summaryrefslogtreecommitdiffstats
path: root/src/st/croco/cr-declaration.c
blob: bf1bcc1cd02db3ffd9ef3cf0e791803f19552dbc (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
/* -*- Mode: C; indent-tabs-mode: nil; c-basic-offset: 8 -*- */

/*
 * This file is part of The Croco Library
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2.1 of the GNU Lesser General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 *
 * Author: Dodji Seketeli.
 * See COPYRIGHTS file for copyright information.
 */


#include <string.h>
#include "cr-declaration.h"
#include "cr-statement.h"
#include "cr-parser.h"

/**
 *@CRDeclaration:
 *
 *The definition of the #CRDeclaration class.
 */

/**
 * dump:
 *@a_this: the current instance of #CRDeclaration.
 *@a_fp: the destination file pointer.
 *@a_indent: the number of indentation white char. 
 *
 *Dumps (serializes) one css declaration to a file.
 */
static void
dump (CRDeclaration const * a_this, FILE * a_fp, glong a_indent)
{
        guchar *str = NULL;

        g_return_if_fail (a_this);

        str = (guchar *) cr_declaration_to_string (a_this, a_indent);
        if (str) {
                fprintf (a_fp, "%s", str);
                g_free (str);
                str = NULL;
        }
}

/**
 * cr_declaration_new:
 * @a_statement: the statement this declaration belongs to. can be NULL.
 *@a_property: the property string of the declaration
 *@a_value: the value expression of the declaration.
 *Constructor of #CRDeclaration.
 *
 *Returns the newly built instance of #CRDeclaration, or NULL in
 *case of error.
 *
 *The returned CRDeclaration takes ownership of @a_property and @a_value.
 *(E.g. cr_declaration_destroy on this CRDeclaration will also free
 *@a_property and @a_value.)
 */
CRDeclaration *
cr_declaration_new (CRStatement * a_statement,
                    CRString * a_property, CRTerm * a_value)
{
        CRDeclaration *result = NULL;

        g_return_val_if_fail (a_property, NULL);

        if (a_statement)
                g_return_val_if_fail (a_statement
                                      && ((a_statement->type == RULESET_STMT)
                                          || (a_statement->type
                                              == AT_FONT_FACE_RULE_STMT)
                                          || (a_statement->type
                                              == AT_PAGE_RULE_STMT)), NULL);

        result = g_try_malloc (sizeof (CRDeclaration));
        if (!result) {
                cr_utils_trace_info ("Out of memory");
                return NULL;
        }
        memset (result, 0, sizeof (CRDeclaration));
        result->property = a_property;
        result->value = a_value;

        if (a_value) {
                cr_term_ref (a_value);
        }
        result->parent_statement = a_statement;
        return result;
}

/**
 * cr_declaration_parse_from_buf:
 *@a_statement: the parent css2 statement of this
 *this declaration. Must be non NULL and of type
 *RULESET_STMT (must be a ruleset).
 *@a_str: the string that contains the statement.
 *@a_enc: the encoding of a_str.
 *
 *Parses a text buffer that contains
 *a css declaration.
 *Returns the parsed declaration, or NULL in case of error.
 */
CRDeclaration *
cr_declaration_parse_from_buf (CRStatement * a_statement,
                               const guchar * a_str, enum CREncoding a_enc)
{
        enum CRStatus status = CR_OK;
        CRTerm *value = NULL;
        CRString *property = NULL;
        CRDeclaration *result = NULL;
        CRParser *parser = NULL;
        gboolean important = FALSE;

        g_return_val_if_fail (a_str, NULL);
        if (a_statement)
                g_return_val_if_fail (a_statement->type == RULESET_STMT,
                                      NULL);

        parser = cr_parser_new_from_buf ((guchar*)a_str, strlen ((const char *) a_str), a_enc, FALSE);
        g_return_val_if_fail (parser, NULL);

        status = cr_parser_try_to_skip_spaces_and_comments (parser);
        if (status != CR_OK)
                goto cleanup;

        status = cr_parser_parse_declaration (parser, &property,
                                              &value, &important);
        if (status != CR_OK || !property)
                goto cleanup;

        result = cr_declaration_new (a_statement, property, value);
        if (result) {
                property = NULL;
                value = NULL;
                result->important = important;
        }

      cleanup:

