Coverage Report

Created: 2020-09-15 12:33

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/Format/BreakableToken.h
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//===--- BreakableToken.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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/// Declares BreakableToken, BreakableStringLiteral, BreakableComment,
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/// BreakableBlockComment and BreakableLineCommentSection classes, that contain
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/// token type-specific logic to break long lines in tokens and reflow content
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/// between tokens.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_LIB_FORMAT_BREAKABLETOKEN_H
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#define LLVM_CLANG_LIB_FORMAT_BREAKABLETOKEN_H
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#include "Encoding.h"
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#include "TokenAnnotator.h"
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#include "WhitespaceManager.h"
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#include "llvm/ADT/StringSet.h"
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#include "llvm/Support/Regex.h"
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#include <utility>
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namespace clang {
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namespace format {
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/// Checks if \p Token switches formatting, like /* clang-format off */.
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/// \p Token must be a comment.
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bool switchesFormatting(const FormatToken &Token);
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struct FormatStyle;
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/// Base class for tokens / ranges of tokens that can allow breaking
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/// within the tokens - for example, to avoid whitespace beyond the column
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/// limit, or to reflow text.
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///
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/// Generally, a breakable token consists of logical lines, addressed by a line
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/// index. For example, in a sequence of line comments, each line comment is its
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/// own logical line; similarly, for a block comment, each line in the block
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/// comment is on its own logical line.
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///
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/// There are two methods to compute the layout of the token:
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/// - getRangeLength measures the number of columns needed for a range of text
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///   within a logical line, and
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/// - getContentStartColumn returns the start column at which we want the
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///   content of a logical line to start (potentially after introducing a line
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///   break).
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///
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/// The mechanism to adapt the layout of the breakable token is organised
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/// around the concept of a \c Split, which is a whitespace range that signifies
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/// a position of the content of a token where a reformatting might be done.
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///
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/// Operating with splits is divided into two operations:
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/// - getSplit, for finding a split starting at a position,
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/// - insertBreak, for executing the split using a whitespace manager.
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///
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/// There is a pair of operations that are used to compress a long whitespace
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/// range with a single space if that will bring the line length under the
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/// column limit:
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/// - getLineLengthAfterCompression, for calculating the size in columns of the
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///   line after a whitespace range has been compressed, and
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/// - compressWhitespace, for executing the whitespace compression using a
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///   whitespace manager; note that the compressed whitespace may be in the
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///   middle of the original line and of the reformatted line.
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///
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/// For tokens where the whitespace before each line needs to be also
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/// reformatted, for example for tokens supporting reflow, there are analogous
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/// operations that might be executed before the main line breaking occurs:
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/// - getReflowSplit, for finding a split such that the content preceding it
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///   needs to be specially reflown,
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/// - reflow, for executing the split using a whitespace manager,
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/// - introducesBreakBefore, for checking if reformatting the beginning
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///   of the content introduces a line break before it,
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/// - adaptStartOfLine, for executing the reflow using a whitespace
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///   manager.
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///
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/// For tokens that require the whitespace after the last line to be
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/// reformatted, for example in multiline jsdoc comments that require the
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/// trailing '*/' to be on a line of itself, there are analogous operations
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/// that might be executed after the last line has been reformatted:
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/// - getSplitAfterLastLine, for finding a split after the last line that needs
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///   to be reflown,
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/// - replaceWhitespaceAfterLastLine, for executing the reflow using a
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///   whitespace manager.
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///
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class BreakableToken {
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public:
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  /// Contains starting character index and length of split.
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  typedef std::pair<StringRef::size_type, unsigned> Split;
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  virtual ~BreakableToken() {}
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  /// Returns the number of lines in this token in the original code.
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  virtual unsigned getLineCount() const = 0;
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  /// Returns the number of columns required to format the text in the
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  /// byte range [\p Offset, \p Offset \c + \p Length).
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  ///
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  /// \p Offset is the byte offset from the start of the content of the line
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  ///    at \p LineIndex.
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  ///
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  /// \p StartColumn is the column at which the text starts in the formatted
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  ///    file, needed to compute tab stops correctly.
