mirror of
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404 lines
13 KiB
C++
404 lines
13 KiB
C++
/////////////////////////////////////////////////////////////////////////////
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/// @file string_collection.h
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/// Definition of the string_collection class for the Paho MQTT C++ library.
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/// @date April 23, 2017
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/// @author Frank Pagliughi
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/////////////////////////////////////////////////////////////////////////////
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/*******************************************************************************
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* Copyright (c) 2017-2024 Frank Pagliughi <fpagliughi@mindspring.com>
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*
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v2.0
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* and Eclipse Distribution License v1.0 which accompany this distribution.
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*
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* The Eclipse Public License is available at
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* http://www.eclipse.org/legal/epl-v20.html
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* and the Eclipse Distribution License is available at
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* http://www.eclipse.org/org/documents/edl-v10.php.
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*
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* Contributors:
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* Frank Pagliughi - initial implementation and documentation
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*******************************************************************************/
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#ifndef __mqtt_string_collection_h
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#define __mqtt_string_collection_h
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#include "MQTTAsync.h"
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#include "mqtt/types.h"
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#include <vector>
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#include <map>
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#include <memory>
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namespace mqtt {
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/////////////////////////////////////////////////////////////////////////////
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/**
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* Type for a collection of strings, such as MQTT topics.
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*
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* This acts like a standard collection of strings but carries an array of
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* pointers to the C strings for easy interactions with the Paho C library.
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*/
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class string_collection
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{
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public:
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/** The type for the collection of strings */
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using collection_type = std::vector<string>;
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/** Iterator over const items */
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using const_iterator = collection_type::const_iterator;
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/** Smart/shared pointer to an object of this type */
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using ptr_t = std::shared_ptr<string_collection>;
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/** Smart/shared pointer to a const object of this type */
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using const_ptr_t = std::shared_ptr<const string_collection>;
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private:
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/** The type for the array of C pointers */
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using c_arr_type = std::vector<const char*>;
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/**
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* The collection of strings.
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*/
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collection_type coll_;
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/**
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* A collection of pointers to NUL-terminated C strings.
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* This is what is required by the Paho C library, and thus the lifetime
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* of the pointers will remain consistent with the lifetime of the
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* object. The value is kept consistent with the current stringss and
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* updated whenever strings are added or removed.
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*/
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c_arr_type cArr_;
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/**
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* Updated the cArr_ object to agree with the values in coll_
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* This should be called any time the coll_ variable is modified
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* <i>in any way</i>.
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*/
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void update_c_arr();
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public:
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/**
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* Construct an empty string collection.
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*/
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string_collection() =default;
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/**
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* Construct a collection initially containing a single string.
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* @param str The string
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*/
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string_collection(const string& str);
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/**
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* Construct a collection initially containing a single string.
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* @param str The string
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*/
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string_collection(string&& str);
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/**
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* Constructs a string collection by copying a vector of strings.
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* @param vec A vector of strings.
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*/
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string_collection(const collection_type& vec);
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/**
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* Constructs a string collection by moving a vector of strings.
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* @param vec A vector of strings.
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*/
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string_collection(collection_type&& vec);
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/**
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* Copy constructor.
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* @param coll An existing string collection.
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*/
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string_collection(const string_collection& coll);
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/**
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* Move constructor.
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* @param coll An existing string collection.
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*/
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string_collection(string_collection&& coll) =default;
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/**
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* Construct a string collection from an initialization list of strings.
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* @param sl An initialization list of strings.
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*/
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string_collection(std::initializer_list<string> sl);
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/**
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* Construct a string collection from an initialization list of C string
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* pointers.
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* @param sl An initialization list of C character arrays.
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*/
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string_collection(std::initializer_list<const char*> sl);
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/**
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* Create an empty string collection on the heap.
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* @return A smart/shared pointer to a string collection.
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*/
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static ptr_t create(const string& str) {
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return std::make_shared<string_collection>(str);
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}
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/**
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* Create a string collection on the heap, initially containing a single
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* string.
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* @param str The string
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* @return A smart/shared pointer to a string collection.
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*/
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static ptr_t create(string&& str) {
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return std::make_shared<string_collection>(str);
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}
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/**
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* Creates a string collection on the heap by copying a vector of
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* strings.
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* @param vec A vector of strings.
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*/
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static ptr_t create(const collection_type& vec) {
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return std::make_shared<string_collection>(vec);
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}
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/**
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* Creates a string collection on the heap by copying a vector of
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* strings.
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* @param vec A vector of strings.
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* @return A smart/shared pointer to a string collection.
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*/
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static ptr_t create(collection_type&& vec) {
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return std::make_shared<string_collection>(vec);
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}
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/**
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* Create a string collection on the heap from an initialization list of
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* strings.
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* @param sl An initialization list of strings.
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* @return A smart/shared pointer to a string collection.
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*/
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static ptr_t create(std::initializer_list<string> sl) {
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return std::make_shared<string_collection>(sl);
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}
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/**
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* Create a string collection on the heap from an initialization list of
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* C string pointers.
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* @param sl An initialization list of C character arrays.
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* @return A smart/shared pointer to a string collection.
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*/
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static ptr_t create(std::initializer_list<const char*> sl) {
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return std::make_shared<string_collection>(sl);
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}
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/**
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* Copy assignment.
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* Copy another string collection to this one.
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* @param coll A string collection
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* @return A reference to this collection.
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*/
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string_collection& operator=(const string_collection& coll);
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/**
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* Move assignment.
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* Move another string collection to this one.
