text: //===--- WhitespaceManager.h - Format C++ code ------------------*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  ///
  /// \file
  /// \brief 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 {
  
  /// \brief 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) {}
  
    /// \brief Prepares the \c WhitespaceManager for another run.
    void reset();
  
    /// \brief Replaces the whitespace in front of \p Tok. Only call once for
    /// each \c AnnotatedToken.
    void replaceWhitespace(FormatToken &Tok, unsigned Newlines,
                           unsigned IndentLevel, unsigned Spaces,
                           unsigned StartOfTokenColumn,
                           bool InPPDirective = false);
  
    /// \brief 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);
  
    /// \brief 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, unsigned IndentLevel,
                                  int Spaces);
  
    /// \brief Returns all the \c Replacements created during formatting.
    const tooling::Replacements &generateReplacements();
  
    /// \brief Represents a change before a token, a break inside a token,
    /// or the layout of an unchanged token (or whitespace within).
    struct Change {
      /// \brief 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;
      };
  
      Change() {}
  
      /// \brief 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(bool CreateReplacement, SourceRange OriginalWhitespaceRange,
             unsigned IndentLevel, int Spaces, unsigned StartOfTokenColumn,
             unsigned NewlinesBefore, StringRef PreviousLinePostfix,
             StringRef CurrentLinePrefix, tok::TokenKind Kind,
             bool ContinuesPPDirective, bool IsStartOfDeclName,
             bool IsInsideToken);
  
      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;
      // 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.
      tok::TokenKind Kind;
      bool ContinuesPPDirective;
      bool IsStartOfDeclName;
  
      // The number of nested blocks the token is in. This is used to add tabs
      // only for the indentation, and not for alignment, when
      // UseTab = US_ForIndentation.
      unsigned IndentLevel;
  
      // 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;
    };
  
  private:
    /// \brief 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 assignments over all \c Changes.
    void alignConsecutiveAssignments();
  
    /// \brief Align consecutive declarations over all \c Changes.
    void alignConsecutiveDeclarations();
  
    /// \brief Align trailing comments over all \c Changes.
    void alignTrailingComments();
  
    /// \brief Align trailing comments from change \p Start to change \p End at
    /// the specified \p Column.
    void alignTrailingComments(unsigned Start, unsigned End, unsigned Column);
  
    /// \brief Align escaped newlines over all \c Changes.
    void alignEscapedNewlines();
  
    /// \brief Align escaped newlines from change \p Start to change \p End at
    /// the specified \p Column.
    void alignEscapedNewlines(unsigned Start, unsigned End, unsigned Column);
  
    /// \brief Fill \c Replaces with the replacements for all effective changes.
    void generateChanges();
  
    /// \brief 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 appendNewlineText(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
  