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  virtual unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
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                                  StringRef::size_type Length,
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                                  unsigned StartColumn) const = 0;
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  /// Returns the number of columns required to format the text following
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  /// the byte \p Offset in the line \p LineIndex, including potentially
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  /// unbreakable sequences of tokens following after the end of the token.
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  ///
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  /// \p Offset is the byte offset from the start of the content of the line
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  ///    at \p LineIndex.
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  ///
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  /// \p StartColumn is the column at which the text starts in the formatted
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  ///    file, needed to compute tab stops correctly.
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  ///
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  /// For breakable tokens that never use extra space at the end of a line, this
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  /// is equivalent to getRangeLength with a Length of StringRef::npos.
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  virtual unsigned getRemainingLength(unsigned LineIndex, unsigned Offset,
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                                      unsigned StartColumn) const {
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    return getRangeLength(LineIndex, Offset, StringRef::npos, StartColumn);
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  }
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  /// Returns the column at which content in line \p LineIndex starts,
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  /// assuming no reflow.
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  ///
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  /// If \p Break is true, returns the column at which the line should start
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  /// after the line break.
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  /// If \p Break is false, returns the column at which the line itself will
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  /// start.
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  virtual unsigned getContentStartColumn(unsigned LineIndex,
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                                         bool Break) const = 0;
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  /// Returns additional content indent required for the second line after the
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  /// content at line \p LineIndex is broken.
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  ///
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  // (Next lines do not start with `///` since otherwise -Wdocumentation picks
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  // up the example annotations and generates warnings for them)
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  // For example, Javadoc @param annotations require and indent of 4 spaces and
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  // in this example getContentIndex(1) returns 4.
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  // /**
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  //  * @param loooooooooooooong line
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  //  *     continuation
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  //  */
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  virtual unsigned getContentIndent(unsigned LineIndex) const { return 0; }
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  /// Returns a range (offset, length) at which to break the line at
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  /// \p LineIndex, if previously broken at \p TailOffset. If possible, do not
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  /// violate \p ColumnLimit, assuming the text starting at \p TailOffset in
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  /// the token is formatted starting at ContentStartColumn in the reformatted
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  /// file.
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  virtual Split getSplit(unsigned LineIndex, unsigned TailOffset,
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                         unsigned ColumnLimit, unsigned ContentStartColumn,
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                         const llvm::Regex &CommentPragmasRegex) const = 0;
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  /// Emits the previously retrieved \p Split via \p Whitespaces.
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  virtual void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
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                           unsigned ContentIndent,
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                           WhitespaceManager &Whitespaces) const = 0;
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  /// Returns the number of columns needed to format
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  /// \p RemainingTokenColumns, assuming that Split is within the range measured
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  /// by \p RemainingTokenColumns, and that the whitespace in Split is reduced
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  /// to a single space.
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  unsigned getLengthAfterCompression(unsigned RemainingTokenColumns,
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                                     Split Split) const;
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  /// Replaces the whitespace range described by \p Split with a single
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  /// space.
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  virtual void compressWhitespace(unsigned LineIndex, unsigned TailOffset,
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                                  Split Split,
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                                  WhitespaceManager &Whitespaces) const = 0;
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  /// Returns whether the token supports reflowing text.
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  virtual bool supportsReflow() const { return false; }
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  /// Returns a whitespace range (offset, length) of the content at \p
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  /// LineIndex such that the content of that line is reflown to the end of the
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  /// previous one.
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  ///
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  /// Returning (StringRef::npos, 0) indicates reflowing is not possible.
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  ///
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  /// The range will include any whitespace preceding the specified line's
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  /// content.
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  ///
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  /// If the split is not contained within one token, for example when reflowing
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  /// line comments, returns (0, <length>).
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  virtual Split getReflowSplit(unsigned LineIndex,
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                               const llvm::Regex &CommentPragmasRegex) const {
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    return Split(StringRef::npos, 0);
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  }
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  /// Reflows the current line into the end of the previous one.
