Add boost::json example and delete problematic constructors

examples/boost_json_example.cpp

@@ -0,0 +1,107 @@
+#include <boost/json/src.hpp>
+#include <valijson/adapters/boost_json_adapter.hpp>
+#include <valijson/schema.hpp>
+#include <valijson/schema_parser.hpp>
+#include <valijson/validator.hpp>
+#include <valijson/validation_results.hpp>
+#include <iostream>
+
+using namespace std::string_literals;
+
+namespace json = boost::json;
+
+const auto schemaJson = R"({
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "title": "Product",
+  "description": "A product from Acme's catalog",
+  "type": "object",
+  "properties": {
+    "id": {
+      "description": "The unique identifier for a product",
+      "type": "integer"
+    },
+    "name": {
+      "description": "Name of the product",
+      "type": "string"
+    },
+    "price": {
+      "type": "number",
+      "minimum": 0
+    },
+    "tags": {
+      "type": "array",
+      "items": { "type": "string" },
+      "minItems": 1,
+      "uniqueItems": true
+    }
+  },
+  "required": ["id", "name", "price" ]
+})"s;
+
+const auto targetJson = R"({
+  "id": 123,
+  "name": "Test"
+})"s;
+
+int main()
+{
+    json::error_code ec;
+    auto schemaDoc = json::parse(schemaJson, ec);
+    if (ec) {
+        std::cerr << "Error parsing schema json: " << ec.message() << std::endl;
+        return 1;
+    }
+
+    auto obj = schemaDoc.as_object();
+    auto iter = obj.find("$schema");
+    if (iter == obj.cend()) {
+        std::cerr << "Error finding key $schema" << std::endl;
+        return 2;
+    }
+
+    iter = obj.find("$ref");
+    if (iter != obj.cend()) {
+        std::cerr << "Invalid iterator for non-existent key $ref" << std::endl;
+        return 3;
+    }
+
+    valijson::Schema schema;
+    valijson::SchemaParser schemaParser;
+
+    // Won't compile because the necessary constructor has been deleted
+    // valijson::adapters::BoostJsonAdapter schemaAdapter(obj);
+
+    valijson::adapters::BoostJsonAdapter schemaAdapter(schemaDoc);
+    std::cerr << "Populating schema..." << std::endl;
+    schemaParser.populateSchema(schemaAdapter, schema);
+
+    auto targetDoc = json::parse(targetJson, ec);
+    if (ec) {
+        std::cerr << "Error parsing target json: " << ec.message() << std::endl;
+        return 1;
+    }
+
+    valijson::Validator validator;
+    valijson::ValidationResults results;
+    valijson::adapters::BoostJsonAdapter targetAdapter(targetDoc);
+    if (validator.validate(schema, targetAdapter, &results)) {
+        std::cerr << "Validation succeeded." << std::endl;
+        return 0;
+    }
+
+    std::cerr << "Validation failed." << std::endl;
+    valijson::ValidationResults::Error error;
+    unsigned int errorNum = 1;
+    while (results.popError(error)) {
+        std::cerr << "Error #" << errorNum << std::endl;
+        std::cerr << "  ";
+        for (const std::string &contextElement : error.context) {
+            std::cerr << contextElement << " ";
+        }
+        std::cerr << std::endl;
+        std::cerr << "    - " << error.description << std::endl;
+        ++errorNum;
+    }
+
+    return 1;
+}

include/valijson/adapters/boost_json_adapter.hpp

@@ -485,12 +485,16 @@ class BoostJsonAdapter:
 {
 public:
 
+    // deleted to avoid holding references to temporaries
+    BoostJsonAdapter(boost::json::array &) = delete;
+    BoostJsonAdapter(boost::json::object &) = delete;
+
     /// Construct a BoostJsonAdapter that contains an empty object
     BoostJsonAdapter()
       : BasicAdapter() { }
 
     /// Construct a BoostJsonAdapter using a specific Boost.JSON value
-    BoostJsonAdapter(const boost::json::value &value)
+    explicit BoostJsonAdapter(const boost::json::value &value)
       : BasicAdapter(value) { }
 };