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libyaml examples
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/* | |
* Example libyaml emitter. | |
* | |
* This is a basic example to demonstrate how to convert raw data to a yaml | |
* stream using the libyaml emitter API. The example data to be converted is | |
* is a simple array of structs, | |
* | |
* struct fruit data[] = { | |
* {"apple", "red", 12}, | |
* {"orange", "orange", 3}, | |
* {"bannana", "yellow", 4}, | |
* {"mango", "green", 1}, | |
* {NULL, NULL, 0} | |
* }; | |
* | |
* The exmaple data is converted into a yaml sequence of mapped values, | |
* | |
* $ ./emit | |
* --- | |
* fruit: | |
* - name: apple | |
* color: red | |
* count: 12 | |
* - name: orange | |
* color: orange | |
* count: 3 | |
* - name: bannana | |
* color: yellow | |
* count: 4 | |
* - name: mango | |
* color: green | |
* count: 1 | |
* ... | |
* | |
* This example can be built and run on linux with the commands: | |
* | |
* gcc -c emit.c -g -O0 -Wall | |
* gcc -o emit emit.o -lyaml | |
* ./emit | |
* | |
* See the libyaml project page http://pyyaml.org/wiki/LibYAML | |
*/ | |
#include <yaml.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
struct fruit { | |
char *name; | |
char *color; | |
int count; | |
}; | |
struct fruit data[] = { | |
{"apple", "red", 12}, | |
{"orange", "orange", 3}, | |
{"bannana", "yellow", 4}, | |
{"mango", "green", 1}, | |
{NULL, NULL, 0} | |
}; | |
int main(int argc, char *argv[]) | |
{ | |
yaml_emitter_t emitter; | |
yaml_event_t event; | |
struct fruit *f; | |
char buffer[64]; | |
yaml_emitter_initialize(&emitter); | |
yaml_emitter_set_output_file(&emitter, stdout); | |
yaml_stream_start_event_initialize(&event, YAML_UTF8_ENCODING); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_document_start_event_initialize(&event, NULL, NULL, NULL, 0); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_mapping_start_event_initialize(&event, NULL, (yaml_char_t *)YAML_MAP_TAG, | |
1, YAML_ANY_MAPPING_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_scalar_event_initialize(&event, NULL, (yaml_char_t *)YAML_STR_TAG, | |
(yaml_char_t *)"fruit", strlen("fruit"), 1, 0, YAML_PLAIN_SCALAR_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_sequence_start_event_initialize(&event, NULL, (yaml_char_t *)YAML_SEQ_TAG, | |
1, YAML_ANY_SEQUENCE_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
for (f = data; f->name; f++) { | |
yaml_mapping_start_event_initialize(&event, NULL, (yaml_char_t *)YAML_MAP_TAG, | |
1, YAML_ANY_MAPPING_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_scalar_event_initialize(&event, NULL, (yaml_char_t *)YAML_STR_TAG, | |
(yaml_char_t *)"name", strlen("name"), 1, 0, YAML_PLAIN_SCALAR_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_scalar_event_initialize(&event, NULL, (yaml_char_t *)YAML_STR_TAG, | |
(yaml_char_t *)f->name, strlen(f->name), 1, 0, YAML_PLAIN_SCALAR_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_scalar_event_initialize(&event, NULL, (yaml_char_t *)YAML_STR_TAG, | |
(yaml_char_t *)"color", strlen("color"), 1, 0, YAML_PLAIN_SCALAR_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_scalar_event_initialize(&event, NULL, (yaml_char_t *)YAML_STR_TAG, | |
(yaml_char_t *)f->color, strlen(f->color), 1, 0, YAML_PLAIN_SCALAR_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_scalar_event_initialize(&event, NULL, (yaml_char_t *)YAML_STR_TAG, | |
(yaml_char_t *)"count", strlen("count"), 1, 0, YAML_PLAIN_SCALAR_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
