// 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
//
// This is an X-macro header. It does not use `#include` guards, and instead is
// designed to be `#include`ed after the x-macro is defined in order for its
// inclusion to expand to the desired output. Macro definitions are cleaned up
// at the end of this file.
//
// Supported x-macros are:
// - CARBON_SEMANTICS_BUILTIN_KIND_NAME(Name)
//   Used as a fallback if other macros are missing. Used directly by Invalid
//   only, which is defined last.
//   - CARBON_SEMANTICS_BUILTIN_KIND(Name, Type, Label)
//     Defines a builtin kind with the associated type, which must also be
//     builtin.
//
// This tree represents the subset relationship between these macros, where if a
// specific x-macro isn't defined, it'll fall back to the parent macro.

#if !(defined(CARBON_SEMANTICS_BUILTIN_KIND_NAME) || \
      defined(CARBON_SEMANTICS_BUILTIN_KIND))
#error \
    "Must define CARBON_SEMANTICS_BUILTIN_KIND family x-macros to use this file."
#endif

// If CARBON_SEMANTICS_BUILTIN_KIND_NAME is undefined, ignore calls.
#ifndef CARBON_SEMANTICS_BUILTIN_KIND_NAME
#define CARBON_SEMANTICS_BUILTIN_KIND_NAME(Name)
#endif

// If CARBON_SEMANTICS_BUILTIN_KIND is undefined, delegate calls to
// CARBON_SEMANTICS_BUILTIN_KIND_NAME.
#ifndef CARBON_SEMANTICS_BUILTIN_KIND
#define CARBON_SEMANTICS_BUILTIN_KIND(Name, ...) \
  CARBON_SEMANTICS_BUILTIN_KIND_NAME(Name)
#endif

// Tracks expressions which are valid as types.
// This has a deliberately self-referential type.
CARBON_SEMANTICS_BUILTIN_KIND(TypeType, TypeType, "Type")

// Used when a SemanticNode has an invalid type, which should then be ignored
// for future type checking.
// This has a deliberately self-referential type.
CARBON_SEMANTICS_BUILTIN_KIND(InvalidType, InvalidType, "<unknown>")

// -----------------------------------------------------------------------------
// TODO: Below types are all placeholders. While the above may last, the below
// are expected to need to change in order to better reflect Carbon's design.
// Keeping distinct placeholders can help find usages for later fixes.
// -----------------------------------------------------------------------------

// The type of integer values and integer literals, currently always i32.
CARBON_SEMANTICS_BUILTIN_KIND(IntegerType, TypeType, "i32")

// The type of floating point values and real literals, currently always f64.
CARBON_SEMANTICS_BUILTIN_KIND(FloatingPointType, TypeType, "f64")

// The type of string values and String literals.
CARBON_SEMANTICS_BUILTIN_KIND(StringType, TypeType, "String")

// The canonical empty struct type.
CARBON_SEMANTICS_BUILTIN_KIND(EmptyStructType, TypeType, "{} as Type")

// The canonical empty struct.
CARBON_SEMANTICS_BUILTIN_KIND(EmptyStruct, EmptyStructType, "{}")

// The canonical empty tuple type.
CARBON_SEMANTICS_BUILTIN_KIND(EmptyTupleType, TypeType, "() as Type")

// The canonical empty tuple.
CARBON_SEMANTICS_BUILTIN_KIND(EmptyTuple, EmptyTupleType, "()")

// Keep invalid last, so that we can use values as array indices without needing
// an invalid entry.
CARBON_SEMANTICS_BUILTIN_KIND_NAME(Invalid)

#undef CARBON_SEMANTICS_BUILTIN_KIND_NAME
#undef CARBON_SEMANTICS_BUILTIN_KIND