        if (parser) {
                cr_parser_destroy (parser);
                parser = NULL;
        }

        if (property) {
                cr_string_destroy (property);
                property = NULL;
        }

        if (value) {
                cr_term_destroy (value);
                value = NULL;
        }

        return result;
}

/**
 * cr_declaration_parse_list_from_buf:
 *@a_str: the input buffer that contains the list of declaration to
 *parse.
 *@a_enc: the encoding of a_str
 *
 *Parses a ';' separated list of properties declaration.
 *Returns the parsed list of declaration, NULL if parsing failed.
 */
CRDeclaration *
cr_declaration_parse_list_from_buf (const guchar * a_str,
                                    enum CREncoding a_enc)
{

        enum CRStatus status = CR_OK;
        CRTerm *value = NULL;
        CRString *property = NULL;
        CRDeclaration *result = NULL,
                *cur_decl = NULL;
        CRParser *parser = NULL;
        CRTknzr *tokenizer = NULL;
        gboolean important = FALSE;

        g_return_val_if_fail (a_str, NULL);

        parser = cr_parser_new_from_buf ((guchar*)a_str, strlen ((const char *) a_str), a_enc, FALSE);
        g_return_val_if_fail (parser, NULL);
        status = cr_parser_get_tknzr (parser, &tokenizer);
        if (status != CR_OK || !tokenizer) {
                if (status == CR_OK)
                        status = CR_ERROR;
                goto cleanup;
        }
        status = cr_parser_try_to_skip_spaces_and_comments (parser);
        if (status != CR_OK)
                goto cleanup;

        status = cr_parser_parse_declaration (parser, &property,
                                              &value, &important);
        if (status != CR_OK || !property) {
                if (status != CR_OK)
                        status = CR_ERROR;
                goto cleanup;
        }
        result = cr_declaration_new (NULL, property, value);
        if (result) {
                property = NULL;
                value = NULL;
                result->important = important;
        }
        /*now, go parse the other declarations */
        for (;;) {
                guint32 c = 0;

                cr_parser_try_to_skip_spaces_and_comments (parser);
                status = cr_tknzr_peek_char (tokenizer, &c);
                if (status != CR_OK) {
                        if (status == CR_END_OF_INPUT_ERROR)
                                status = CR_OK;
                        goto cleanup;
                }
                if (c == ';') {
                        status = cr_tknzr_read_char (tokenizer, &c);
                } else {
                        break;
                }
                important = FALSE;
                cr_parser_try_to_skip_spaces_and_comments (parser);
                status = cr_parser_parse_declaration (parser, &property,
                                                      &value, &important);
                if (status != CR_OK || !property) {
                        if (status == CR_END_OF_INPUT_ERROR) {
                                status = CR_OK;
                        }
                        break;
                }
                cur_decl = cr_declaration_new (NULL, property, value);
                if (cur_decl) {
                        cur_decl->important = important;
                        result = cr_declaration_append (result, cur_decl);
                        property = NULL;
                        value = NULL;
                        cur_decl = NULL;
                } else {
                        break;
                }
        }

      cleanup:

        if (parser) {
                cr_parser_destroy (parser);
                parser = NULL;
        }

        if (property) {
                cr_string_destroy (property);
                property = NULL;
        }

        if (value) {
                cr_term_destroy (value);
                value = NULL;
        }

        if (status != CR_OK && result) {
                cr_declaration_destroy (result);
                result = NULL;
        }
        return result;
}

/**
 * cr_declaration_append:
 *@a_this: the current declaration list.
 *@a_new: the declaration to append.
 *
 *Appends a new declaration to the current declarations list.
 *Returns the declaration list with a_new appended to it, or NULL
 *in case of error.
 */
CRDeclaration *
cr_declaration_append (CRDeclaration * a_this, CRDeclaration * a_new)
{
        CRDeclaration *cur = NULL;

        g_return_val_if_fail (a_new, NULL);

        if (!a_this)
                return a_new;

        for (cur = a_this; cur && cur->next; cur = cur->next) ;

        cur->next = a_new;
        a_new->prev = cur;

        return a_this;
}

/**
 * cr_declaration_unlink:
 *@a_decls: the declaration to unlink.
 *
 *Unlinks the declaration from the declaration list.
 *case of a successful completion, NULL otherwise.
 *
 *Returns a pointer to the unlinked declaration in
 */
CRDeclaration *
cr_declaration_unlink (CRDeclaration * a_decl)
{
        CRDeclaration *result = a_decl;

        g_return_val_if_fail (result, NULL);

