clang-tools-extra/clangd/ClangdServer.h - external/github.com/llvm/llvm-project.git - Git at Google

 //===--- ClangdServer.h - Main clangd server code ----------------*- 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_CLANGDSERVER_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_CLANGDSERVER_H

 #include "../clang-tidy/ClangTidyOptions.h"
 #include "CodeComplete.h"
 #include "ConfigProvider.h"
 #include "GlobalCompilationDatabase.h"
 #include "Hover.h"
 #include "Protocol.h"
 #include "SemanticHighlighting.h"
 #include "TUScheduler.h"
 #include "XRefs.h"
 #include "index/Background.h"
 #include "index/FileIndex.h"
 #include "index/Index.h"
 #include "refactor/Rename.h"
 #include "refactor/Tweak.h"
 #include "support/Cancellation.h"
 #include "support/Function.h"
 #include "support/ThreadsafeFS.h"
 #include "clang/Tooling/CompilationDatabase.h"
 #include "clang/Tooling/Core/Replacement.h"
 #include "llvm/ADT/FunctionExtras.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include <functional>
 #include <future>
 #include <string>
 #include <type_traits>
 #include <utility>

 namespace clang {
 namespace clangd {

 /// When set, used by ClangdServer to get clang-tidy options for each particular
 /// file. Must be thread-safe. We use this instead of ClangTidyOptionsProvider
 /// to allow reading tidy configs from the VFS used for parsing.
 using ClangTidyOptionsBuilder = std::function<tidy::ClangTidyOptions(
     llvm::vfs::FileSystem &, llvm::StringRef /*File*/)>;

 /// Manages a collection of source files and derived data (ASTs, indexes),
 /// and provides language-aware features such as code completion.
 ///
 /// The primary client is ClangdLSPServer which exposes these features via
 /// the Language Server protocol. ClangdServer may also be embedded directly,
 /// though its API is not stable over time.
 ///
 /// ClangdServer should be used from a single thread. Many potentially-slow
 /// operations have asynchronous APIs and deliver their results on another
 /// thread.
 /// Such operations support cancellation: if the caller sets up a cancelable
 /// context, many operations will notice cancellation and fail early.
 /// (ClangdLSPServer uses this to implement $/cancelRequest).
 class ClangdServer {
 public:
   /// Interface with hooks for users of ClangdServer to be notified of events.
   class Callbacks {
   public:
     virtual ~Callbacks() = default;

     /// Called by ClangdServer when \p Diagnostics for \p File are ready.
     /// May be called concurrently for separate files, not for a single file.
     virtual void onDiagnosticsReady(PathRef File, llvm::StringRef Version,
                                     std::vector<Diag> Diagnostics) {}
     /// Called whenever the file status is updated.
     /// May be called concurrently for separate files, not for a single file.
     virtual void onFileUpdated(PathRef File, const TUStatus &Status) {}

     /// Called by ClangdServer when some \p Highlightings for \p File are ready.
     /// May be called concurrently for separate files, not for a single file.
     virtual void
     onHighlightingsReady(PathRef File, llvm::StringRef Version,
                          std::vector<HighlightingToken> Highlightings) {}

     /// Called when background indexing tasks are enqueued/started/completed.
     /// Not called concurrently.
     virtual void
     onBackgroundIndexProgress(const BackgroundQueue::Stats &Stats) {}
   };

   struct Options {
     /// To process requests asynchronously, ClangdServer spawns worker threads.
     /// If this is zero, no threads are spawned. All work is done on the calling
     /// thread, and callbacks are invoked before "async" functions return.
     unsigned AsyncThreadsCount = getDefaultAsyncThreadsCount();

     /// AST caching policy. The default is to keep up to 3 ASTs in memory.
     ASTRetentionPolicy RetentionPolicy;

     /// Cached preambles are potentially large. If false, store them on disk.
     bool StorePreamblesInMemory = true;
     /// Reuse even stale preambles, and rebuild them in the background.
     /// This improves latency at the cost of accuracy.
     bool AsyncPreambleBuilds = true;