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  virtual void reflow(unsigned LineIndex,
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                      WhitespaceManager &Whitespaces) const {}
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  /// Returns whether there will be a line break at the start of the
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  /// token.
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  virtual bool introducesBreakBeforeToken() const { return false; }
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  /// Replaces the whitespace between \p LineIndex-1 and \p LineIndex.
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  virtual void adaptStartOfLine(unsigned LineIndex,
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                                WhitespaceManager &Whitespaces) const {}
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  /// Returns a whitespace range (offset, length) of the content at
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  /// the last line that needs to be reformatted after the last line has been
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  /// reformatted.
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  ///
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  /// A result having offset == StringRef::npos means that no reformat is
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  /// necessary.
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  virtual Split getSplitAfterLastLine(unsigned TailOffset) const {
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    return Split(StringRef::npos, 0);
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  }
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  /// Replaces the whitespace from \p SplitAfterLastLine on the last line
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  /// after the last line has been formatted by performing a reformatting.
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  void replaceWhitespaceAfterLastLine(unsigned TailOffset,
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                                      Split SplitAfterLastLine,
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                                      WhitespaceManager &Whitespaces) const {
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    insertBreak(getLineCount() - 1, TailOffset, SplitAfterLastLine,
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                /*ContentIndent=*/0, Whitespaces);
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  }
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  /// Updates the next token of \p State to the next token after this
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  /// one. This can be used when this token manages a set of underlying tokens
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  /// as a unit and is responsible for the formatting of the them.
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  virtual void updateNextToken(LineState &State) const {}
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protected:
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  BreakableToken(const FormatToken &Tok, bool InPPDirective,
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                 encoding::Encoding Encoding, const FormatStyle &Style)
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      : Tok(Tok), InPPDirective(InPPDirective), Encoding(Encoding),
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        Style(Style) {}
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  const FormatToken &Tok;
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  const bool InPPDirective;
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  const encoding::Encoding Encoding;
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  const FormatStyle &Style;
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};
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class BreakableStringLiteral : public BreakableToken {
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public:
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  /// Creates a breakable token for a single line string literal.
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  ///
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  /// \p StartColumn specifies the column in which the token will start
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  /// after formatting.
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  BreakableStringLiteral(const FormatToken &Tok, unsigned StartColumn,
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                         StringRef Prefix, StringRef Postfix,
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                         unsigned UnbreakableTailLength, bool InPPDirective,
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                         encoding::Encoding Encoding, const FormatStyle &Style);
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  Split getSplit(unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
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                 unsigned ContentStartColumn,
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                 const llvm::Regex &CommentPragmasRegex) const override;
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  void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
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                   unsigned ContentIndent,
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                   WhitespaceManager &Whitespaces) const override;
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  void compressWhitespace(unsigned LineIndex, unsigned TailOffset, Split Split,
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                          WhitespaceManager &Whitespaces) const override {}
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  unsigned getLineCount() const override;
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  unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
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                          StringRef::size_type Length,
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                          unsigned StartColumn) const override;
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  unsigned getRemainingLength(unsigned LineIndex, unsigned Offset,
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                              unsigned StartColumn) const override;
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  unsigned getContentStartColumn(unsigned LineIndex, bool Break) const override;
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protected:
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  // The column in which the token starts.
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  unsigned StartColumn;
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  // The prefix a line needs after a break in the token.
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  StringRef Prefix;
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  // The postfix a line needs before introducing a break.
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  StringRef Postfix;
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  // The token text excluding the prefix and postfix.
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  StringRef Line;
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  // Length of the sequence of tokens after this string literal that cannot
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  // contain line breaks.
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  unsigned UnbreakableTailLength;
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};
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class BreakableComment : public BreakableToken {
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protected:
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  /// Creates a breakable token for a comment.
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  ///
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  /// \p StartColumn specifies the column in which the comment will start after
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  /// formatting.