        /*
         *some sanity checks first
         */
        if (a_decl->prev) {
                g_return_val_if_fail (a_decl->prev->next == a_decl, NULL);

        }
        if (a_decl->next) {
                g_return_val_if_fail (a_decl->next->prev == a_decl, NULL);
        }

        /*
         *now, the real unlinking job.
         */
        if (a_decl->prev) {
                a_decl->prev->next = a_decl->next;
        }
        if (a_decl->next) {
                a_decl->next->prev = a_decl->prev;
        }
        if (a_decl->parent_statement) {
                CRDeclaration **children_decl_ptr = NULL;

                switch (a_decl->parent_statement->type) {
                case RULESET_STMT:
                        if (a_decl->parent_statement->kind.ruleset) {
                                children_decl_ptr =
                                        &a_decl->parent_statement->
                                        kind.ruleset->decl_list;
                        }

                        break;

                case AT_FONT_FACE_RULE_STMT:
                        if (a_decl->parent_statement->kind.font_face_rule) {
                                children_decl_ptr =
                                        &a_decl->parent_statement->
                                        kind.font_face_rule->decl_list;
                        }
                        break;
                case AT_PAGE_RULE_STMT:
                        if (a_decl->parent_statement->kind.page_rule) {
                                children_decl_ptr =
                                        &a_decl->parent_statement->
                                        kind.page_rule->decl_list;
                        }

                default:
                        break;
                }
                if (children_decl_ptr
                    && *children_decl_ptr && *children_decl_ptr == a_decl)
                        *children_decl_ptr = (*children_decl_ptr)->next;
        }

        a_decl->next = NULL;
        a_decl->prev = NULL;
        a_decl->parent_statement = NULL;

        return result;
}

/**
 * cr_declaration_prepend:
 * @a_this: the current declaration list.
 * @a_new: the declaration to prepend.
 *
 * prepends a declaration to the current declaration list.
 *
 * Returns the list with a_new prepended or NULL in case of error.
 */
CRDeclaration *
cr_declaration_prepend (CRDeclaration * a_this, CRDeclaration * a_new)
{
        CRDeclaration *cur = NULL;

        g_return_val_if_fail (a_new, NULL);

        if (!a_this)
                return a_new;

        a_this->prev = a_new;
        a_new->next = a_this;

        for (cur = a_new; cur && cur->prev; cur = cur->prev) ;

        return cur;
}

/**
 * cr_declaration_append2:
 *@a_this: the current declaration list.
 *@a_prop: the property string of the declaration to append.
 *@a_value: the value of the declaration to append.
 *
 *Appends a declaration to the current declaration list.
 *Returns the list with the new property appended to it, or NULL in
 *case of an error.
 */
CRDeclaration *
cr_declaration_append2 (CRDeclaration * a_this,
                        CRString * a_prop, CRTerm * a_value)
{
        CRDeclaration *new_elem = NULL;

        if (a_this) {
                new_elem = cr_declaration_new (a_this->parent_statement,
                                               a_prop, a_value);
        } else {
                new_elem = cr_declaration_new (NULL, a_prop, a_value);
        }

        g_return_val_if_fail (new_elem, NULL);

        return cr_declaration_append (a_this, new_elem);
}

/**
 * cr_declaration_dump:
 *@a_this: the current instance of #CRDeclaration.
 *@a_fp: the destination file.
 *@a_indent: the number of indentation white char.
 *@a_one_per_line: whether to put one declaration per line of not .
 *
 *
 *Dumps a declaration list to a file.
 */
void
cr_declaration_dump (CRDeclaration const * a_this, FILE * a_fp, glong a_indent,
                     gboolean a_one_per_line)
{
        CRDeclaration const *cur = NULL;

        g_return_if_fail (a_this);

        for (cur = a_this; cur; cur = cur->next) {
                if (cur->prev) {
                        if (a_one_per_line == TRUE)
                                fprintf (a_fp, ";\n");
                        else
                                fprintf (a_fp, "; ");
                }
                dump (cur, a_fp, a_indent);
        }
}

