3 **Table of Contents** *generated with [DocToc](http://doctoc.herokuapp.com/)*
5 - [Synopsis](#synopsis)
6 - [Description](#description)
7 - [Parser functions](#parser-functions)
8 - [Emitting functions](#emitting-functions)
9 - [Conversion functions](#conversion-functions)
10 - [Generation functions](#generation-functions)
11 - [Iteration functions](#iteration-functions)
12 - [Validation functions](#validation-functions)
13 - [Utility functions](#utility-functions)
14 - [Parser functions](#parser-functions-1)
15 - [ucl_parser_new](#ucl_parser_new)
16 - [ucl_parser_register_macro](#ucl_parser_register_macro)
17 - [ucl_parser_register_variable](#ucl_parser_register_variable)
18 - [ucl_parser_add_chunk](#ucl_parser_add_chunk)
19 - [ucl_parser_add_string](#ucl_parser_add_string)
20 - [ucl_parser_add_file](#ucl_parser_add_file)
21 - [ucl_parser_get_object](#ucl_parser_get_object)
22 - [ucl_parser_get_error](#ucl_parser_get_error)
23 - [ucl_parser_free](#ucl_parser_free)
24 - [ucl_pubkey_add](#ucl_pubkey_add)
25 - [ucl_parser_set_filevars](#ucl_parser_set_filevars)
26 - [Parser usage example](#parser-usage-example)
27 - [Emitting functions](#emitting-functions-1)
28 - [ucl_object_emit](#ucl_object_emit)
29 - [ucl_object_emit_full](#ucl_object_emit_full)
30 - [Conversion functions](#conversion-functions-1)
31 - [Generation functions](#generation-functions-1)
32 - [ucl_object_new](#ucl_object_new)
33 - [ucl_object_typed_new](#ucl_object_typed_new)
34 - [Primitive objects generation](#primitive-objects-generation)
35 - [ucl_object_fromstring_common](#ucl_object_fromstring_common)
36 - [Iteration functions](#iteration-functions-1)
37 - [ucl_iterate_object](#ucl_iterate_object)
38 - [Validation functions](#validation-functions-1)
39 - [ucl_object_validate](#ucl_object_validate)
47 Libucl is a parser and `C` API to parse and generate `ucl` objects. Libucl consist of several groups of functions:
50 Used to parse `ucl` files and provide interface to extract `ucl` object. Currently, `libucl` can parse only full `ucl` documents, for instance, it is impossible to parse a part of document and therefore it is impossible to use `libucl` as a streaming parser. In future, this limitation can be removed.
52 ### Emitting functions
53 Convert `ucl` objects to some textual or binary representation. Currently, libucl supports the following exports:
55 - `JSON` - valid json format (can possibly loose some original data, such as implicit arrays)
56 - `Config` - human-readable configuration format (losseless)
57 - `YAML` - embedded yaml format (has the same limitations as `json` output)
59 ### Conversion functions
60 Help to convert `ucl` objects to C types. These functions are used to convert `ucl_object_t` to C primitive types, such as numbers, strings or boolean values.
62 ### Generation functions
63 Allow creating of `ucl` objects from C types and creating of complex `ucl` objects, such as hashes or arrays from primitive `ucl` objects, such as numbers or strings.
65 ### Iteration functions
66 Iterate over `ucl` complex objects or over a chain of values, for example when a key in an object has multiple values (that can be treated as implicit array or implicit consolidation).
68 ### Validation functions
69 Validation functions are used to validate some object `obj` using json-schema compatible object `schema`. Both input and schema must be UCL objects to perform validation.
72 Provide basic utilities to manage `ucl` objects: creating, removing, retaining and releasing reference count and so on.
76 Parser functions operates with `struct ucl_parser`.
81 struct ucl_parser* ucl_parser_new (int flags);
84 Creates new parser with the specified flags:
86 - `UCL_PARSER_KEY_LOWERCASE` - lowercase keys parsed
87 - `UCL_PARSER_ZEROCOPY` - try to use zero-copy mode when reading files (in zero-copy mode text chunk being parsed without copying strings so it should exist till any object parsed is used)
88 - `UCL_PARSER_NO_TIME` - treat time values as strings without parsing them as floats
90 ### ucl_parser_register_macro
93 void ucl_parser_register_macro (struct ucl_parser *parser,
94 const char *macro, ucl_macro_handler handler, void* ud);
97 Register new macro with name .`macro` parsed by handler `handler` that accepts opaque data pointer `ud`. Macro handler should be of the following type:
100 bool (*ucl_macro_handler) (const unsigned char *data,
101 size_t len, void* ud);`
104 Handler function accepts macro text `data` of length `len` and the opaque pointer `ud`. If macro is parsed successfully the handler should return `true`. `false` indicates parsing failure and the parser can be terminated.
