xref: /freebsd/contrib/libucl/src/ucl_emitter.c (revision 1f4bcc459a76b7aa664f3fd557684cd0ba6da352)
1 /* Copyright (c) 2013, Vsevolod Stakhov
2  * All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are met:
6  *       * Redistributions of source code must retain the above copyright
7  *         notice, this list of conditions and the following disclaimer.
8  *       * Redistributions in binary form must reproduce the above copyright
9  *         notice, this list of conditions and the following disclaimer in the
10  *         documentation and/or other materials provided with the distribution.
11  *
12  * THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
13  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
14  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
15  * DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
16  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
17  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
18  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
19  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
20  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
21  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
22  */
23 
24 #ifdef HAVE_CONFIG_H
25 #include "config.h"
26 #endif
27 
28 #include "ucl.h"
29 #include "ucl_internal.h"
30 #include "ucl_chartable.h"
31 #ifdef HAVE_FLOAT_H
32 #include <float.h>
33 #endif
34 #ifdef HAVE_MATH_H
35 #include <math.h>
36 #endif
37 
38 /**
39  * @file ucl_emitter.c
40  * Serialise UCL object to various of output formats
41  */
42 
43 static void ucl_emitter_common_elt (struct ucl_emitter_context *ctx,
44 		const ucl_object_t *obj, bool first, bool print_key, bool compact);
45 
46 #define UCL_EMIT_TYPE_OPS(type)		\
47 	static void ucl_emit_ ## type ## _elt (struct ucl_emitter_context *ctx,	\
48 		const ucl_object_t *obj, bool first, bool print_key);	\
49 	static void ucl_emit_ ## type ## _start_obj (struct ucl_emitter_context *ctx,	\
50 		const ucl_object_t *obj, bool print_key);	\
51 	static void ucl_emit_ ## type## _start_array (struct ucl_emitter_context *ctx,	\
52 		const ucl_object_t *obj, bool print_key);	\
53 	static void ucl_emit_ ##type## _end_object (struct ucl_emitter_context *ctx,	\
54 		const ucl_object_t *obj);	\
55 	static void ucl_emit_ ##type## _end_array (struct ucl_emitter_context *ctx,	\
56 		const ucl_object_t *obj)
57 
58 /*
59  * JSON format operations
60  */
61 UCL_EMIT_TYPE_OPS(json);
62 UCL_EMIT_TYPE_OPS(json_compact);
63 UCL_EMIT_TYPE_OPS(config);
64 UCL_EMIT_TYPE_OPS(yaml);
65 UCL_EMIT_TYPE_OPS(msgpack);
66 
67 #define UCL_EMIT_TYPE_CONTENT(type) {	\
68 	.ucl_emitter_write_elt = ucl_emit_ ## type ## _elt,	\
69 	.ucl_emitter_start_object = ucl_emit_ ## type ##_start_obj,	\
70 	.ucl_emitter_start_array = ucl_emit_ ## type ##_start_array,	\
71 	.ucl_emitter_end_object = ucl_emit_ ## type ##_end_object,	\
72 	.ucl_emitter_end_array = ucl_emit_ ## type ##_end_array	\
73 }
74 
75 const struct ucl_emitter_operations ucl_standartd_emitter_ops[] = {
76 	[UCL_EMIT_JSON] = UCL_EMIT_TYPE_CONTENT(json),
77 	[UCL_EMIT_JSON_COMPACT] = UCL_EMIT_TYPE_CONTENT(json_compact),
78 	[UCL_EMIT_CONFIG] = UCL_EMIT_TYPE_CONTENT(config),
79 	[UCL_EMIT_YAML] = UCL_EMIT_TYPE_CONTENT(yaml),
80 	[UCL_EMIT_MSGPACK] = UCL_EMIT_TYPE_CONTENT(msgpack)
81 };
82 
