llvm/clang-tools-extra/clangd/ScanningProjectModules.cpp

//===------------------ ProjectModules.h -------------------------*- 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
//
//===----------------------------------------------------------------------===//

#include "ProjectModules.h"
#include "support/Logger.h"
#include "clang/Tooling/DependencyScanning/DependencyScanningService.h"
#include "clang/Tooling/DependencyScanning/DependencyScanningTool.h"

namespace clang::clangd {
namespace {
/// A scanner to query the dependency information for C++20 Modules.
///
/// The scanner can scan a single file with `scan(PathRef)` member function
/// or scan the whole project with `globalScan(vector<PathRef>)` member
/// function. See the comments of `globalScan` to see the details.
///
/// The ModuleDependencyScanner can get the directly required module names for a
/// specific source file. Also the ModuleDependencyScanner can get the source
/// file declaring the primary module interface for a specific module name.
///
/// IMPORTANT NOTE: we assume that every module unit is only declared once in a
/// source file in the project. But the assumption is not strictly true even
/// besides the invalid projects. The language specification requires that every
/// module unit should be unique in a valid program. But a project can contain
/// multiple programs. Then it is valid that we can have multiple source files
/// declaring the same module in a project as long as these source files don't
/// interfere with each other.
class ModuleDependencyScanner { … };

std::optional<ModuleDependencyScanner::ModuleDependencyInfo>
ModuleDependencyScanner::scan(PathRef FilePath) { … }

void ModuleDependencyScanner::globalScan() { … }

PathRef ModuleDependencyScanner::getSourceForModuleName(
    llvm::StringRef ModuleName) const { … }

std::vector<std::string>
ModuleDependencyScanner::getRequiredModules(PathRef File) { … }
} // namespace

/// TODO: The existing `ScanningAllProjectModules` is not efficient. See the
/// comments in ModuleDependencyScanner for detail.
///
/// In the future, we wish the build system can provide a well design
/// compilation database for modules then we can query that new compilation
/// database directly. Or we need to have a global long-live scanner to detect
/// the state of each file.
class ScanningAllProjectModules : public ProjectModules { … };

std::unique_ptr<ProjectModules> scanningProjectModules(
    std::shared_ptr<const clang::tooling::CompilationDatabase> CDB,
    const ThreadsafeFS &TFS) { … }

} // namespace clang::clangd