginalWhitespaceRange with a concatenation of
104    /// \p PreviousLinePostfix, \p NewlinesBefore line breaks, \p Spaces spaces
105    /// and \p CurrentLinePrefix.
106    ///
107    /// \p StartOfTokenColumn and \p InPPDirective will be used to lay out
108    /// trailing comments and escaped newlines.
109    Change(const FormatToken &Tok, bool CreateReplacement,
110           SourceRange OriginalWhitespaceRange, int Spaces,
111           unsigned StartOfTokenColumn, unsigned NewlinesBefore,
112           StringRef PreviousLinePostfix, StringRef CurrentLinePrefix,
113           bool IsAligned, bool ContinuesPPDirective, bool IsInsideToken);
114
115    // The kind of the token whose whitespace this change replaces, or in which
116    // this change inserts whitespace.
117    // FIXME: Currently this is not set correctly for breaks inside comments, as
118    // the \c BreakableToken is still doing its own alignment.
119    const FormatToken *Tok;
120
121    bool CreateReplacement;
122    // Changes might be in the middle of a token, so we cannot just keep the
123    // FormatToken around to query its information.
124    SourceRange OriginalWhitespaceRange;
125    unsigned StartOfTokenColumn;
126    unsigned NewlinesBefore;
127    std::string PreviousLinePostfix;
128    std::string CurrentLinePrefix;
129    bool IsAligned;
130    bool ContinuesPPDirective;
131
132    // The number of spaces in front of the token or broken part of the token.
133    // This will be adapted when aligning tokens.
134    // Can be negative to retain information about the initial relative offset
135    // of the lines in a block comment. This is used when aligning trailing
136    // comments. Uncompensated negative offset is truncated to 0.
137    int Spaces;
138
139    // If this change is inside of a token but not at the start of the token or
140    // directly after a newline.
141    bool IsInsideToken;
142
143    // \c IsTrailingComment, \c TokenLength, \c PreviousEndOfTokenColumn and
144    // \c EscapedNewlineColumn will be calculated in
145    // \c calculateLineBreakInformation.
146    bool IsTrailingComment;
147    unsigned TokenLength;
148    unsigned PreviousEndOfTokenColumn;
149    unsigned EscapedNewlineColumn;
150
151    // These fields are used to retain correct relative line indentation in a
152    // block comment when aligning trailing comments.
153    //
154    // If this Change represents a continuation of a block comment,
155    // \c StartOfBlockComment is pointer to the first Change in the block
156    // comment. \c IndentationOffset is a relative column offset to this
157    // change, so that the correct column can be reconstructed at the end of
158    // the alignment process.
159    const Change *StartOfBlockComment;
160    int IndentationOffset;
161
162    // Depth of conditionals. Computed from tracking fake parenthesis, except
163    // it does not increase the indent for "chained" conditionals.
164    int ConditionalsLevel;
165
166    // A combination of indent, nesting and conditionals levels, which are used
167    // in tandem to compute lexical scope, for the purposes of deciding
168    // when to stop consecutive alignment runs.
169    std::tuple<unsigned, unsigned, unsigned> indentAndNestingLevel() const {
170      return std::make_tuple(Tok->IndentLevel, Tok->NestingLevel,
171                             ConditionalsLevel);
172    }
173  };
174
175private:
176  /// Calculate \c IsTrailingComment, \c TokenLength for the last tokens
177  /// or token parts in a line and \c PreviousEndOfTokenColumn and
178  /// \c EscapedNewlineColumn for the first tokens or token parts in a line.
179  void calculateLineBreakInformation();
180
181  /// \brief Align consecutive C/C++ preprocessor macros over all \c Changes.
182  void alignConsecutiveMacros();
183
184  /// Align consecutive assignments over all \c Changes.
185  void alignConsecutiveAssignments();
186
187  /// Align consecutive bitfields over all \c Changes.
188  void alignConsecutiveBitFields();
189
190  /// Align consecutive declarations over all \c Changes.
191  void alignConsecutiveDeclarations();
192
193  /// Align consecutive declarations over all \c Changes.
194  void alignChainedConditionals();
195
196  /// Align trailing comments over all \c Changes.
197  void alignTrailingComments();
198
199  /// Align trailing comments from change \p Start to change \p End at
200  /// the specified \p Column.
201  void alignTrailingComments(unsigned Start, unsigned End, unsigned Column);
202
203  /// Align escaped newlines over all \c Changes.
204  void alignEscapedNewlines();
205
206  /// Align escaped newlines from change \p Start to change \p End at
207  /// the specified \p Column.
208  void alignEscapedNewlines(unsigned Start, unsigned End, unsigned Column);
209
210  /// Fill \c Replaces with the replacements for all effective changes.
211  void generateChanges();
212
213  /// Stores \p Text as the replacement for the whitespace in \p Range.
214  void storeReplacement(SourceRange Range, StringRef Text);
215  void appendNewlineText(std::string &Text, unsigned Newlines);
216  void appendEscapedNewlineText(std::string &Text, unsigned Newlines,
217                                unsigned PreviousEndOfTokenColumn,
218                                unsigned EscapedNewlineColumn);
219  void appendIndentText(std::string &Text, unsigned IndentLevel,
220                        unsigned Spaces, unsigned WhitespaceStartColumn,
221                        bool IsAligned);
222  unsigned appendTabIndent(std::string &Text, unsigned Spaces,
223                           unsigned Indentation);
224
225  SmallVector<Change, 16> Changes;
226  const SourceManager &SourceMgr;
227  tooling::Replacements Replaces;
228  const FormatStyle &Style;
229  bool UseCRLF;
230};
231
232} // namespace format
233} // namespace clang
234
235#endif
236