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/*
* path-queries.c - Path-based YAML queries example
*
* Demonstrates:
* - Using YPATH expressions to query YAML
* - scanf-style value extraction
* - Single node lookup by path
* - String comparison with nodes
*
* Copyright (c) 2019-2025 Pantelis Antoniou <pantelis.antoniou@konsulko.com>
*
* SPDX-License-Identifier: MIT
*/
#include <stdlib.h>
#include <stdio.h>
#include <libfyaml.h>
int main(void)
{
const char *yaml =
"server:\n"
" host: localhost\n"
" port: 8080\n"
" ssl: true\n"
" max_connections: 100\n";
struct fy_document *fyd = fy_document_build_from_string(NULL, yaml, FY_NT);
if (!fyd) {
fprintf(stderr, "Failed to parse YAML\n");
return EXIT_FAILURE;
}
// Extract multiple values at once using scanf-style API
char host[256];
unsigned int port;
int count = fy_document_scanf(fyd,
"/server/host %255s "
"/server/port %u",
host, &port);
if (count == 2) {
printf("Server configuration:\n");
printf(" Host: %s\n", host);
printf(" Port: %u\n", port);
} else {
fprintf(stderr, "Failed to extract server configuration (got %d/2)\n", count);
}
// Query single node by path
struct fy_node *ssl_node = fy_node_by_path(
fy_document_root(fyd), "/server/ssl", FY_NT, FYNWF_DONT_FOLLOW);
if (ssl_node) {
// Compare node value with string
if (fy_node_compare_string(ssl_node, "true", FY_NT) == 0) {
printf(" SSL: enabled\n");
} else {
printf(" SSL: disabled\n");
}
}
// Extract another value
unsigned int max_conn;
count = fy_document_scanf(fyd, "/server/max_connections %u", &max_conn);
if (count == 1) {
printf(" Max connections: %u\n", max_conn);
}
// Try to query a non-existent path
struct fy_node *missing = fy_node_by_path(
fy_document_root(fyd), "/server/timeout", FY_NT, FYNWF_DONT_FOLLOW);
if (!missing) {
printf(" Timeout: not configured (using default)\n");
}
fy_document_destroy(fyd);
return EXIT_SUCCESS;
}
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