Sat, 12 May 2018 14:13:53 +0200
documentation for the testing framework
1 ---
2 title: Modules
3 ---
5 UCX provides several modules for data structures and algorithms.
6 You may choose to use specific modules by inclueding the corresponding header
7 file.
8 Please note, that some modules make use of other UCX modules.
9 For instance, the [Allocator](#allocator) module is used by many other modules
10 to allow flexible memory allocation.
11 By default the header files are placed into an `ucx` directory within your
12 systems include directory. In this case you can use a module by including it
13 via `#include <ucx/MODULENAME.h>`.
14 Required modules are included automatically.
16 <div id="modules" align="center">
18 ----------------------- ---------------------- ---------------------------- -------------------------
19 [Allocator](#allocator) [AVL Tree](#avl-tree) [Buffer](#buffer) [List](#list)
20 [Logging](#logging) [Map](#map) [Memory Pool](#memory-pool) [Properties](#properties)
21 [Stack](#stack) [String](#string) [Testing](#testing) [Utilities](#utilities)
22 ----------------------- ---------------------- ---------------------------- -------------------------
24 </div>
26 ## Allocator
28 *Header file:* [allocator.h](api/allocator_8h.html)
29 *Required modules:* None.
31 A UCX allocator consists of a pointer to the memory area / pool and four
32 function pointers to memory management functions operating on this memory
33 area / pool. These functions shall behave equivalent to the standard libc
34 functions `malloc`, `calloc`, `realloc` and `free`.
36 The signature of the memory management functions is based on the signature
37 of the respective libc function but each of them takes the pointer to the
38 memory area / pool as first argument.
40 As the pointer to the memory area / pool can be arbitrarily chosen, any data
41 can be provided to the memory management functions. One example is the
42 [UCX Memory Pool](#memory-pool).
44 ## AVL Tree
46 *Header file:* [avl.h](api/avl_8h.html)
47 *Required modules:* [Allocator](#allocator)
49 This binary search tree implementation allows average O(1) insertion and
50 removal of elements (excluding binary search time).
51 All common binary tree operations are implemented. Furthermore, this module
52 provides search functions via lower and upper bounds.
54 ### Filtering items with a time window
56 Suppose you have a list of items which contain a `time_t` value and your task
57 is to find all items within a time window `[t_start, t_end]`.
58 With AVL Trees this is easy:
59 ```C
60 /* ---------------------
61 * Somewhere in a header
62 */
63 typedef struct {
64 time_t ts;
65 /* other important data */
66 } MyObject;
68 /* -----------
69 * Source code
70 */
72 UcxAVLTree* tree = ucx_avl_new(ucx_longintcmp);
73 /* ... populate tree with objects, use '& MyObject.ts' as key ... */
76 /* Now find every item, with 30 <= ts <= 70 */
77 time_t ts_start = 30;
78 time_t ts_end = 70;
80 printf("Values in range:\n");
81 for (
82 UcxAVLNode* node = ucx_avl_find_node(
83 tree, (intptr_t) &ts_start,
84 ucx_longintdist, UCX_AVL_FIND_LOWER_BOUNDED);
85 node && (*(time_t*)node->key) <= ts_end;
86 node = ucx_avl_succ(node)
87 ) {
88 printf(" ts: %ld\n", ((MyObject*)node->value)->ts);
89 }
91 ucx_avl_free_content(tree, free);
92 ucx_avl_free(tree);
93 ```
95 ## Buffer
97 *Header file:* [buffer.h](api/buffer_8h.html)
98 *Required modules:* None.
100 Instances of this buffer implementation can be used to read from or to write to
101 memory like you would do with a stream. This allows the use of
102 `ucx_stream_copy()` from the [Utilities](#utilities) module to copy contents
103 from one buffer to another or from file or network streams to the buffer and
104 vice-versa.
106 More features for convenient use of the buffer can be enabled, like automatic
107 memory management and automatic resizing of the buffer space.
108 See the documentation of the macro constants in the header file for more
109 information.
111 ### Add line numbers to a file
113 When reading a file line by line, you have three options: first, you could limit
114 the maximum supported line length.
115 Second, you allocate a god buffer large
116 enough for the most lines a text file could have.
117 And third, undoubtedly the best option, you start with a small buffer, which
118 adjusts on demand.
