Coverage Report

Created: 2022-01-18 06:27

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/Format/WhitespaceManager.h
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//===--- WhitespaceManager.h - Format C++ code ------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// WhitespaceManager class manages whitespace around tokens and their
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/// replacements.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_LIB_FORMAT_WHITESPACEMANAGER_H
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#define LLVM_CLANG_LIB_FORMAT_WHITESPACEMANAGER_H
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#include "TokenAnnotator.h"
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#include "clang/Basic/SourceManager.h"
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#include "clang/Format/Format.h"
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#include "llvm/ADT/SmallVector.h"
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#include <algorithm>
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#include <string>
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#include <tuple>
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namespace clang {
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namespace format {
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/// Manages the whitespaces around tokens and their replacements.
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///
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/// This includes special handling for certain constructs, e.g. the alignment of
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/// trailing line comments.
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///
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/// To guarantee correctness of alignment operations, the \c WhitespaceManager
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/// must be informed about every token in the source file; for each token, there
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/// must be exactly one call to either \c replaceWhitespace or
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/// \c addUntouchableToken.
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///
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/// There may be multiple calls to \c breakToken for a given token.
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class WhitespaceManager {
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public:
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  WhitespaceManager(const SourceManager &SourceMgr, const FormatStyle &Style,
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                    bool UseCRLF)
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      : SourceMgr(SourceMgr), Style(Style), UseCRLF(UseCRLF) {}
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  bool useCRLF() const { return UseCRLF; }
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  /// Infers whether the input is using CRLF.
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  static bool inputUsesCRLF(StringRef Text, bool DefaultToCRLF);
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  /// Replaces the whitespace in front of \p Tok. Only call once for
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  /// each \c AnnotatedToken.
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  ///
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  /// \p StartOfTokenColumn is the column at which the token will start after
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  /// this replacement. It is needed for determining how \p Spaces is turned
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  /// into tabs and spaces for some format styles.
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  void replaceWhitespace(FormatToken &Tok, unsigned Newlines, unsigned Spaces,
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                         unsigned StartOfTokenColumn, bool isAligned = false,
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                         bool InPPDirective = false);
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  /// Adds information about an unchangeable token's whitespace.
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  ///
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  /// Needs to be called for every token for which \c replaceWhitespace
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  /// was not called.
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  void addUntouchableToken(const FormatToken &Tok, bool InPPDirective);
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  llvm::Error addReplacement(const tooling::Replacement &Replacement);
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  /// Inserts or replaces whitespace in the middle of a token.
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  ///
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  /// Inserts \p PreviousPostfix, \p Newlines, \p Spaces and \p CurrentPrefix
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  /// (in this order) at \p Offset inside \p Tok, replacing \p ReplaceChars
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  /// characters.
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  ///
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  /// Note: \p Spaces can be negative to retain information about initial
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  /// relative column offset between a line of a block comment and the start of
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  /// the comment. This negative offset may be compensated by trailing comment
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  /// alignment here. In all other cases negative \p Spaces will be truncated to
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  /// 0.
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  ///
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  /// When \p InPPDirective is true, escaped newlines are inserted. \p Spaces is
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  /// used to align backslashes correctly.
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  void replaceWhitespaceInToken(const FormatToken &Tok, unsigned Offset,
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                                unsigned ReplaceChars,
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                                StringRef PreviousPostfix,
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                                StringRef CurrentPrefix, bool InPPDirective,
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                                unsigned Newlines, int Spaces);
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  /// Returns all the \c Replacements created during formatting.
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  const tooling::Replacements &generateReplacements();
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  /// Represents a change before a token, a break inside a token,
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  /// or the layout of an unchanged token (or whitespace within).
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  struct Change {
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    /// Functor to sort changes in original source order.
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    class IsBeforeInFile {
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    public:
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      IsBeforeInFile(const SourceManager &SourceMgr) : SourceMgr(SourceMgr) {}
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      bool operator()(const Change &C1, const Change &C2) const;
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    private:
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      const SourceManager &SourceMgr;
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    };
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    /// Creates a \c Change.
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    ///
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    /// The generated \c Change will replace the characters at
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    /// \p OriginalWhitespaceRange with a concatenation of
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    /// \p PreviousLinePostfix, \p NewlinesBefore line breaks, \p Spaces spaces
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    /// and \p CurrentLinePrefix.
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    ///
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    /// \p StartOfTokenColumn and \p InPPDirective will be used to lay out
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    /// trailing comments and escaped newlines.
