//===--- 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 "llvm/ADT/SmallVector.h"

#include <algorithm>

#include <string>

#include <tuple>

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; }

  /// Infers whether the input is using CRLF.

  static bool inputUsesCRLF(StringRef Text, bool DefaultToCRLF);

  /// 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 isAligned = false,

                         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 IsAligned, 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 IsAligned;

    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;

    // Depth of conditionals. Computed from tracking fake parenthesis, except

    // it does not increase the indent for "chained" conditionals.

    int ConditionalsLevel;

    // A combination of indent, nesting and conditionals levels, which are used

    // in tandem to compute lexical scope, for the purposes of deciding

    // when to stop consecutive alignment runs.

    std::tuple<unsigned, unsigned, unsigned> indentAndNestingLevel() const {

      return std::make_tuple(Tok->IndentLevel, Tok->NestingLevel,

                             ConditionalsLevel);

    }

  };

private:

  struct CellDescription {

    unsigned Index = 0;

    unsigned Cell = 0;

    unsigned EndIndex = 0;

    bool HasSplit = false;

    CellDescription *NextColumnElement = nullptr;

    constexpr bool operator==(const CellDescription &Other) const {

      return Index == Other.Index && Cell == Other.Cell &&

             EndIndex == Other.EndIndex;

    }

    constexpr bool operator!=(const CellDescription &Other) const {

      return !(*this == Other);

    }

  };

  struct CellDescriptions {

    SmallVector<CellDescription> Cells;

    SmallVector<unsigned> CellCounts;

    unsigned InitialSpaces = 0;

    // Determine if every row in the array

    // has the same number of columns.

    bool isRectangular() const {

      if (CellCounts.size() < 2)

        return false;

      for (auto NumberOfColumns : CellCounts)

        if (NumberOfColumns != CellCounts[0])

          return false;

      return true;

    }

  };

  /// 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 bitfields over all \c Changes.

  void alignConsecutiveBitFields();

  /// Align consecutive declarations over all \c Changes.

  void alignConsecutiveDeclarations();

  /// Align consecutive declarations over all \c Changes.

  void alignChainedConditionals();

  /// Align consecutive short case statements over all \c Changes.

  void alignConsecutiveShortCaseStatements();

  /// 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);

  /// Align Array Initializers over all \c Changes.

  void alignArrayInitializers();

  /// Align Array Initializers from change \p Start to change \p End at

  /// the specified \p Column.

  void alignArrayInitializers(unsigned Start, unsigned End);

  /// Align Array Initializers being careful to right justify the columns

  /// as described by \p CellDescs.

  void alignArrayInitializersRightJustified(CellDescriptions &&CellDescs);

  /// Align Array Initializers being careful to left justify the columns

  /// as described by \p CellDescs.

  void alignArrayInitializersLeftJustified(CellDescriptions &&CellDescs);

  /// Calculate the cell width between two indexes.

  unsigned calculateCellWidth(unsigned Start, unsigned End,

                              bool WithSpaces = false) const;

  /// Get a set of fully specified CellDescriptions between \p Start and

  /// \p End of the change list.

  CellDescriptions getCells(unsigned Start, unsigned End);

  /// Does this \p Cell contain a split element?

  static bool isSplitCell(const CellDescription &Cell);

  /// Get the width of the preceding cells from \p Start to \p End.

  template <typename I>

  auto getNetWidth(const I &Start, const I &End, unsigned InitialSpaces) const {

    auto NetWidth = InitialSpaces;

    for (auto PrevIter = Start; PrevIter != End; ++PrevIter) {

      // If we broke the line the initial spaces are already

      // accounted for.

      assert(PrevIter->Index < Changes.size());

      if (Changes[PrevIter->Index].NewlinesBefore > 0)

        NetWidth = 0;

      NetWidth +=

          calculateCellWidth(PrevIter->Index, PrevIter->EndIndex, true) + 1;

    }

    return NetWidth;

  }

  /// Get the maximum width of a cell in a sequence of columns.

  template <typename I>

  unsigned getMaximumCellWidth(I CellIter, unsigned NetWidth) const {

    unsigned CellWidth =

        calculateCellWidth(CellIter->Index, CellIter->EndIndex, true);

    if (Changes[CellIter->Index].NewlinesBefore == 0)

      CellWidth += NetWidth;

    for (const auto *Next = CellIter->NextColumnElement; Next;

         Next = Next->NextColumnElement) {

      auto ThisWidth = calculateCellWidth(Next->Index, Next->EndIndex, true);

      if (Changes[Next->Index].NewlinesBefore == 0)

        ThisWidth += NetWidth;

      CellWidth = std::max(CellWidth, ThisWidth);

    }

    return CellWidth;

  }

  /// Get The maximum width of all columns to a given cell.

  template <typename I>

  unsigned getMaximumNetWidth(const I &CellStart, const I &CellStop,

                              unsigned InitialSpaces, unsigned CellCount,

                              unsigned MaxRowCount) const {

    auto MaxNetWidth = getNetWidth(CellStart, CellStop, InitialSpaces);

    auto RowCount = 1U;

    auto Offset = std::distance(CellStart, CellStop);

    for (const auto *Next = CellStop->NextColumnElement; Next;

         Next = Next->NextColumnElement) {

      if (RowCount >= MaxRowCount)

        break;

      auto Start = (CellStart + RowCount * CellCount);

      auto End = Start + Offset;

      MaxNetWidth =

          std::max(MaxNetWidth, getNetWidth(Start, End, InitialSpaces));

      ++RowCount;

    }

    return MaxNetWidth;

  }

  /// Align a split cell with a newline to the first element in the cell.

  void alignToStartOfCell(unsigned Start, unsigned End);

  /// Link the Cell pointers in the list of Cells.

  static CellDescriptions linkCells(CellDescriptions &&CellDesc);

  /// 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,

                        bool IsAligned);

  unsigned appendTabIndent(std::string &Text, unsigned Spaces,

                           unsigned Indentation);

  SmallVector<Change, 16> Changes;

  const SourceManager &SourceMgr;

  tooling::Replacements Replaces;

  const FormatStyle &Style;

  bool UseCRLF;

};

} // namespace format

} // namespace clang

#endif