106 ### ucl_parser_register_variable
109 void ucl_parser_register_variable (struct ucl_parser *parser,
110 const char *var, const char *value);
113 Register new variable $`var` that should be replaced by the parser to the `value` string.
115 ### ucl_parser_add_chunk
118 bool ucl_parser_add_chunk (struct ucl_parser *parser,
119 const unsigned char *data, size_t len);
122 Add new text chunk with `data` of length `len` to the parser. At the moment, `libucl` parser is not a streamlined parser and chunk *must* contain the *valid* ucl object. For example, this object should be valid:
128 while this one won't be parsed correctly:
134 This limitation may possible be removed in future.
136 ### ucl_parser_add_string
138 bool ucl_parser_add_string (struct ucl_parser *parser,
139 const char *data, size_t len);
142 This function acts exactly like `ucl_parser_add_chunk` does but if `len` argument is zero, then the string `data` must be zero-terminated and the actual length is calculated up to `\0` character.
144 ### ucl_parser_add_file
147 bool ucl_parser_add_file (struct ucl_parser *parser,
148 const char *filename);
151 Load file `filename` and parse it with the specified `parser`. This function uses `mmap` call to load file, therefore, it should not be `shrinked` during parsing. Otherwise, `libucl` can cause memory corruption and terminate the calling application. This function is also used by the internal handler of `include` macro, hence, this macro has the same limitation.
153 ### ucl_parser_get_object
156 ucl_object_t* ucl_parser_get_object (struct ucl_parser *parser);
159 If the `ucl` data has been parsed correctly this function returns the top object for the parser. Otherwise, this function returns the `NULL` pointer. The reference count for `ucl` object returned is increased by one, therefore, a caller should decrease reference by using `ucl_object_unref` to free object after usage.
161 ### ucl_parser_get_error
164 const char *ucl_parser_get_error(struct ucl_parser *parser);
167 Returns the constant error string for the parser object. If no error occurred during parsing a `NULL` object is returned. A caller should not try to free or modify this string.
172 void ucl_parser_free (struct ucl_parser *parser);
175 Frees memory occupied by the parser object. The reference count for top object is decreased as well, however if the function `ucl_parser_get_object` was called previously then the top object won't be freed.
180 bool ucl_pubkey_add (struct ucl_parser *parser,
181 const unsigned char *key, size_t len);
184 This function adds a public key from text blob `key` of length `len` to the `parser` object. This public key should be in the `PEM` format and can be used by `.includes` macro for checking signatures of files included. `Openssl` support should be enabled to make this function working. If a key cannot be added (e.g. due to format error) or `openssl` was not linked to `libucl` then this function returns `false`.
186 ### ucl_parser_set_filevars
189 bool ucl_parser_set_filevars (struct ucl_parser *parser,
190 const char *filename, bool need_expand);
193 Add the standard file variables to the `parser` based on the `filename` specified:
195 - `$FILENAME` - a filename of `ucl` input
196 - `$CURDIR` - a current directory of the input
198 For example, if a `filename` param is `../something.conf` then the variables will have the following values:
200 - `$FILENAME` - "../something.conf"
203 if `need_expand` parameter is `true` then all relative paths are expanded using `realpath` call. In this example if `..` is `/etc/dir` then variables will have these values:
205 - `$FILENAME` - "/etc/something.conf"
208 ## Parser usage example
210 The following example loads, parses and extracts `ucl` object from stdin using `libucl` parser functions (the length of input is limited to 8K):
214 struct ucl_parser *parser = NULL;
216 ucl_object_t *obj = NULL;
220 parser = ucl_parser_new (0);
221 while (!feof (in) && r < (int)sizeof (inbuf)) {
222 r += fread (inbuf + r, 1, sizeof (inbuf) - r, in);
224 ucl_parser_add_chunk (parser, inbuf, r);
227 if (ucl_parser_get_error (parser)) {
228 printf ("Error occured: %s\n", ucl_parser_get_error (parser));
232 obj = ucl_parser_get_object (parser);
235 if (parser != NULL) {
236 ucl_parser_free (parser);
239 ucl_object_unref (obj);
246 Libucl can transform UCL objects to a number of tectual formats:
248 - configuration (`UCL_EMIT_CONFIG`) - nginx like human readable configuration file where implicit arrays are transformed to the duplicate keys
249 - compact json: `UCL_EMIT_JSON_COMPACT` - single line valid json without spaces
250 - formatted json: `UCL_EMIT_JSON` - pretty formatted JSON with newlines and spaces
251 - compact yaml: `UCL_EMIT_YAML` - compact YAML output
253 Moreover, libucl API allows to select a custom set of emitting functions allowing
254 efficent and zero-copy output of libucl objects. Libucl uses the following structure to support this feature:
257 struct ucl_emitter_functions {
258 /** Append a single character */
259 int (*ucl_emitter_append_character) (unsigned char c, size_t nchars, void *ud);
260 /** Append a string of a specified length */
261 int (*ucl_emitter_append_len) (unsigned const char *str, size_t len, void *ud);
262 /** Append a 64 bit integer */
263 int (*ucl_emitter_append_int) (int64_t elt, void *ud);
264 /** Append floating point element */
265 int (*ucl_emitter_append_double) (double elt, void *ud);
266 /** Opaque userdata pointer */
271 This structure defines the following callbacks:
273 - `ucl_emitter_append_character` - a function that is called to append `nchars` characters equal to `c`
274 - `ucl_emitter_append_len` - used to append a string of length `len` starting from pointer `str`
275 - `ucl_emitter_append_int` - this function applies to integer numbers
276 - `ucl_emitter_append_double` - this function is intended to output floating point variable