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    Change(const FormatToken &Tok, bool CreateReplacement,
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           SourceRange OriginalWhitespaceRange, int Spaces,
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           unsigned StartOfTokenColumn, unsigned NewlinesBefore,
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           StringRef PreviousLinePostfix, StringRef CurrentLinePrefix,
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           bool IsAligned, bool ContinuesPPDirective, bool IsInsideToken);
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    // The kind of the token whose whitespace this change replaces, or in which
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    // this change inserts whitespace.
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    // FIXME: Currently this is not set correctly for breaks inside comments, as
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    // the \c BreakableToken is still doing its own alignment.
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    const FormatToken *Tok;
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    bool CreateReplacement;
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    // Changes might be in the middle of a token, so we cannot just keep the
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    // FormatToken around to query its information.
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    SourceRange OriginalWhitespaceRange;
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    unsigned StartOfTokenColumn;
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    unsigned NewlinesBefore;
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    std::string PreviousLinePostfix;
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    std::string CurrentLinePrefix;
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    bool IsAligned;
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    bool ContinuesPPDirective;
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    // The number of spaces in front of the token or broken part of the token.
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    // This will be adapted when aligning tokens.
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    // Can be negative to retain information about the initial relative offset
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    // of the lines in a block comment. This is used when aligning trailing
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    // comments. Uncompensated negative offset is truncated to 0.
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    int Spaces;
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    // If this change is inside of a token but not at the start of the token or
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    // directly after a newline.
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    bool IsInsideToken;
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    // \c IsTrailingComment, \c TokenLength, \c PreviousEndOfTokenColumn and
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    // \c EscapedNewlineColumn will be calculated in
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    // \c calculateLineBreakInformation.
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    bool IsTrailingComment;
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    unsigned TokenLength;
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    unsigned PreviousEndOfTokenColumn;
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    unsigned EscapedNewlineColumn;
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    // These fields are used to retain correct relative line indentation in a
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    // block comment when aligning trailing comments.
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    //
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    // If this Change represents a continuation of a block comment,
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    // \c StartOfBlockComment is pointer to the first Change in the block
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    // comment. \c IndentationOffset is a relative column offset to this
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    // change, so that the correct column can be reconstructed at the end of
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    // the alignment process.
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    const Change *StartOfBlockComment;
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    int IndentationOffset;
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    // Depth of conditionals. Computed from tracking fake parenthesis, except
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    // it does not increase the indent for "chained" conditionals.
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    int ConditionalsLevel;
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    // A combination of indent, nesting and conditionals levels, which are used
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    // in tandem to compute lexical scope, for the purposes of deciding
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    // when to stop consecutive alignment runs.
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    std::tuple<unsigned, unsigned, unsigned> indentAndNestingLevel() const {
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      return std::make_tuple(Tok->IndentLevel, Tok->NestingLevel,
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                             ConditionalsLevel);
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    }
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  };
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private:
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  struct CellDescription {
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    unsigned Index = 0;
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    unsigned Cell = 0;
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    unsigned EndIndex = 0;
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    bool HasSplit = false;
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    CellDescription *NextColumnElement = nullptr;
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    constexpr bool operator==(const CellDescription &Other) const {
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      return Index == Other.Index && Cell == Other.Cell &&
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             EndIndex == Other.EndIndex;
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    }
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    constexpr bool operator!=(const CellDescription &Other) const {
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      return !(*this == Other);
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    }
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  };
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  struct CellDescriptions {
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    SmallVector<CellDescription> Cells;
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    unsigned CellCount = 0;
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    unsigned InitialSpaces = 0;
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  };
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  /// Calculate \c IsTrailingComment, \c TokenLength for the last tokens
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  /// or token parts in a line and \c PreviousEndOfTokenColumn and
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  /// \c EscapedNewlineColumn for the first tokens or token parts in a line.
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  void calculateLineBreakInformation();
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  /// \brief Align consecutive C/C++ preprocessor macros over all \c Changes.
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  void alignConsecutiveMacros();
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  /// Align consecutive assignments over all \c Changes.
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  void alignConsecutiveAssignments();
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  /// Align consecutive bitfields over all \c Changes.
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  void alignConsecutiveBitFields();
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  /// Align consecutive declarations over all \c Changes.
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  void alignConsecutiveDeclarations();
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  /// Align consecutive declarations over all \c Changes.
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  void alignChainedConditionals();
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  /// Align trailing comments over all \c Changes.
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  void alignTrailingComments();
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  /// Align trailing comments from change \p Start to change \p End at
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  /// the specified \p Column.
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  void alignTrailingComments(unsigned Start, unsigned End, unsigned Column);
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  /// Align escaped newlines over all \c Changes.
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  void alignEscapedNewlines();
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  /// Align escaped newlines from change \p Start to change \p End at
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  /// the specified \p Column.
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  void alignEscapedNewlines(unsigned Start, unsigned End, unsigned Column);
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  /// Align Array Initializers over all \c Changes.
