jsmn/example/jsondump.c

#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 *tmp, *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;
			}
		}

		tmp = realloc(js, jslen + r + 1);
		if (tmp == NULL) {
			free (js);
			fprintf(stderr, "realloc(): errno=%d\n", errno);
			return 3;
		}
		js = tmp;
		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) {
				jsmntok_t *tmptok;

				tokcount = tokcount * 2;
				tmptok = realloc(tok, sizeof(*tok) * tokcount);
				if (tmptok == NULL) {
					free (tok);
					fprintf(stderr, "realloc(): errno=%d\n", errno);
					return 3;
				}
				tok = tmptok;
				goto again;
			}
		} else {
			dump(js, tok, p.toknext, 0);
			eof_expected = 1;
		}
	}

	return 0;
}