llvm/clang/include/clang/ASTMatchers/Dynamic/VariantValue.h

//===--- VariantValue.h - Polymorphic value type ----------------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Polymorphic value type.
///
/// Supports all the types required for dynamic Matcher construction.
///  Used by the registry to construct matchers in a generic way.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_ASTMATCHERS_DYNAMIC_VARIANTVALUE_H
#define LLVM_CLANG_ASTMATCHERS_DYNAMIC_VARIANTVALUE_H

#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/ASTMatchers/ASTMatchersInternal.h"
#include "llvm/ADT/IntrusiveRefCntPtr.h"
#include <memory>
#include <optional>
#include <vector>

namespace clang {
namespace ast_matchers {
namespace dynamic {

/// Kind identifier.
///
/// It supports all types that VariantValue can contain.
class ArgKind { … };

DynTypedMatcher;

/// A variant matcher object.
///
/// The purpose of this object is to abstract simple and polymorphic matchers
/// into a single object type.
/// Polymorphic matchers might be implemented as a list of all the possible
/// overloads of the matcher. \c VariantMatcher knows how to select the
/// appropriate overload when needed.
/// To get a real matcher object out of a \c VariantMatcher you can do:
///  - getSingleMatcher() which returns a matcher, only if it is not ambiguous
///    to decide which matcher to return. Eg. it contains only a single
///    matcher, or a polymorphic one with only one overload.
///  - hasTypedMatcher<T>()/getTypedMatcher<T>(): These calls will determine if
///    the underlying matcher(s) can unambiguously return a Matcher<T>.
class VariantMatcher { … };

/// Variant value class.
///
/// Basically, a tagged union with value type semantics.
/// It is used by the registry as the return value and argument type for the
/// matcher factory methods.
/// It can be constructed from any of the supported types. It supports
/// copy/assignment.
///
/// Supported types:
///  - \c bool
//   - \c double
///  - \c unsigned
///  - \c llvm::StringRef
///  - \c VariantMatcher (\c DynTypedMatcher / \c Matcher<T>)
class VariantValue { … };

} // end namespace dynamic
} // end namespace ast_matchers
} // end namespace clang

#endif // LLVM_CLANG_ASTMATCHERS_DYNAMIC_VARIANTVALUE_H