/* 
 * tkAtom.c --
 *
 *	This file manages a cache of X Atoms in order to avoid
 *	interactions with the X server.  It's much like the Xmu
 *	routines, except it has a cleaner interface (caller
 *	doesn't have to provide permanent storage for atom names,
 *	for example).
 *
 * Copyright (c) 1990-1994 The Regents of the University of California.
 * All rights reserved.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 * 
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

static char sccsid[] = "@(#) tkAtom.c 1.9 94/08/16 09:54:02";

#include "tkPort.h"
#include "tkInt.h"

/*
 * Forward references to procedures defined in this file:
 */

static void	AtomInit _ANSI_ARGS_((TkDisplay *dispPtr));

/*
 *--------------------------------------------------------------
 *
 * Tk_InternAtom --
 *
 *	Given a string, produce the equivalent X atom.  This
 *	procedure is equivalent to XInternAtom, except that it
 *	keeps a local cache of atoms.  Once a name is known,
 *	the server need not be contacted again for that name.
 *
 * Results:
 *	The return value is the Atom corresponding to name.
 *
 * Side effects:
 *	A new entry may be added to the local atom cache.
 *
 *--------------------------------------------------------------
 */

Atom
Tk_InternAtom(tkwin, name)
    Tk_Window tkwin;		/* Window token;  map name to atom
				 * for this window's display. */
    char *name;			/* Name to turn into atom. */
{
    register TkDisplay *dispPtr;
    register Tcl_HashEntry *hPtr;
    int new;

    dispPtr = ((TkWindow *) tkwin)->dispPtr;
    if (!dispPtr->atomInit) {
	AtomInit(dispPtr);
    }

    hPtr = Tcl_CreateHashEntry(&dispPtr->nameTable, name, &new);
    if (new) {
	Tcl_HashEntry *hPtr2;
	Atom atom;

	atom = XInternAtom(dispPtr->display, name, False);
	Tcl_SetHashValue(hPtr, atom);
	hPtr2 = Tcl_CreateHashEntry(&dispPtr->atomTable, (char *) atom,
		&new);
	Tcl_SetHashValue(hPtr2, Tcl_GetHashKey(&dispPtr->nameTable, hPtr));
    }
    return (Atom) Tcl_GetHashValue(hPtr);
}

/*
 *--------------------------------------------------------------
 *
 * Tk_GetAtomName --
 *
 *	This procedure is equivalent to XGetAtomName except that
 *	it uses the local atom cache to avoid contacting the
 *	server.
 *
 * Results:
 *	The return value is a character string corresponding to
 *	the atom given by "atom".  This string's storage space
 *	is static:  it need not be freed by the caller, and should
 *	not be modified by the caller.  If "atom" doesn't exist
 *	on tkwin's display, then the string "?bad atom?" is returned.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */

char *
Tk_GetAtomName(tkwin, atom)
    Tk_Window tkwin;		/* Window token;  map atom to name
				 * relative to this window's
				 * display. */
    Atom atom;			/* Atom whose name is wanted. */
{
    register TkDisplay *dispPtr;
    register Tcl_HashEntry *hPtr;

    dispPtr = ((TkWindow *) tkwin)->dispPtr;
    if (!dispPtr->atomInit) {
	AtomInit(dispPtr);
    }

    hPtr = Tcl_FindHashEntry(&dispPtr->atomTable, (char *) atom);
    if (hPtr == NULL) {
	char *name;
	Tk_ErrorHandler handler;
	int new, mustFree;

	handler= Tk_CreateErrorHandler(dispPtr->display, BadAtom,
		-1, -1, (int (*)()) NULL, (ClientData) NULL);
	name = XGetAtomName(dispPtr->display, atom);
	mustFree = 1;
	if (name == NULL) {
	    name = "?bad atom?";
	    mustFree = 0;
	}
	Tk_DeleteErrorHandler(handler);
	hPtr = Tcl_CreateHashEntry(&dispPtr->nameTable, (char *) name,
		&new);
	Tcl_SetHashValue(hPtr, atom);
	if (mustFree) {
	    XFree(name);
	}
	name = Tcl_GetHashKey(&dispPtr->nameTable, hPtr);
	hPtr = Tcl_CreateHashEntry(&dispPtr->atomTable, (char *) atom,
		&new);
	Tcl_SetHashValue(hPtr, name);
    }
    return (char *) Tcl_GetHashValue(hPtr);
}

/*
 *--------------------------------------------------------------
 *
 * AtomInit --
 *
 *	Initialize atom-related information for a display.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Tables get initialized, etc. etc..
 *
 *--------------------------------------------------------------
 */

static void
AtomInit(dispPtr)
    register TkDisplay *dispPtr;	/* Display to initialize. */
{
    dispPtr->atomInit = 1;
    Tcl_InitHashTable(&dispPtr->nameTable, TCL_STRING_KEYS);
    Tcl_InitHashTable(&dispPtr->atomTable, TCL_ONE_WORD_KEYS);
}