# A1 for COMPSCI340/SOFTENG370 2015
# Prepared by Robert Sheehan
# Modified by ...

# You are not allowed to use any sleep calls.

from threading import Lock, Event
from process import State

class Dispatcher():
    """The dispatcher."""

    MAX_PROCESSES = 8

    def __init__(self):
        """Construct the dispatcher."""
        # ...

    def set_io_sys(self, io_sys):
        """Set the io subsystem."""
        self.io_sys = io_sys

    def add_process(self, process):
        """Add and start the process."""
        # ...

    def dispatch_next_process(self):
        """Dispatch the process at the top of the stack."""
        # ...

    def to_top(self, process):
        """Move the process to the top of the stack."""
        # ...


    def pause_system(self):
        """Pause the currently running process.
        As long as the dispatcher doesn't dispatch another process this
        effectively pauses the system.
        """
        # ...

    def resume_system(self):
        """Resume running the system."""
        # ...

    def wait_until_finished(self):
        """Hang around until all runnable processes are finished."""
        # ...

    def proc_finished(self, process):
        """Receive notification that "proc" has finished.
        Only called from running processes.
        """
        # ...

    def proc_waiting(self, process):
        """Receive notification that process is waiting for input."""
        # ...

    def process_with_id(self, id):
        """Return the process with the id."""
        # ...
        return None