119 An `UcxBuffer` can be created to do just that for you.
120 Just pass the `UCX_BUFFER_AUTOEXTEND` option to the initialization function.
121 Here is a full working program, which adds line numbers to a file.
122 ```C
123 #include <stdio.h>
124 #include <ucx/buffer.h>
125 #include <ucx/utils.h>
127 int main(int argc, char** argv) {
129 if (argc != 2) {
130 fprintf(stderr, "Usage: %s <file>\n", argv[0]);
131 return 1;
132 }
134 FILE* input = fopen(argv[1], "r");
135 if (!input) {
136 perror("Canno read input");
137 return 1;
138 }
140 const size_t chunksize = 256;
142 UcxBuffer* linebuf =
143 ucx_buffer_new(
144 NULL, /* the buffer should manage the memory area for us */
145 2*chunksize, /* initial size should be twice the chunk size */
146 UCX_BUFFER_AUTOEXTEND); /* the buffer will grow when necessary */
148 size_t lineno = 1;
149 do {
150 /* read line chunk */
151 size_t read = ucx_stream_ncopy(
152 input, linebuf, fread, ucx_buffer_write, chunksize);
153 if (read == 0) break;
155 /* handle line endings */
156 do {
157 sstr_t bufstr = ucx_buffer_to_sstr(linebuf);
158 sstr_t nl = sstrchr(bufstr, '\n');
159 if (nl.length == 0) break;
161 size_t linelen = bufstr.length - nl.length;
162 sstr_t linestr = sstrsubsl(bufstr, 0, linelen);
164 printf("%zu: %" PRIsstr "\n", lineno++, SFMT(linestr));
166 /* shift the buffer to the next line */
167 ucx_buffer_shift_left(linebuf, linelen+1);
168 } while(1);
170 } while(1);
172 /* print the 'noeol' line, if any */
173 sstr_t lastline = ucx_buffer_to_sstr(linebuf);
174 if (lastline.length > 0) {
175 printf("%zu: %" PRIsstr, lineno, SFMT(lastline));
176 }
178 fclose(input);
179 ucx_buffer_free(linebuf);
181 return 0;
182 }
183 ```
185 ## List
187 *Header file:* [list.h](api/list_8h.html)
188 *Required modules:* [Allocator](#allocator)
190 This module provides the data structure and several functions for a doubly
191 linked list. Among the common operations like insert, remove, search and sort,
192 we allow convenient iteration via a special `UCX_FOREACH` macro.
194 ### Remove duplicates from an array of strings
196 Assume you are given an array of `sstr_t` and want to create a list of these
197 strings without duplicates.
198 ```C
199 #include <stdio.h>
200 #include <ucx/list.h>
201 #include <ucx/string.h>
202 #include <ucx/utils.h>
204 UcxList* remove_duplicates(sstr_t* array, size_t arrlen) {
205 UcxList* list = NULL;
206 for (size_t i = 0 ; i < arrlen ; ++i) {
207 if (ucx_list_find(list, array+i, ucx_sstrcmp, NULL) == -1) {
208 sstr_t* s = malloc(sizeof(sstr_t));
209 *s = sstrdup(array[i]);
210 list = ucx_list_append(list, s);
211 }
212 }
213 return list;
214 }
216 /* we will need this function to clean up the list contents later */
217 void free_sstr(void* ptr) {
218 sstr_t* s = ptr;
219 free(s->ptr);
220 free(s);
221 }
223 /* ... */
225 sstr_t* array = /* some array of strings */
226 size_t arrlen = /* the length of the array */
228 UcxList* list = remove_duplicates(array,arrlen);
230 /* Iterate over the list and print the elements */
231 UCX_FOREACH(elem, list) {
232 sstr_t s = *((sstr_t*)elem->data);
233 printf("%" PRIsstr "\n", SFMT(s));
234 }
236 /* Use our free function to free the duplicated strings. */
237 ucx_list_free_content(list, free_sstr);
238 ucx_list_free(list);
239 ```
241 ## Logging
243 *Header file:* [logging.h](api/logging_8h.html)
244 *Required modules:* [Map](#map), [String](#string)
246 The logging module comes with some predefined log levels and allows some more
247 customization. You may choose if you want to get timestamps or source file and
248 line number logged automatically when outputting a message.
249 The following function call initializes a debug logger with all of the above
250 information:
251 ```C
252 log = ucx_logger_new(stdout, UCX_LOGGER_DEBUG,
253 UCX_LOGGER_LEVEL | UCX_LOGGER_TIMESTAMP | UCX_LOGGER_SOURCE);
254 ```
255 Afterwards you can use this logger with the predefined macros
256 ```C
257 ucx_logger_trace(log, "Verbose output");
258 ucx_logger_debug(log, "Debug message");
259 ucx_logger_info(log, "Information");
260 ucx_logger_warn(log, "Warning");
261 ucx_logger_error(log, "Error message");
262 ```
263 or you use
264 ```C
265 ucx_logger_log(log, CUSTOM_LEVEL, "Some message")
266 ```
267 When you use your custom log level, don't forget to register it with
268 ```C
269 ucx_logger_register_level(log, CUSTOM_LEVEL, "CUSTOM")
270 ```
271 where the last argument must be a string literal.
