//===- TokenLexer.h - Lex from a token buffer -------------------*- 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

//

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

//

// This file defines the TokenLexer interface.

//

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

#ifndef LLVM_CLANG_LEX_TOKENLEXER_H

#define LLVM_CLANG_LEX_TOKENLEXER_H

#include "clang/Basic/SourceLocation.h"

#include "llvm/ADT/ArrayRef.h"

namespace clang {

class MacroArgs;

class MacroInfo;

class Preprocessor;

class Token;

class VAOptExpansionContext;

/// TokenLexer - This implements a lexer that returns tokens from a macro body

/// or token stream instead of lexing from a character buffer.  This is used for

/// macro expansion and _Pragma handling, for example.

class TokenLexer {

  friend class Preprocessor;

  /// The macro we are expanding from. This is null if expanding a token stream.

  MacroInfo *Macro = nullptr;

  /// The actual arguments specified for a function-like macro, or null. The

  /// TokenLexer owns the pointed-to object.

  MacroArgs *ActualArgs = nullptr;

  /// The current preprocessor object we are expanding for.

  Preprocessor &PP;

  /// This is the pointer to an array of tokens that the macro is

  /// defined to, with arguments expanded for function-like macros.  If this is

  /// a token stream, these are the tokens we are returning.  This points into

  /// the macro definition we are lexing from, a cache buffer that is owned by

  /// the preprocessor, or some other buffer that we may or may not own

  /// (depending on OwnsTokens).

  /// Note that if it points into Preprocessor's cache buffer, the Preprocessor

  /// may update the pointer as needed.

  const Token *Tokens;

  /// This is the length of the Tokens array.

  unsigned NumTokens;

  /// This is the index of the next token that Lex will return.

  unsigned CurTokenIdx;

  /// The source location range where this macro was expanded.

  SourceLocation ExpandLocStart, ExpandLocEnd;

  /// Source location pointing at the source location entry chunk that

  /// was reserved for the current macro expansion.

  SourceLocation MacroExpansionStart;

  /// The offset of the macro expansion in the

  /// "source location address space".

  unsigned MacroStartSLocOffset;

  /// Location of the macro definition.

  SourceLocation MacroDefStart;

  /// Length of the macro definition.

  unsigned MacroDefLength;

  /// Lexical information about the expansion point of the macro: the identifier

  /// that the macro expanded from had these properties.

  bool AtStartOfLine : 1;

  bool HasLeadingSpace : 1;

  // When this is true, the next token appended to the

  // output list during function argument expansion will get a leading space,

  // regardless of whether it had one to begin with or not. This is used for

  // placemarker support. If still true after function argument expansion, the

  // leading space will be applied to the first token following the macro

  // expansion.

  bool NextTokGetsSpace : 1;

  /// This is true if this TokenLexer allocated the Tokens

  /// array, and thus needs to free it when destroyed.  For simple object-like

  /// macros (for example) we just point into the token buffer of the macro

  /// definition, we don't make a copy of it.

  bool OwnsTokens : 1;

  /// This is true when tokens lexed from the TokenLexer

  /// should not be subject to further macro expansion.

  bool DisableMacroExpansion : 1;

  /// When true, the produced tokens have Token::IsReinjected flag set.

  /// See the flag documentation for details.

  bool IsReinject : 1;

public:

  /// Create a TokenLexer for the specified macro with the specified actual

  /// arguments.  Note that this ctor takes ownership of the ActualArgs pointer.

  /// ILEnd specifies the location of the ')' for a function-like macro or the

  /// identifier for an object-like macro.

  TokenLexer(Token &Tok, SourceLocation ILEnd, MacroInfo *MI,

             MacroArgs *ActualArgs, Preprocessor &pp)

      : PP(pp), OwnsTokens(false) {

    Init(Tok, ILEnd, MI, ActualArgs);

  }

  /// Create a TokenLexer for the specified token stream.  If 'OwnsTokens' is

  /// specified, this takes ownership of the tokens and delete[]'s them when

  /// the token lexer is empty.

  TokenLexer(const Token *TokArray, unsigned NumToks, bool DisableExpansion,

             bool ownsTokens, bool isReinject, Preprocessor &pp)

      : PP(pp), OwnsTokens(false) {

    Init(TokArray, NumToks, DisableExpansion, ownsTokens, isReinject);

  }

  TokenLexer(const TokenLexer &) = delete;

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

  ~TokenLexer() { destroy(); }

  /// Initialize this TokenLexer to expand from the specified macro

  /// with the specified argument information.  Note that this ctor takes

  /// ownership of the ActualArgs pointer.  ILEnd specifies the location of the

  /// ')' for a function-like macro or the identifier for an object-like macro.

  void Init(Token &Tok, SourceLocation ELEnd, MacroInfo *MI,

            MacroArgs *Actuals);

  /// Initialize this TokenLexer with the specified token stream.

