summaryrefslogtreecommitdiffstats
path: root/generic/tclResult.c
blob: 9e837962bc9c8f09ec3c5d702ea1686be2210fd7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
/* 
 * tclResult.c --
 *
 *	This file contains code to manage the interpreter result.
 *
 * 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: tclResult.c,v 1.11 2004/09/30 23:06:48 dgp Exp $
 */

#include "tclInt.h"

/*
 * Function prototypes for local procedures in this file:
 */

static void             ResetObjResult _ANSI_ARGS_((Interp *iPtr));
static void		SetupAppendBuffer _ANSI_ARGS_((Interp *iPtr,
			    int newSpace));


/*
 *----------------------------------------------------------------------
 *
 * Tcl_SaveResult --
 *
 *      Takes a snapshot of the current result state of the interpreter.
 *      The snapshot can be restored at any point by
 *      Tcl_RestoreResult. Note that this routine does not 
 *	preserve the errorCode, errorInfo, or flags fields so it
 *	should not be used if an error is in progress.
 *
 *      Once a snapshot is saved, it must be restored by calling
 *      Tcl_RestoreResult, or discarded by calling
 *      Tcl_DiscardResult.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Resets the interpreter result.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SaveResult(interp, statePtr)
    Tcl_Interp *interp;		/* Interpreter to save. */
    Tcl_SavedResult *statePtr;	/* Pointer to state structure. */
{
    Interp *iPtr = (Interp *) interp;

    /*
     * Move the result object into the save state.  Note that we don't need
     * to change its refcount because we're moving it, not adding a new
     * reference.  Put an empty object into the interpreter.
     */

    statePtr->objResultPtr = iPtr->objResultPtr;
    iPtr->objResultPtr = Tcl_NewObj(); 
    Tcl_IncrRefCount(iPtr->objResultPtr); 

    /*
     * Save the string result. 
     */

    statePtr->freeProc = iPtr->freeProc;
    if (iPtr->result == iPtr->resultSpace) {
	/*
	 * Copy the static string data out of the interp buffer.
	 */

	statePtr->result = statePtr->resultSpace;
	strcpy(statePtr->result, iPtr->result);
	statePtr->appendResult = NULL;
    } else if (iPtr->result == iPtr->appendResult) {
	/*
	 * Move the append buffer out of the interp.
	 */

	statePtr->appendResult = iPtr->appendResult;
	statePtr->appendAvl = iPtr->appendAvl;
	statePtr->appendUsed = iPtr->appendUsed;
	statePtr->result = statePtr->appendResult;
	iPtr->appendResult = NULL;
	iPtr->appendAvl = 0;
	iPtr->appendUsed = 0;
    } else {
	/*
	 * Move the dynamic or static string out of the interpreter.
	 */

	statePtr->result = iPtr->result;
	statePtr->appendResult = NULL;
    }

    iPtr->result = iPtr->resultSpace;
    iPtr->resultSpace[0] = 0;
    iPtr->freeProc = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_RestoreResult --
 *
 *      Restores the state of the interpreter to a snapshot taken
 *      by Tcl_SaveResult.  After this call, the token for
 *      the interpreter state is no longer valid.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Restores the interpreter result.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_RestoreResult(interp, statePtr)
    Tcl_Interp* interp;		/* Interpreter being restored. */
    Tcl_SavedResult *statePtr;	/* State returned by Tcl_SaveResult. */
{
    Interp *iPtr = (Interp *) interp;

    Tcl_ResetResult(interp);