273 ## Map
275 *Header file:* [map.h](api/map_8h.html)
276 *Required modules:* [Allocator](#allocator), [String](#string)
278 This module provides a hash map implementation using murmur hash 2 and separate
279 chaining with linked lists. Similarly to the list module, we provide a
280 `UCX_MAP_FOREACH` macro to conveniently iterate through the key/value pairs.
282 ## Memory Pool
284 *Header file:* [mempool.h](api/mempool_8h.html)
285 *Required modules:* [Allocator](#allocator)
287 Here we have a concrete allocator implementation in the sense of a memory pool.
288 This pool allows you to register destructor functions for the allocated memory,
289 which are automatically called on the destruction of the pool.
290 But you may also register *independent* destructor functions within a pool in
291 case, some external library allocated memory for you, which you wish to be
292 destroyed together with this pool.
294 ## Properties
296 *Header file:* [properties.h](api/properties_8h.html)
297 *Required modules:* [Map](#map)
299 This module provides load and store function for `*.properties` files.
300 The key/value pairs are stored within an UCX Map.
302 ### Example: Loading properties from a file
304 ```C
305 /* Open the file as usual */
306 FILE* file = fopen("myprops.properties", "r");
307 if (!file) {
308 // error handling
309 return 1;
310 }
312 /* Load the properties from the file */
313 UcxMap* myprops = ucx_map_new(16);
314 if (ucx_properties_load(myprops, file)) {
315 /* ... error handling ... */
316 fclose(file);
317 ucx_map_free(myprops);
318 return 1;
319 }
321 /* Print out the key/value pairs */
322 char* propval;
323 UcxMapIterator propiter = ucx_map_iterator(myprops);
324 UCX_MAP_FOREACH(key, propval, propiter) {
325 printf("%s = %s\n", (char*)key.data, propval);
326 }
328 /* Don't forget to free the values before freeing the map */
329 ucx_map_free_content(myprops, NULL);
330 ucx_map_free(myprops);
331 fclose(file);
332 ```
334 ## Stack
336 *Header file:* [stack.h](api/stack_8h.html)
337 *Required modules:* [Allocator](#allocator)
339 This concrete implementation of an UCX Allocator allows you to grab some amount
340 of memory which is then handled as a stack.
341 Please note, that the term *stack* only refers to the behavior of this
342 allocator. You may still choose if you want to use stack or heap memory
343 for the underlying space.
345 A typical use case is an algorithm where you need to allocate and free large
346 amounts of memory very frequently.
348 ## String
350 *Header file:* [string.h](api/string_8h.html)
351 *Required modules:* [Allocator](#allocator)
353 This module provides a safe implementation of bounded string.
354 Usually C strings do not carry a length. While for zero-terminated strings you
355 can easily get the length with `strlen`, this is not generally possible for
356 arbitrary strings.
357 The `sstr_t` type of this module always carries the string and its length to
358 reduce the risk of buffer overflows dramatically.
360 ### Initialization
362 There are several ways to create an `sstr_t`:
364 ```C
365 /* (1) sstr() uses strlen() internally, hence cstr MUST be zero-terminated */
366 sstr_t a = sstr(cstr);
368 /* (2) cstr does not need to be zero-terminated, if length is specified */
369 sstr_t b = sstrn(cstr, len);
371 /* (3) S() macro creates sstr_t from a string using sizeof() and using sstrn().
372 This version is especially useful for function arguments */
373 sstr_t c = S("hello");
375 /* (4) ST() macro creates sstr_t struct literal using sizeof() */
376 sstr_t d = ST("hello");
377 ```
379 You should not use the `S()` or `ST()` macro with string of unknown origin,
380 since the `sizeof()` call might not coincide with the string length in those
381 cases. If you know what you are doing, it can save you some performance,
382 because you do not need the `strlen()` call.
384 ### Finding the position of a substring
386 The `sstrstr()` function gives you a new `sstr_t` object starting with the
387 requested substring. Thus determining the position comes down to a simple
388 subtraction.
390 ```C
391 sstr_t haystack = ST("Here we go!");
392 sstr_t needle = ST("we");
393 sstr_t result = sstrstr(haystack, needle);
394 if (result.ptr)
395 printf("Found at position %zd.\n", haystack.length-result.length);
396 else
397 printf("Not found.\n");
398 ```
400 ### Spliting a string by a delimiter
402 The `sstrsplit()` function (and its allocator based version `sstrsplit_a()`) is
403 very powerful and might look a bit nasty at a first glance. But it is indeed
404 very simple to use. It is even more convenient in combination with a memory
405 pool.
