text: //===- CompilationDatabase.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
  //
  //===----------------------------------------------------------------------===//
  //
  //  This file provides an interface and multiple implementations for
  //  CompilationDatabases.
  //
  //  While C++ refactoring and analysis tools are not compilers, and thus
  //  don't run as part of the build system, they need the exact information
  //  of a build in order to be able to correctly understand the C++ code of
  //  the project. This information is provided via the CompilationDatabase
  //  interface.
  //
  //  To create a CompilationDatabase from a build directory one can call
  //  CompilationDatabase::loadFromDirectory(), which deduces the correct
  //  compilation database from the root of the build tree.
  //
  //  See the concrete subclasses of CompilationDatabase for currently supported
  //  formats.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_CLANG_TOOLING_COMPILATIONDATABASE_H
  #define LLVM_CLANG_TOOLING_COMPILATIONDATABASE_H
  
  #include "clang/Basic/LLVM.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/Support/VirtualFileSystem.h"
  #include <memory>
  #include <string>
  #include <utility>
  #include <vector>
  
  namespace clang {
  namespace tooling {
  
  /// Specifies the working directory and command of a compilation.
  struct CompileCommand {
    CompileCommand() = default;
    CompileCommand(const Twine &Directory, const Twine &Filename,
                   std::vector<std::string> CommandLine, const Twine &Output)
        : Directory(Directory.str()), Filename(Filename.str()),
          CommandLine(std::move(CommandLine)), Output(Output.str()) {}
  
    /// The working directory the command was executed from.
    std::string Directory;
  
    /// The source file associated with the command.
    std::string Filename;
  
    /// The command line that was executed.
    std::vector<std::string> CommandLine;
  
    /// The output file associated with the command.
    std::string Output;
  
    /// If this compile command was guessed rather than read from an authoritative
    /// source, a short human-readable explanation.
    /// e.g. "inferred from foo/bar.h".
    std::string Heuristic;
  
    friend bool operator==(const CompileCommand &LHS, const CompileCommand &RHS) {
      return LHS.Directory == RHS.Directory && LHS.Filename == RHS.Filename &&
             LHS.CommandLine == RHS.CommandLine && LHS.Output == RHS.Output &&
             LHS.Heuristic == RHS.Heuristic;
    }
  
    friend bool operator!=(const CompileCommand &LHS, const CompileCommand &RHS) {
      return !(LHS == RHS);
    }
  };
  
  /// Interface for compilation databases.
  ///
  /// A compilation database allows the user to retrieve compile command lines
  /// for the files in a project.
  ///
  /// Many implementations are enumerable, allowing all command lines to be
  /// retrieved. These can be used to run clang tools over a subset of the files
  /// in a project.
  class CompilationDatabase {
  public:
    virtual ~CompilationDatabase();
  
    /// Loads a compilation database from a build directory.
    ///
    /// Looks at the specified 'BuildDirectory' and creates a compilation database
    /// that allows to query compile commands for source files in the
    /// corresponding source tree.
    ///
    /// Returns NULL and sets ErrorMessage if we were not able to build up a
    /// compilation database for the build directory.
    ///
    /// FIXME: Currently only supports JSON compilation databases, which
    /// are named 'compile_commands.json' in the given directory. Extend this
    /// for other build types (like ninja build files).
    static std::unique_ptr<CompilationDatabase>
    loadFromDirectory(StringRef BuildDirectory, std::string &ErrorMessage);
  
    /// Tries to detect a compilation database location and load it.
    ///
    /// Looks for a compilation database in all parent paths of file 'SourceFile'
    /// by calling loadFromDirectory.
    static std::unique_ptr<CompilationDatabase>
    autoDetectFromSource(StringRef SourceFile, std::string &ErrorMessage);
  
    /// Tries to detect a compilation database location and load it.
    ///
    /// Looks for a compilation database in directory 'SourceDir' and all
    /// its parent paths by calling loadFromDirectory.
    static std::unique_ptr<CompilationDatabase>
    autoDetectFromDirectory(StringRef SourceDir, std::string &ErrorMessage);
  
    /// Returns all compile commands in which the specified file was
    /// compiled.
    ///
    /// This includes compile commands that span multiple source files.
    /// For example, consider a project with the following compilations:
    /// $ clang++ -o test a.cc b.cc t.cc
    /// $ clang++ -o production a.cc b.cc -DPRODUCTION
    /// A compilation database representing the project would return both command
    /// lines for a.cc and b.cc and only the first command line for t.cc.
    virtual std::vector<CompileCommand> getCompileCommands(
        StringRef FilePath) const = 0;
  
    /// Returns the list of all files available in the compilation database.
    ///
    /// By default, returns nothing. Implementations should override this if they
    /// can enumerate their source files.
    virtual std::vector<std::string> getAllFiles() const { return {}; }
  
