1 files changed, 219 insertions, 0 deletions
diff --git a/clang/lib/Format/WhitespaceManager.h b/clang/lib/Format/WhitespaceManager.h
new file mode 100644
index 000000000000..f47bf40204b3
--- /dev/null
+++ b/clang/lib/Format/WhitespaceManager.h
@@ -0,0 +1,219 @@
+//===--- WhitespaceManager.h - Format C++ code ------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// WhitespaceManager class manages whitespace around tokens and their
+/// replacements.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_FORMAT_WHITESPACEMANAGER_H
+#define LLVM_CLANG_LIB_FORMAT_WHITESPACEMANAGER_H
+
+#include "TokenAnnotator.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Format/Format.h"
+#include <string>
+
+namespace clang {
+namespace format {
+
+/// Manages the whitespaces around tokens and their replacements.
+///
+/// This includes special handling for certain constructs, e.g. the alignment of
+/// trailing line comments.
+///
+/// To guarantee correctness of alignment operations, the \c WhitespaceManager
+/// must be informed about every token in the source file; for each token, there
+/// must be exactly one call to either \c replaceWhitespace or
+/// \c addUntouchableToken.
+///
+/// There may be multiple calls to \c breakToken for a given token.
+class WhitespaceManager {
+public:
+  WhitespaceManager(const SourceManager &SourceMgr, const FormatStyle &Style,
+                    bool UseCRLF)
+      : SourceMgr(SourceMgr), Style(Style), UseCRLF(UseCRLF) {}
+
+  bool useCRLF() const { return UseCRLF; }
+
+  /// Replaces the whitespace in front of \p Tok. Only call once for
+  /// each \c AnnotatedToken.
+  ///
+  /// \p StartOfTokenColumn is the column at which the token will start after
+  /// this replacement. It is needed for determining how \p Spaces is turned
+  /// into tabs and spaces for some format styles.
+  void replaceWhitespace(FormatToken &Tok, unsigned Newlines, unsigned Spaces,
+                         unsigned StartOfTokenColumn,
+                         bool InPPDirective = false);
+
+  /// Adds information about an unchangeable token's whitespace.
+  ///
+  /// Needs to be called for every token for which \c replaceWhitespace
+  /// was not called.
+  void addUntouchableToken(const FormatToken &Tok, bool InPPDirective);
+
+  llvm::Error addReplacement(const tooling::Replacement &Replacement);
+
+  /// Inserts or replaces whitespace in the middle of a token.
+  ///
+  /// Inserts \p PreviousPostfix, \p Newlines, \p Spaces and \p CurrentPrefix
+  /// (in this order) at \p Offset inside \p Tok, replacing \p ReplaceChars
+  /// characters.
+  ///
+  /// Note: \p Spaces can be negative to retain information about initial
+  /// relative column offset between a line of a block comment and the start of
+  /// the comment. This negative offset may be compensated by trailing comment
+  /// alignment here. In all other cases negative \p Spaces will be truncated to
+  /// 0.
+  ///
+  /// When \p InPPDirective is true, escaped newlines are inserted. \p Spaces is
+  /// used to align backslashes correctly.
+  void replaceWhitespaceInToken(const FormatToken &Tok, unsigned Offset,
+                                unsigned ReplaceChars,
+                                StringRef PreviousPostfix,
+                                StringRef CurrentPrefix, bool InPPDirective,
+                                unsigned Newlines, int Spaces);
+
+  /// Returns all the \c Replacements created during formatting.
+  const tooling::Replacements &generateReplacements();
+
+  /// Represents a change before a token, a break inside a token,
+  /// or the layout of an unchanged token (or whitespace within).
+  struct Change {
+    /// Functor to sort changes in original source order.
+    class IsBeforeInFile {
+    public:
+      IsBeforeInFile(const SourceManager &SourceMgr) : SourceMgr(SourceMgr) {}
+      bool operator()(const Change &C1, const Change &C2) const;
+
+    private:
+      const SourceManager &SourceMgr;
+    };
+
+    /// Creates a \c Change.
+    ///
+    /// The generated \c Change will replace the characters at
+    /// \p OriginalWhitespaceRange with a concatenation of
+    /// \p PreviousLinePostfix, \p NewlinesBefore line breaks, \p Spaces spaces
+    /// and \p CurrentLinePrefix.
+    ///
+    /// \p StartOfTokenColumn and \p InPPDirective will be used to lay out
+    /// trailing comments and escaped newlines.
