llvm/clang/include/clang/Interpreter/Value.h

//===--- Value.h - Definition of interpreter value --------------*- 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
//
//===----------------------------------------------------------------------===//
//
// Value is a lightweight struct that is used for carrying execution results in
// clang-repl. It's a special runtime that acts like a messager between compiled
// code and interpreted code. This makes it possible to exchange interesting
// information between the compiled & interpreted world.
//
// A typical usage is like the below:
//
// Value V;
// Interp.ParseAndExecute("int x = 42;");
// Interp.ParseAndExecute("x", &V);
// V.getType(); // <-- Yields a clang::QualType.
// V.getInt(); // <-- Yields 42.
//
// The current design is still highly experimental and nobody should rely on the
// API being stable because we're hopefully going to make significant changes to
// it in the relatively near future. For example, Value also intends to be used
// as an exchange token for JIT support enabling remote execution on the embed
// devices where the JIT infrastructure cannot fit. To support that we will need
// to split the memory storage in a different place and perhaps add a resource
// header is similar to intrinsics headers which have stricter performance
// constraints.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_INTERPRETER_VALUE_H
#define LLVM_CLANG_INTERPRETER_VALUE_H

#include "llvm/Support/Compiler.h"
#include <cstdint>

// NOTE: Since the REPL itself could also include this runtime, extreme caution
// should be taken when MAKING CHANGES to this file, especially when INCLUDE NEW
// HEADERS, like <string>, <memory> and etc. (That pulls a large number of
// tokens and will impact the runtime performance of the REPL)

namespace llvm {
class raw_ostream;

} // namespace llvm

namespace clang {

class ASTContext;
class Interpreter;
class QualType;

#if defined(_WIN32)
// REPL_EXTERNAL_VISIBILITY are symbols that we need to be able to locate
// at runtime. On Windows, this requires them to be exported from any of the
// modules loaded at runtime. Marking them as dllexport achieves this; both
// for DLLs (that normally export symbols as part of their interface) and for
// EXEs (that normally don't export anything).
// For a build with libclang-cpp.dll, this doesn't make any difference - the
// functions would have been exported anyway. But for cases when these are
// statically linked into an EXE, it makes sure that they're exported.
#define REPL_EXTERNAL_VISIBILITY …
#elif __has_attribute(visibility)
#if defined(LLVM_BUILD_LLVM_DYLIB) || defined(LLVM_BUILD_SHARED_LIBS)
#define REPL_EXTERNAL_VISIBILITY …
#else
#define REPL_EXTERNAL_VISIBILITY
#endif
#else
#define REPL_EXTERNAL_VISIBILITY
#endif

#define REPL_BUILTIN_TYPES …

class REPL_EXTERNAL_VISIBILITY Value { … };

template <> inline void *Value::as() const { … }

} // namespace clang
#endif