sprintf(buffer, "%d", f->count); | |
yaml_scalar_event_initialize(&event, NULL, (yaml_char_t *)YAML_INT_TAG, | |
(yaml_char_t *)buffer, strlen(buffer), 1, 0, YAML_PLAIN_SCALAR_STYLE); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_mapping_end_event_initialize(&event); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
} | |
yaml_sequence_end_event_initialize(&event); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_mapping_end_event_initialize(&event); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_document_end_event_initialize(&event, 0); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_stream_end_event_initialize(&event); | |
if (!yaml_emitter_emit(&emitter, &event)) goto error; | |
yaml_emitter_delete(&emitter); | |
return 0; | |
error: | |
fprintf(stderr, "Failed to emit event %d: %s\n", event.type, emitter.problem); | |
yaml_emitter_delete(&emitter); | |
return 1; | |
} |
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all: emit scan parse | |
emit.o: emit.c | |
gcc -c emit.c -g -O0 -Wall | |
emit: emit.o | |
gcc -o emit emit.o -lyaml | |
scan.o: scan.c | |
gcc -c scan.c -g -O0 -Wall | |
scan: scan.o | |
gcc -o scan scan.o -lyaml | |
parse.o: parse.c | |
gcc -c parse.c -g -O0 -Wall | |
parse: parse.o | |
gcc -o parse parse.o -lyaml | |
clean: | |
rm -f emit scan parse | |
rm -f *.o core |
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/* | |
* Example libyaml parser. | |
* | |
* This is a basic example to demonstrate how to convert yaml to raw data | |
* using the libyaml emitter API. Example yaml data to be parsed: | |
* | |
* $ cat fruit.yaml | |
* --- | |
* fruit: | |
* - name: apple | |
* color: red | |
* count: 12 | |
* - name: orange | |
* color: orange | |
* count: 3 | |
* - name: bannana | |
* color: yellow | |
* count: 4 | |
* - name: mango | |
* color: green | |
* count: 1 | |
* ... | |
* | |
* $ ./parse < fruit.yaml | |
* data[0]={name=apple, color=red, count=12} | |
* data[1]={name=orange, color=orange, count=3} | |
* data[2]={name=bannana, color=yellow, count=4} | |
* data[3]={name=mango, color=green, count=1} | |
* | |
* See the libyaml project page http://pyyaml.org/wiki/LibYAML | |
*/ | |
#include <yaml.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
/* Example data structure */ | |
struct fruit { | |
char *name; | |
char *color; | |
int count; | |
}; | |
/* Our example parser states. */ | |
enum state_value { | |
START, | |
ACCEPT_SECTION, | |
ACCEPT_LIST, | |
ACCEPT_VALUES, | |
ACCEPT_KEY, | |
ACCEPT_VALUE, | |
STOP, | |
ERROR, | |
}; | |
struct parser_state { | |
enum state_value state; | |
int accepted; | |
int error; | |
char *key; | |
char *value; | |
struct fruit data; | |
}; | |
/* | |
* Consume yaml events generated by the libyaml parser to | |
* import our data into raw c data structures. Error processing | |
* is keep to a mimimum since this is just an example. | |
* | |
* The expected sequence of events is: | |
* | |
* stream ::= STREAM-START document* STREAM-END | |
* document ::= DOCUMENT-START section* DOCUMENT-END | |
* section ::= MAPPING-START (key list) MAPPING-END | |
* list ::= SEQUENCE-START values* SEQUENCE-END | |
* values ::= MAPPING-START (key value)* MAPPING-END | |
* key = SCALAR | |
* value = SCALAR | |
* | |
* For example: | |
* | |
* stream-start-event | |
* document-start-event | |
* mapping-start-event | |
* scalar-event={value="fruit", length=5} | |
* sequence-start-event | |
* mapping-start-event | |