     /// If true, ClangdServer builds a dynamic in-memory index for symbols in
     /// opened files and uses the index to augment code completion results.
     bool BuildDynamicSymbolIndex = false;
     /// Use a heavier and faster in-memory index implementation.
     bool HeavyweightDynamicSymbolIndex = true;
     /// If true, ClangdServer automatically indexes files in the current project
     /// on background threads. The index is stored in the project root.
     bool BackgroundIndex = false;

     /// Store refs to main-file symbols in the index.
     bool CollectMainFileRefs = false;

     /// If set, use this index to augment code completion results.
     SymbolIndex *StaticIndex = nullptr;

     /// If set, queried to obtain the configuration to handle each request.
     config::Provider *ConfigProvider = nullptr;

     /// If set, enable clang-tidy in clangd and use to it get clang-tidy
     /// configurations for a particular file.
     /// Clangd supports only a small subset of ClangTidyOptions, these options
     /// (Checks, CheckOptions) are about which clang-tidy checks will be
     /// enabled.
     ClangTidyOptionsBuilder GetClangTidyOptions;

     /// If true, turn on the `-frecovery-ast` clang flag.
     bool BuildRecoveryAST = true;

     /// If true, turn on the `-frecovery-ast-type` clang flag.
     bool PreserveRecoveryASTType = false;

     /// Clangd's workspace root. Relevant for "workspace" operations not bound
     /// to a particular file.
     /// FIXME: If not set, should use the current working directory.
     llvm::Optional<std::string> WorkspaceRoot;

     /// The resource directory is used to find internal headers, overriding
     /// defaults and -resource-dir compiler flag).
     /// If None, ClangdServer calls CompilerInvocation::GetResourcePath() to
     /// obtain the standard resource directory.
     llvm::Optional<std::string> ResourceDir = llvm::None;

     /// Time to wait after a new file version before computing diagnostics.
     DebouncePolicy UpdateDebounce = DebouncePolicy{
         /*Min=*/std::chrono::milliseconds(50),
         /*Max=*/std::chrono::milliseconds(500),
         /*RebuildRatio=*/1,
     };

     bool SuggestMissingIncludes = false;

     /// Clangd will execute compiler drivers matching one of these globs to
     /// fetch system include path.
     std::vector<std::string> QueryDriverGlobs;

     /// Enable notification-based semantic highlighting.
     bool TheiaSemanticHighlighting = false;

     /// Enable preview of FoldingRanges feature.
     bool FoldingRanges = false;

     /// Returns true if the tweak should be enabled.
     std::function<bool(const Tweak &)> TweakFilter = [](const Tweak &T) {
       return !T.hidden(); // only enable non-hidden tweaks.
     };

     explicit operator TUScheduler::Options() const;
   };
   // Sensible default options for use in tests.
   // Features like indexing must be enabled if desired.
   static Options optsForTest();

   /// Creates a new ClangdServer instance.
   ///
   /// ClangdServer uses \p CDB to obtain compilation arguments for parsing. Note
   /// that ClangdServer only obtains compilation arguments once for each newly
   /// added file (i.e., when processing a first call to addDocument) and reuses
   /// those arguments for subsequent reparses. However, ClangdServer will check
   /// if compilation arguments changed on calls to forceReparse().
   ClangdServer(const GlobalCompilationDatabase &CDB, const ThreadsafeFS &TFS,
                const Options &Opts, Callbacks *Callbacks = nullptr);

   /// Add a \p File to the list of tracked C++ files or update the contents if
   /// \p File is already tracked. Also schedules parsing of the AST for it on a
   /// separate thread. When the parsing is complete, DiagConsumer passed in
   /// constructor will receive onDiagnosticsReady callback.
   /// Version identifies this snapshot and is propagated to ASTs, preambles,
   /// diagnostics etc built from it.
   void addDocument(PathRef File, StringRef Contents,
                    llvm::StringRef Version = "null",
                    WantDiagnostics WD = WantDiagnostics::Auto,
                    bool ForceRebuild = false);

   /// Remove \p File from list of tracked files, schedule a request to free
   /// resources associated with it. Pending diagnostics for closed files may not
   /// be delivered, even if requested with WantDiags::Auto or WantDiags::Yes.
   /// An empty set of diagnostics will be delivered, with Version = "".
   void removeDocument(PathRef File);