    /*
     * Restore the string result.
     */

    iPtr->freeProc = statePtr->freeProc;
    if (statePtr->result == statePtr->resultSpace) {
	/*
	 * Copy the static string data into the interp buffer.
	 */

	iPtr->result = iPtr->resultSpace;
	strcpy(iPtr->result, statePtr->result);
    } else if (statePtr->result == statePtr->appendResult) {
	/*
	 * Move the append buffer back into the interp.
	 */

	if (iPtr->appendResult != NULL) {
	    ckfree((char *)iPtr->appendResult);
	}

	iPtr->appendResult = statePtr->appendResult;
	iPtr->appendAvl = statePtr->appendAvl;
	iPtr->appendUsed = statePtr->appendUsed;
	iPtr->result = iPtr->appendResult;
    } else {
	/*
	 * Move the dynamic or static string back into the interpreter.
	 */

	iPtr->result = statePtr->result;
    }

    /*
     * Restore the object result.
     */

    Tcl_DecrRefCount(iPtr->objResultPtr);
    iPtr->objResultPtr = statePtr->objResultPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DiscardResult --
 *
 *      Frees the memory associated with an interpreter snapshot
 *      taken by Tcl_SaveResult.  If the snapshot is not
 *      restored, this procedure must be called to discard it,
 *      or the memory will be lost.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DiscardResult(statePtr)
    Tcl_SavedResult *statePtr;	/* State returned by Tcl_SaveResult. */
{
    TclDecrRefCount(statePtr->objResultPtr);

    if (statePtr->result == statePtr->appendResult) {
	ckfree(statePtr->appendResult);
    } else if (statePtr->freeProc) {
	if (statePtr->freeProc == TCL_DYNAMIC) {
	    ckfree(statePtr->result);
	} else {
	    (*statePtr->freeProc)(statePtr->result);
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetResult --
 *
 *	Arrange for "string" to be the Tcl return value.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	interp->result is left pointing either to "string" (if "copy" is 0)
 *	or to a copy of string. Also, the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetResult(interp, string, freeProc)
    Tcl_Interp *interp;		/* Interpreter with which to associate the
				 * return value. */
    register char *string;	/* Value to be returned.  If NULL, the
				 * result is set to an empty string. */
    Tcl_FreeProc *freeProc;	/* Gives information about the string:
				 * TCL_STATIC, TCL_VOLATILE, or the address
				 * of a Tcl_FreeProc such as free. */
{
    Interp *iPtr = (Interp *) interp;
    int length;
    register Tcl_FreeProc *oldFreeProc = iPtr->freeProc;
    char *oldResult = iPtr->result;

    if (string == NULL) {
	iPtr->resultSpace[0] = 0;
	iPtr->result = iPtr->resultSpace;
	iPtr->freeProc = 0;
    } else if (freeProc == TCL_VOLATILE) {
	length = strlen(string);
	if (length > TCL_RESULT_SIZE) {
	    iPtr->result = (char *) ckalloc((unsigned) length+1);
	    iPtr->freeProc = TCL_DYNAMIC;
	} else {
	    iPtr->result = iPtr->resultSpace;
	    iPtr->freeProc = 0;
	}
	strcpy(iPtr->result, string);
    } else {
	iPtr->result = string;
	iPtr->freeProc = freeProc;
    }

    /*
     * If the old result was dynamically-allocated, free it up.  Do it
     * here, rather than at the beginning, in case the new result value
     * was part of the old result value.
     */

    if (oldFreeProc != 0) {
	if (oldFreeProc == TCL_DYNAMIC) {
	    ckfree(oldResult);
	} else {
	    (*oldFreeProc)(oldResult);
	}
    }

    /*
     * Reset the object result since we just set the string result.
     */

    ResetObjResult(iPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetStringResult --
 *
 *	Returns an interpreter's result value as a string.
 *
 * Results:
 *	The interpreter's result as a string.
 *
 * Side effects:
 *	If the string result is empty, the object result is moved to the
 *	string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

