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//===- VariadicMacroSupport.h - state machines and scope guards -*- 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 support types to help with preprocessing variadic macro

// (i.e. macros that use: ellipses __VA_ARGS__ ) definitions and

// expansions.

//

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

#ifndef LLVM_CLANG_LEX_VARIADICMACROSUPPORT_H

#define LLVM_CLANG_LEX_VARIADICMACROSUPPORT_H

#include "clang/Lex/Preprocessor.h"

#include "llvm/ADT/SmallVector.h"

namespace clang {

  class Preprocessor;

  /// An RAII class that tracks when the Preprocessor starts and stops lexing

  /// the definition of a (ISO C/C++) variadic macro.  As an example, this is

  /// useful for unpoisoning and repoisoning certain identifiers (such as

  /// __VA_ARGS__) that are only allowed in this context.  Also, being a friend

  /// of the Preprocessor class allows it to access PP's cached identifiers

  /// directly (as opposed to performing a lookup each time).

  class VariadicMacroScopeGuard {

    const Preprocessor &PP;

    IdentifierInfo *const Ident__VA_ARGS__;

    IdentifierInfo *const Ident__VA_OPT__;

  public:

    VariadicMacroScopeGuard(const Preprocessor &P)

        : PP(P), Ident__VA_ARGS__(PP.Ident__VA_ARGS__),

          Ident__VA_OPT__(PP.Ident__VA_OPT__) {

      assert(Ident__VA_ARGS__->isPoisoned() && "__VA_ARGS__ should be poisoned "

                                              "outside an ISO C/C++ variadic "

                                              "macro definition!");

      assert(Ident__VA_OPT__->isPoisoned() && "__VA_OPT__ should be poisoned!");

    }

    /// Client code should call this function just before the Preprocessor is

    /// about to Lex tokens from the definition of a variadic (ISO C/C++) macro.

    void enterScope() {

      Ident__VA_ARGS__->setIsPoisoned(false);

      Ident__VA_OPT__->setIsPoisoned(false);

    }

    /// Client code should call this function as soon as the Preprocessor has

    /// either completed lexing the macro's definition tokens, or an error

    /// occurred and the context is being exited.  This function is idempotent

    /// (might be explicitly called, and then reinvoked via the destructor).

    void exitScope() {

      Ident__VA_ARGS__->setIsPoisoned(true);

      Ident__VA_OPT__->setIsPoisoned(true);

    }

    ~VariadicMacroScopeGuard() { exitScope(); }

  };

  /// A class for tracking whether we're inside a VA_OPT during a

  /// traversal of the tokens of a variadic macro definition.

  class VAOptDefinitionContext {

    /// Contains all the locations of so far unmatched lparens.

    SmallVector<SourceLocation, 8> UnmatchedOpeningParens;

    const IdentifierInfo *const Ident__VA_OPT__;

  public:

    VAOptDefinitionContext(Preprocessor &PP)

        : Ident__VA_OPT__(PP.Ident__VA_OPT__) {}

    bool isVAOptToken(const Token &T) const {

      return Ident__VA_OPT__ && T.getIdentifierInfo() == Ident__VA_OPT__;

    }

    /// Returns true if we have seen the __VA_OPT__ and '(' but before having

    /// seen the matching ')'.

    bool isInVAOpt() const { return UnmatchedOpeningParens.size(); }

    /// Call this function as soon as you see __VA_OPT__ and '('.

    void sawVAOptFollowedByOpeningParens(const SourceLocation LParenLoc) {

      assert(!isInVAOpt() && "Must NOT be within VAOPT context to call this");

      UnmatchedOpeningParens.push_back(LParenLoc);

    }

    SourceLocation getUnmatchedOpeningParenLoc() const {

      assert(isInVAOpt() && "Must be within VAOPT context to call this");

      return UnmatchedOpeningParens.back();

    }

    /// Call this function each time an rparen is seen.  It returns true only if

    /// the rparen that was just seen was the eventual (non-nested) closing

    /// paren for VAOPT, and ejects us out of the VAOPT context.

    bool sawClosingParen() {

      assert(isInVAOpt() && "Must be within VAOPT context to call this");

      UnmatchedOpeningParens.pop_back();

      return !UnmatchedOpeningParens.size();

    }

    /// Call this function each time an lparen is seen.

    void sawOpeningParen(SourceLocation LParenLoc) {

      assert(isInVAOpt() && "Must be within VAOPT context to call this");

      UnmatchedOpeningParens.push_back(LParenLoc);

    }

    /// Are we at the top level within the __VA_OPT__?

    bool isAtTopLevel() const { return UnmatchedOpeningParens.size() == 1; }

  };

  /// A class for tracking whether we're inside a VA_OPT during a

  /// traversal of the tokens of a macro during macro expansion.

  class VAOptExpansionContext : VAOptDefinitionContext {

    Token SyntheticEOFToken;

    // The (spelling) location of the current __VA_OPT__ in the replacement list

    // of the function-like macro being expanded.