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  BreakableComment(const FormatToken &Token, unsigned StartColumn,
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                   bool InPPDirective, encoding::Encoding Encoding,
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                   const FormatStyle &Style);
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public:
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  bool supportsReflow() const override { return true; }
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  unsigned getLineCount() const override;
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  Split getSplit(unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
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                 unsigned ContentStartColumn,
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                 const llvm::Regex &CommentPragmasRegex) const override;
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  void compressWhitespace(unsigned LineIndex, unsigned TailOffset, Split Split,
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                          WhitespaceManager &Whitespaces) const override;
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protected:
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  // Returns the token containing the line at LineIndex.
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  const FormatToken &tokenAt(unsigned LineIndex) const;
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  // Checks if the content of line LineIndex may be reflown with the previous
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  // line.
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  virtual bool mayReflow(unsigned LineIndex,
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                         const llvm::Regex &CommentPragmasRegex) const = 0;
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  // Contains the original text of the lines of the block comment.
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  //
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  // In case of a block comments, excludes the leading /* in the first line and
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  // trailing */ in the last line. In case of line comments, excludes the
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  // leading // and spaces.
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  SmallVector<StringRef, 16> Lines;
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  // Contains the text of the lines excluding all leading and trailing
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  // whitespace between the lines. Note that the decoration (if present) is also
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  // not considered part of the text.
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  SmallVector<StringRef, 16> Content;
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  // Tokens[i] contains a reference to the token containing Lines[i] if the
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  // whitespace range before that token is managed by this block.
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  // Otherwise, Tokens[i] is a null pointer.
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  SmallVector<FormatToken *, 16> Tokens;
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  // ContentColumn[i] is the target column at which Content[i] should be.
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  // Note that this excludes a leading "* " or "*" in case of block comments
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  // where all lines have a "*" prefix, or the leading "// " or "//" in case of
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  // line comments.
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  //
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  // In block comments, the first line's target column is always positive. The
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  // remaining lines' target columns are relative to the first line to allow
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  // correct indentation of comments in \c WhitespaceManager. Thus they can be
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  // negative as well (in case the first line needs to be unindented more than
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  // there's actual whitespace in another line).
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  SmallVector<int, 16> ContentColumn;
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  // The intended start column of the first line of text from this section.
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  unsigned StartColumn;
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  // The prefix to use in front a line that has been reflown up.
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  // For example, when reflowing the second line after the first here:
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  // // comment 1
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  // // comment 2
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  // we expect:
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  // // comment 1 comment 2
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  // and not:
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  // // comment 1comment 2
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  StringRef ReflowPrefix = " ";
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};
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class BreakableBlockComment : public BreakableComment {
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public:
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  BreakableBlockComment(const FormatToken &Token, unsigned StartColumn,
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                        unsigned OriginalStartColumn, bool FirstInLine,
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                        bool InPPDirective, encoding::Encoding Encoding,
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                        const FormatStyle &Style, bool UseCRLF);
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  Split getSplit(unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
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                 unsigned ContentStartColumn,
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                 const llvm::Regex &CommentPragmasRegex) const override;
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  unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
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                          StringRef::size_type Length,
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                          unsigned StartColumn) const override;
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  unsigned getRemainingLength(unsigned LineIndex, unsigned Offset,
371
                              unsigned StartColumn) const override;
372
  unsigned getContentStartColumn(unsigned LineIndex, bool Break) const override;
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  unsigned getContentIndent(unsigned LineIndex) const override;
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  void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
375
                   unsigned ContentIndent,
376
                   WhitespaceManager &Whitespaces) const override;
377
  Split getReflowSplit(unsigned LineIndex,
378
                       const llvm::Regex &CommentPragmasRegex) const override;
379
  void reflow(unsigned LineIndex,
380
              WhitespaceManager &Whitespaces) const override;
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  bool introducesBreakBeforeToken() const override;
382
  void adaptStartOfLine(unsigned LineIndex,
383
                        WhitespaceManager &Whitespaces) const override;
384
  Split getSplitAfterLastLine(unsigned TailOffset) const override;
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  bool mayReflow(unsigned LineIndex,
387
                 const llvm::Regex &CommentPragmasRegex) const override;
388
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  // Contains Javadoc annotations that require additional indent when continued
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  // on multiple lines.