+    Change(const FormatToken &Tok, bool CreateReplacement,
+           SourceRange OriginalWhitespaceRange, int Spaces,
+           unsigned StartOfTokenColumn, unsigned NewlinesBefore,
+           StringRef PreviousLinePostfix, StringRef CurrentLinePrefix,
+           bool ContinuesPPDirective, bool IsInsideToken);
+
+    // The kind of the token whose whitespace this change replaces, or in which
+    // this change inserts whitespace.
+    // FIXME: Currently this is not set correctly for breaks inside comments, as
+    // the \c BreakableToken is still doing its own alignment.
+    const FormatToken *Tok;
+
+    bool CreateReplacement;
+    // Changes might be in the middle of a token, so we cannot just keep the
+    // FormatToken around to query its information.
+    SourceRange OriginalWhitespaceRange;
+    unsigned StartOfTokenColumn;
+    unsigned NewlinesBefore;
+    std::string PreviousLinePostfix;
+    std::string CurrentLinePrefix;
+    bool ContinuesPPDirective;
+
+    // The number of spaces in front of the token or broken part of the token.
+    // This will be adapted when aligning tokens.
+    // Can be negative to retain information about the initial relative offset
+    // of the lines in a block comment. This is used when aligning trailing
+    // comments. Uncompensated negative offset is truncated to 0.
+    int Spaces;
+
+    // If this change is inside of a token but not at the start of the token or
+    // directly after a newline.
+    bool IsInsideToken;
+
+    // \c IsTrailingComment, \c TokenLength, \c PreviousEndOfTokenColumn and
+    // \c EscapedNewlineColumn will be calculated in
+    // \c calculateLineBreakInformation.
+    bool IsTrailingComment;
+    unsigned TokenLength;
+    unsigned PreviousEndOfTokenColumn;
+    unsigned EscapedNewlineColumn;
+
+    // These fields are used to retain correct relative line indentation in a
+    // block comment when aligning trailing comments.
+    //
+    // If this Change represents a continuation of a block comment,
+    // \c StartOfBlockComment is pointer to the first Change in the block
+    // comment. \c IndentationOffset is a relative column offset to this
+    // change, so that the correct column can be reconstructed at the end of
+    // the alignment process.
+    const Change *StartOfBlockComment;
+    int IndentationOffset;
+
+    // A combination of indent level and nesting level, which are used in
+    // tandem to compute lexical scope, for the purposes of deciding
+    // when to stop consecutive alignment runs.
+    std::pair<unsigned, unsigned> indentAndNestingLevel() const {
+      return std::make_pair(Tok->IndentLevel, Tok->NestingLevel);
+    }
+  };
+
+private:
+  /// Calculate \c IsTrailingComment, \c TokenLength for the last tokens
+  /// or token parts in a line and \c PreviousEndOfTokenColumn and
+  /// \c EscapedNewlineColumn for the first tokens or token parts in a line.
+  void calculateLineBreakInformation();
+
+  /// \brief Align consecutive C/C++ preprocessor macros over all \c Changes.
+  void alignConsecutiveMacros();
+
+  /// Align consecutive assignments over all \c Changes.
+  void alignConsecutiveAssignments();
+
+  /// Align consecutive declarations over all \c Changes.
+  void alignConsecutiveDeclarations();
+
+  /// Align trailing comments over all \c Changes.
+  void alignTrailingComments();
+
+  /// Align trailing comments from change \p Start to change \p End at
+  /// the specified \p Column.
+  void alignTrailingComments(unsigned Start, unsigned End, unsigned Column);
+
+  /// Align escaped newlines over all \c Changes.
+  void alignEscapedNewlines();
+
+  /// Align escaped newlines from change \p Start to change \p End at
+  /// the specified \p Column.
+  void alignEscapedNewlines(unsigned Start, unsigned End, unsigned Column);
+
+  /// Fill \c Replaces with the replacements for all effective changes.
+  void generateChanges();
+
+  /// Stores \p Text as the replacement for the whitespace in \p Range.
+  void storeReplacement(SourceRange Range, StringRef Text);
+  void appendNewlineText(std::string &Text, unsigned Newlines);
+  void appendEscapedNewlineText(std::string &Text, unsigned Newlines,
+                                unsigned PreviousEndOfTokenColumn,
+                                unsigned EscapedNewlineColumn);
+  void appendIndentText(std::string &Text, unsigned IndentLevel,
+                        unsigned Spaces, unsigned WhitespaceStartColumn);
+
+  SmallVector<Change, 16> Changes;
+  const SourceManager &SourceMgr;
+  tooling::Replacements Replaces;
+  const FormatStyle &Style;
+  bool UseCRLF;
+};
+
+} // namespace format
+} // namespace clang
+
+#endif