83 /*
84  * Utility to check whether we need a top object
85  */
86 #define UCL_EMIT_IDENT_TOP_OBJ(ctx, obj) ((ctx)->top != (obj) || \
87 		((ctx)->id == UCL_EMIT_JSON_COMPACT || (ctx)->id == UCL_EMIT_JSON))
88 
89 
90 /**
91  * Add tabulation to the output buffer
92  * @param buf target buffer
93  * @param tabs number of tabs to add
94  */
95 static inline void
96 ucl_add_tabs (const struct ucl_emitter_functions *func, unsigned int tabs,
97 		bool compact)
98 {
99 	if (!compact && tabs > 0) {
100 		func->ucl_emitter_append_character (' ', tabs * 4, func->ud);
101 	}
102 }
103 
104 /**
105  * Print key for the element
106  * @param ctx
107  * @param obj
108  */
109 static void
110 ucl_emitter_print_key (bool print_key, struct ucl_emitter_context *ctx,
111 		const ucl_object_t *obj, bool compact)
112 {
113 	const struct ucl_emitter_functions *func = ctx->func;
114 
115 	if (!print_key) {
116 		return;
117 	}
118 
119 	if (ctx->id == UCL_EMIT_CONFIG) {
120 		if (obj->flags & UCL_OBJECT_NEED_KEY_ESCAPE) {
121 			ucl_elt_string_write_json (obj->key, obj->keylen, ctx);
122 		}
123 		else {
124 			func->ucl_emitter_append_len (obj->key, obj->keylen, func->ud);
125 		}
126 
127 		if (obj->type != UCL_OBJECT && obj->type != UCL_ARRAY) {
128 			func->ucl_emitter_append_len (" = ", 3, func->ud);
129 		}
130 		else {
131 			func->ucl_emitter_append_character (' ', 1, func->ud);
132 		}
133 	}
134 	else if (ctx->id == UCL_EMIT_YAML) {
135 		if (obj->keylen > 0 && (obj->flags & UCL_OBJECT_NEED_KEY_ESCAPE)) {
136 			ucl_elt_string_write_json (obj->key, obj->keylen, ctx);
137 		}
138 		else if (obj->keylen > 0) {
139 			func->ucl_emitter_append_len (obj->key, obj->keylen, func->ud);
140 		}
141 		else {
142 			func->ucl_emitter_append_len ("null", 4, func->ud);
143 		}
144 
145 		func->ucl_emitter_append_len (": ", 2, func->ud);
146 	}
147 	else {
148 		if (obj->keylen > 0) {
149 			ucl_elt_string_write_json (obj->key, obj->keylen, ctx);
150 		}
151 		else {
152 			func->ucl_emitter_append_len ("null", 4, func->ud);
153 		}
154 
155 		if (compact) {
156 			func->ucl_emitter_append_character (':', 1, func->ud);
157 		}
158 		else {
159 			func->ucl_emitter_append_len (": ", 2, func->ud);
160 		}
161 	}
162 }
163 
164 static void
165 ucl_emitter_finish_object (struct ucl_emitter_context *ctx,
166 		const ucl_object_t *obj, bool compact, bool is_array)
167 {
168 	const struct ucl_emitter_functions *func = ctx->func;
169 
170 	if (ctx->id == UCL_EMIT_CONFIG && obj != ctx->top) {
171 		if (obj->type != UCL_OBJECT && obj->type != UCL_ARRAY) {
172 			if (!is_array) {
173 				/* Objects are split by ';' */
174 				func->ucl_emitter_append_len (";\n", 2, func->ud);
175 			}
176 			else {
177 				/* Use commas for arrays */
178 				func->ucl_emitter_append_len (",\n", 2, func->ud);
179 			}
180 		}
181 		else {
182 			func->ucl_emitter_append_character ('\n', 1, func->ud);
183 		}
184 	}
185 }
186 
187 /**
188  * End standard ucl object
189  * @param ctx emitter context
190  * @param compact compact flag
191  */
192 static void
193 ucl_emitter_common_end_object (struct ucl_emitter_context *ctx,
194 		const ucl_object_t *obj, bool compact)
195 {
196 	const struct ucl_emitter_functions *func = ctx->func;
197 
198 	if (UCL_EMIT_IDENT_TOP_OBJ(ctx, obj)) {
199 		ctx->indent --;