391
  static const llvm::StringSet<> ContentIndentingJavadocAnnotations;
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private:
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  // Rearranges the whitespace between Lines[LineIndex-1] and Lines[LineIndex].
395
  //
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  // Updates Content[LineIndex-1] and Content[LineIndex] by stripping off
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  // leading and trailing whitespace.
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  //
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  // Sets ContentColumn to the intended column in which the text at
400
  // Lines[LineIndex] starts (note that the decoration, if present, is not
401
  // considered part of the text).
402
  void adjustWhitespace(unsigned LineIndex, int IndentDelta);
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404
  // The column at which the text of a broken line should start.
405
  // Note that an optional decoration would go before that column.
406
  // IndentAtLineBreak is a uniform position for all lines in a block comment,
407
  // regardless of their relative position.
408
  // FIXME: Revisit the decision to do this; the main reason was to support
409
  // patterns like
410
  // /**************//**
411
  //  * Comment
412
  // We could also support such patterns by special casing the first line
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  // instead.
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  unsigned IndentAtLineBreak;
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  // This is to distinguish between the case when the last line was empty and
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  // the case when it started with a decoration ("*" or "* ").
418
  bool LastLineNeedsDecoration;
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  // Either "* " if all lines begin with a "*", or empty.
421
  StringRef Decoration;
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  // If this block comment has decorations, this is the column of the start of
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  // the decorations.
425
  unsigned DecorationColumn;
426
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  // If true, make sure that the opening '/**' and the closing '*/' ends on a
428
  // line of itself. Styles like jsdoc require this for multiline comments.
429
  bool DelimitersOnNewline;
430
431
  // Length of the sequence of tokens after this string literal that cannot
432
  // contain line breaks.
433
  unsigned UnbreakableTailLength;
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};
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436
class BreakableLineCommentSection : public BreakableComment {
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public:
438
  BreakableLineCommentSection(const FormatToken &Token, unsigned StartColumn,
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                              unsigned OriginalStartColumn, bool FirstInLine,
440
                              bool InPPDirective, encoding::Encoding Encoding,
441
                              const FormatStyle &Style);
442
443
  unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
444
                          StringRef::size_type Length,
445
                          unsigned StartColumn) const override;
446
  unsigned getContentStartColumn(unsigned LineIndex, bool Break) const override;
447
  void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
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                   unsigned ContentIndent,
449
                   WhitespaceManager &Whitespaces) const override;
450
  Split getReflowSplit(unsigned LineIndex,
451
                       const llvm::Regex &CommentPragmasRegex) const override;
452
  void reflow(unsigned LineIndex,
453
              WhitespaceManager &Whitespaces) const override;
454
  void adaptStartOfLine(unsigned LineIndex,
455
                        WhitespaceManager &Whitespaces) const override;
456
  void updateNextToken(LineState &State) const override;
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  bool mayReflow(unsigned LineIndex,
458
                 const llvm::Regex &CommentPragmasRegex) const override;
459
460
private:
461
  // OriginalPrefix[i] contains the original prefix of line i, including
462
  // trailing whitespace before the start of the content. The indentation
463
  // preceding the prefix is not included.
464
  // For example, if the line is:
465
  // // content
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  // then the original prefix is "// ".
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  SmallVector<StringRef, 16> OriginalPrefix;
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  // Prefix[i] contains the intended leading "//" with trailing spaces to
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  // account for the indentation of content within the comment at line i after
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  // formatting. It can be different than the original prefix when the original
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  // line starts like this:
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  // //content
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  // Then the original prefix is "//", but the prefix is "// ".
475
  SmallVector<StringRef, 16> Prefix;
476
477
  SmallVector<unsigned, 16> OriginalContentColumn;
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  /// The token to which the last line of this breakable token belongs
480
  /// to; nullptr if that token is the initial token.
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  ///
482
  /// The distinction is because if the token of the last line of this breakable
483
  /// token is distinct from the initial token, this breakable token owns the
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  /// whitespace before the token of the last line, and the whitespace manager
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  /// must be able to modify it.
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  FormatToken *LastLineTok = nullptr;
487
};
488
} // namespace format
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} // namespace clang
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#endif