CONST char *
Tcl_GetStringResult(interp)
     register Tcl_Interp *interp; /* Interpreter whose result to return. */
{
    /*
     * If the string result is empty, move the object result to the
     * string result, then reset the object result.
     */
    
    if (*(interp->result) == 0) {
	Tcl_SetResult(interp, TclGetString(Tcl_GetObjResult(interp)),
	        TCL_VOLATILE);
    }
    return interp->result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetObjResult --
 *
 *	Arrange for objPtr to be an interpreter's result value.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	interp->objResultPtr is left pointing to the object referenced
 *	by objPtr. The object's reference count is incremented since
 *	there is now a new reference to it. The reference count for any
 *	old objResultPtr value is decremented. Also, the string result
 *	is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetObjResult(interp, objPtr)
    Tcl_Interp *interp;		/* Interpreter with which to associate the
				 * return object value. */
    register Tcl_Obj *objPtr;	/* Tcl object to be returned. If NULL, the
				 * obj result is made an empty string
				 * object. */
{
    register Interp *iPtr = (Interp *) interp;
    register Tcl_Obj *oldObjResult = iPtr->objResultPtr;

    iPtr->objResultPtr = objPtr;
    Tcl_IncrRefCount(objPtr);	/* since interp result is a reference */

    /*
     * We wait until the end to release the old object result, in case
     * we are setting the result to itself.
     */
    
    TclDecrRefCount(oldObjResult);

    /*
     * Reset the string result since we just set the result object.
     */

    if (iPtr->freeProc != NULL) {
	if (iPtr->freeProc == TCL_DYNAMIC) {
	    ckfree(iPtr->result);
	} else {
	    (*iPtr->freeProc)(iPtr->result);
	}
	iPtr->freeProc = 0;
    }
    iPtr->result = iPtr->resultSpace;
    iPtr->resultSpace[0] = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetObjResult --
 *
 *	Returns an interpreter's result value as a Tcl object. The object's
 *	reference count is not modified; the caller must do that if it
 *	needs to hold on to a long-term reference to it.
 *
 * Results:
 *	The interpreter's result as an object.
 *
 * Side effects:
 *	If the interpreter has a non-empty string result, the result object
 *	is either empty or stale because some procedure set interp->result
 *	directly. If so, the string result is moved to the result object
 *	then the string result is reset.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_GetObjResult(interp)
    Tcl_Interp *interp;		/* Interpreter whose result to return. */
{
    register Interp *iPtr = (Interp *) interp;
    Tcl_Obj *objResultPtr;
    int length;

    /*
     * If the string result is non-empty, move the string result to the
     * object result, then reset the string result.
     */
    
    if (*(iPtr->result) != 0) {
	ResetObjResult(iPtr);
	
	objResultPtr = iPtr->objResultPtr;
	length = strlen(iPtr->result);
	TclInitStringRep(objResultPtr, iPtr->result, length);
	
	if (iPtr->freeProc != NULL) {
	    if (iPtr->freeProc == TCL_DYNAMIC) {
		ckfree(iPtr->result);
	    } else {
		(*iPtr->freeProc)(iPtr->result);
	    }
	    iPtr->freeProc = 0;
	}
	iPtr->result = iPtr->resultSpace;
	iPtr->resultSpace[0] = 0;
    }
    return iPtr->objResultPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_AppendResultVA --
 *
 *	Append a variable number of strings onto the interpreter's string
 *	result.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The result of the interpreter given by the first argument is
 *	extended by the strings in the va_list (up to a terminating NULL
 *	argument).
 *
 *	If the string result is empty, the object result is moved to the
 *	string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_AppendResultVA (interp, argList)
    Tcl_Interp *interp;		/* Interpreter with which to associate the
				 * return value. */
    va_list argList;		/* Variable argument list. */
{
#define STATIC_LIST_SIZE 16
    Interp *iPtr = (Interp *) interp;
    char *string, *static_list[STATIC_LIST_SIZE];
    char **args = static_list;
    int nargs_space = STATIC_LIST_SIZE;
    int nargs, newSpace, i;

    /*
     * If the string result is empty, move the object result to the
     * string result, then reset the object result.
     */

    if (*(iPtr->result) == 0) {
	Tcl_SetResult((Tcl_Interp *) iPtr,
	        TclGetString(Tcl_GetObjResult((Tcl_Interp *) iPtr)),
	        TCL_VOLATILE);
    }
    
