1 files changed, 130 insertions, 0 deletions
diff --git a/libqpdf/qpdf/JSONHandler.hh b/libqpdf/qpdf/JSONHandler.hh
new file mode 100644
index 00000000..dbea505f
--- /dev/null
+++ b/libqpdf/qpdf/JSONHandler.hh
@@ -0,0 +1,130 @@
+#ifndef JSONHANDLER_HH
+#define JSONHANDLER_HH
+
+#include <qpdf/DLL.h>
+#include <qpdf/PointerHolder.hh>
+#include <qpdf/JSON.hh>
+#include <string>
+#include <map>
+#include <functional>
+#include <memory>
+
+// This class allows a sax-like walk through a JSON object with
+// functionality that mostly mirrors QPDFArgParser. It is primarily
+// here to facilitate automatic generation of some of the code to help
+// keep QPDFJob json consistent with command-line arguments.
+
+class JSONHandler
+{
+  public:
+    // A QPDFUsage exception is thrown if there are any errors
+    // validating the JSON object.
+    QPDF_DLL
+    JSONHandler();
+
+    QPDF_DLL
+    ~JSONHandler() = default;
+
+    // Based on the type of handler, expect the object to be of a
+    // certain type. QPDFUsage is thrown otherwise. Multiple handlers
+    // may be registered, which allows the object to be of various
+    // types. If an anyHandler is added, no other handler will be
+    // called. There is no "final" handler -- if the top-level is a
+    // dictionary or array, just use its end handler.
+
+    typedef std::function<void(
+        std::string const& path, JSON value)> json_handler_t;
+    typedef std::function<void(
+        std::string const& path)> void_handler_t;
+    typedef std::function<void(
+        std::string const& path, std::string const& value)> string_handler_t;
+    typedef std::function<void(
+        std::string const& path, bool value)> bool_handler_t;
+
+    // If an any handler is added, it will be called for any value
+    // including null, and no other handler will be called.
+    QPDF_DLL
+    void addAnyHandler(json_handler_t fn);
+
+    // If any of the remaining handlers are registered, each
+    // registered handle will be called.
+    QPDF_DLL
+    void addNullHandler(void_handler_t fn);
+    QPDF_DLL
+    void addStringHandler(string_handler_t fn);
+    QPDF_DLL
+    void addNumberHandler(string_handler_t fn);
+    QPDF_DLL
+    void addBoolHandler(bool_handler_t fn);
+
+    QPDF_DLL
+    void addDictHandlers(void_handler_t start_fn, void_handler_t end_fn);
+    QPDF_DLL
+    void addDictKeyHandler(
+        std::string const& key, std::shared_ptr<JSONHandler>);
+    QPDF_DLL
+    void addFallbackDictHandler(std::shared_ptr<JSONHandler>);
+
+    QPDF_DLL
+    void addArrayHandlers(void_handler_t start_fn,
+                          void_handler_t end_fn,
+                          std::shared_ptr<JSONHandler> item_handlers);
+
+    // Apply handlers recursively to a JSON object.
+    QPDF_DLL
+    void handle(std::string const& path, JSON j);
+
+  private:
+    JSONHandler(JSONHandler const&) = delete;
+
+    static void usage(std::string const& msg);
+
+    struct Handlers
+    {
+        Handlers() :
+            any_handler(nullptr),
+            null_handler(nullptr),
+            string_handler(nullptr),
+            number_handler(nullptr),
+            bool_handler(nullptr),
+            dict_start_handler(nullptr),
+            dict_end_handler(nullptr),
+            array_start_handler(nullptr),
+            array_end_handler(nullptr),
+            final_handler(nullptr)
+        {
+        }
+
+        json_handler_t any_handler;
+        void_handler_t null_handler;
+        string_handler_t string_handler;
+        string_handler_t number_handler;
+        bool_handler_t bool_handler;
+        void_handler_t dict_start_handler;
+        void_handler_t dict_end_handler;
+        void_handler_t array_start_handler;
+        void_handler_t array_end_handler;
+        void_handler_t final_handler;
+        std::map<std::string, std::shared_ptr<JSONHandler>> dict_handlers;
+        std::shared_ptr<JSONHandler> fallback_dict_handler;
+        std::shared_ptr<JSONHandler> array_item_handler;
+    };
+
+    class Members
+    {
+        friend class JSONHandler;
+
+      public:
+        QPDF_DLL
+        ~Members() = default;
+
+      private:
+        Members();
+        Members(Members const&) = delete;
+
+        Handlers h;
+    };
+    PointerHolder<Members> m;
+};
+
+#endif // JSONHANDLER_HH