// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#ifndef CARBON_TOOLCHAIN_BASE_VALUE_IDS_H_
#define CARBON_TOOLCHAIN_BASE_VALUE_IDS_H_

#include "common/check.h"
#include "common/ostream.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/YAMLParser.h"
#include "toolchain/base/index_base.h"

namespace Carbon {

// The value of a real literal token.
//
// This is either a dyadic fraction (mantissa * 2^exponent) or a decadic
// fraction (mantissa * 10^exponent).
//
// These values are not canonicalized, because we don't expect them to repeat.
// We use RealIds in SemIR::FloatLiteralValues, and this results in all real
// literals being distinct constants, even if they represent the same value.
// TODO: Address this by using a different representation in SemIR.
struct Real : public Printable<Real> {
  auto Print(llvm::raw_ostream& output_stream) const -> void {
    mantissa.print(output_stream, /*isSigned=*/false);
    output_stream << "*" << (is_decimal ? "10" : "2") << "^" << exponent;
  }

  // The mantissa, represented as an unsigned integer.
  llvm::APInt mantissa;

  // The exponent, represented as a signed integer.
  llvm::APInt exponent;

  // If false, the value is mantissa * 2^exponent.
  // If true, the value is mantissa * 10^exponent.
  // TODO: This field increases Real from 32 bytes to 40 bytes. Consider
  // changing how it's tracked for space savings.
  bool is_decimal;
};

// Corresponds to a float value represented by an APFloat. This is used for
// floating-point values in SemIR.
struct FloatId : public IdBase<FloatId> {
  static constexpr llvm::StringLiteral Label = "float";
  static const FloatId None;
  using IdBase::IdBase;
};
constexpr FloatId FloatId::None(FloatId::NoneIndex);

// Corresponds to a Real value.
struct RealId : public IdBase<RealId> {
  // TODO: We don't use Diagnostics::TypeInfo here for layering reasons.
  struct DiagnosticType {
    using StorageType = std::string;
  };

  static constexpr llvm::StringLiteral Label = "real";
  static const RealId None;
  using IdBase::IdBase;
};
constexpr RealId RealId::None(RealId::NoneIndex);

// Corresponds to StringRefs for identifiers.
//
// `NameId` relies on the values of this type other than `None` all being
// non-negative.
struct IdentifierId : public IdBase<IdentifierId> {
  static constexpr llvm::StringLiteral Label = "identifier";
  static const IdentifierId None;
  using IdBase::IdBase;
};
constexpr IdentifierId IdentifierId::None(IdentifierId::NoneIndex);

// The name of a package, which is either an identifier or the special `Core`
// package name.
//
// TODO: Consider also treating `Main` and `Cpp` as special package names.
struct PackageNameId : public IdBase<PackageNameId> {
  static constexpr llvm::StringLiteral Label = "package";
  static const PackageNameId None;
  static const PackageNameId Core;

  // Returns the PackageNameId corresponding to a particular IdentifierId.
  static auto ForIdentifier(IdentifierId id) -> PackageNameId {
    return PackageNameId(id.index);
  }

  using IdBase::IdBase;

  // Returns the IdentifierId corresponding to this PackageNameId, or `None` if
  // this is a special package name.
  auto AsIdentifierId() const -> IdentifierId {
    return index >= 0 ? IdentifierId(index) : IdentifierId::None;
  }

  // Returns the special package name corresponding to this PackageNameId.
  // Requires that this name is not an identifier name.
  auto AsSpecialName() const -> llvm::StringLiteral {
    if (*this == None) {
      return "Main";
    }
    if (*this == Core) {
      return "Core";
    }
    CARBON_FATAL("Unknown special package name kind {0}", *this);
  }
};
constexpr PackageNameId PackageNameId::None(PackageNameId::NoneIndex);
constexpr PackageNameId PackageNameId::Core(PackageNameId::NoneIndex - 1);

// Corresponds to StringRefs for string literals.
struct StringLiteralValueId : public IdBase<StringLiteralValueId> {
  static constexpr llvm::StringLiteral Label = "string";
  static const StringLiteralValueId None;
  using IdBase::IdBase;
};
constexpr StringLiteralValueId StringLiteralValueId::None(
    StringLiteralValueId::NoneIndex);

}  // namespace Carbon

#endif  // CARBON_TOOLCHAIN_BASE_VALUE_IDS_H_