    /// Returns all compile commands for all the files in the compilation
    /// database.
    ///
    /// FIXME: Add a layer in Tooling that provides an interface to run a tool
    /// over all files in a compilation database. Not all build systems have the
    /// ability to provide a feasible implementation for \c getAllCompileCommands.
    ///
    /// By default, this is implemented in terms of getAllFiles() and
    /// getCompileCommands(). Subclasses may override this for efficiency.
    virtual std::vector<CompileCommand> getAllCompileCommands() const;
  };
  
  /// A compilation database that returns a single compile command line.
  ///
  /// Useful when we want a tool to behave more like a compiler invocation.
  /// This compilation database is not enumerable: getAllFiles() returns {}.
  class FixedCompilationDatabase : public CompilationDatabase {
  public:
    /// Creates a FixedCompilationDatabase from the arguments after "--".
    ///
    /// Parses the given command line for "--". If "--" is found, the rest of
    /// the arguments will make up the command line in the returned
    /// FixedCompilationDatabase.
    /// The arguments after "--" must not include positional parameters or the
    /// argv[0] of the tool. Those will be added by the FixedCompilationDatabase
    /// when a CompileCommand is requested. The argv[0] of the returned command
    /// line will be "clang-tool".
    ///
    /// Returns NULL in case "--" is not found.
    ///
    /// The argument list is meant to be compatible with normal llvm command line
    /// parsing in main methods.
    /// int main(int argc, char **argv) {
    ///   std::unique_ptr<FixedCompilationDatabase> Compilations(
    ///     FixedCompilationDatabase::loadFromCommandLine(argc, argv));
    ///   cl::ParseCommandLineOptions(argc, argv);
    ///   ...
    /// }
    ///
    /// \param Argc The number of command line arguments - will be changed to
    /// the number of arguments before "--", if "--" was found in the argument
    /// list.
    /// \param Argv Points to the command line arguments.
    /// \param ErrorMsg Contains error text if the function returns null pointer.
    /// \param Directory The base directory used in the FixedCompilationDatabase.
    static std::unique_ptr<FixedCompilationDatabase>
    loadFromCommandLine(int &Argc, const char *const *Argv, std::string &ErrorMsg,
                        const Twine &Directory = ".");
  
    /// Reads flags from the given file, one-per-line.
    /// Returns nullptr and sets ErrorMessage if we can't read the file.
    static std::unique_ptr<FixedCompilationDatabase>
    loadFromFile(StringRef Path, std::string &ErrorMsg);
  
    /// Reads flags from the given buffer, one-per-line.
    /// Directory is the command CWD, typically the parent of compile_flags.txt.
    static std::unique_ptr<FixedCompilationDatabase>
    loadFromBuffer(StringRef Directory, StringRef Data, std::string &ErrorMsg);
  
    /// Constructs a compilation data base from a specified directory
    /// and command line.
    FixedCompilationDatabase(const Twine &Directory,
                             ArrayRef<std::string> CommandLine);
  
    /// Returns the given compile command.
    ///
    /// Will always return a vector with one entry that contains the directory
    /// and command line specified at construction with "clang-tool" as argv[0]
    /// and 'FilePath' as positional argument.
    std::vector<CompileCommand>
    getCompileCommands(StringRef FilePath) const override;
  
  private:
    /// This is built up to contain a single entry vector to be returned from
    /// getCompileCommands after adding the positional argument.
    std::vector<CompileCommand> CompileCommands;
  };
  
  /// Returns a wrapped CompilationDatabase that defers to the provided one,
  /// but getCompileCommands() will infer commands for unknown files.
  /// The return value of getAllFiles() or getAllCompileCommands() is unchanged.
  /// See InterpolatingCompilationDatabase.cpp for details on heuristics.
  std::unique_ptr<CompilationDatabase>
      inferMissingCompileCommands(std::unique_ptr<CompilationDatabase>);
  
  /// Returns a wrapped CompilationDatabase that will add -target and -mode flags
  /// to commandline when they can be deduced from argv[0] of commandline returned
  /// by underlying database.
  std::unique_ptr<CompilationDatabase>
  inferTargetAndDriverMode(std::unique_ptr<CompilationDatabase> Base);
  
  /// Returns a wrapped CompilationDatabase that will expand all rsp(response)
  /// files on commandline returned by underlying database.
  std::unique_ptr<CompilationDatabase>
  expandResponseFiles(std::unique_ptr<CompilationDatabase> Base,
                      llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS);
  
  } // namespace tooling
  } // namespace clang
  
  #endif // LLVM_CLANG_TOOLING_COMPILATIONDATABASE_H
  