//===- Constraint.h - Constraint class --------------------------*- 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
//
//===----------------------------------------------------------------------===//
//
// Constraint wrapper to simplify using TableGen Record for constraints.
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_TABLEGEN_CONSTRAINT_H_
#define MLIR_TABLEGEN_CONSTRAINT_H_

#include "mlir/Support/LLVM.h"
#include "mlir/TableGen/Predicate.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"

namespace llvm {
class Record;
} // namespace llvm

namespace mlir {
namespace tblgen {

// Wrapper class with helper methods for accessing Constraint defined in
// TableGen.
class Constraint {
public:
  // Constraint kind
  enum Kind {
    CK_Attr,
    CK_Prop,
    CK_Region,
    CK_Successor,
    CK_Type,
    CK_Uncategorized
  };

  // Create a constraint with a TableGen definition and a kind.
  Constraint(const llvm::Record *record, Kind kind) : def(record), kind(kind) {}
  // Create a constraint with a TableGen definition, and infer the kind.
  Constraint(const llvm::Record *record);

  /// Constraints are pointer-comparable.
  bool operator==(const Constraint &that) { return def == that.def; }
  bool operator!=(const Constraint &that) { return def != that.def; }

  // Returns the predicate for this constraint.
  Pred getPredicate() const;

  // Returns the condition template that can be used to check if a type or
  // attribute satisfies this constraint.  The template may contain "{0}" that
  // must be substituted with an expression returning an mlir::Type or
  // mlir::Attribute.
  std::string getConditionTemplate() const;

  // Returns the user-readable summary of this constraint. If the summary is not
  // provided, returns the TableGen def name.
  StringRef getSummary() const;

  // Returns the long-form description of this constraint. If the description is
  // not provided, returns an empty string.
  StringRef getDescription() const;

  /// Returns the name of the TablGen def of this constraint. In some cases
  /// where the current def is anonymous, the name of the base def is used (e.g.
  /// `std::optional<>`/`Variadic<>` type constraints).
  StringRef getDefName() const;

  /// Returns a unique name for the TablGen def of this constraint. This is
  /// generally just the name of the def, but in some cases where the current
  /// def is anonymous, the name of the base def is attached (to provide more
  /// context on the def).
  std::string getUniqueDefName() const;

  /// Returns the name of the C++ function that should be generated for this
  /// constraint, or std::nullopt if no C++ function should be generated.
  std::optional<StringRef> getCppFunctionName() const;

  Kind getKind() const { return kind; }

  /// Return the underlying def.
  const llvm::Record &getDef() const { return *def; }

protected:
  // The TableGen definition of this constraint.
  const llvm::Record *def;

private:
  /// Return the name of the base def if there is one, or std::nullopt
  /// otherwise.
  std::optional<StringRef> getBaseDefName() const;

  // What kind of constraint this is.
  Kind kind;
};

// An constraint and the concrete entities to place the constraint on.
struct AppliedConstraint {
  AppliedConstraint(Constraint &&constraint, StringRef self,
                    std::vector<std::string> &&entities);

  Constraint constraint;
  // The symbol to replace `$_self` special placeholder in the constraint.
  std::string self;
  // The symbols to replace `$N` positional placeholders in the constraint.
  std::vector<std::string> entities;
};

} // namespace tblgen
} // namespace mlir

namespace llvm {
/// Unique constraints by their predicate and summary. Constraints that share
/// the same predicate may have different descriptions; ensure that the
/// correct error message is reported when verification fails.
template <>
struct DenseMapInfo<mlir::tblgen::Constraint> {
  static unsigned getHashValue(mlir::tblgen::Constraint constraint);
  static bool isEqual(mlir::tblgen::Constraint lhs,
                      mlir::tblgen::Constraint rhs);
};
} // namespace llvm

#endif // MLIR_TABLEGEN_CONSTRAINT_H_