    SourceLocation VAOptLoc;

    // NumOfTokensPriorToVAOpt : when != -1, contains the index *of* the first

    // token of the current VAOPT contents (so we know where to start eager

    // token-pasting and stringification) *within*  the substituted tokens of

    // the function-like macro's new replacement list.

    int NumOfTokensPriorToVAOpt = -1;

    unsigned LeadingSpaceForStringifiedToken : 1;

    unsigned StringifyBefore : 1;

    unsigned CharifyBefore : 1;

    unsigned BeginsWithPlaceholder : 1;

    unsigned EndsWithPlaceholder : 1;

    bool hasStringifyBefore() const {

      assert(!isReset() &&

             "Must only be called if the state has not been reset");

      return StringifyBefore;

    }

    bool isReset() const {

      return NumOfTokensPriorToVAOpt == -1 ||

             VAOptLoc.isInvalid();

    }

  public:

    VAOptExpansionContext(Preprocessor &PP)

        : VAOptDefinitionContext(PP), LeadingSpaceForStringifiedToken(false),

          StringifyBefore(false), CharifyBefore(false),

          BeginsWithPlaceholder(false), EndsWithPlaceholder(false) {

      SyntheticEOFToken.startToken();

      SyntheticEOFToken.setKind(tok::eof);

    }

    void reset() {

      VAOptLoc = SourceLocation();

      NumOfTokensPriorToVAOpt = -1;

      LeadingSpaceForStringifiedToken = false;

      StringifyBefore = false;

      CharifyBefore = false;

      BeginsWithPlaceholder = false;

      EndsWithPlaceholder = false;

    }

    const Token &getEOFTok() const { return SyntheticEOFToken; }

    void sawHashOrHashAtBefore(const bool HasLeadingSpace,

                               const bool IsHashAt) {

      StringifyBefore = !IsHashAt;

      CharifyBefore = IsHashAt;

      LeadingSpaceForStringifiedToken = HasLeadingSpace;

    }

    void hasPlaceholderAfterHashhashAtStart() { BeginsWithPlaceholder = true; }

    void hasPlaceholderBeforeRParen() {

      if (isAtTopLevel())

        EndsWithPlaceholder = true;

    }

    bool beginsWithPlaceholder() const {

      assert(!isReset() &&

             "Must only be called if the state has not been reset");

      return BeginsWithPlaceholder;

    }

    bool endsWithPlaceholder() const {

      assert(!isReset() &&

             "Must only be called if the state has not been reset");

      return EndsWithPlaceholder;

    }

    bool hasCharifyBefore() const {

      assert(!isReset() &&

             "Must only be called if the state has not been reset");

      return CharifyBefore;

    }

    bool hasStringifyOrCharifyBefore() const {

      return hasStringifyBefore() || hasCharifyBefore();

    }

    unsigned int getNumberOfTokensPriorToVAOpt() const {

      assert(!isReset() &&

             "Must only be called if the state has not been reset");

      return NumOfTokensPriorToVAOpt;

    }

    bool getLeadingSpaceForStringifiedToken() const {

      assert(hasStringifyBefore() &&

             "Must only be called if this has been marked for stringification");

      return LeadingSpaceForStringifiedToken;

    }

    void sawVAOptFollowedByOpeningParens(const SourceLocation VAOptLoc,

                                         const unsigned int NumPriorTokens) {

      assert(VAOptLoc.isFileID() && "Must not come from a macro expansion");

      assert(isReset() && "Must only be called if the state has been reset");

      VAOptDefinitionContext::sawVAOptFollowedByOpeningParens(SourceLocation());

      this->VAOptLoc = VAOptLoc;

      NumOfTokensPriorToVAOpt = NumPriorTokens;

      assert(NumOfTokensPriorToVAOpt > -1 &&

             "Too many prior tokens");

    }

    SourceLocation getVAOptLoc() const {

      assert(!isReset() &&

             "Must only be called if the state has not been reset");

      assert(VAOptLoc.isValid() && "__VA_OPT__ location must be valid");

      return VAOptLoc;

    }

    using VAOptDefinitionContext::isVAOptToken;

    using VAOptDefinitionContext::isInVAOpt;

    using VAOptDefinitionContext::sawClosingParen;

    using VAOptDefinitionContext::sawOpeningParen;

  };

}  // end namespace clang

#endif