diff options
Diffstat (limited to 'libjsmn/example')
-rw-r--r-- | libjsmn/example/jsondump.c | 112 | ||||
-rw-r--r-- | libjsmn/example/simple.c | 75 |
2 files changed, 187 insertions, 0 deletions
diff --git a/libjsmn/example/jsondump.c b/libjsmn/example/jsondump.c new file mode 100644 index 0000000000000..3490bbf499007 --- /dev/null +++ b/libjsmn/example/jsondump.c @@ -0,0 +1,112 @@ +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include "../jsmn.h" + +/* + * An example of reading JSON from stdin and printing its content to stdout. + * The output looks like YAML, but I'm not sure if it's really compatible. + */ + +static int dump(const char *js, jsmntok_t *t, size_t count, int indent) { + int i, j, k; + if (count == 0) { + return 0; + } + if (t->type == JSMN_PRIMITIVE) { + printf("%.*s", t->end - t->start, js+t->start); + return 1; + } else if (t->type == JSMN_STRING) { + printf("'%.*s'", t->end - t->start, js+t->start); + return 1; + } else if (t->type == JSMN_OBJECT) { + printf("\n"); + j = 0; + for (i = 0; i < t->size; i++) { + for (k = 0; k < indent; k++) printf(" "); + j += dump(js, t+1+j, count-j, indent+1); + printf(": "); + j += dump(js, t+1+j, count-j, indent+1); + printf("\n"); + } + return j+1; + } else if (t->type == JSMN_ARRAY) { + j = 0; + printf("\n"); + for (i = 0; i < t->size; i++) { + for (k = 0; k < indent-1; k++) printf(" "); + printf(" - "); + j += dump(js, t+1+j, count-j, indent+1); + printf("\n"); + } + return j+1; + } + return 0; +} + +int main() { + int r; + int eof_expected = 0; + char *js = NULL; + size_t jslen = 0; + char buf[BUFSIZ]; + + jsmn_parser p; + jsmntok_t *tok; + size_t tokcount = 2; + + /* Prepare parser */ + jsmn_init(&p); + + /* Allocate some tokens as a start */ + tok = malloc(sizeof(*tok) * tokcount); + if (tok == NULL) { + fprintf(stderr, "malloc(): errno=%d\n", errno); + return 3; + } + + for (;;) { + /* Read another chunk */ + r = fread(buf, 1, sizeof(buf), stdin); + if (r < 0) { + fprintf(stderr, "fread(): %d, errno=%d\n", r, errno); + return 1; + } + if (r == 0) { + if (eof_expected != 0) { + return 0; + } else { + fprintf(stderr, "fread(): unexpected EOF\n"); + return 2; + } + } + + js = realloc(js, jslen + r + 1); + if (js == NULL) { + fprintf(stderr, "realloc(): errno=%d\n", errno); + return 3; + } + strncpy(js + jslen, buf, r); + jslen = jslen + r; + +again: + r = jsmn_parse(&p, js, jslen, tok, tokcount); + if (r < 0) { + if (r == JSMN_ERROR_NOMEM) { + tokcount = tokcount * 2; + tok = realloc(tok, sizeof(*tok) * tokcount); + if (tok == NULL) { + fprintf(stderr, "realloc(): errno=%d\n", errno); + return 3; + } + goto again; + } + } else { + dump(js, tok, p.toknext, 0); + eof_expected = 1; + } + } + + return 0; +} diff --git a/libjsmn/example/simple.c b/libjsmn/example/simple.c new file mode 100644 index 0000000000000..a6f8e6a98f7ef --- /dev/null +++ b/libjsmn/example/simple.c @@ -0,0 +1,75 @@ +#include <stdio.h> +#include <string.h> +#include "../jsmn.h" + +/* + * A small example of jsmn parsing when JSON structure is known and number of + * tokens is predictable. + */ + +const char *JSON_STRING = + "{\"user\": \"johndoe\", \"admin\": false, \"uid\": 1000,\n " + "\"groups\": [\"users\", \"wheel\", \"audio\", \"video\"]}"; + +static int jsoneq(const char *json, jsmntok_t *tok, const char *s) { + if (tok->type == JSMN_STRING && (int) strlen(s) == tok->end - tok->start && + strncmp(json + tok->start, s, tok->end - tok->start) == 0) { + return 0; + } + return -1; +} + +int main() { + int i; + int r; + jsmn_parser p; + jsmntok_t t[128]; /* We expect no more than 128 tokens */ + + jsmn_init(&p); + r = jsmn_parse(&p, JSON_STRING, strlen(JSON_STRING), t, sizeof(t)/sizeof(t[0])); + if (r < 0) { + printf("Failed to parse JSON: %d\n", r); + return 1; + } + + /* Assume the top-level element is an object */ + if (r < 1 || t[0].type != JSMN_OBJECT) { + printf("Object expected\n"); + return 1; + } + + /* Loop over all keys of the root object */ + for (i = 1; i < r; i++) { + if (jsoneq(JSON_STRING, &t[i], "user") == 0) { + /* We may use strndup() to fetch string value */ + printf("- User: %.*s\n", t[i+1].end-t[i+1].start, + JSON_STRING + t[i+1].start); + i++; + } else if (jsoneq(JSON_STRING, &t[i], "admin") == 0) { + /* We may additionally check if the value is either "true" or "false" */ + printf("- Admin: %.*s\n", t[i+1].end-t[i+1].start, + JSON_STRING + t[i+1].start); + i++; + } else if (jsoneq(JSON_STRING, &t[i], "uid") == 0) { + /* We may want to do strtol() here to get numeric value */ + printf("- UID: %.*s\n", t[i+1].end-t[i+1].start, + JSON_STRING + t[i+1].start); + i++; + } else if (jsoneq(JSON_STRING, &t[i], "groups") == 0) { + int j; + printf("- Groups:\n"); + if (t[i+1].type != JSMN_ARRAY) { + continue; /* We expect groups to be an array of strings */ + } + for (j = 0; j < t[i+1].size; j++) { + jsmntok_t *g = &t[i+j+2]; + printf(" * %.*s\n", g->end - g->start, JSON_STRING + g->start); + } + i += t[i+1].size + 1; + } else { + printf("Unexpected key: %.*s\n", t[i].end-t[i].start, + JSON_STRING + t[i].start); + } + } + return 0; +} |