JSONHandler: add fallback handler support

2 files changed, 15 insertions, 1 deletions

diff --git a/libqpdf/JSONHandler.cc b/libqpdf/JSONHandler.cc
index 4a69fd60..a8116cb0 100644
--- a/libqpdf/JSONHandler.cc
+++ b/libqpdf/JSONHandler.cc
@@ -17,10 +17,10 @@ struct Handlers
     JSONHandler::void_handler_t dict_end_handler{nullptr};
     JSONHandler::json_handler_t array_start_handler{nullptr};
     JSONHandler::void_handler_t array_end_handler{nullptr};
-    JSONHandler::void_handler_t final_handler{nullptr};
     std::map<std::string, std::shared_ptr<JSONHandler>> dict_handlers;
     std::shared_ptr<JSONHandler> fallback_dict_handler;
     std::shared_ptr<JSONHandler> array_item_handler;
+    std::shared_ptr<JSONHandler> fallback_handler;
 };
 
 class JSONHandler::Members
@@ -111,6 +111,12 @@ JSONHandler::addArrayHandlers(
 }
 
 void
+JSONHandler::addFallbackHandler(std::shared_ptr<JSONHandler> h)
+{
+    m->h.fallback_handler = std::move(h);
+}
+
+void
 JSONHandler::handle(std::string const& path, JSON j)
 {
     if (m->h.any_handler) {
@@ -169,6 +175,11 @@ JSONHandler::handle(std::string const& path, JSON j)
         return;
     }
 
+    if (m->h.fallback_handler) {
+        m->h.fallback_handler->handle(path, j);
+        return;
+    }
+
     // It would be nice to include information about what type the object was and what types were
     // allowed, but we're relying on schema validation to make sure input is properly structured
     // before calling the handlers. It would be different if this code were trying to be part of a
diff --git a/libqpdf/qpdf/JSONHandler.hh b/libqpdf/qpdf/JSONHandler.hh
index 9b2a0b33..1c53e32d 100644
--- a/libqpdf/qpdf/JSONHandler.hh
+++ b/libqpdf/qpdf/JSONHandler.hh
@@ -45,6 +45,9 @@ class JSONHandler
     void addArrayHandlers(
         json_handler_t start_fn, void_handler_t end_fn, std::shared_ptr<JSONHandler> item_handlers);
 
+    // If no handlers is called, the fallback handler will be used to try to handle the item.
+    void addFallbackHandler(std::shared_ptr<JSONHandler>);
+
     // Apply handlers recursively to a JSON object.
     void handle(std::string const& path, JSON j);