Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===-- SemaConcept.h - Semantic Analysis for Constraints and Concepts ----===//

//

// 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 provides semantic analysis for C++ constraints and concepts.

///

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

#ifndef LLVM_CLANG_SEMA_SEMACONCEPT_H

#define LLVM_CLANG_SEMA_SEMACONCEPT_H

#include "clang/AST/ASTConcept.h"

#include "clang/AST/ASTContext.h"

#include "clang/AST/Expr.h"

#include "clang/AST/DeclTemplate.h"

#include "clang/Basic/SourceLocation.h"

#include "llvm/ADT/PointerUnion.h"

#include "llvm/ADT/SmallVector.h"

#include <optional>

#include <string>

#include <utility>

namespace clang {

class Sema;

struct AtomicConstraint {

  const Expr *ConstraintExpr;

  std::optional<ArrayRef<TemplateArgumentLoc>> ParameterMapping;

  AtomicConstraint(Sema &S, const Expr *ConstraintExpr) :

      ConstraintExpr(ConstraintExpr) { };

  bool hasMatchingParameterMapping(ASTContext &C,

                                   const AtomicConstraint &Other) const {

    if (!ParameterMapping != !Other.ParameterMapping)

      return false;

    if (!ParameterMapping)

      return true;

    if (ParameterMapping->size() != Other.ParameterMapping->size())

      return false;

    for (unsigned I = 0, S = ParameterMapping->size(); I < S; ++I) {

      llvm::FoldingSetNodeID IDA, IDB;

      C.getCanonicalTemplateArgument((*ParameterMapping)[I].getArgument())

          .Profile(IDA, C);

      C.getCanonicalTemplateArgument((*Other.ParameterMapping)[I].getArgument())

          .Profile(IDB, C);

      if (IDA != IDB)

        return false;

    }

    return true;

  }

  bool subsumes(ASTContext &C, const AtomicConstraint &Other) const {

    // C++ [temp.constr.order] p2

    //   - an atomic constraint A subsumes another atomic constraint B

    //     if and only if the A and B are identical [...]

    //

    // C++ [temp.constr.atomic] p2

    //   Two atomic constraints are identical if they are formed from the

    //   same expression and the targets of the parameter mappings are

    //   equivalent according to the rules for expressions [...]

    // We do not actually substitute the parameter mappings into the

    // constraint expressions, therefore the constraint expressions are

    // the originals, and comparing them will suffice.

    if (ConstraintExpr != Other.ConstraintExpr)

      return false;

    // Check that the parameter lists are identical

    return hasMatchingParameterMapping(C, Other);

  }

};

/// \brief A normalized constraint, as defined in C++ [temp.constr.normal], is

/// either an atomic constraint, a conjunction of normalized constraints or a

/// disjunction of normalized constraints.

struct NormalizedConstraint {

  friend class Sema;

  enum CompoundConstraintKind { CCK_Conjunction, CCK_Disjunction };

  using CompoundConstraint = llvm::PointerIntPair<

      std::pair<NormalizedConstraint, NormalizedConstraint> *, 1,

      CompoundConstraintKind>;

  llvm::PointerUnion<AtomicConstraint *, CompoundConstraint> Constraint;

  NormalizedConstraint(AtomicConstraint *C): Constraint{C} { };

  NormalizedConstraint(ASTContext &C, NormalizedConstraint LHS,

                       NormalizedConstraint RHS, CompoundConstraintKind Kind)

      : Constraint{CompoundConstraint{

            new (C) std::pair<NormalizedConstraint, NormalizedConstraint>{

                std::move(LHS), std::move(RHS)}, Kind}} { };

  NormalizedConstraint(ASTContext &C, const NormalizedConstraint &Other) {

    if (Other.isAtomic()) {

      Constraint = new (C) AtomicConstraint(*Other.getAtomicConstraint());

    } else {

      Constraint = CompoundConstraint(

          new (C) std::pair<NormalizedConstraint, NormalizedConstraint>{

              NormalizedConstraint(C, Other.getLHS()),

              NormalizedConstraint(C, Other.getRHS())},

              Other.getCompoundKind());

    }

  }

  NormalizedConstraint(NormalizedConstraint &&Other):

      Constraint(Other.Constraint) {

    Other.Constraint = nullptr;

  }

  NormalizedConstraint &operator=(const NormalizedConstraint &Other) = delete;

  NormalizedConstraint &operator=(NormalizedConstraint &&Other) {

    if (&Other != this) {

      NormalizedConstraint Temp(std::move(Other));

      std::swap(Constraint, Temp.Constraint);

    }

    return *this;

  }

  CompoundConstraintKind getCompoundKind() const {

    assert(!isAtomic() && "getCompoundKind called on atomic constraint.");

    return Constraint.get<CompoundConstraint>().getInt();

  }

  bool isAtomic() const { return Constraint.is<AtomicConstraint *>(); }

  NormalizedConstraint &getLHS() const {

    assert(!isAtomic() && "getLHS called on atomic constraint.");

    return Constraint.get<CompoundConstraint>().getPointer()->first;

  }

  NormalizedConstraint &getRHS() const {

    assert(!isAtomic() && "getRHS called on atomic constraint.");

    return Constraint.get<CompoundConstraint>().getPointer()->second;

  }

  AtomicConstraint *getAtomicConstraint() const {

    assert(isAtomic() &&

           "getAtomicConstraint called on non-atomic constraint.");

    return Constraint.get<AtomicConstraint *>();

  }

private:

  static std::optional<NormalizedConstraint>

  fromConstraintExprs(Sema &S, NamedDecl *D, ArrayRef<const Expr *> E);

  static std::optional<NormalizedConstraint>

  fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E);

};

} // clang

#endif // LLVM_CLANG_SEMA_SEMACONCEPT_H