    /*
     * Scan through all the arguments to see how much space is needed
     * and save pointers to the arguments in the args array,
     * reallocating as necessary.
     */

    nargs = 0;
    newSpace = 0;
    while (1) {
 	string = va_arg(argList, char *);
	if (string == NULL) {
	    break;
	}
 	if (nargs >= nargs_space) {
 	    /* 
 	     * Expand the args buffer
 	     */
 	    nargs_space += STATIC_LIST_SIZE;
 	    if (args == static_list) {
 	    	args = (void *)ckalloc(nargs_space * sizeof(char *));
 		for (i = 0; i < nargs; ++i) {
 		    args[i] = static_list[i];
 		}
 	    } else {
 		args = (void *)ckrealloc((void *)args,
			nargs_space * sizeof(char *));
 	    }
 	}
  	newSpace += strlen(string);
	args[nargs++] = string;
    }

    /*
     * If the append buffer isn't already setup and large enough to hold
     * the new data, set it up.
     */

    if ((iPtr->result != iPtr->appendResult)
	    || (iPtr->appendResult[iPtr->appendUsed] != 0)
	    || ((newSpace + iPtr->appendUsed) >= iPtr->appendAvl)) {
       SetupAppendBuffer(iPtr, newSpace);
    }

    /*
     * Now go through all the argument strings again, copying them into the
     * buffer.
     */

    for (i = 0; i < nargs; ++i) {
 	string = args[i];
  	strcpy(iPtr->appendResult + iPtr->appendUsed, string);
  	iPtr->appendUsed += strlen(string);
    }
 
    /*
     * If we had to allocate a buffer from the heap, 
     * free it now.
     */
 
    if (args != static_list) {
     	ckfree((void *)args);
    }
#undef STATIC_LIST_SIZE
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_AppendResult --
 *
 *	Append a variable number of strings onto the interpreter's string
 *	result.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The result of the interpreter given by the first argument is
 *	extended by the strings given by the second and following arguments
 *	(up to a terminating NULL argument).
 *
 *	If the string result is empty, the object result is moved to the
 *	string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_AppendResult TCL_VARARGS_DEF(Tcl_Interp *,arg1)
{
    Tcl_Interp *interp;
    va_list argList;

    interp = TCL_VARARGS_START(Tcl_Interp *,arg1,argList);
    Tcl_AppendResultVA(interp, argList);
    va_end(argList);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_AppendElement --
 *
 *	Convert a string to a valid Tcl list element and append it to the
 *	result (which is ostensibly a list).
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The result in the interpreter given by the first argument is
 *	extended with a list element converted from string. A separator
 *	space is added before the converted list element unless the current
 *	result is empty, contains the single character "{", or ends in " {".
 *
 *	If the string result is empty, the object result is moved to the
 *	string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_AppendElement(interp, string)
    Tcl_Interp *interp;		/* Interpreter whose result is to be
				 * extended. */
    CONST char *string;		/* String to convert to list element and
				 * add to result. */
{
    Interp *iPtr = (Interp *) interp;
    char *dst;
    int size;
    int flags;

    /*
     * If the string result is empty, move the object result to the
     * string result, then reset the object result.
     */

    if (*(iPtr->result) == 0) {
	Tcl_SetResult(interp, TclGetString(Tcl_GetObjResult(interp)),
	        TCL_VOLATILE);
    }

    /*
     * See how much space is needed, and grow the append buffer if
     * needed to accommodate the list element.
     */

    size = Tcl_ScanElement(string, &flags) + 1;
    if ((iPtr->result != iPtr->appendResult)
	    || (iPtr->appendResult[iPtr->appendUsed] != 0)
	    || ((size + iPtr->appendUsed) >= iPtr->appendAvl)) {
       SetupAppendBuffer(iPtr, size+iPtr->appendUsed);
    }