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  void alignArrayInitializers();
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  /// Align Array Initializers from change \p Start to change \p End at
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  /// the specified \p Column.
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  void alignArrayInitializers(unsigned Start, unsigned End);
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  /// Align Array Initializers being careful to right justify the columns
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  /// as described by \p CellDescs.
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  void alignArrayInitializersRightJustified(CellDescriptions &&CellDescs);
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  /// Align Array Initializers being careful to left justify the columns
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  /// as described by \p CellDescs.
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  void alignArrayInitializersLeftJustified(CellDescriptions &&CellDescs);
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  /// Calculate the cell width between two indexes.
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  unsigned calculateCellWidth(unsigned Start, unsigned End,
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                              bool WithSpaces = false) const;
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  /// Get a set of fully specified CellDescriptions between \p Start and
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  /// \p End of the change list.
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  CellDescriptions getCells(unsigned Start, unsigned End);
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  /// Does this \p Cell contain a split element?
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  static bool isSplitCell(const CellDescription &Cell);
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  /// Get the width of the preceding cells from \p Start to \p End.
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  template <typename I>
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  auto getNetWidth(const I &Start, const I &End, unsigned InitialSpaces) const {
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    auto NetWidth = InitialSpaces;
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    for (auto PrevIter = Start; PrevIter != End; 
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) {
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      // If we broke the line the initial spaces are already
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      // accounted for.
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      if (Changes[PrevIter->Index].NewlinesBefore > 0)
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        NetWidth = 0;
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      NetWidth +=
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          calculateCellWidth(PrevIter->Index, PrevIter->EndIndex, true) + 1;
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    }
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    return NetWidth;
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  }
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  /// Get the maximum width of a cell in a sequence of columns.
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  template <typename I>
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  unsigned getMaximumCellWidth(I CellIter, unsigned NetWidth) const {
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    unsigned CellWidth =
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        calculateCellWidth(CellIter->Index, CellIter->EndIndex, true);
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    if (Changes[CellIter->Index].NewlinesBefore == 0)
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      CellWidth += NetWidth;
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    for (const auto *Next = CellIter->NextColumnElement; Next != nullptr;
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         Next = Next->NextColumnElement) {
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      auto ThisWidth = calculateCellWidth(Next->Index, Next->EndIndex, true);
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      if (Changes[Next->Index].NewlinesBefore == 0)
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        ThisWidth += NetWidth;
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      CellWidth = std::max(CellWidth, ThisWidth);
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    }
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    return CellWidth;
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  }
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  /// Get The maximum width of all columns to a given cell.
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  template <typename I>
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  unsigned getMaximumNetWidth(const I &CellStart, const I &CellStop,
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                              unsigned InitialSpaces,
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                              unsigned CellCount) const {
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    auto MaxNetWidth = getNetWidth(CellStart, CellStop, InitialSpaces);
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    auto RowCount = 1U;
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    auto Offset = std::distance(CellStart, CellStop);
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    for (const auto *Next = CellStop->NextColumnElement; Next != nullptr;
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         Next = Next->NextColumnElement) {
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      auto Start = (CellStart + RowCount * CellCount);
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      auto End = Start + Offset;
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      MaxNetWidth =
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          std::max(MaxNetWidth, getNetWidth(Start, End, InitialSpaces));
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      ++RowCount;
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    }
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    return MaxNetWidth;
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  }
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  /// Align a split cell with a newline to the first element in the cell.
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  void alignToStartOfCell(unsigned Start, unsigned End);
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  /// Link the Cell pointers in the list of Cells.
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  static CellDescriptions linkCells(CellDescriptions &&CellDesc);
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  /// Fill \c Replaces with the replacements for all effective changes.
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  void generateChanges();
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  /// Stores \p Text as the replacement for the whitespace in \p Range.
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  void storeReplacement(SourceRange Range, StringRef Text);
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  void appendNewlineText(std::string &Text, unsigned Newlines);
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  void appendEscapedNewlineText(std::string &Text, unsigned Newlines,
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                                unsigned PreviousEndOfTokenColumn,
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                                unsigned EscapedNewlineColumn);
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  void appendIndentText(std::string &Text, unsigned IndentLevel,
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                        unsigned Spaces, unsigned WhitespaceStartColumn,
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                        bool IsAligned);
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  unsigned appendTabIndent(std::string &Text, unsigned Spaces,
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                           unsigned Indentation);
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  SmallVector<Change, 16> Changes;
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  const SourceManager &SourceMgr;
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  tooling::Replacements Replaces;
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  const FormatStyle &Style;
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  bool UseCRLF;
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};
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} // namespace format
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} // namespace clang
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#endif