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