    /*
     * Convert the string into a list element and copy it to the
     * buffer that's forming, with a space separator if needed.
     */

    dst = iPtr->appendResult + iPtr->appendUsed;
    if (TclNeedSpace(iPtr->appendResult, dst)) {
	iPtr->appendUsed++;
	*dst = ' ';
	dst++;
	/*
	 * If we need a space to separate this element from preceding
	 * stuff, then this element will not lead a list, and need not
	 * have it's leading '#' quoted.
	 */
	flags |= TCL_DONT_QUOTE_HASH;
    }
    iPtr->appendUsed += Tcl_ConvertElement(string, dst, flags);
}

/*
 *----------------------------------------------------------------------
 *
 * SetupAppendBuffer --
 *
 *	This procedure makes sure that there is an append buffer properly
 *	initialized, if necessary, from the interpreter's result, and
 *	that it has at least enough room to accommodate newSpace new
 *	bytes of information.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static void
SetupAppendBuffer(iPtr, newSpace)
    Interp *iPtr;		/* Interpreter whose result is being set up. */
    int newSpace;		/* Make sure that at least this many bytes
				 * of new information may be added. */
{
    int totalSpace;

    /*
     * Make the append buffer larger, if that's necessary, then copy the
     * result into the append buffer and make the append buffer the official
     * Tcl result.
     */

    if (iPtr->result != iPtr->appendResult) {
	/*
	 * If an oversized buffer was used recently, then free it up
	 * so we go back to a smaller buffer.  This avoids tying up
	 * memory forever after a large operation.
	 */

	if (iPtr->appendAvl > 500) {
	    ckfree(iPtr->appendResult);
	    iPtr->appendResult = NULL;
	    iPtr->appendAvl = 0;
	}
	iPtr->appendUsed = strlen(iPtr->result);
    } else if (iPtr->result[iPtr->appendUsed] != 0) {
	/*
	 * Most likely someone has modified a result created by
	 * Tcl_AppendResult et al. so that it has a different size.
	 * Just recompute the size.
	 */

	iPtr->appendUsed = strlen(iPtr->result);
    }
    
    totalSpace = newSpace + iPtr->appendUsed;
    if (totalSpace >= iPtr->appendAvl) {
	char *new;

	if (totalSpace < 100) {
	    totalSpace = 200;
	} else {
	    totalSpace *= 2;
	}
	new = (char *) ckalloc((unsigned) totalSpace);
	strcpy(new, iPtr->result);
	if (iPtr->appendResult != NULL) {
	    ckfree(iPtr->appendResult);
	}
	iPtr->appendResult = new;
	iPtr->appendAvl = totalSpace;
    } else if (iPtr->result != iPtr->appendResult) {
	strcpy(iPtr->appendResult, iPtr->result);
    }
    
    Tcl_FreeResult((Tcl_Interp *) iPtr);
    iPtr->result = iPtr->appendResult;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_FreeResult --
 *
 *	This procedure frees up the memory associated with an interpreter's
 *	string result. It also resets the interpreter's result object.
 *	Tcl_FreeResult is most commonly used when a procedure is about to
 *	replace one result value with another.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Frees the memory associated with interp's string result and sets
 *	interp->freeProc to zero, but does not change interp->result or
 *	clear error state. Resets interp's result object to an unshared
 *	empty object.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_FreeResult(interp)
    register Tcl_Interp *interp; /* Interpreter for which to free result. */
{
    register Interp *iPtr = (Interp *) interp;
    
    if (iPtr->freeProc != NULL) {
	if (iPtr->freeProc == TCL_DYNAMIC) {
	    ckfree(iPtr->result);
	} else {
	    (*iPtr->freeProc)(iPtr->result);
	}
	iPtr->freeProc = 0;
    }
    
    ResetObjResult(iPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ResetResult --
 *
 *	This procedure resets both the interpreter's string and object
 *	results.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	It resets the result object to an unshared empty object. It
 *	then restores the interpreter's string result area to its default
 *	initialized state, freeing up any memory that may have been
 *	allocated. It also clears any error information for the interpreter.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_ResetResult(interp)
    register Tcl_Interp *interp; /* Interpreter for which to clear result. */
{
    register Interp *iPtr = (Interp *) interp;