   /// Run code completion for \p File at \p Pos.
   /// Request is processed asynchronously.
   ///
   /// This method should only be called for currently tracked files. However, it
   /// is safe to call removeDocument for \p File after this method returns, even
   /// while returned future is not yet ready.
   /// A version of `codeComplete` that runs \p Callback on the processing thread
   /// when codeComplete results become available.
   void codeComplete(PathRef File, Position Pos,
                     const clangd::CodeCompleteOptions &Opts,
                     Callback<CodeCompleteResult> CB);

   /// Provide signature help for \p File at \p Pos.  This method should only be
   /// called for tracked files.
   void signatureHelp(PathRef File, Position Pos, Callback<SignatureHelp> CB);

   /// Find declaration/definition locations of symbol at a specified position.
   void locateSymbolAt(PathRef File, Position Pos,
                       Callback<std::vector<LocatedSymbol>> CB);

   /// Switch to a corresponding source file when given a header file, and vice
   /// versa.
   void switchSourceHeader(PathRef Path,
                           Callback<llvm::Optional<clangd::Path>> CB);

   /// Get document highlights for a given position.
   void findDocumentHighlights(PathRef File, Position Pos,
                               Callback<std::vector<DocumentHighlight>> CB);

   /// Get code hover for a given position.
   void findHover(PathRef File, Position Pos,
                  Callback<llvm::Optional<HoverInfo>> CB);

   /// Get information about type hierarchy for a given position.
   void typeHierarchy(PathRef File, Position Pos, int Resolve,
                      TypeHierarchyDirection Direction,
                      Callback<llvm::Optional<TypeHierarchyItem>> CB);

   /// Resolve type hierarchy item in the given direction.
   void resolveTypeHierarchy(TypeHierarchyItem Item, int Resolve,
                             TypeHierarchyDirection Direction,
                             Callback<llvm::Optional<TypeHierarchyItem>> CB);

   /// Retrieve the top symbols from the workspace matching a query.
   void workspaceSymbols(StringRef Query, int Limit,
                         Callback<std::vector<SymbolInformation>> CB);

   /// Retrieve the symbols within the specified file.
   void documentSymbols(StringRef File,
                        Callback<std::vector<DocumentSymbol>> CB);

   /// Retrieve ranges that can be used to fold code within the specified file.
   void foldingRanges(StringRef File, Callback<std::vector<FoldingRange>> CB);

   /// Retrieve locations for symbol references.
   void findReferences(PathRef File, Position Pos, uint32_t Limit,
                       Callback<ReferencesResult> CB);

   /// Run formatting for \p Rng inside \p File with content \p Code.
   void formatRange(PathRef File, StringRef Code, Range Rng,
                    Callback<tooling::Replacements> CB);

   /// Run formatting for the whole \p File with content \p Code.
   void formatFile(PathRef File, StringRef Code,
                   Callback<tooling::Replacements> CB);

   /// Run formatting after \p TriggerText was typed at \p Pos in \p File with
   /// content \p Code.
   void formatOnType(PathRef File, StringRef Code, Position Pos,
                     StringRef TriggerText, Callback<std::vector<TextEdit>> CB);

   /// Test the validity of a rename operation.
   void prepareRename(PathRef File, Position Pos,
                      const RenameOptions &RenameOpts,
                      Callback<llvm::Optional<Range>> CB);

   /// Rename all occurrences of the symbol at the \p Pos in \p File to
   /// \p NewName.
   /// If WantFormat is false, the final TextEdit will be not formatted,
   /// embedders could use this method to get all occurrences of the symbol (e.g.
   /// highlighting them in prepare stage).
   void rename(PathRef File, Position Pos, llvm::StringRef NewName,
               const RenameOptions &Opts, Callback<FileEdits> CB);

   struct TweakRef {
     std::string ID;    /// ID to pass for applyTweak.
     std::string Title; /// A single-line message to show in the UI.
     Tweak::Intent Intent;
   };
   /// Enumerate the code tweaks available to the user at a specified point.
   void enumerateTweaks(PathRef File, Range Sel,
                        Callback<std::vector<TweakRef>> CB);

   /// Apply the code tweak with a specified \p ID.
   void applyTweak(PathRef File, Range Sel, StringRef ID,
                   Callback<Tweak::Effect> CB);