200 		if (compact) {
201 			func->ucl_emitter_append_character ('}', 1, func->ud);
202 		}
203 		else {
204 			if (ctx->id != UCL_EMIT_CONFIG) {
205 				/* newline is already added for this format */
206 				func->ucl_emitter_append_character ('\n', 1, func->ud);
207 			}
208 			ucl_add_tabs (func, ctx->indent, compact);
209 			func->ucl_emitter_append_character ('}', 1, func->ud);
210 		}
211 	}
212 
213 	ucl_emitter_finish_object (ctx, obj, compact, false);
214 }
215 
216 /**
217  * End standard ucl array
218  * @param ctx emitter context
219  * @param compact compact flag
220  */
221 static void
222 ucl_emitter_common_end_array (struct ucl_emitter_context *ctx,
223 		const ucl_object_t *obj, bool compact)
224 {
225 	const struct ucl_emitter_functions *func = ctx->func;
226 
227 	ctx->indent --;
228 	if (compact) {
229 		func->ucl_emitter_append_character (']', 1, func->ud);
230 	}
231 	else {
232 		if (ctx->id != UCL_EMIT_CONFIG) {
233 			/* newline is already added for this format */
234 			func->ucl_emitter_append_character ('\n', 1, func->ud);
235 		}
236 		ucl_add_tabs (func, ctx->indent, compact);
237 		func->ucl_emitter_append_character (']', 1, func->ud);
238 	}
239 
240 	ucl_emitter_finish_object (ctx, obj, compact, true);
241 }
242 
243 /**
244  * Start emit standard UCL array
245  * @param ctx emitter context
246  * @param obj object to write
247  * @param compact compact flag
248  */
249 static void
250 ucl_emitter_common_start_array (struct ucl_emitter_context *ctx,
251 		const ucl_object_t *obj, bool print_key, bool compact)
252 {
253 	const ucl_object_t *cur;
254 	ucl_object_iter_t iter = NULL;
255 	const struct ucl_emitter_functions *func = ctx->func;
256 	bool first = true;
257 
258 	ucl_emitter_print_key (print_key, ctx, obj, compact);
259 
260 	if (compact) {
261 		func->ucl_emitter_append_character ('[', 1, func->ud);
262 	}
263 	else {
264 		func->ucl_emitter_append_len ("[\n", 2, func->ud);
265 	}
266 
267 	ctx->indent ++;
268 
269 	if (obj->type == UCL_ARRAY) {
270 		/* explicit array */
271 		while ((cur = ucl_iterate_object (obj, &iter, true)) != NULL) {
272 			ucl_emitter_common_elt (ctx, cur, first, false, compact);
273 			first = false;
274 		}
275 	}
276 	else {
277 		/* implicit array */
278 		cur = obj;
279 		while (cur) {
280 			ucl_emitter_common_elt (ctx, cur, first, false, compact);
281 			first = false;
282 			cur = cur->next;
283 		}
284 	}
285 
286 
287 }
288 
289 /**
290  * Start emit standard UCL object
291  * @param ctx emitter context
292  * @param obj object to write
293  * @param compact compact flag
294  */
295 static void
296 ucl_emitter_common_start_object (struct ucl_emitter_context *ctx,
297 		const ucl_object_t *obj, bool print_key, bool compact)
298 {
299 	ucl_hash_iter_t it = NULL;
300 	const ucl_object_t *cur, *elt;
301 	const struct ucl_emitter_functions *func = ctx->func;
302 	bool first = true;
303 
304 	ucl_emitter_print_key (print_key, ctx, obj, compact);
305 	/*
306 	 * Print <ident_level>{
307 	 * <ident_level + 1><object content>
308 	 */
309 	if (UCL_EMIT_IDENT_TOP_OBJ(ctx, obj)) {
310 		if (compact) {
311 			func->ucl_emitter_append_character ('{', 1, func->ud);
312 		}
313 		else {
314 			func->ucl_emitter_append_len ("{\n", 2, func->ud);
315 		}
316 		ctx->indent ++;
317 	}
318 
