Driver.h

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//===- Driver.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
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_SUPPORT_DRIVER_H
#define LLVM_SUPPORT_DRIVER_H
 
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorOr.h"
 
#include <functional>
#include <memory>
 
namespace llvm {
 
class ToolSession;
class ToolContext;
 
using ToolMainFn = std::function<int(int, char **, const ToolContext &)>;
 
/// An LLVM command-line tool that can be invoked without creating a process.
struct CallableTool {
  StringRef Name;
  ToolMainFn Main;
 
  explicit operator bool() const { return static_cast<bool>(Main); }
};
 
/// Describes how a tool was invoked and provides access to its host session.
class ToolContext {
  ToolSession *Session = nullptr;
 
  friend class ToolSession;
 
public:
  const char *Path;
  const char *PrependArg;
  // PrependArg will be added unconditionally by the llvm-driver, but
  // NeedsPrependArg will be false if Path is adequate to reinvoke the tool.
  // This is useful if realpath is ever called on Path, in which case it will
  // point to the llvm-driver executable, where PrependArg will be needed to
  // invoke the correct tool.
  bool NeedsPrependArg;
 
  ToolContext(const char *Path, const char *PrependArg, bool NeedsPrependArg)
      : Path(Path), PrependArg(PrependArg), NeedsPrependArg(NeedsPrependArg) {}
 
  /// Finds a tool registered with the session that owns this context.
  LLVM_ABI ErrorOr<CallableTool> getCallableTool(StringRef Name) const;
 
  /// Invokes another tool registered with the same host session.
  LLVM_ABI ErrorOr<int> callTool(ArrayRef<const char *> Args) const;
};
 
/// Owns LLVM process initialization and an in-process tool registry.
///
/// A long-lived host constructs one session and uses it for every embedded
/// tool invocation. The individual tools borrow a ToolContext and therefore do
/// not initialize or shut down LLVM themselves.
///
/// LLVM tools may use process-global state. Tool invocations must be externally
/// serialized; concurrent calls are not supported.
class LLVM_ABI ToolSession {
public:
  ToolSession(int &Argc, char **&Argv, ArrayRef<CallableTool> Tools,
              bool InstallPipeSignalExitHandler = true,
              bool NeedsPOSIXUtilitySignalHandling = false);
  ~ToolSession();
 
  ToolSession(const ToolSession &) = delete;
  ToolSession &operator=(const ToolSession &) = delete;
 
  /// Invokes the tool named by Args[0]. Args may instead contain a
  /// process-style argv beginning with the session executable or an LLVM
  /// multicall name.
  ErrorOr<int> callTool(ArrayRef<const char *> Args);
 
private:
  struct Impl;
  std::unique_ptr<Impl> PImpl;
 
  ErrorOr<CallableTool> findTool(StringRef Name) const;
  ToolContext makeContext(StringRef RegisteredName, const char *PrependArg);
 
  friend class ToolContext;
};
 
} // namespace llvm
 
#endif