   /// Called when an event occurs for a watched file in the workspace.
   void onFileEvent(const DidChangeWatchedFilesParams &Params);

   /// Get symbol info for given position.
   /// Clangd extension - not part of official LSP.
   void symbolInfo(PathRef File, Position Pos,
                   Callback<std::vector<SymbolDetails>> CB);

   /// Get semantic ranges around a specified position in a file.
   void semanticRanges(PathRef File, const std::vector<Position> &Pos,
                       Callback<std::vector<SelectionRange>> CB);

   /// Get all document links in a file.
   void documentLinks(PathRef File, Callback<std::vector<DocumentLink>> CB);

   void semanticHighlights(PathRef File,
                           Callback<std::vector<HighlightingToken>>);

   /// Runs an arbitrary action that has access to the AST of the specified file.
   /// The action will execute on one of ClangdServer's internal threads.
   /// The AST is only valid for the duration of the callback.
   /// As with other actions, the file must have been opened.
   void customAction(PathRef File, llvm::StringRef Name,
                     Callback<InputsAndAST> Action);

   /// Returns estimated memory usage and other statistics for each of the
   /// currently open files.
   /// Overall memory usage of clangd may be significantly more than reported
   /// here, as this metric does not account (at least) for:
   ///   - memory occupied by static and dynamic index,
   ///   - memory required for in-flight requests,
   /// FIXME: those metrics might be useful too, we should add them.
   llvm::StringMap<TUScheduler::FileStats> fileStats() const;

   // Blocks the main thread until the server is idle. Only for use in tests.
   // Returns false if the timeout expires.
   LLVM_NODISCARD bool
   blockUntilIdleForTest(llvm::Optional<double> TimeoutSeconds = 10);

 private:
   void formatCode(PathRef File, llvm::StringRef Code,
                   ArrayRef<tooling::Range> Ranges,
                   Callback<tooling::Replacements> CB);

   /// Derives a context for a task processing the specified source file.
   /// This includes the current configuration (see Options::ConfigProvider).
   /// The empty string means no particular file is the target.
   /// Rather than called by each feature, this is exposed to the components
   /// that control worker threads, like TUScheduler and BackgroundIndex.
   /// This means it's OK to do some IO here, and it cuts across all features.
   Context createProcessingContext(PathRef) const;
   config::Provider *ConfigProvider = nullptr;

   const ThreadsafeFS &TFS;

   Path ResourceDir;
   // The index used to look up symbols. This could be:
   //   - null (all index functionality is optional)
   //   - the dynamic index owned by ClangdServer (DynamicIdx)
   //   - the static index passed to the constructor
   //   - a merged view of a static and dynamic index (MergedIndex)
   const SymbolIndex *Index = nullptr;
   // If present, an index of symbols in open files. Read via *Index.
   std::unique_ptr<FileIndex> DynamicIdx;
   // If present, the new "auto-index" maintained in background threads.
   std::unique_ptr<BackgroundIndex> BackgroundIdx;
   // Storage for merged views of the various indexes.
   std::vector<std::unique_ptr<SymbolIndex>> MergedIdx;

   // When set, provides clang-tidy options for a specific file.
   ClangTidyOptionsBuilder GetClangTidyOptions;

   // If this is true, suggest include insertion fixes for diagnostic errors that
   // can be caused by missing includes (e.g. member access in incomplete type).
   bool SuggestMissingIncludes = false;

   // If true, preserve expressions in AST for broken code.
   bool BuildRecoveryAST = true;
   // If true, preserve the type for recovery AST.
   bool PreserveRecoveryASTType = false;

   std::function<bool(const Tweak &)> TweakFilter;

   // GUARDED_BY(CachedCompletionFuzzyFindRequestMutex)
   llvm::StringMap<llvm::Optional<FuzzyFindRequest>>
       CachedCompletionFuzzyFindRequestByFile;
   mutable std::mutex CachedCompletionFuzzyFindRequestMutex;

   llvm::Optional<std::string> WorkspaceRoot;
   // WorkScheduler has to be the last member, because its destructor has to be
   // called before all other members to stop the worker thread that references
   // ClangdServer.
   TUScheduler WorkScheduler;
 };