319 	while ((cur = ucl_hash_iterate (obj->value.ov, &it))) {
320 
321 		if (ctx->id == UCL_EMIT_CONFIG) {
322 			LL_FOREACH (cur, elt) {
323 				ucl_emitter_common_elt (ctx, elt, first, true, compact);
324 			}
325 		}
326 		else {
327 			/* Expand implicit arrays */
328 			if (cur->next != NULL) {
329 				if (!first) {
330 					if (compact) {
331 						func->ucl_emitter_append_character (',', 1, func->ud);
332 					}
333 					else {
334 						func->ucl_emitter_append_len (",\n", 2, func->ud);
335 					}
336 				}
337 				ucl_add_tabs (func, ctx->indent, compact);
338 				ucl_emitter_common_start_array (ctx, cur, true, compact);
339 				ucl_emitter_common_end_array (ctx, cur, compact);
340 			}
341 			else {
342 				ucl_emitter_common_elt (ctx, cur, first, true, compact);
343 			}
344 		}
345 
346 		first = false;
347 	}
348 }
349 
350 /**
351  * Common choice of object emitting
352  * @param ctx emitter context
353  * @param obj object to print
354  * @param first flag to mark the first element
355  * @param print_key print key of an object
356  * @param compact compact output
357  */
358 static void
359 ucl_emitter_common_elt (struct ucl_emitter_context *ctx,
360 		const ucl_object_t *obj, bool first, bool print_key, bool compact)
361 {
362 	const struct ucl_emitter_functions *func = ctx->func;
363 	bool flag;
364 	struct ucl_object_userdata *ud;
365 	const char *ud_out = "";
366 
367 	if (ctx->id != UCL_EMIT_CONFIG && !first) {
368 		if (compact) {
369 			func->ucl_emitter_append_character (',', 1, func->ud);
370 		}
371 		else {
372 			if (ctx->id == UCL_EMIT_YAML && ctx->indent == 0) {
373 				func->ucl_emitter_append_len ("\n", 1, func->ud);
374 			} else {
375 				func->ucl_emitter_append_len (",\n", 2, func->ud);
376 			}
377 		}
378 	}
379 
380 	ucl_add_tabs (func, ctx->indent, compact);
381 
382 	switch (obj->type) {
383 	case UCL_INT:
384 		ucl_emitter_print_key (print_key, ctx, obj, compact);
385 		func->ucl_emitter_append_int (ucl_object_toint (obj), func->ud);
386 		ucl_emitter_finish_object (ctx, obj, compact, !print_key);
387 		break;
388 	case UCL_FLOAT:
389 	case UCL_TIME:
390 		ucl_emitter_print_key (print_key, ctx, obj, compact);
391 		func->ucl_emitter_append_double (ucl_object_todouble (obj), func->ud);
392 		ucl_emitter_finish_object (ctx, obj, compact, !print_key);
393 		break;
394 	case UCL_BOOLEAN:
395 		ucl_emitter_print_key (print_key, ctx, obj, compact);
396 		flag = ucl_object_toboolean (obj);
397 		if (flag) {
398 			func->ucl_emitter_append_len ("true", 4, func->ud);
399 		}
400 		else {
401 			func->ucl_emitter_append_len ("false", 5, func->ud);
402 		}
403 		ucl_emitter_finish_object (ctx, obj, compact, !print_key);
404 		break;
405 	case UCL_STRING:
406 		ucl_emitter_print_key (print_key, ctx, obj, compact);
407 		if (ctx->id == UCL_EMIT_CONFIG && ucl_maybe_long_string (obj)) {
408 			ucl_elt_string_write_multiline (obj->value.sv, obj->len, ctx);
409 		}
410 		else {
411 			ucl_elt_string_write_json (obj->value.sv, obj->len, ctx);
412 		}
413 		ucl_emitter_finish_object (ctx, obj, compact, !print_key);
414 		break;
415 	case UCL_NULL:
416 		ucl_emitter_print_key (print_key, ctx, obj, compact);
417 		func->ucl_emitter_append_len ("null", 4, func->ud);
418 		ucl_emitter_finish_object (ctx, obj, compact, !print_key);
419 		break;
420 	case UCL_OBJECT:
