deploy: 4155e2938f

examples/basic_json_view__materialize.cpp

@@ -0,0 +1,33 @@
+#include <array>
+#include <iostream>
+#include <nlohmann/json_view.hpp>
+
+using json_document = nlohmann::json_document;
+
+int main()
+{
+    // three incoming messages; skip the ones that are not useful without ever
+    // building a nlohmann::json value for them
+    json_document heartbeat = json_document::parse("null");
+    json_document empty_batch = json_document::parse("[]");
+    json_document batch = json_document::parse(R"([{"id": 1}, {"id": 2}, {"id": 3}])");
+    std::array<const json_document*, 3> messages = {{&heartbeat, &empty_batch, &batch}};
+
+    for (const json_document* d : messages)
+    {
+        // is_array()/empty() only look at the flat index: a discarded
+        // heartbeat or an empty batch is never turned into a nlohmann::json
+        // value, so no per-element allocation happens for them
+        if (!d->root().is_array() || d->root().empty())
+        {
+            std::cout << "skipped\n";
+            continue;
+        }
+
+        // materialize() replays the subtree through the same SAX builder
+        // basic_json::parse() uses, so the result is exactly what
+        // basic_json::parse() would have produced for the same text
+        nlohmann::json value = d->root().materialize();
+        std::cout << value.dump() << '\n';
+    }
+}