 } // namespace clangd
 } // namespace clang

 #endif
	//===--- ClangdServer.h - Main clangd server code ----------------- 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_CLANGDSERVER_H
	#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_CLANGDSERVER_H

	#include "../clang-tidy/ClangTidyOptions.h"
	#include "CodeComplete.h"
	#include "ConfigProvider.h"
	#include "GlobalCompilationDatabase.h"
	#include "Hover.h"
	#include "Protocol.h"
	#include "SemanticHighlighting.h"
	#include "TUScheduler.h"
	#include "XRefs.h"
	#include "index/Background.h"
	#include "index/FileIndex.h"
	#include "index/Index.h"
	#include "refactor/Rename.h"
	#include "refactor/Tweak.h"
	#include "support/Cancellation.h"
	#include "support/Function.h"
	#include "support/ThreadsafeFS.h"
	#include "clang/Tooling/CompilationDatabase.h"
	#include "clang/Tooling/Core/Replacement.h"
	#include "llvm/ADT/FunctionExtras.h"
	#include "llvm/ADT/IntrusiveRefCntPtr.h"
	#include "llvm/ADT/Optional.h"
	#include "llvm/ADT/StringRef.h"
	#include <functional>
	#include <future>
	#include <string>
	#include <type_traits>
	#include <utility>

	namespace clang {
	namespace clangd {

	/// When set, used by ClangdServer to get clang-tidy options for each particular
	/// file. Must be thread-safe. We use this instead of ClangTidyOptionsProvider
	/// to allow reading tidy configs from the VFS used for parsing.
	using ClangTidyOptionsBuilder = std::function<tidy::ClangTidyOptions(
	llvm::vfs::FileSystem &, llvm::StringRef /File/)>;

	/// Manages a collection of source files and derived data (ASTs, indexes),
	/// and provides language-aware features such as code completion.
	///
	/// The primary client is ClangdLSPServer which exposes these features via
	/// the Language Server protocol. ClangdServer may also be embedded directly,
	/// though its API is not stable over time.
	///
	/// ClangdServer should be used from a single thread. Many potentially-slow
	/// operations have asynchronous APIs and deliver their results on another
	/// thread.
	/// Such operations support cancellation: if the caller sets up a cancelable
	/// context, many operations will notice cancellation and fail early.
	/// (ClangdLSPServer uses this to implement $/cancelRequest).
	class ClangdServer {
	public:
	/// Interface with hooks for users of ClangdServer to be notified of events.
	class Callbacks {
	public:
	virtual ~Callbacks() = default;

	/// Called by ClangdServer when \p Diagnostics for \p File are ready.
	/// May be called concurrently for separate files, not for a single file.
	virtual void onDiagnosticsReady(PathRef File, llvm::StringRef Version,
	std::vector<Diag> Diagnostics) {}
	/// Called whenever the file status is updated.
	/// May be called concurrently for separate files, not for a single file.
	virtual void onFileUpdated(PathRef File, const TUStatus &Status) {}

	/// Called by ClangdServer when some \p Highlightings for \p File are ready.
	/// May be called concurrently for separate files, not for a single file.
	virtual void
	onHighlightingsReady(PathRef File, llvm::StringRef Version,
	std::vector<HighlightingToken> Highlightings) {}

	/// Called when background indexing tasks are enqueued/started/completed.
	/// Not called concurrently.
	virtual void
	onBackgroundIndexProgress(const BackgroundQueue::Stats &Stats) {}
	};

	struct Options {
	/// To process requests asynchronously, ClangdServer spawns worker threads.
	/// If this is zero, no threads are spawned. All work is done on the calling
	/// thread, and callbacks are invoked before "async" functions return.
	unsigned AsyncThreadsCount = getDefaultAsyncThreadsCount();

	/// AST caching policy. The default is to keep up to 3 ASTs in memory.
	ASTRetentionPolicy RetentionPolicy;

	/// Cached preambles are potentially large. If false, store them on disk.
	bool StorePreamblesInMemory = true;
	/// Reuse even stale preambles, and rebuild them in the background.
	/// This improves latency at the cost of accuracy.
	bool AsyncPreambleBuilds = true;