421 		ucl_emitter_common_start_object (ctx, obj, print_key, compact);
422 		ucl_emitter_common_end_object (ctx, obj, compact);
423 		break;
424 	case UCL_ARRAY:
425 		ucl_emitter_common_start_array (ctx, obj, print_key, compact);
426 		ucl_emitter_common_end_array (ctx, obj, compact);
427 		break;
428 	case UCL_USERDATA:
429 		ud = (struct ucl_object_userdata *)obj;
430 		ucl_emitter_print_key (print_key, ctx, obj, compact);
431 		if (ud->emitter) {
432 			ud_out = ud->emitter (obj->value.ud);
433 			if (ud_out == NULL) {
434 				ud_out = "null";
435 			}
436 		}
437 		ucl_elt_string_write_json (ud_out, strlen (ud_out), ctx);
438 		ucl_emitter_finish_object (ctx, obj, compact, !print_key);
439 		break;
440 	}
441 }
442 
443 /*
444  * Specific standard implementations of the emitter functions
445  */
446 #define UCL_EMIT_TYPE_IMPL(type, compact)		\
447 	static void ucl_emit_ ## type ## _elt (struct ucl_emitter_context *ctx,	\
448 		const ucl_object_t *obj, bool first, bool print_key) {	\
449 		ucl_emitter_common_elt (ctx, obj, first, print_key, (compact));	\
450 	}	\
451 	static void ucl_emit_ ## type ## _start_obj (struct ucl_emitter_context *ctx,	\
452 		const ucl_object_t *obj, bool print_key) {	\
453 		ucl_emitter_common_start_object (ctx, obj, print_key, (compact));	\
454 	}	\
455 	static void ucl_emit_ ## type## _start_array (struct ucl_emitter_context *ctx,	\
456 		const ucl_object_t *obj, bool print_key) {	\
457 		ucl_emitter_common_start_array (ctx, obj, print_key, (compact));	\
458 	}	\
459 	static void ucl_emit_ ##type## _end_object (struct ucl_emitter_context *ctx,	\
460 		const ucl_object_t *obj) {	\
461 		ucl_emitter_common_end_object (ctx, obj, (compact));	\
462 	}	\
463 	static void ucl_emit_ ##type## _end_array (struct ucl_emitter_context *ctx,	\
464 		const ucl_object_t *obj) {	\
465 		ucl_emitter_common_end_array (ctx, obj, (compact));	\
466 	}
467 
468 UCL_EMIT_TYPE_IMPL(json, false)
469 UCL_EMIT_TYPE_IMPL(json_compact, true)
470 UCL_EMIT_TYPE_IMPL(config, false)
471 UCL_EMIT_TYPE_IMPL(yaml, false)
472 
473 static void
474 ucl_emit_msgpack_elt (struct ucl_emitter_context *ctx,
475 		const ucl_object_t *obj, bool first, bool print_key)
476 {
477 	ucl_object_iter_t it;
478 	struct ucl_object_userdata *ud;
479 	const char *ud_out;
480 	const ucl_object_t *cur, *celt;
481 
482 	switch (obj->type) {
483 	case UCL_INT:
484 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
485 		ucl_emitter_print_int_msgpack (ctx, ucl_object_toint (obj));
486 		break;
487 
488 	case UCL_FLOAT:
489 	case UCL_TIME:
490 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
491 		ucl_emitter_print_double_msgpack (ctx, ucl_object_todouble (obj));
492 		break;
493 
494 	case UCL_BOOLEAN:
495 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
496 		ucl_emitter_print_bool_msgpack (ctx, ucl_object_toboolean (obj));
497 		break;
498 
499 	case UCL_STRING:
500 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
501 
502 		if (obj->flags & UCL_OBJECT_BINARY) {
503 			ucl_emitter_print_binary_string_msgpack (ctx, obj->value.sv,
504 					obj->len);
505 		}
506 		else {
507 			ucl_emitter_print_string_msgpack (ctx, obj->value.sv, obj->len);
508 		}
509 		break;
510 
511 	case UCL_NULL:
512 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
