111 lines
4.3 KiB
C++
111 lines
4.3 KiB
C++
//===--- StdLib.h - Index the C and C++ standard library ---------*- C++-*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// Eagerly indexing the standard library gives a much friendlier "warm start"
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// with working code completion in a standalone file or small project.
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//
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// We act as if we saw a file which included the whole standard library:
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// #include <array>
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// #include <bitset>
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// #include <chrono>
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// ...
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// We index this TU and feed the result into the dynamic index.
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//
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// This happens within the context of some particular open file, and we reuse
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// its CompilerInvocation. Matching its include path, LangOpts etc ensures that
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// we see the standard library and configuration that matches the project.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_STDLIB_H
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#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_STDLIB_H
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#include "index/Symbol.h"
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#include "support/ThreadsafeFS.h"
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#include "llvm/ADT/StringRef.h"
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#include <string>
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namespace clang {
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class CompilerInvocation;
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class LangOptions;
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class HeaderSearch;
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namespace clangd {
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// The filesystem location where a standard library was found.
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//
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// This is the directory containing <vector> or <stdio.h>.
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// It's used to ensure we only index files that are in the standard library.
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//
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// The paths are canonicalized (FS "real path" with symlinks resolved).
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// This allows them to be easily compared against paths the indexer returns.
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struct StdLibLocation {
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llvm::SmallVector<std::string> Paths;
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};
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// Tracks the state of standard library indexing within a particular index.
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//
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// In general, we don't want to index the standard library multiple times.
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// In most cases, this class just acts as a flag to ensure we only do it once.
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//
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// However, if we first open a C++11 file, and then a C++20 file, we *do*
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// want the index to be upgraded to include the extra symbols.
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// Similarly, the C and C++ standard library can coexist.
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class StdLibSet {
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std::atomic<int> Best[2] = {{-1}, {-1}};
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public:
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// Determines if we should index the standard library in a configuration.
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//
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// This is true if:
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// - standard library indexing is enabled for the file
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// - the language version is higher than any previous add() for the language
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// - the standard library headers exist on the search path
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// Returns the location where the standard library was found.
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//
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// This function is threadsafe.
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llvm::Optional<StdLibLocation> add(const LangOptions &, const HeaderSearch &);
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// Indicates whether a built index should be used.
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// It should not be used if a newer version has subsequently been added.
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//
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// Intended pattern is:
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// if (add()) {
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// symbols = indexStandardLibrary();
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// if (isBest())
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// index.update(symbols);
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// }
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//
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// This is still technically racy: we could return true here, then another
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// thread could add->index->update a better library before we can update.
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// We'd then overwrite it with the older version.
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// However, it's very unlikely: indexing takes a long time.
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bool isBest(const LangOptions &) const;
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};
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// Index a standard library and return the discovered symbols.
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//
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// The compiler invocation should describe the file whose config we're reusing.
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// We overwrite its virtual buffer with a lot of #include statements.
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SymbolSlab indexStandardLibrary(std::unique_ptr<CompilerInvocation> Invocation,
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const StdLibLocation &Loc,
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const ThreadsafeFS &TFS);
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// Variant that allows the umbrella header source to be specified.
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// Exposed for testing.
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SymbolSlab indexStandardLibrary(llvm::StringRef HeaderSources,
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std::unique_ptr<CompilerInvocation> CI,
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const StdLibLocation &Loc,
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const ThreadsafeFS &TFS);
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// Generate header containing #includes for all standard library headers.
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// Exposed for testing.
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llvm::StringRef getStdlibUmbrellaHeader(const LangOptions &);
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} // namespace clangd
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} // namespace clang
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#endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_STDLIB_H
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