Implement nlohmann/json utils

include/valijson/utils/nlohmann_json_utils.hpp

@@ -0,0 +1,35 @@
+#pragma once
+#ifndef VALIJSON_NLOHMANN_JSON_UTILS_HPP_HPP
+#define VALIJSON_NLOHMANN_JSON_UTILS_HPP_HPP
+
+#include <json.hpp>
+#include <valijson/utils/file_utils.hpp>
+
+namespace valijson {
+namespace utils {
+
+inline bool loadDocument(const std::string &path, nlohmann::json &document) {
+    // Load schema JSON from file
+    std::string file;
+    if (!loadFile(path, file)) {
+        std::cerr << "Failed to load json from file '" << path << "'." << std::endl;
+        return false;
+    }
+
+    // Parse schema
+    std::string err;
+    try {
+        document = nlohmann::json::parse(file);
+    } catch (std::invalid_argument const& exception) {
+        std::cerr << "nlohmann::json failed to parse the document\n"
+            << "Parse error:" << exception.what() << "\n";
+        return false;
+    }
+
+    return true;
+}
+
+}
+}
+
+#endif //VALIJSON_NLOHMANN_JSON_UTILS_HPP_HPP