feat:export data while running or close

components/ffmsep/presist/presist.cc

@@ -6,6 +6,7 @@
 
 #include "components/ffmsep/cpstream_core.hh"
 
+#include <algorithm>
 #include <chrono>
 #include <filesystem>
 #include <fstream>
@@ -19,6 +20,73 @@ namespace {
 
 using nlohmann::json;
 
+bool is_simple_array(const json& value) {
+    if (!value.is_array()) {
+        return false;
+    }
+    return std::all_of(value.begin(), value.end(), [](const json& item) {
+        return item.is_primitive();
+    });
+}
+
+void dump_compact_json(std::ostream& out,
+                       const json& value,
+                       int indent = 0,
+                       int indent_step = 2) {
+    const auto indent_str = std::string(static_cast<std::size_t>(indent), ' ');
+    const auto child_indent = indent + indent_step;
+    const auto child_indent_str = std::string(static_cast<std::size_t>(child_indent), ' ');
+
+    if (value.is_object()) {
+        out << "{\n";
+        bool first = true;
+        for (auto it = value.begin(); it != value.end(); ++it) {
+            if (!first) {
+                out << ",\n";
+            }
+            first = false;
+            out << child_indent_str << json(it.key()).dump() << ": ";
+            dump_compact_json(out, it.value(), child_indent, indent_step);
+        }
+        out << '\n' << indent_str << '}';
+        return;
+    }
+
+    if (value.is_array()) {
+        if (value.empty()) {
+            out << "[]";
+            return;
+        }
+
+        if (is_simple_array(value)) {
+            out << '[';
+            for (std::size_t idx = 0; idx < value.size(); ++idx) {
+                if (idx != 0U) {
+                    out << ", ";
+                }
+                out << value[static_cast<json::size_type>(idx)].dump();
+            }
+            out << ']';
+            return;
+        }
+
+        out << "[\n";
+        bool first = true;
+        for (const auto& item : value) {
+            if (!first) {
+                out << ",\n";
+            }
+            first = false;
+            out << child_indent_str;
+            dump_compact_json(out, item, child_indent, indent_step);
+        }
+        out << '\n' << indent_str << ']';
+        return;
+    }
+
+    out << value.dump();
+}
+
 json serialize_tactile_frame(const DecodedFrame& frame) {
     json result = {
         {"pts", frame.pts},
@@ -165,7 +233,8 @@ WriteResult JsonWritter::write_once(const std::string& path,
         return {false, "failed to open export file", path};
     }
 
-    stream << std::setw(2) << root;
+    dump_compact_json(stream, root);
+    stream << '\n';
     stream.flush();
     if (!stream.good()) {
         return {false, "failed to write export file", path};