/**
 * cr_declaration_dump_one:
 *@a_this: the current instance of #CRDeclaration.
 *@a_fp: the destination file.
 *@a_indent: the number of indentation white char.
 *
 *Dumps the first declaration of the declaration list to a file.
 */
void
cr_declaration_dump_one (CRDeclaration const * a_this, FILE * a_fp, glong a_indent)
{
        g_return_if_fail (a_this);

        dump (a_this, a_fp, a_indent);
}

/**
 * cr_declaration_to_string:
 *@a_this: the current instance of #CRDeclaration.
 *@a_indent: the number of indentation white char
 *to put before the actual serialisation.
 *
 *Serializes the declaration into a string
 *Returns the serialized form the declaration. The caller must
 *free the string using g_free().
 */
gchar *
cr_declaration_to_string (CRDeclaration const * a_this, gulong a_indent)
{
        GString *stringue = NULL;

        gchar *str = NULL,
                *result = NULL;

        g_return_val_if_fail (a_this, NULL);

	stringue = g_string_new (NULL);

	if (a_this->property 
	    && a_this->property->stryng
	    && a_this->property->stryng->str) {
		str = g_strndup (a_this->property->stryng->str,
				 a_this->property->stryng->len);
		if (str) {
			cr_utils_dump_n_chars2 (' ', stringue, 
						a_indent);
			g_string_append (stringue, str);
			g_free (str);
			str = NULL;
		} else
                        goto error;

                if (a_this->value) {
                        guchar *value_str = NULL;

                        value_str = cr_term_to_string (a_this->value);
                        if (value_str) {
                                g_string_append_printf (stringue, " : %s",
                                                        value_str);
                                g_free (value_str);
                        } else
                                goto error;
                }
                if (a_this->important == TRUE) {
                        g_string_append_printf (stringue, " %s",
                                                "!important");
                }
        }
        if (stringue && stringue->str) {
                result = stringue->str;
                g_string_free (stringue, FALSE);
        }
        return result;

      error:
        if (stringue) {
                g_string_free (stringue, TRUE);
                stringue = NULL;
        }
        if (str) {
                g_free (str);
                str = NULL;
        }

        return result;
}

/**
 * cr_declaration_list_to_string:
 *@a_this: the current instance of #CRDeclaration.
 *@a_indent: the number of indentation white char
 *to put before the actual serialisation.
 *
 *Serializes the declaration list into a string
 */
guchar *
cr_declaration_list_to_string (CRDeclaration const * a_this, gulong a_indent)
{
        CRDeclaration const *cur = NULL;
        GString *stringue = NULL;
        guchar *str = NULL,
                *result = NULL;

        g_return_val_if_fail (a_this, NULL);

        stringue = g_string_new (NULL);

        for (cur = a_this; cur; cur = cur->next) {
                str = (guchar *) cr_declaration_to_string (cur, a_indent);
                if (str) {
                        g_string_append_printf (stringue, "%s;", str);
                        g_free (str);
                } else
                        break;
        }
        if (stringue && stringue->str) {
                result = (guchar *) stringue->str;
                g_string_free (stringue, FALSE);
        }

        return result;
}

/**
 * cr_declaration_list_to_string2:
 *@a_this: the current instance of #CRDeclaration.
 *@a_indent: the number of indentation white char
 *@a_one_decl_per_line: whether to output one doc per line or not.
 *to put before the actual serialisation.
 *
 *Serializes the declaration list into a string
 *Returns the serialized form the declararation.
 */
guchar *
cr_declaration_list_to_string2 (CRDeclaration const * a_this,
                                gulong a_indent, gboolean a_one_decl_per_line)
{
        CRDeclaration const *cur = NULL;
        GString *stringue = NULL;
        guchar *str = NULL,
                *result = NULL;

        g_return_val_if_fail (a_this, NULL);

        stringue = g_string_new (NULL);

        for (cur = a_this; cur; cur = cur->next) {
                str = (guchar *) cr_declaration_to_string (cur, a_indent);
                if (str) {
                        if (a_one_decl_per_line == TRUE) {
                                if (cur->next)
                                        g_string_append_printf (stringue,
                                                                "%s;\n", str);
                                else
                                        g_string_append (stringue,
                                                         (const gchar *) str);
                        } else {
                                if (cur->next)
                                        g_string_append_printf (stringue,
                                                                "%s;", str);
                                else
                                        g_string_append (stringue,
                                                         (const gchar *) str);
                        }
                        g_free (str);
                } else
                        break;
        }
        if (stringue && stringue->str) {
                result = (guchar *) stringue->str;
                g_string_free (stringue, FALSE);
        }

