1 //===--- ConfigProvider.h - Loading of user configuration --------*- C++-*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Various clangd features have configurable behaviour (or can be disabled). 10 // The configuration system allows users to control this: 11 // - in a user config file, a project config file, via LSP, or via flags 12 // - specifying different settings for different files 13 // This file defines the structures used for this, that produce a Config. 14 // 15 //===----------------------------------------------------------------------===// 16 17 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_CONFIGPROVIDER_H 18 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_CONFIGPROVIDER_H 19 20 #include "llvm/ADT/StringRef.h" 21 #include "llvm/Support/SourceMgr.h" 22 #include <chrono> 23 #include <string> 24 #include <vector> 25 26 namespace clang { 27 namespace clangd { 28 struct Config; 29 class ThreadsafeFS; 30 namespace config { 31 32 /// Describes the context used to evaluate configuration fragments. 33 struct Params { 34 /// Absolute path to a source file we're applying the config to. Unix slashes. 35 /// Empty if not configuring a particular file. 36 llvm::StringRef Path; 37 /// Hint that stale data is OK to improve performance (e.g. avoid IO). 38 /// FreshTime sets a bound for how old the data can be. 39 /// By default, providers should validate caches against the data source. 40 std::chrono::steady_clock::time_point FreshTime = 41 std::chrono::steady_clock::time_point::max(); 42 }; 43 44 /// Used to report problems in parsing or interpreting a config. 45 /// Errors reflect structurally invalid config that should be user-visible. 46 /// Warnings reflect e.g. unknown properties that are recoverable. 47 /// Notes are used to report files and fragments. 48 /// (This can be used to track when previous warnings/errors have been "fixed"). 49 using DiagnosticCallback = llvm::function_ref<void(const llvm::SMDiagnostic &)>; 50 51 /// A chunk of configuration that has been fully analyzed and is ready to apply. 52 /// Typically this is obtained from a Fragment by calling Fragment::compile(). 53 /// 54 /// Calling it updates the configuration to reflect settings from the fragment. 55 /// Returns true if the condition was met and the settings were used. 56 using CompiledFragment = std::function<bool(const Params &, Config &)>; 57 58 /// A source of configuration fragments. 59 /// Generally these providers reflect a fixed policy for obtaining config, 60 /// but return different concrete configuration over time. 61 /// e.g. a provider that reads config from files is responsive to file changes. 62 class Provider { 63 public: 64 virtual ~Provider() = default; 65 66 /// Reads fragments from a single YAML file with a fixed path. If non-empty, 67 /// Directory will be used to resolve relative paths in the fragments. 68 static std::unique_ptr<Provider> fromYAMLFile(llvm::StringRef AbsPath, 69 llvm::StringRef Directory, 70 const ThreadsafeFS &, 71 bool Trusted = false); 72 // Reads fragments from YAML files found relative to ancestors of Params.Path. 73 // 74 // All fragments that exist are returned, starting from distant ancestors. 75 // For instance, given RelPath of ".clangd", then for source file /foo/bar.cc, 76 // the searched fragments are [/.clangd, /foo/.clangd]. 77 // 78 // If Params does not specify a path, no fragments are returned. 79 static std::unique_ptr<Provider> 80 fromAncestorRelativeYAMLFiles(llvm::StringRef RelPath, const ThreadsafeFS &, 81 bool Trusted = false); 82 83 /// A provider that includes fragments from all the supplied providers. 84 /// Order is preserved; later providers take precedence over earlier ones. 85 static std::unique_ptr<Provider> combine(std::vector<const Provider *>); 86 87 /// Build a config based on this provider. 88 Config getConfig(const Params &, DiagnosticCallback) const; 89 90 private: 91 /// Provide fragments that may be relevant to the file. 92 /// The configuration provider is not responsible for testing conditions. 93 /// 94 /// Providers are expected to cache compiled fragments, and only 95 /// reparse/recompile when the source data has changed. 96 /// Despite the need for caching, this function must be threadsafe. 97 /// 98 /// When parsing/compiling, the DiagnosticCallback is used to report errors. 99 virtual std::vector<CompiledFragment> 100 getFragments(const Params &, DiagnosticCallback) const = 0; 101 }; 102 103 } // namespace config 104 } // namespace clangd 105 } // namespace clang 106 107 #endif 108