    ResetObjResult(iPtr);
    if (iPtr->freeProc != NULL) {
	if (iPtr->freeProc == TCL_DYNAMIC) {
	    ckfree(iPtr->result);
	} else {
	    (*iPtr->freeProc)(iPtr->result);
	}
	iPtr->freeProc = 0;
    }
    iPtr->result = iPtr->resultSpace;
    iPtr->resultSpace[0] = 0;
    iPtr->flags &= ~(ERR_ALREADY_LOGGED | ERR_IN_PROGRESS | ERROR_CODE_SET);
}

/*
 *----------------------------------------------------------------------
 *
 * ResetObjResult --
 *
 *	Procedure used to reset an interpreter's Tcl result object.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Resets the interpreter's result object to an unshared empty string
 *	object with ref count one. It does not clear any error information
 *	in the interpreter.
 *
 *----------------------------------------------------------------------
 */

static void
ResetObjResult(iPtr)
    register Interp *iPtr;	/* Points to the interpreter whose result
				 * object should be reset. */
{
    register Tcl_Obj *objResultPtr = iPtr->objResultPtr;

    if (Tcl_IsShared(objResultPtr)) {
	TclDecrRefCount(objResultPtr);
	TclNewObj(objResultPtr);
	Tcl_IncrRefCount(objResultPtr);
	iPtr->objResultPtr = objResultPtr;
    } else {
	if ((objResultPtr->bytes != NULL)
	        && (objResultPtr->bytes != tclEmptyStringRep)) {
	    ckfree((char *) objResultPtr->bytes);
	}
	objResultPtr->bytes  = tclEmptyStringRep;
	objResultPtr->length = 0;
	TclFreeIntRep(objResultPtr);
	objResultPtr->typePtr = (Tcl_ObjType *) NULL;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetErrorCodeVA --
 *
 *	This procedure is called to record machine-readable information
 *	about an error that is about to be returned.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The errorCode global variable is modified to hold all of the
 *	arguments to this procedure, in a list form with each argument
 *	becoming one element of the list.  A flag is set internally
 *	to remember that errorCode has been set, so the variable doesn't
 *	get set automatically when the error is returned.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetErrorCodeVA (interp, argList)
    Tcl_Interp *interp;		/* Interpreter in which to access the errorCode
				 * variable. */
    va_list argList;		/* Variable argument list. */
{
    Tcl_Obj *errorObj = Tcl_NewObj();

    /*
     * Scan through the arguments one at a time, appending them to
     * $errorCode as list elements.
     */

    while (1) {
	char *elem = va_arg(argList, char *);
	if (elem == NULL) {
	    break;
	}
	Tcl_ListObjAppendElement(NULL, errorObj, Tcl_NewStringObj(elem, -1));
    }
    Tcl_SetObjErrorCode(interp, errorObj);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetErrorCode --
 *
 *	This procedure is called to record machine-readable information
 *	about an error that is about to be returned.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The errorCode global variable is modified to hold all of the
 *	arguments to this procedure, in a list form with each argument
 *	becoming one element of the list.  A flag is set internally
 *	to remember that errorCode has been set, so the variable doesn't
 *	get set automatically when the error is returned.
 *
 *----------------------------------------------------------------------
 */
	/* VARARGS2 */
void
Tcl_SetErrorCode TCL_VARARGS_DEF(Tcl_Interp *,arg1)
{
    Tcl_Interp *interp;
    va_list argList;