        return result;
}

/**
 * cr_declaration_nr_props:
 *@a_this: the current instance of #CRDeclaration.
 *Return the number of properties in the declaration
 */
gint
cr_declaration_nr_props (CRDeclaration const * a_this)
{
        CRDeclaration const *cur = NULL;
        int nr = 0;

        g_return_val_if_fail (a_this, -1);

        for (cur = a_this; cur; cur = cur->next)
                nr++;
        return nr;
}

/**
 * cr_declaration_get_from_list:
 *@a_this: the current instance of #CRDeclaration.
 *@itemnr: the index into the declaration list.
 *
 *Use an index to get a CRDeclaration from the declaration list.
 *
 *Returns #CRDeclaration at position itemnr, 
 *if itemnr > number of declarations - 1,
 *it will return NULL.
 */
CRDeclaration *
cr_declaration_get_from_list (CRDeclaration * a_this, int itemnr)
{
        CRDeclaration *cur = NULL;
        int nr = 0;

        g_return_val_if_fail (a_this, NULL);

        for (cur = a_this; cur; cur = cur->next)
                if (nr++ == itemnr)
                        return cur;
        return NULL;
}

/**
 * cr_declaration_get_by_prop_name:
 *@a_this: the current instance of #CRDeclaration.
 *@a_prop: the property name to search for.
 *
 *Use property name to get a CRDeclaration from the declaration list.
 *Returns #CRDeclaration with property name a_prop, or NULL if not found.
 */
CRDeclaration *
cr_declaration_get_by_prop_name (CRDeclaration * a_this,
                                 const guchar * a_prop)
{
        CRDeclaration *cur = NULL;

        g_return_val_if_fail (a_this, NULL);
        g_return_val_if_fail (a_prop, NULL);

        for (cur = a_this; cur; cur = cur->next) {
		if (cur->property 
		    && cur->property->stryng
		    && cur->property->stryng->str) {
			if (!strcmp (cur->property->stryng->str, 
				     (const char *) a_prop)) {
				return cur;
			}
		}
	}
        return NULL;
}

/**
 * cr_declaration_ref:
 *@a_this: the current instance of #CRDeclaration.
 *
 *Increases the ref count of the current instance of #CRDeclaration.
 */
void
cr_declaration_ref (CRDeclaration * a_this)
{
        g_return_if_fail (a_this);

        a_this->ref_count++;
}

/**
 * cr_declaration_unref:
 *@a_this: the current instance of #CRDeclaration.
 *
 *Decrements the ref count of the current instance of #CRDeclaration.
 *If the ref count reaches zero, the current instance of #CRDeclaration
 *if destroyed.
 *Returns TRUE if @a_this was destroyed (ref count reached zero),
 *FALSE otherwise.
 */
gboolean
cr_declaration_unref (CRDeclaration * a_this)
{
        g_return_val_if_fail (a_this, FALSE);

        if (a_this->ref_count) {
                a_this->ref_count--;
        }

        if (a_this->ref_count == 0) {
                cr_declaration_destroy (a_this);
                return TRUE;
        }
        return FALSE;
}

/**
 * cr_declaration_destroy:
 *@a_this: the current instance of #CRDeclaration.
 *
 *Destructor of the declaration list.
 */
void
cr_declaration_destroy (CRDeclaration * a_this)
{
        CRDeclaration *cur = NULL;

        g_return_if_fail (a_this);

        /*
         * Go to the last element of the list.
         */
        for (cur = a_this; cur->next; cur = cur->next)
                g_assert (cur->next->prev == cur);

        /*
         * Walk backward the list and free each "next" element.
         * Meanwhile, free each property/value pair contained in the list.
         */
        for (; cur; cur = cur->prev) {
                g_free (cur->next);
                cur->next = NULL;

                if (cur->property) {
                        cr_string_destroy (cur->property);
                        cur->property = NULL;
                }

                if (cur->value) {
                        cr_term_destroy (cur->value);
                        cur->value = NULL;
                }
        }

        g_free (a_this);
}