	/// If true, ClangdServer builds a dynamic in-memory index for symbols in
	/// opened files and uses the index to augment code completion results.
	bool BuildDynamicSymbolIndex = false;
	/// Use a heavier and faster in-memory index implementation.
	bool HeavyweightDynamicSymbolIndex = true;
	/// If true, ClangdServer automatically indexes files in the current project
	/// on background threads. The index is stored in the project root.
	bool BackgroundIndex = false;

	/// Store refs to main-file symbols in the index.
	bool CollectMainFileRefs = false;

	/// If set, use this index to augment code completion results.
	SymbolIndex *StaticIndex = nullptr;

	/// If set, queried to obtain the configuration to handle each request.
	config::Provider *ConfigProvider = nullptr;

	/// If set, enable clang-tidy in clangd and use to it get clang-tidy
	/// configurations for a particular file.
	/// Clangd supports only a small subset of ClangTidyOptions, these options
	/// (Checks, CheckOptions) are about which clang-tidy checks will be
	/// enabled.
	ClangTidyOptionsBuilder GetClangTidyOptions;

	/// If true, turn on the `-frecovery-ast` clang flag.
	bool BuildRecoveryAST = true;

	/// If true, turn on the `-frecovery-ast-type` clang flag.
	bool PreserveRecoveryASTType = false;

	/// Clangd's workspace root. Relevant for "workspace" operations not bound
	/// to a particular file.
	/// FIXME: If not set, should use the current working directory.
	llvm::Optional<std::string> WorkspaceRoot;

	/// The resource directory is used to find internal headers, overriding
	/// defaults and -resource-dir compiler flag).
	/// If None, ClangdServer calls CompilerInvocation::GetResourcePath() to
	/// obtain the standard resource directory.
	llvm::Optional<std::string> ResourceDir = llvm::None;

	/// Time to wait after a new file version before computing diagnostics.
	DebouncePolicy UpdateDebounce = DebouncePolicy{
	/Min=/std::chrono::milliseconds(50),
	/Max=/std::chrono::milliseconds(500),
	/RebuildRatio=/1,
	};

	bool SuggestMissingIncludes = false;

	/// Clangd will execute compiler drivers matching one of these globs to
	/// fetch system include path.
	std::vector<std::string> QueryDriverGlobs;

	/// Enable notification-based semantic highlighting.
	bool TheiaSemanticHighlighting = false;

	/// Enable preview of FoldingRanges feature.
	bool FoldingRanges = false;

	/// Returns true if the tweak should be enabled.
	std::function<bool(const Tweak &)> TweakFilter = [](const Tweak &T) {
	return !T.hidden(); // only enable non-hidden tweaks.
	};

	explicit operator TUScheduler::Options() const;
	};
	// Sensible default options for use in tests.
	// Features like indexing must be enabled if desired.
	static Options optsForTest();

	/// Creates a new ClangdServer instance.
	///
	/// ClangdServer uses \p CDB to obtain compilation arguments for parsing. Note
	/// that ClangdServer only obtains compilation arguments once for each newly
	/// added file (i.e., when processing a first call to addDocument) and reuses
	/// those arguments for subsequent reparses. However, ClangdServer will check
	/// if compilation arguments changed on calls to forceReparse().
	ClangdServer(const GlobalCompilationDatabase &CDB, const ThreadsafeFS &TFS,
	const Options &Opts, Callbacks *Callbacks = nullptr);

	/// Add a \p File to the list of tracked C++ files or update the contents if
	/// \p File is already tracked. Also schedules parsing of the AST for it on a
	/// separate thread. When the parsing is complete, DiagConsumer passed in
	/// constructor will receive onDiagnosticsReady callback.
	/// Version identifies this snapshot and is propagated to ASTs, preambles,
	/// diagnostics etc built from it.
	void addDocument(PathRef File, StringRef Contents,
	llvm::StringRef Version = "null",
	WantDiagnostics WD = WantDiagnostics::Auto,
	bool ForceRebuild = false);

	/// Remove \p File from list of tracked files, schedule a request to free
	/// resources associated with it. Pending diagnostics for closed files may not
	/// be delivered, even if requested with WantDiags::Auto or WantDiags::Yes.
	/// An empty set of diagnostics will be delivered, with Version = "".
	void removeDocument(PathRef File);

