//===- PreprocessorLexer.h - C Language Family Lexer ------------*- 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

/// Defines the PreprocessorLexer interface.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LEX_PREPROCESSORLEXER_H

#define LLVM_CLANG_LEX_PREPROCESSORLEXER_H

#include "clang/Lex/MultipleIncludeOpt.h"

#include "clang/Lex/Token.h"

#include "clang/Basic/SourceLocation.h"

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/SmallVector.h"

#include <cassert>

namespace clang {

class FileEntry;

class Preprocessor;

class PreprocessorLexer {

  virtual void anchor();

protected:

  friend class Preprocessor;

  // Preprocessor object controlling lexing.

  Preprocessor *PP = nullptr;

  /// The SourceManager FileID corresponding to the file being lexed.

  const FileID FID;

  /// Number of SLocEntries before lexing the file.

  unsigned InitialNumSLocEntries = 0;

  //===--------------------------------------------------------------------===//

  // Context-specific lexing flags set by the preprocessor.

  //===--------------------------------------------------------------------===//

  /// True when parsing \#XXX; turns '\\n' into a tok::eod token.

  bool ParsingPreprocessorDirective = false;

  /// True after \#include; turns \<xx> or "xxx" into a tok::header_name token.

  bool ParsingFilename = false;

  /// True if in raw mode.

  ///

  /// Raw mode disables interpretation of tokens and is a far faster mode to

  /// lex in than non-raw-mode.  This flag:

  ///  1. If EOF of the current lexer is found, the include stack isn't popped.

  ///  2. Identifier information is not looked up for identifier tokens.  As an

  ///     effect of this, implicit macro expansion is naturally disabled.

  ///  3. "#" tokens at the start of a line are treated as normal tokens, not

  ///     implicitly transformed by the lexer.

  ///  4. All diagnostic messages are disabled.

  ///  5. No callbacks are made into the preprocessor.

  ///

  /// Note that in raw mode that the PP pointer may be null.

  bool LexingRawMode = false;

  /// A state machine that detects the \#ifndef-wrapping a file

  /// idiom for the multiple-include optimization.

  MultipleIncludeOpt MIOpt;

  /// Information about the set of \#if/\#ifdef/\#ifndef blocks

  /// we are currently in.

  SmallVector<PPConditionalInfo, 4> ConditionalStack;

  PreprocessorLexer() : FID() {}

  PreprocessorLexer(Preprocessor *pp, FileID fid);

  virtual ~PreprocessorLexer() = default;

  virtual void IndirectLex(Token& Result) = 0;

  /// Return the source location for the next observable location.

  virtual SourceLocation getSourceLocation() = 0;

  //===--------------------------------------------------------------------===//

  // #if directive handling.

  /// pushConditionalLevel - When we enter a \#if directive, this keeps track of

  /// what we are currently in for diagnostic emission (e.g. \#if with missing

  /// \#endif).

  void pushConditionalLevel(SourceLocation DirectiveStart, bool WasSkipping,

                            bool FoundNonSkip, bool FoundElse) {

    PPConditionalInfo CI;

    CI.IfLoc = DirectiveStart;

    CI.WasSkipping = WasSkipping;

    CI.FoundNonSkip = FoundNonSkip;

    CI.FoundElse = FoundElse;

    ConditionalStack.push_back(CI);

  }

  void pushConditionalLevel(const PPConditionalInfo &CI) {

    ConditionalStack.push_back(CI);

  }

  /// popConditionalLevel - Remove an entry off the top of the conditional

  /// stack, returning information about it.  If the conditional stack is empty,

  /// this returns true and does not fill in the arguments.

  bool popConditionalLevel(PPConditionalInfo &CI) {

    if (ConditionalStack.empty())

      return true;

    CI = ConditionalStack.pop_back_val();

    return false;

  }

  /// Return the top of the conditional stack.

  /// \pre This requires that there be a conditional active.

  PPConditionalInfo &peekConditionalLevel() {

    assert(!ConditionalStack.empty() && "No conditionals active!");

    return ConditionalStack.back();

  }

  unsigned getConditionalStackDepth() const { return ConditionalStack.size(); }

public:

  PreprocessorLexer(const PreprocessorLexer &) = delete;

  PreprocessorLexer &operator=(const PreprocessorLexer &) = delete;

  //===--------------------------------------------------------------------===//

  // Misc. lexing methods.

  /// Lex a token, producing a header-name token if possible.

  void LexIncludeFilename(Token &FilenameTok);

  /// Inform the lexer whether or not we are currently lexing a

  /// preprocessor directive.

  void setParsingPreprocessorDirective(bool f) {

    ParsingPreprocessorDirective = f;

  }

  /// Return true if this lexer is in raw mode or not.

  bool isLexingRawMode() const { return LexingRawMode; }

  /// Return the preprocessor object for this lexer.

  Preprocessor *getPP() const { return PP; }

  FileID getFileID() const {

    assert(PP &&

      "PreprocessorLexer::getFileID() should only be used with a Preprocessor");

    return FID;

  }

  /// Number of SLocEntries before lexing the file.

  unsigned getInitialNumSLocEntries() const {

    return InitialNumSLocEntries;

  }

  /// getFileEntry - Return the FileEntry corresponding to this FileID.  Like

  /// getFileID(), this only works for lexers with attached preprocessors.

  const FileEntry *getFileEntry() const;

  /// Iterator that traverses the current stack of preprocessor

  /// conditional directives (\#if/\#ifdef/\#ifndef).

  using conditional_iterator =

      SmallVectorImpl<PPConditionalInfo>::const_iterator;

  conditional_iterator conditional_begin() const {

    return ConditionalStack.begin();

  }

  conditional_iterator conditional_end() const {

    return ConditionalStack.end();

  }

  void setConditionalLevels(ArrayRef<PPConditionalInfo> CL) {

    ConditionalStack.clear();

    ConditionalStack.append(CL.begin(), CL.end());

  }

};

} // namespace clang

#endif // LLVM_CLANG_LEX_PREPROCESSORLEXER_H