tclxtnotify.c

tcl是工具命令语言

/* 
 * tclXtNotify.c --
 *
 *	This file contains the notifier driver implementation for the
 *	Xt intrinsics.
 *
 * Copyright (c) 1997 by Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclXtNotify.c,v 1.4 1999/07/02 06:05:34 welch Exp $
 */

#include <X11/Intrinsic.h>
#include <tclInt.h>

/*
 * This structure is used to keep track of the notifier info for a 
 * a registered file.
 */

typedef struct FileHandler {
    int fd;
    int mask;			/* Mask of desired events: TCL_READABLE, etc. */
    int readyMask;		/* Events that have been seen since the
				   last time FileHandlerEventProc was called
				   for this file. */
    XtInputId read;		/* Xt read callback handle. */
    XtInputId write;		/* Xt write callback handle. */
    XtInputId except;		/* Xt exception callback handle. */
    Tcl_FileProc *proc;		/* Procedure to call, in the style of
				 * Tcl_CreateFileHandler. */
    ClientData clientData;	/* Argument to pass to proc. */
    struct FileHandler *nextPtr;/* Next in list of all files we care about. */
} FileHandler;

/*
 * The following structure is what is added to the Tcl event queue when
 * file handlers are ready to fire.
 */

typedef struct FileHandlerEvent {
    Tcl_Event header;		/* Information that is standard for
				 * all events. */
    int fd;			/* File descriptor that is ready.  Used
				 * to find the FileHandler structure for
				 * the file (can't point directly to the
				 * FileHandler structure because it could
				 * go away while the event is queued). */
} FileHandlerEvent;

/*
 * The following static structure contains the state information for the
 * Xt based implementation of the Tcl notifier.
 */

static struct NotifierState {
    XtAppContext appContext;		/* The context used by the Xt
                                         * notifier. Can be set with
                                         * TclSetAppContext. */
    int appContextCreated;		/* Was it created by us? */
    XtIntervalId currentTimeout;	/* Handle of current timer. */
    FileHandler *firstFileHandlerPtr;	/* Pointer to head of file handler
					 * list. */
} notifier;

/*
 * The following static indicates whether this module has been initialized.
 */

static int initialized = 0;

/*
 * Static routines defined in this file.
 */

static int		FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr,
			    int flags));
static void		FileProc _ANSI_ARGS_((caddr_t clientData,
			    int *source, XtInputId *id));
void			InitNotifier _ANSI_ARGS_((void));
static void		NotifierExitHandler _ANSI_ARGS_((
			    ClientData clientData));
static void		TimerProc _ANSI_ARGS_((caddr_t clientData,
			    XtIntervalId *id));
static void		CreateFileHandler _ANSI_ARGS_((int fd, int mask, 
				Tcl_FileProc * proc, ClientData clientData));
static void		DeleteFileHandler _ANSI_ARGS_((int fd));
static void		SetTimer _ANSI_ARGS_((Tcl_Time * timePtr));
static int		WaitForEvent _ANSI_ARGS_((Tcl_Time * timePtr));

/*
 * Functions defined in this file for use by users of the Xt Notifier:
 */

EXTERN XtAppContext	TclSetAppContext _ANSI_ARGS_((XtAppContext ctx));

/*
 *----------------------------------------------------------------------
 *
 * TclSetAppContext --
 *
 *	Set the notifier application context.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Sets the application context used by the notifier. Panics if
 *	the context is already set when called.
 *
 *----------------------------------------------------------------------
 */

XtAppContext
TclSetAppContext(appContext)
    XtAppContext	appContext;
{
    if (!initialized) {
        InitNotifier();
    }

    /*
     * If we already have a context we check whether we were asked to set a
     * new context. If so, we panic because we try to prevent switching
     * contexts by mistake. Otherwise, we return the one we have.
     */
    
    if (notifier.appContext != NULL) {
        if (appContext != NULL) {

	    /*
             * We already have a context. We do not allow switching contexts
             * after initialization, so we panic.
             */
        
            panic("TclSetAppContext:  multiple application contexts");