	/// Run code completion for \p File at \p Pos.
	/// Request is processed asynchronously.
	///
	/// This method should only be called for currently tracked files. However, it
	/// is safe to call removeDocument for \p File after this method returns, even
	/// while returned future is not yet ready.
	/// A version of `codeComplete` that runs \p Callback on the processing thread
	/// when codeComplete results become available.
	void codeComplete(PathRef File, Position Pos,
	const clangd::CodeCompleteOptions &Opts,
	Callback<CodeCompleteResult> CB);

	/// Provide signature help for \p File at \p Pos. This method should only be
	/// called for tracked files.
	void signatureHelp(PathRef File, Position Pos, Callback<SignatureHelp> CB);

	/// Find declaration/definition locations of symbol at a specified position.
	void locateSymbolAt(PathRef File, Position Pos,
	Callback<std::vector<LocatedSymbol>> CB);

	/// Switch to a corresponding source file when given a header file, and vice
	/// versa.
	void switchSourceHeader(PathRef Path,
	Callback<llvm::Optional<clangd::Path>> CB);

	/// Get document highlights for a given position.
	void findDocumentHighlights(PathRef File, Position Pos,
	Callback<std::vector<DocumentHighlight>> CB);

	/// Get code hover for a given position.
	void findHover(PathRef File, Position Pos,
	Callback<llvm::Optional<HoverInfo>> CB);

	/// Get information about type hierarchy for a given position.
	void typeHierarchy(PathRef File, Position Pos, int Resolve,
	TypeHierarchyDirection Direction,
	Callback<llvm::Optional<TypeHierarchyItem>> CB);

	/// Resolve type hierarchy item in the given direction.
	void resolveTypeHierarchy(TypeHierarchyItem Item, int Resolve,
	TypeHierarchyDirection Direction,
	Callback<llvm::Optional<TypeHierarchyItem>> CB);

	/// Retrieve the top symbols from the workspace matching a query.
	void workspaceSymbols(StringRef Query, int Limit,
	Callback<std::vector<SymbolInformation>> CB);

	/// Retrieve the symbols within the specified file.
	void documentSymbols(StringRef File,
	Callback<std::vector<DocumentSymbol>> CB);

	/// Retrieve ranges that can be used to fold code within the specified file.
	void foldingRanges(StringRef File, Callback<std::vector<FoldingRange>> CB);

	/// Retrieve locations for symbol references.
	void findReferences(PathRef File, Position Pos, uint32_t Limit,
	Callback<ReferencesResult> CB);

	/// Run formatting for \p Rng inside \p File with content \p Code.
	void formatRange(PathRef File, StringRef Code, Range Rng,
	Callback<tooling::Replacements> CB);

	/// Run formatting for the whole \p File with content \p Code.
	void formatFile(PathRef File, StringRef Code,
	Callback<tooling::Replacements> CB);

	/// Run formatting after \p TriggerText was typed at \p Pos in \p File with
	/// content \p Code.
	void formatOnType(PathRef File, StringRef Code, Position Pos,
	StringRef TriggerText, Callback<std::vector<TextEdit>> CB);

	/// Test the validity of a rename operation.
	void prepareRename(PathRef File, Position Pos,
	const RenameOptions &RenameOpts,
	Callback<llvm::Optional<Range>> CB);

	/// Rename all occurrences of the symbol at the \p Pos in \p File to
	/// \p NewName.
	/// If WantFormat is false, the final TextEdit will be not formatted,
	/// embedders could use this method to get all occurrences of the symbol (e.g.
	/// highlighting them in prepare stage).
	void rename(PathRef File, Position Pos, llvm::StringRef NewName,
	const RenameOptions &Opts, Callback<FileEdits> CB);

	struct TweakRef {
	std::string ID; /// ID to pass for applyTweak.
	std::string Title; /// A single-line message to show in the UI.
	Tweak::Intent Intent;
	};
	/// Enumerate the code tweaks available to the user at a specified point.
	void enumerateTweaks(PathRef File, Range Sel,
	Callback<std::vector<TweakRef>> CB);

	/// Apply the code tweak with a specified \p ID.
	void applyTweak(PathRef File, Range Sel, StringRef ID,
	Callback<Tweak::Effect> CB);

