//===- llvm/System/Program.h ------------------------------------*- C++ -*-===//
// 
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Reid Spencer and is distributed under the 
// University of Illinois Open Source License. See LICENSE.TXT for details.
// 
//===----------------------------------------------------------------------===//
//
// This file declares the llvm::sys::Program class.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SYSTEM_PROGRAM_H
#define LLVM_SYSTEM_PROGRAM_H

#include "llvm/System/Path.h"
#include <vector>

namespace llvm {
namespace sys {

  /// This class provides an abstraction for programs that are executable by the
  /// operating system. It provides a platform generic way to find executable
  /// programs from the path and to execute them in various ways. The sys::Path
  /// class is used to specify the location of the Program.
  /// @since 1.4
  /// @brief An abstraction for finding and executing programs.
  class Program {
    /// @name Methods
    /// @{
    public:
      /// This static constructor (factory) will attempt to locate a program in
      /// the operating system's file system using some pre-determined set of 
      /// locations to search (e.g. the PATH on Unix). 
      /// @returns A Path object initialized to the path of the program or a
      /// Path object that is empty (invalid) if the program could not be found.
      /// @throws nothing
      /// @brief Construct a Program by finding it by name.
      static Path FindProgramByName(const std::string& name);

      /// This function executes the program using the \p arguments provided and
      /// waits for the program to exit. This function will block the current
      /// program until the invoked program exits. The invoked program will 
      /// inherit the stdin, stdout, and stderr file descriptors, the
      /// environment and other configuration settings of the invoking program.
      /// If Path::executable() does not return true when this function is
      /// called then a std::string is thrown. 
      /// @param path A sys::Path object providing the path of the program to be
      /// executed. It is presumed this is the result of the FindProgramByName
      /// method.
      /// @returns an integer result code indicating the status of the program.
      /// @throws std::string on a variety of error conditions or if the invoked
      /// program aborted abnormally.
      /// @see FindProgrambyName
      /// @brief Executes the program with the given set of \p args.
      static int ExecuteAndWait(
        const Path& path,  ///< The path to the program to execute
        const char** args,
          ///< A vector of strings that are passed to the program.
          ///< The first element should be the name of the program. The list
          ///< *must* be terminated by a null char* entry.
        const char ** env = 0,
          ///< An optional vector of strings to use for the program's 
          ///< environment. If not provided, the current program's environment
          ///< will be used.
        const sys::Path** redirects = 0,
          ///< An optional array of pointers to Paths. If the array is null,
          ///< no redirection is done. The array should have a size of at least
          ///< three. If the pointer in the array are not null, then the 
          ///< inferior process's stdin(0), stdout(1), and stderr(2) will be 
          ///< redirected to the corresponding Paths. 
        unsigned secondsToWait = 0
          ///< If non-zero, this specifies the amount of time to wait for the
          ///< child process to exit. If the time expires, the child is killed
          ///< and this call returns. If zero, this function will wait until
          ///< the child finishes or forever if it doesn't.
      );
  };
}
}

// vim: sw=2

#endif