513 		ucl_emitter_print_null_msgpack (ctx);
514 		break;
515 
516 	case UCL_OBJECT:
517 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
518 		ucl_emit_msgpack_start_obj (ctx, obj, print_key);
519 		it = NULL;
520 
521 		while ((cur = ucl_iterate_object (obj, &it, true)) != NULL) {
522 			LL_FOREACH (cur, celt) {
523 				ucl_emit_msgpack_elt (ctx, celt, false, true);
524 				/* XXX:
525 				 * in msgpack the length of objects is encoded within a single elt
526 				 * so in case of multi-value keys we are using merely the first
527 				 * element ignoring others
528 				 */
529 				break;
530 			}
531 		}
532 
533 		break;
534 
535 	case UCL_ARRAY:
536 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
537 		ucl_emit_msgpack_start_array (ctx, obj, print_key);
538 		it = NULL;
539 
540 		while ((cur = ucl_iterate_object (obj, &it, true)) != NULL) {
541 			ucl_emit_msgpack_elt (ctx, cur, false, false);
542 		}
543 
544 		break;
545 
546 	case UCL_USERDATA:
547 		ud = (struct ucl_object_userdata *)obj;
548 		ucl_emitter_print_key_msgpack (print_key, ctx, obj);
549 
550 		if (ud->emitter) {
551 			ud_out = ud->emitter (obj->value.ud);
552 			if (ud_out == NULL) {
553 				ud_out = "null";
554 			}
555 		}
556 		ucl_emitter_print_string_msgpack (ctx, obj->value.sv, obj->len);
557 		break;
558 	}
559 }
560 
561 static void
562 ucl_emit_msgpack_start_obj (struct ucl_emitter_context *ctx,
563 		const ucl_object_t *obj, bool print_key)
564 {
565 	ucl_emitter_print_object_msgpack (ctx, obj->len);
566 }
567 
568 static void
569 ucl_emit_msgpack_start_array (struct ucl_emitter_context *ctx,
570 		const ucl_object_t *obj, bool print_key)
571 {
572 	ucl_emitter_print_array_msgpack (ctx, obj->len);
573 }
574 
575 static void
576 ucl_emit_msgpack_end_object (struct ucl_emitter_context *ctx,
577 		const ucl_object_t *obj)
578 {
579 
580 }
581 
582 static void
583 ucl_emit_msgpack_end_array (struct ucl_emitter_context *ctx,
584 		const ucl_object_t *obj)
585 {
586 
587 }
588 
589 unsigned char *
590 ucl_object_emit (const ucl_object_t *obj, enum ucl_emitter emit_type)
591 {
592 	return ucl_object_emit_len (obj, emit_type, NULL);
593 }
594 
595 unsigned char *
596 ucl_object_emit_len (const ucl_object_t *obj, enum ucl_emitter emit_type,
597 		size_t *outlen)
598 {
599 	unsigned char *res = NULL;
600 	struct ucl_emitter_functions *func;
601 	UT_string *s;
602 
603 	if (obj == NULL) {
604 		return NULL;
605 	}
606 
607 	func = ucl_object_emit_memory_funcs ((void **)&res);
608 	s = func->ud;
609 
610 	if (func != NULL) {
611 		ucl_object_emit_full (obj, emit_type, func);
612 
613 		if (outlen != NULL) {
614 			*outlen = s->i;
615 		}
616 
617 		ucl_object_emit_funcs_free (func);
618 	}
619 
620 	return res;
621 }
622 
623 bool
624 ucl_object_emit_full (const ucl_object_t *obj, enum ucl_emitter emit_type,
625 		struct ucl_emitter_functions *emitter)
626 {
627 	const struct ucl_emitter_context *ctx;
628 	struct ucl_emitter_context my_ctx;
629 	bool res = false;
630 
631 	ctx = ucl_emit_get_standard_context (emit_type);
632 	if (ctx != NULL) {
633 		memcpy (&my_ctx, ctx, sizeof (my_ctx));
634 		my_ctx.func = emitter;
635 		my_ctx.indent = 0;
636 		my_ctx.top = obj;
637 
638 		my_ctx.ops->ucl_emitter_write_elt (&my_ctx, obj, true, false);
639 		res = true;
640 	}
641 
642 	return res;
643 }
644