	/// Called when an event occurs for a watched file in the workspace.
	void onFileEvent(const DidChangeWatchedFilesParams &Params);

	/// Get symbol info for given position.
	/// Clangd extension - not part of official LSP.
	void symbolInfo(PathRef File, Position Pos,
	Callback<std::vector<SymbolDetails>> CB);

	/// Get semantic ranges around a specified position in a file.
	void semanticRanges(PathRef File, const std::vector<Position> &Pos,
	Callback<std::vector<SelectionRange>> CB);

	/// Get all document links in a file.
	void documentLinks(PathRef File, Callback<std::vector<DocumentLink>> CB);

	void semanticHighlights(PathRef File,
	Callback<std::vector<HighlightingToken>>);

	/// Runs an arbitrary action that has access to the AST of the specified file.
	/// The action will execute on one of ClangdServer's internal threads.
	/// The AST is only valid for the duration of the callback.
	/// As with other actions, the file must have been opened.
	void customAction(PathRef File, llvm::StringRef Name,
	Callback<InputsAndAST> Action);

	/// Returns estimated memory usage and other statistics for each of the
	/// currently open files.
	/// Overall memory usage of clangd may be significantly more than reported
	/// here, as this metric does not account (at least) for:
	/// - memory occupied by static and dynamic index,
	/// - memory required for in-flight requests,
	/// FIXME: those metrics might be useful too, we should add them.
	llvm::StringMap<TUScheduler::FileStats> fileStats() const;

	// Blocks the main thread until the server is idle. Only for use in tests.
	// Returns false if the timeout expires.
	LLVM_NODISCARD bool
	blockUntilIdleForTest(llvm::Optional<double> TimeoutSeconds = 10);

	private:
	void formatCode(PathRef File, llvm::StringRef Code,
	ArrayRef<tooling::Range> Ranges,
	Callback<tooling::Replacements> CB);

	/// Derives a context for a task processing the specified source file.
	/// This includes the current configuration (see Options::ConfigProvider).
	/// The empty string means no particular file is the target.
	/// Rather than called by each feature, this is exposed to the components
	/// that control worker threads, like TUScheduler and BackgroundIndex.
	/// This means it's OK to do some IO here, and it cuts across all features.
	Context createProcessingContext(PathRef) const;
	config::Provider *ConfigProvider = nullptr;

	const ThreadsafeFS &TFS;

	Path ResourceDir;
	// The index used to look up symbols. This could be:
	// - null (all index functionality is optional)
	// - the dynamic index owned by ClangdServer (DynamicIdx)
	// - the static index passed to the constructor
	// - a merged view of a static and dynamic index (MergedIndex)
	const SymbolIndex *Index = nullptr;
	// If present, an index of symbols in open files. Read via *Index.
	std::unique_ptr<FileIndex> DynamicIdx;
	// If present, the new "auto-index" maintained in background threads.
	std::unique_ptr<BackgroundIndex> BackgroundIdx;
	// Storage for merged views of the various indexes.
	std::vector<std::unique_ptr<SymbolIndex>> MergedIdx;

	// When set, provides clang-tidy options for a specific file.
	ClangTidyOptionsBuilder GetClangTidyOptions;

	// If this is true, suggest include insertion fixes for diagnostic errors that
	// can be caused by missing includes (e.g. member access in incomplete type).
	bool SuggestMissingIncludes = false;

	// If true, preserve expressions in AST for broken code.
	bool BuildRecoveryAST = true;
	// If true, preserve the type for recovery AST.
	bool PreserveRecoveryASTType = false;

	std::function<bool(const Tweak &)> TweakFilter;

	// GUARDED_BY(CachedCompletionFuzzyFindRequestMutex)
	llvm::StringMap<llvm::Optional<FuzzyFindRequest>>
	CachedCompletionFuzzyFindRequestByFile;
	mutable std::mutex CachedCompletionFuzzyFindRequestMutex;

	llvm::Optional<std::string> WorkspaceRoot;
	// WorkScheduler has to be the last member, because its destructor has to be
	// called before all other members to stop the worker thread that references
	// ClangdServer.
	TUScheduler WorkScheduler;
	};

	} // namespace clangd
	} // namespace clang

	#endif