  /// This does not take ownership of the specified token vector.

  ///

  /// DisableExpansion is true when macro expansion of tokens lexed from this

  /// stream should be disabled.

  void Init(const Token *TokArray, unsigned NumToks, bool DisableMacroExpansion,

            bool OwnsTokens, bool IsReinject);

  /// If the next token lexed will pop this macro off the

  /// expansion stack, return 2.  If the next unexpanded token is a '(', return

  /// 1, otherwise return 0.

  unsigned isNextTokenLParen() const;

  /// Lex and return a token from this macro stream.

  bool Lex(Token &Tok);

  /// isParsingPreprocessorDirective - Return true if we are in the middle of a

  /// preprocessor directive.

  bool isParsingPreprocessorDirective() const;

private:

  void destroy();

  /// Return true if the next lex call will pop this macro off the include

  /// stack.

  bool isAtEnd() const {

    return CurTokenIdx == NumTokens;

  }

  /// Concatenates the next (sub-)sequence of \p Tokens separated by '##'

  /// starting with LHSTok - stopping when we encounter a token that is neither

  /// '##' nor preceded by '##'.  Places the result back into \p LHSTok and sets

  /// \p CurIdx to point to the token following the last one that was pasted.

  ///

  /// Also performs the MSVC extension wide-literal token pasting involved with:

  ///       \code L #macro-arg. \endcode

  ///

  /// \param[in,out] LHSTok - Contains the token to the left of '##' in \p

  /// Tokens upon entry and will contain the resulting concatenated Token upon

  /// exit.

  ///

  /// \param[in] TokenStream - The stream of Tokens we are lexing from.

  ///

  /// \param[in,out] CurIdx - Upon entry, \pTokens[\pCurIdx] must equal '##'

  /// (with the exception of the MSVC extension mentioned above).  Upon exit, it

  /// is set to the index of the token following the last token that was

  /// concatenated together.

  ///

  /// \returns If this returns true, the caller should immediately return the

  /// token.

  bool pasteTokens(Token &LHSTok, ArrayRef<Token> TokenStream,

                   unsigned int &CurIdx);

  /// Calls pasteTokens above, passing in the '*this' object's Tokens and

  /// CurTokenIdx data members.

  bool pasteTokens(Token &Tok);

  /// Takes the tail sequence of tokens within ReplacementToks that represent

  /// the just expanded __VA_OPT__ tokens (possibly zero tokens) and transforms

  /// them into a string.  \p VCtx is used to determine which token represents

  /// the first __VA_OPT__ replacement token.

  ///

  /// \param[in,out] ResultToks - Contains the current Replacement Tokens

  /// (prior to rescanning and token pasting), the tail end of which represents

  /// the tokens just expanded through __VA_OPT__ processing.  These (sub)

  /// sequence of tokens are folded into one stringified token.

  ///

  /// \param[in] VCtx - contains relevant contextual information about the

  /// state of the tokens around and including the __VA_OPT__ token, necessary

  /// for stringification.

  void stringifyVAOPTContents(SmallVectorImpl<Token> &ResultToks,

                              const VAOptExpansionContext &VCtx,

                              SourceLocation VAOPTClosingParenLoc);

  /// Expand the arguments of a function-like macro so that we can quickly

  /// return preexpanded tokens from Tokens.

  void ExpandFunctionArguments();

  /// In microsoft compatibility mode, /##/ pastes

  /// together to form a comment that comments out everything in the current

  /// macro, other active macros, and anything left on the current physical

  /// source line of the expanded buffer.  Handle this by returning the

  /// first token on the next line.

  void HandleMicrosoftCommentPaste(Token &Tok, SourceLocation OpLoc);

  /// If \p loc is a FileID and points inside the current macro

  /// definition, returns the appropriate source location pointing at the

  /// macro expansion source location entry.

  SourceLocation getExpansionLocForMacroDefLoc(SourceLocation loc) const;

  /// Creates SLocEntries and updates the locations of macro argument

  /// tokens to their new expanded locations.

  ///

  /// \param ArgIdSpellLoc the location of the macro argument id inside the

  /// macro definition.

  void updateLocForMacroArgTokens(SourceLocation ArgIdSpellLoc,

                                  Token *begin_tokens, Token *end_tokens);

  /// Remove comma ahead of __VA_ARGS__, if present, according to compiler

  /// dialect settings.  Returns true if the comma is removed.

  bool MaybeRemoveCommaBeforeVaArgs(SmallVectorImpl<Token> &ResultToks,

                                    bool HasPasteOperator,

                                    MacroInfo *Macro, unsigned MacroArgNo,

                                    Preprocessor &PP);

  void PropagateLineStartLeadingSpaceInfo(Token &Result);

};

} // namespace clang

#endif // LLVM_CLANG_LEX_TOKENLEXER_H