278 The set of these functions could be used to output text formats of `UCL` objects to different structures or streams.
280 Libucl provides the following functions for emitting UCL objects:
285 unsigned char *ucl_object_emit (const ucl_object_t *obj, enum ucl_emitter emit_type);
288 Allocate a string that is suitable to fit the underlying UCL object `obj` and fill it with the textual representation of the object `obj` according to style `emit_type`. The caller should free the returned string after using.
290 ### ucl_object_emit_full
293 bool ucl_object_emit_full (const ucl_object_t *obj, enum ucl_emitter emit_type,
294 struct ucl_emitter_functions *emitter);
297 This function is similar to the previous with the exception that it accepts the additional argument `emitter` that defines the concrete set of output functions. This emit function could be useful for custom structures or streams emitters (including C++ ones, for example).
299 # Conversion functions
301 Conversion functions are used to convert UCL objects to primitive types, such as strings, numbers or boolean values. There are two types of conversion functions:
303 - safe: try to convert an ucl object to a primitive type and fail if such a conversion is not possible
304 - unsafe: return primitive type without additional checks, if the object cannot be converted then some reasonable default is returned (NULL for strings and 0 for numbers)
306 Also there is a single `ucl_object_tostring_forced` function that converts any UCL object (including compound types - arrays and objects) to a string representation. For compound and numeric types this function performs emitting to a compact json format actually.
308 Here is a list of all conversion functions:
310 - `ucl_object_toint` - returns `int64_t` of UCL object
311 - `ucl_object_todouble` - returns `double` of UCL object
312 - `ucl_object_toboolean` - returns `bool` of UCL object
313 - `ucl_object_tostring` - returns `const char *` of UCL object (this string is NULL terminated)
314 - `ucl_object_tolstring` - returns `const char *` and `size_t` len of UCL object (string can be not NULL terminated)
315 - `ucl_object_tostring_forced` - returns string representation of any UCL object
317 Strings returned by these pointers are associated with the UCL object and exist over its lifetime. A caller should not free this memory.
319 # Generation functions
321 It is possible to generate UCL objects from C primitive types. Moreover, libucl permits to create and modify complex UCL objects, such as arrays or associative objects.
325 ucl_object_t * ucl_object_new (void)
328 Creates new object of type `UCL_NULL`. This object should be released by caller.
330 ## ucl_object_typed_new
332 ucl_object_t * ucl_object_typed_new (unsigned int type)
335 Create an object of a specified type:
336 - `UCL_OBJECT` - UCL object - key/value pairs
337 - `UCL_ARRAY` - UCL array
338 - `UCL_INT` - integer number
339 - `UCL_FLOAT` - floating point number
340 - `UCL_STRING` - NULL terminated string
341 - `UCL_BOOLEAN` - boolean value
342 - `UCL_TIME` - time value (floating point number of seconds)
343 - `UCL_USERDATA` - opaque userdata pointer (may be used in macros)
344 - `UCL_NULL` - null value
346 This object should be released by caller.
348 ## Primitive objects generation
349 Libucl provides the functions similar to inverse conversion functions called with the specific C type:
350 - `ucl_object_fromint` - converts `int64_t` to UCL object
351 - `ucl_object_fromdouble` - converts `double` to UCL object
352 - `ucl_object_fromboolean` - converts `bool` to UCL object
353 - `ucl_object_fromstring` - converts `const char *` to UCL object (this string is NULL terminated)
354 - `ucl_object_fromlstring` - converts `const char *` and `size_t` len to UCL object (string can be not NULL terminated)
356 Also there is a function to generate UCL object from a string performing various parsing or conversion operations called `ucl_object_fromstring_common`.