        }
    } else {

        /*
         * If we get here we have not yet gotten a context, so either create
         * one or use the one supplied by our caller.
         */

        if (appContext == NULL) {

	    /*
             * We must create a new context and tell our caller what it is, so
             * she can use it too.
             */
    
            notifier.appContext = XtCreateApplicationContext();
            notifier.appContextCreated = 1;
        } else {

	    /*
             * Otherwise we remember the context that our caller gave us
             * and use it.
             */
    
            notifier.appContextCreated = 0;
            notifier.appContext = appContext;
        }
    }
    
    return notifier.appContext;
}

/*
 *----------------------------------------------------------------------
 *
 * InitNotifier --
 *
 *	Initializes the notifier state.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Creates a new exit handler.
 *
 *----------------------------------------------------------------------
 */

void
InitNotifier()
{
    Tcl_NotifierProcs notifier;
    /*
     * Only reinitialize if we are not in exit handling. The notifier
     * can get reinitialized after its own exit handler has run, because
     * of exit handlers for the I/O and timer sub-systems (order dependency).
     */

    if (TclInExit()) {
        return;
    }

    notifier.createFileHandlerProc = CreateFileHandler;
    notifier.deleteFileHandlerProc = DeleteFileHandler;
    notifier.setTimerProc = SetTimer;
    notifier.waitForEventProc = WaitForEvent;
    Tcl_SetNotifier(&notifier);

    /*
     * DO NOT create the application context yet; doing so would prevent
     * external applications from setting it for us to their own ones.
     */
    
    initialized = 1;
    memset(&notifier, 0, sizeof(notifier));
    Tcl_CreateExitHandler(NotifierExitHandler, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * NotifierExitHandler --
 *
 *	This function is called to cleanup the notifier state before
 *	Tcl is unloaded.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Destroys the notifier window.
 *
 *----------------------------------------------------------------------
 */

static void
NotifierExitHandler(
    ClientData clientData)	/* Not used. */
{
    if (notifier.currentTimeout != 0) {
        XtRemoveTimeOut(notifier.currentTimeout);
    }
    for (; notifier.firstFileHandlerPtr != NULL; ) {
        Tcl_DeleteFileHandler(notifier.firstFileHandlerPtr->fd);
    }
    if (notifier.appContextCreated) {
        XtDestroyApplicationContext(notifier.appContext);
        notifier.appContextCreated = 0;
        notifier.appContext = NULL;
    }
    initialized = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * SetTimer --
 *
 *	This procedure sets the current notifier timeout value.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Replaces any previous timer.
 *
 *----------------------------------------------------------------------
 */

static void
SetTimer(timePtr)
    Tcl_Time *timePtr;		/* Timeout value, may be NULL. */
{
    long timeout;

    if (!initialized) {
	InitNotifier();
    }

    TclSetAppContext(NULL);
    if (notifier.currentTimeout != 0) {
	XtRemoveTimeOut(notifier.currentTimeout);
    }
    if (timePtr) {
	timeout = timePtr->sec * 1000 + timePtr->usec / 1000;
	notifier.currentTimeout =
            XtAppAddTimeOut(notifier.appContext, (unsigned long) timeout,
                    TimerProc, NULL);
    } else {
	notifier.currentTimeout = 0;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TimerProc --
 *
 *	This procedure is the XtTimerCallbackProc used to handle
 *	timeouts.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *      Processes all queued events.
 *
 *----------------------------------------------------------------------
 */

static void
TimerProc(data, id)
    caddr_t data;		/* Not used. */
    XtIntervalId *id;
{
    if (*id != notifier.currentTimeout) {
	return;
    }
    notifier.currentTimeout = 0;

    Tcl_ServiceAll();
}

/*
 *----------------------------------------------------------------------
 *
 * CreateFileHandler --
 *
 *	This procedure registers a file handler with the Xt notifier.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Creates a new file handler structure and registers one or more
 *	input procedures with Xt.