deploy: 1c63a120b6

examples/parser_callback_t.cpp

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+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // a JSON text with an array and a number inside an object
+    auto text = R"({"IDs": [116, 943], "Width": 800})";
+
+    // discard the array when the parser reads its opening bracket
+    json j_array_start = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
+    {
+        return event != json::parse_event_t::array_start;
+    });
+
+    // discard the same array when the parser reads its closing bracket
+    json j_array_end = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
+    {
+        return event != json::parse_event_t::array_end;
+    });
+
+    // discard the number, but keep its key
+    json j_value = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & parsed)
+    {
+        return !(event == json::parse_event_t::value && parsed == json(800));
+    });
+
+    // discard the key of the number
+    json j_key = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & parsed)
+    {
+        return !(event == json::parse_event_t::key && parsed == json("Width"));
+    });
+
+    // discard the top-level object
+    json j_root = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
+    {
+        return event != json::parse_event_t::object_end;
+    });
+
+    // in every case, the discarded value is removed together with its key
+    std::cout << j_array_start << '\n'
+              << j_array_end << '\n'
+              << j_value << '\n'
+              << j_key << '\n'
+              << j_root << '\n';
+}

examples/parser_callback_t.output

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+{"Width":800}
+{"Width":800}
+{"IDs":[116,943]}
+{"IDs":[116,943]}
+null