    /*
     * Scan through the arguments one at a time, appending them to
     * $errorCode as list elements.
     */

    interp = TCL_VARARGS_START(Tcl_Interp *,arg1,argList);
    Tcl_SetErrorCodeVA(interp, argList);
    va_end(argList);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetObjErrorCode --
 *
 *	This procedure is called to record machine-readable information
 *	about an error that is about to be returned. The caller should
 *	build a list object up and pass it to this routine.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The errorCode global variable is modified to be the new value.
 *	A flag is set internally to remember that errorCode has been
 *	set, so the variable doesn't get set automatically when the
 *	error is returned.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetObjErrorCode(interp, errorObjPtr)
    Tcl_Interp *interp;
    Tcl_Obj *errorObjPtr;
{
    Interp *iPtr = (Interp *) interp;
    
    Tcl_ObjSetVar2(interp, iPtr->execEnvPtr->errorCode, NULL,
	    errorObjPtr, TCL_GLOBAL_ONLY);
    iPtr->flags |= ERROR_CODE_SET;
}

/*
 *-------------------------------------------------------------------------
 *
 * TclTransferResult --
 *
 *	Copy the result (and error information) from one interp to 
 *	another.  Used when one interp has caused another interp to 
 *	evaluate a script and then wants to transfer the results back
 *	to itself.
 *
 *	This routine copies the string reps of the result and error 
 *	information.  It does not simply increment the refcounts of the
 *	result and error information objects themselves.
 *	It is not legal to exchange objects between interps, because an
 *	object may be kept alive by one interp, but have an internal rep 
 *	that is only valid while some other interp is alive.  
 *
 * Results:
 *	The target interp's result is set to a copy of the source interp's
 *	result.  The source's error information "$errorInfo" may be
 *	appended to the target's error information and the source's error
 *	code "$errorCode" may be stored in the target's error code.
 *
 * Side effects:
 *	None.
 *
 *-------------------------------------------------------------------------
 */
	
void
TclTransferResult(sourceInterp, result, targetInterp)
    Tcl_Interp *sourceInterp;	/* Interp whose result and error information
				 * should be moved to the target interp.  
				 * After moving result, this interp's result 
				 * is reset. */
    int result;			/* TCL_OK if just the result should be copied, 
				 * TCL_ERROR if both the result and error 
				 * information should be copied. */
    Tcl_Interp *targetInterp;	/* Interp where result and error information 
				 * should be stored.  If source and target
				 * are the same, nothing is done. */
{
    Interp *iPtr;
    Tcl_Obj *objPtr;

    if (sourceInterp == targetInterp) {
	return;
    }

    if (result == TCL_ERROR) {
	/*
	 * An error occurred, so transfer error information from the source
	 * interpreter to the target interpreter.  Setting the flags tells
	 * the target interp that it has inherited a partial traceback
	 * chain, not just a simple error message.
	 */

	iPtr = (Interp *) sourceInterp;
        if ((iPtr->flags & ERR_ALREADY_LOGGED) == 0) {
            Tcl_AddErrorInfo(sourceInterp, "");
        }
        iPtr->flags &= ~(ERR_ALREADY_LOGGED);
        
        Tcl_ResetResult(targetInterp);
        
	objPtr = Tcl_GetVar2Ex(sourceInterp, "errorInfo", NULL,
		TCL_GLOBAL_ONLY);
	if (objPtr) {
	    Tcl_SetVar2Ex(targetInterp, "errorInfo", NULL, objPtr,
		    TCL_GLOBAL_ONLY);
	    ((Interp *) targetInterp)->flags |= ERR_IN_PROGRESS;
	}

	objPtr = Tcl_GetVar2Ex(sourceInterp, "errorCode", NULL,
		TCL_GLOBAL_ONLY);
	if (objPtr) {
	    Tcl_SetObjErrorCode(targetInterp, objPtr);
	}
    }

    /* This may need examination for safety */
    Tcl_DecrRefCount( ((Interp *) targetInterp)->returnOpts );
    ((Interp *) targetInterp)->returnOpts = 
	    ((Interp *) sourceInterp)->returnOpts;
    Tcl_IncrRefCount( ((Interp *) targetInterp)->returnOpts );

    Tcl_SetObjResult(targetInterp, Tcl_GetObjResult(sourceInterp));
    Tcl_ResetResult(sourceInterp);
}