358 ## ucl_object_fromstring_common
360 ucl_object_t * ucl_object_fromstring_common (const char *str,
361 size_t len, enum ucl_string_flags flags)
364 This function is used to convert a string `str` of size `len` to an UCL objects applying `flags` conversions. If `len` is equal to zero then a `str` is assumed as NULL-terminated. This function supports the following flags (a set of flags can be specified using logical `OR` operation):
366 - `UCL_STRING_ESCAPE` - perform JSON escape
367 - `UCL_STRING_TRIM` - trim leading and trailing whitespaces
368 - `UCL_STRING_PARSE_BOOLEAN` - parse passed string and detect boolean
369 - `UCL_STRING_PARSE_INT` - parse passed string and detect integer number
370 - `UCL_STRING_PARSE_DOUBLE` - parse passed string and detect integer or float number
371 - `UCL_STRING_PARSE_TIME` - parse time values as floating point numbers
372 - `UCL_STRING_PARSE_NUMBER` - parse passed string and detect number (both float, integer and time types)
373 - `UCL_STRING_PARSE` - parse passed string (and detect booleans, numbers and time values)
374 - `UCL_STRING_PARSE_BYTES` - assume that numeric multipliers are in bytes notation, for example `10k` means `10*1024` and not `10*1000` as assumed without this flag
376 If parsing operations fail then the resulting UCL object will be a `UCL_STRING`. A caller should always check the type of the returned object and release it after using.
378 # Iteration functions
380 Iteration are used to iterate over UCL compound types: arrays and objects. Moreover, iterations could be performed over the keys with multiple values (implicit arrays). To iterate over an object, an array or a key with multiple values there is a function `ucl_iterate_object`.
382 ## ucl_iterate_object
384 const ucl_object_t* ucl_iterate_object (const ucl_object_t *obj,
385 ucl_object_iter_t *iter, bool expand_values);
388 This function accept opaque iterator pointer `iter`. In the first call this iterator *must* be initialized to `NULL`. Iterator is changed by this function call. `ucl_iterate_object` returns the next UCL object in the compound object `obj` or `NULL` if all objects have been iterated. The reference count of the object returned is not increased, so a caller should not unref the object or modify its content (e.g. by inserting to another compound object). The object `obj` should not be changed during the iteration process as well. `expand_values` flag speicifies whether `ucl_iterate_object` should expand keys with multiple values. The general rule is that if you need to iterate throught the *object* or *explicit array*, then you always need to set this flag to `true`. However, if you get some key in the object and want to extract all its values then you should set `expand_values` to `false`. Mixing of iteration types are not permitted since the iterator is set according to the iteration type and cannot be reused. Here is an example of iteration over the objects using libucl API (assuming that `top` is `UCL_OBJECT` in this example):
391 ucl_object_iter_t it = NULL, it_obj = NULL;
392 const ucl_object_t *cur, *tmp;
394 /* Iterate over the object */
395 while ((obj = ucl_iterate_object (top, &it, true))) {
396 printf ("key: \"%s\"\n", ucl_object_key (obj));
397 /* Iterate over the values of a key */
398 while ((cur = ucl_iterate_object (obj, &it_obj, false))) {
399 printf ("value: \"%s\"\n",
400 ucl_object_tostring_forced (cur));
405 # Validation functions
407 Currently, there is only one validation function called `ucl_object_validate`. It performs validation of object using the specified schema. This function is defined as following:
409 ## ucl_object_validate
411 bool ucl_object_validate (const ucl_object_t *schema,
412 const ucl_object_t *obj, struct ucl_schema_error *err);
415 This function uses ucl object `schema`, that must be valid in terms of `json-schema` draft v4, to validate input object `obj`. If this function returns `true` then validation procedure has been succeed. Otherwise, `false` is returned and `err` is set to a specific value. If caller set `err` to NULL then this function does not set any error just returning `false`. Error is the structure defined as following:
418 struct ucl_schema_error {
419 enum ucl_schema_error_code code; /* error code */
420 char msg[128]; /* error message */
421 ucl_object_t *obj; /* object where error occured */
425 Caller may use `code` field to get a numeric error code:
428 enum ucl_schema_error_code {
429 UCL_SCHEMA_OK = 0, /* no error */
430 UCL_SCHEMA_TYPE_MISMATCH, /* type of object is incorrect */
431 UCL_SCHEMA_INVALID_SCHEMA, /* schema is invalid */
432 UCL_SCHEMA_MISSING_PROPERTY,/* missing properties */
433 UCL_SCHEMA_CONSTRAINT, /* constraint found */
434 UCL_SCHEMA_MISSING_DEPENDENCY, /* missing dependency */
435 UCL_SCHEMA_UNKNOWN /* generic error */
439 `msg` is a stiring description of an error and `obj` is an object where error has been occurred. Error object is not allocated by libucl, so there is no need to free it after validation (a static object should thus be used).