407 ```C
408 sstr_t test = ST("here::are::some::strings");
409 sstr_t delim = ST("::");
411 ssize_t count = 0; /* no limit */
412 UcxMempool* pool = ucx_mempool_new_default();
414 sstr_t* result = sstrsplit_a(pool->allocator, test, delim, &count);
415 for (ssize_t i = 0 ; i < count ; i++) {
416 /* don't forget to specify the length via the %*s format specifier */
417 printf("%*s\n", result[i].length, result[i].ptr);
418 }
420 ucx_mempool_destroy(pool);
421 ```
422 The output is:
424 here
425 are
426 some
427 strings
429 The memory pool ensures, that all strings are freed.
431 ## Testing
433 *Header file:* [test.h](api/test_8h.html)
434 *Required modules:* None.
436 This module provides a testing framework which allows you to execute test cases
437 within test suites.
438 To avoid code duplication within tests, we also provide the possibility to
439 define test subroutines.
441 You should declare test cases and subroutines in a header file per test unit
442 and implement them as you would implement normal functions.
443 ```C
444 /* myunit.h */
445 UCX_TEST(function_name);
446 UCX_TEST_SUBROUTINE(subroutine_name, paramlist); /* optional */
449 /* myunit.c */
450 UCX_TEST_SUBROUTINE(subroutine_name, paramlist) {
451 /* ... reusable tests with UCX_TEST_ASSERT() ... */
452 }
454 UCX_TEST(function_name) {
455 /* ... resource allocation and other test preparation ... */
457 /* mandatory marker for the start of the tests */
458 UCX_TEST_BEGIN
460 /* ... verifications with UCX_TEST_ASSERT() ...
461 * (and/or calls with UCX_TEST_CALL_SUBROUTINE())
462 */
464 /* mandatory marker for the end of the tests */
465 UCX_TEST_END
467 /* ... resource cleanup ...
468 * (all code after UCX_TEST_END is always executed)
469 */
470 }
471 ```
472 If you want to use the `UCX_TEST_ASSERT()` macro in a function, you are
473 *required* to use a `UCX_TEST_SUBROUTINE`.
474 Otherwise the testing framework does not know where to jump, when the assertion
475 fails.
477 After implementing the tests, you can easily build a test suite and execute it:
478 ```C
479 UcxTestSuite* suite = ucx_test_suite_new();
480 ucx_test_register(suite, testMyTestCase01);
481 ucx_test_register(suite, testMyTestCase02);
482 /* ... */
483 ucx_test_run(suite, stdout); /* stdout, or any other FILE stream */
484 ```
486 ## Utilities
488 *Header file:* [utils.h](api/utils_8h.html)
489 *Required modules:* [Allocator](#allocator), [String](#string)
491 In this module we provide very general utility function for copy and compare
492 operations.
493 We also provide several `printf` variants to conveniently print formatted data
494 to streams or strings.
496 ### A simple copy program
498 The utilities package provides several stream copy functions.
499 One of them has a very simple interface and can, for instance, be used to copy
500 whole files in a single call.
501 This is a minimal working example:
502 ```C
503 #include <stdio.h>
504 #include <ucx/utils.h>
506 int main(int argc, char** argv) {
508 if (argc != 3) {
509 fprintf(stderr, "Use %s <src> <dest>", argv[0]);
510 return 1;
511 }
513 FILE *srcf = fopen(argv[1], "r"); /* insert error handling on your own */
514 FILE *destf = fopen(argv[2], "w");
516 size_t n = ucx_stream_copy(srcf, destf, fread, fwrite);
517 printf("%zu bytes copied.\n", n);
519 fclose(srcf);
520 fclose(destf);
523 return 0;
524 }
525 ```
527 ### Automatic allocation for formatted strings
529 The UCX utility function `ucx_asprintf()` and it's convenient shortcut
530 `ucx_sprintf` allow easy formatting of strings, without ever having to worry
531 about the required space.
532 ```C
533 sstr_t mystring = ucx_sprintf("The answer is: %d!", 42);
534 ```
535 Still, you have to pass `mystring.ptr` to `free()` (or the free function of
536 your allocator, if you use `ucx_asprintf`).
537 If you don't have all the information ready to build your string, you can even
538 use a [UcxBuffer](#buffer) as a target with the utility function
539 `ucx_bprintf()`.
540 ```C
541 UcxBuffer* strbuffer = ucx_buffer_new(NULL, 512, UCX_BUFFER_AUTOEXTEND);
543 for (unsigned int i = 2 ; i < 100 ; i++) {
544 ucx_bprintf(strbuffer, "Integer %d is %s\n",
545 i, prime(i) ? "prime" : "not prime");
546 }
548 /* print the result to stdout */
549 printf("%s", (char*)strbuffer->space);
551 ucx_buffer_free(strbuffer);
552 ```