JSONHandler.hh
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#ifndef JSONHANDLER_HH
#define JSONHANDLER_HH
#include <qpdf/JSON.hh>
#include <functional>
#include <map>
#include <memory>
#include <string>
// 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.
JSONHandler();
~JSONHandler();
// 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.
void addAnyHandler(json_handler_t fn);
// If any of the remaining handlers are registered, each registered handle will be called.
void addNullHandler(void_handler_t fn);
void addStringHandler(string_handler_t fn);
void addNumberHandler(string_handler_t fn);
void addBoolHandler(bool_handler_t fn);
void addDictHandlers(json_handler_t start_fn, void_handler_t end_fn);
void addDictKeyHandler(std::string const& key, std::shared_ptr<JSONHandler>);
void addFallbackDictHandler(std::shared_ptr<JSONHandler>);
void addArrayHandlers(
json_handler_t start_fn, void_handler_t end_fn, std::shared_ptr<JSONHandler> item_handlers);
// Apply handlers recursively to a JSON object.
void handle(std::string const& path, JSON j);
private:
JSONHandler(JSONHandler const&) = delete;
static void usage(std::string const& msg);
class Members;
std::unique_ptr<Members> m;
};
#endif // JSONHANDLER_HH