* scalar-event={value="name", length=4} | |
* scalar-event={value="apple", length=5} | |
* scalar-event={value="color", length=5} | |
* scalar-event={value="red", length=3} | |
* scalar-event={value="count", length=5} | |
* scalar-event={value="12", length=2} | |
* mapping-end-event | |
* mapping-start-event | |
* scalar-event={value="name", length=4} | |
* scalar-event={value="orange", length=6} | |
* scalar-event={value="color", length=5} | |
* scalar-event={value="orange", length=6} | |
* scalar-event={value="count", length=5} | |
* scalar-event={value="3", length=1} | |
* mapping-end-event | |
* sequence-end-event | |
* mapping-end-event | |
* document-end-event | |
* stream-end-event | |
* | |
*/ | |
int consume_event(struct parser_state *s, yaml_event_t *event) | |
{ | |
s->accepted = 0; | |
switch (s->state) { | |
case START: | |
switch (event->type) { | |
case YAML_MAPPING_START_EVENT: | |
s->state = ACCEPT_SECTION; | |
break; | |
case YAML_SCALAR_EVENT: | |
fprintf(stderr, "Ignoring unexpected scalar: %s\n", | |
(char*)event->data.scalar.value); | |
break; | |
case YAML_SEQUENCE_START_EVENT: | |
fprintf(stderr, "Unexpected sequence.\n"); | |
s->state = ERROR; | |
break; | |
case YAML_STREAM_END_EVENT: s->state = STOP; break; | |
default: | |
break; | |
} | |
break; | |
case ACCEPT_SECTION: | |
switch (event->type) { | |
case YAML_SCALAR_EVENT: | |
if (strcmp((char*)event->data.scalar.value, "fruit") == 0) { | |
s->state = ACCEPT_LIST; | |
} else { | |
fprintf(stderr, "Unexpected scalar: %s\n", | |
(char*)event->data.scalar.value); | |
s->state = ERROR; | |
} | |
break; | |
default: | |
fprintf(stderr, "Unexpected event while getting scalar: %d\n", event->type); | |
s->state = ERROR; | |
break; | |
} | |
break; | |
case ACCEPT_LIST: | |
switch (event->type) { | |
case YAML_SEQUENCE_START_EVENT: s->state = ACCEPT_VALUES; break; | |
default: | |
fprintf(stderr, "Unexpected event while getting sequence: %d\n", event->type); | |
s->state = ERROR; | |
break; | |
} | |
break; | |
case ACCEPT_VALUES: | |
switch (event->type) { | |
case YAML_MAPPING_START_EVENT: | |
memset(&(s->data), 0, sizeof(s->data)); | |
s->state = ACCEPT_KEY; | |
break; | |
case YAML_SEQUENCE_END_EVENT: s->state = START; break; | |
case YAML_DOCUMENT_END_EVENT: s->state = START; break; | |
default: | |
fprintf(stderr, "Unexpected event while getting mapped values: %d\n", | |
event->type); | |
s->state = ERROR; | |
break; | |
} | |
break; | |
case ACCEPT_KEY: | |
switch (event->type) { | |
case YAML_SCALAR_EVENT: | |
s->key = strdup((char*)event->data.scalar.value); | |
s->state = ACCEPT_VALUE; | |
break; | |
case YAML_MAPPING_END_EVENT: | |
s->accepted = 1; | |
s->state = ACCEPT_VALUES; | |
break; | |
default: | |
fprintf(stderr, "Unexpected event while getting key: %d\n", | |
event->type); | |
s->state = ERROR; | |
break; | |
} | |
break; | |
case ACCEPT_VALUE: | |
switch (event->type) { | |
case YAML_SCALAR_EVENT: | |
s->value = (char*)event->data.scalar.value; | |
if (strcmp(s->key, "name") == 0) { | |
s->data.name = strdup((char*)s->value); | |
} else if (strcmp(s->key, "color") == 0) { | |
s->data.color = strdup((char*)s->value); | |
} else if (strcmp(s->key, "count") == 0) { | |
s->data.count = atoi(s->value); | |
} else { | |
fprintf(stderr, "Ignoring unknown key: %s\n", s->key); | |
} | |
free(s->key); | |
s->state = ACCEPT_KEY; | |
break; | |
default: | |
fprintf(stderr, "Unexpected event while getting value: %d\n", | |
event->type); | |
s->state = ERROR; | |
break; | |
} | |
break; | |
