llvm/clang-tools-extra/clangd/FeatureModule.h

//===--- FeatureModule.h - Plugging features into clangd ----------*-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
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_FEATUREMODULE_H
#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_FEATUREMODULE_H

#include "support/Function.h"
#include "support/Threading.h"
#include "clang/Basic/Diagnostic.h"
#include "llvm/ADT/FunctionExtras.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/JSON.h"
#include <memory>
#include <optional>
#include <type_traits>
#include <vector>

namespace clang {
class CompilerInstance;
namespace clangd {
struct Diag;
class LSPBinder;
class SymbolIndex;
class ThreadsafeFS;
class TUScheduler;
class Tweak;

/// A FeatureModule contributes a vertical feature to clangd.
///
/// The lifetime of a module is roughly:
///  - feature modules are created before the LSP server, in ClangdMain.cpp
///  - these modules are then passed to ClangdLSPServer in a FeatureModuleSet
///  - initializeLSP() is called when the editor calls initialize.
//   - initialize() is then called by ClangdServer as it is constructed.
///  - module hooks can be called by the server at this point.
///    Server facilities (scheduler etc) are available.
///  - ClangdServer will not be destroyed until all the requests are done.
///    FIXME: Block server shutdown until all the modules are idle.
///  - When shutting down, ClangdServer will wait for all requests to
///    finish, call stop(), and then blockUntilIdle().
///  - feature modules will be destroyed after ClangdLSPServer is destroyed.
///
/// FeatureModules are not threadsafe in general. A module's entrypoints are:
///   - method handlers registered in initializeLSP()
///   - public methods called directly via ClangdServer.featureModule<T>()->...
///   - specific overridable "hook" methods inherited from FeatureModule
/// Unless otherwise specified, these are only called on the main thread.
///
/// Conventionally, standard feature modules live in the `clangd` namespace,
/// and other exposed details live in a sub-namespace.
class FeatureModule { … };

/// A FeatureModuleSet is a collection of feature modules installed in clangd.
///
/// Modules can be looked up by type, or used via the FeatureModule interface.
/// This allows individual modules to expose a public API.
/// For this reason, there can be only one feature module of each type.
///
/// The set owns the modules. It is itself owned by main, not ClangdServer.
class FeatureModuleSet { … };

template <typename Mod> int FeatureModuleSet::ID<Mod>::Key;

} // namespace clangd
} // namespace clang
#endif