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158 lines
4.9 KiB
C++
158 lines
4.9 KiB
C++
// Copyright (c) 2005-2021 Jay Berkenbilt
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//
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// This file is part of qpdf.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Versions of qpdf prior to version 7 were released under the terms
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// of version 2.0 of the Artistic License. At your option, you may
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// continue to consider qpdf to be licensed under those terms. Please
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// see the manual for additional information.
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#ifndef JSONHANDLER_HH
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#define JSONHANDLER_HH
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#include <qpdf/DLL.h>
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#include <qpdf/PointerHolder.hh>
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#include <qpdf/JSON.hh>
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#include <string>
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#include <map>
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#include <functional>
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#include <stdexcept>
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#include <memory>
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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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// Error exception is thrown if there are any errors validating
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// the JSON object.
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class QPDF_DLL_CLASS Error: public std::runtime_error
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{
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public:
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QPDF_DLL
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Error(std::string const&);
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};
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QPDF_DLL
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JSONHandler();
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QPDF_DLL
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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. JSONHandler::Error is thrown otherwise. Multiple
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// handlers may be registered, which allows the object to be of
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// various types. If an anyHandler is added, no other handler will
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// be 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(
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std::string const& path, JSON value)> json_handler_t;
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typedef std::function<void(
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std::string const& path)> void_handler_t;
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typedef std::function<void(
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std::string const& path, std::string const& value)> string_handler_t;
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typedef std::function<void(
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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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QPDF_DLL
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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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QPDF_DLL
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void addNullHandler(void_handler_t fn);
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QPDF_DLL
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void addStringHandler(string_handler_t fn);
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QPDF_DLL
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void addNumberHandler(string_handler_t fn);
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QPDF_DLL
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void addBoolHandler(bool_handler_t fn);
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QPDF_DLL
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void addDictHandlers(void_handler_t start_fn, void_handler_t end_fn);
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QPDF_DLL
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void addDictKeyHandler(
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std::string const& key, std::shared_ptr<JSONHandler>);
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QPDF_DLL
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void addFallbackDictHandler(std::shared_ptr<JSONHandler>);
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QPDF_DLL
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void addArrayHandlers(void_handler_t start_fn,
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void_handler_t end_fn,
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std::shared_ptr<JSONHandler> item_handlers);
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// Apply handlers recursively to a JSON object.
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QPDF_DLL
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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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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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void_handler_t dict_start_handler;
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void_handler_t dict_end_handler;
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void_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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QPDF_DLL
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~Members() = default;
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private:
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Members();
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Members(Members const&) = delete;
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Handlers h;
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};
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PointerHolder<Members> m;
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};
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#endif // JSONHANDLER_HH
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