case ERROR: | |
case STOP: | |
break; | |
} | |
return (s->state == ERROR ? 0 : 1); | |
} | |
int main(int argc, char *argv[]) | |
{ | |
yaml_parser_t parser; | |
yaml_event_t event; | |
struct parser_state state = {.state=START, .accepted=0, .error=0}; | |
struct fruit data[64]; | |
int i = 0; | |
memset(data, 0, sizeof(data)); | |
yaml_parser_initialize(&parser); | |
yaml_parser_set_input_file(&parser, stdin); | |
do { | |
if (!yaml_parser_parse(&parser, &event)) { | |
goto error; | |
} | |
if (!consume_event(&state, &event)) { | |
goto error; | |
} | |
if (state.accepted && i < sizeof(data)/sizeof(*data)) { | |
data[i].name = state.data.name; | |
data[i].color = state.data.color; | |
data[i].count = state.data.count; | |
printf("data[%d]={name=%s, color=%s, count=%d}\n", | |
i, data[i].name, data[i].color, data[i].count); | |
i++; | |
} | |
yaml_event_delete(&event); | |
} while (state.state != STOP); | |
yaml_parser_delete(&parser); | |
return 0; | |
error: | |
yaml_parser_delete(&parser); | |
return 1; | |
} |
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/* | |
* Example libyaml parser. | |
* | |
* This is a simple libyaml parser example which scans and prints | |
* the libyaml parser events. | |
* | |
*/ | |
#include <yaml.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#define INDENT " " | |
#define STRVAL(x) ((x) ? (char*)(x) : "") | |
void indent(int level) | |
{ | |
int i; | |
for (i = 0; i < level; i++) { | |
printf("%s", INDENT); | |
} | |
} | |
void print_event(yaml_event_t *event) | |
{ | |
static int level = 0; | |
switch (event->type) { | |
case YAML_NO_EVENT: | |
indent(level); | |
printf("no-event\n"); | |
break; | |
case YAML_STREAM_START_EVENT: | |
indent(level++); | |
printf("stream-start-event\n"); | |
break; | |
case YAML_STREAM_END_EVENT: | |
indent(--level); | |
printf("stream-end-event\n"); | |
break; | |
case YAML_DOCUMENT_START_EVENT: | |
indent(level++); | |
printf("document-start-event\n"); | |
break; | |
case YAML_DOCUMENT_END_EVENT: | |
indent(--level); | |
printf("document-end-event\n"); | |
break; | |
case YAML_ALIAS_EVENT: | |
indent(level); | |
printf("alias-event\n"); | |
break; | |
case YAML_SCALAR_EVENT: | |
indent(level); | |
printf("scalar-event={value=\"%s\", length=%d}\n", | |
STRVAL(event->data.scalar.value), | |
(int)event->data.scalar.length); | |
break; | |
case YAML_SEQUENCE_START_EVENT: | |
indent(level++); | |
printf("sequence-start-event\n"); | |
break; | |
case YAML_SEQUENCE_END_EVENT: | |
indent(--level); | |
printf("sequence-end-event\n"); | |
break; | |
case YAML_MAPPING_START_EVENT: | |
indent(level++); | |
printf("mapping-start-event\n"); | |
break; | |
case YAML_MAPPING_END_EVENT: | |
indent(--level); | |
printf("mapping-end-event\n"); | |
break; | |
} | |
if (level < 0) { | |
fprintf(stderr, "indentation underflow!\n"); | |
level = 0; | |
} | |
} | |
int main(int argc, char *argv[]) | |
{ | |
yaml_parser_t parser; | |
yaml_event_t event; | |
yaml_event_type_t event_type; | |
yaml_parser_initialize(&parser); | |
yaml_parser_set_input_file(&parser, stdin); | |
do { | |
if (!yaml_parser_parse(&parser, &event)) | |
goto error; | |
print_event(&event); | |
event_type = event.type; | |
yaml_event_delete(&event); | |
} while (event_type != YAML_STREAM_END_EVENT); | |
yaml_parser_delete(&parser); | |
return 0; | |
error: | |
fprintf(stderr, "Failed to parse: %s\n", parser.problem); | |
yaml_parser_delete(&parser); | |
return 1; | |
} |
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