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* @param coll A string collection
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* @return A reference to this collection.
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*/
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string_collection& operator=(string_collection&& coll) =default;
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/**
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* Gets a const iterator to the beginning of the collection.
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* @return A const iterator to the beginning of the collection.
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*/
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const_iterator begin() const { return coll_.begin(); }
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/**
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* Gets a const iterator to the end of the collection.
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* @return A const iterator to the end of the collection.
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*/
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const_iterator end() const { return coll_.end(); }
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/**
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* Gets a const iterator to the beginning of the collection.
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* @return A const iterator to the beginning of the collection.
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*/
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const_iterator cbegin() const { return coll_.cbegin(); }
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/**
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* Gets a const iterator to the end of the collection.
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* @return A const iterator to the end of the collection.
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*/
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const_iterator cend() const { return coll_.cend(); }
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/**
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* Determines if the collection is empty.
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* @return @em true if the collection is empty, @em false if not.
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*/
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bool empty() const { return coll_.empty(); }
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/**
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* Gets the number of strings in the collection.
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* @return The number of strings in the collection.
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*/
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size_t size() const { return coll_.size(); }
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/**
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* Copies a string onto the back of the collection.
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* @param str A string.
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*/
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void push_back(const string& str);
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/**
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* Moves a string onto the back of the collection.
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* @param str A string.
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*/
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void push_back(string&& str);
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/**
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* Removes all the strings from the collection.
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*/
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void clear();
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/**
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* Gets the n'th string in the collection.
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* @param i Index to the desired string.
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* @return A const reference to the string.
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*/
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const string& operator[](size_t i) const { return coll_[i]; }
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/**
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* Gets a pointer to an array of NUL-terminated C string pointers.
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* This is the collection type supported by the underlying Paho C
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* library. The returned pointer is guaranteed valid so long as the
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* object is not updated. The return value may change if the object is
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* modified, so the application should not cache the return value, but
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* rather request the value when needed.
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* @return pointer to an array of NUL-terminated C string pointers of
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* the C++ strings in the object.
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*
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*/
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char* const* c_arr() const { return (char* const *) cArr_.data(); }
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};
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/////////////////////////////////////////////////////////////////////////////
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/** Smart/shared pointer to a string collection */
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using string_collection_ptr = string_collection::ptr_t;
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/** Smart/shared pointer to a const string_collection */
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using const_string_collection_ptr = string_collection::const_ptr_t;
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/////////////////////////////////////////////////////////////////////////////
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/**
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* A colleciton of name/value string pairs.
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*/
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class name_value_collection
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{
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/** The type for the collection of name/value pairs */
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using collection_type = std::map<string, string>;
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/** The type for the C pointers to pass to Paho C */
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using c_arr_type = std::vector<MQTTAsync_nameValue>;
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/**
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* The name/value pairs.
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*/
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collection_type map_;
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/**
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* A collection of pairs of NUL-terminated C strings.
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*/
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c_arr_type cArr_;
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/**
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* Updated the cArr_ object to agree with the values in coll_
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* This should be called any time the coll_ variable is modified
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* <i>in any way</i>.
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*/
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void update_c_arr();
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public:
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/** Smart/shared pointer to an object of this type */
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using ptr_t = std::shared_ptr<name_value_collection>;
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/** Smart/shared pointer to a const object of this type */
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using const_ptr_t = std::shared_ptr<const name_value_collection>;
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/** The type of the string/string pair of values */
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using value_type = collection_type::value_type;
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/**
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* Default constructor for an empty collection.
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*/
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name_value_collection() =default;
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/**
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* Creates a name/value collection from an underlying STL collection.
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* @param map The collection of name/value pairs.
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*/
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name_value_collection(const collection_type& map) : map_(map) {
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update_c_arr();
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}
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/**
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* Creates a name/value collection from an underlying STL collection.
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* @param map The collection of name/value pairs.
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*/
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name_value_collection(collection_type&& map) : map_(std::move(map)) {
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update_c_arr();
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}
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/**
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* Copy constructor.
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* @param other Another collection of name/value pairs.
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*/
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name_value_collection(const name_value_collection& other)
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: map_(other.map_) {
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update_c_arr();
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}
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/**
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* Move constructor.
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* @param other Another collection of name/value pairs
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*/
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name_value_collection(name_value_collection&& other) =default;
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/**
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* Constructs the collection with an initializer list.
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*
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* This works identically to initializing a std::map<> with string/tring
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* pairs.
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*
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* @param init Initializer list to construct the members of the
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* collection.
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*/
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name_value_collection(std::initializer_list<value_type> init)
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: map_{ init } {
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update_c_arr();
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}
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/**
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* Copy assignment.
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* @param other Another collection of name/value pairs.
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*/
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name_value_collection& operator=(const name_value_collection& other) {
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map_ = other.map_;
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update_c_arr();
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return *this;
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}
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/**
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* Move constructor.
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* @param other Another collection of name/value pairs
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*/
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name_value_collection& operator=(name_value_collection&& other) =default;
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/**
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* Determines if the collection is empty.
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* @return @em true if the container is empty, @em false if it contains
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* one or more items.
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*/
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bool empty() const { return map_.empty(); }
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/**
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* Gets the number of name/value pairs in the collection.
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* @return The number of name/value pairs in the collection.
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*/
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size_t size() const { return map_.size(); }
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/**
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* Removes all items from the collection.
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*/
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void clear() {
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map_.clear();
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update_c_arr();
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}
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/**
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* Inserts a name/value pair into the collection.
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* @param nvpair The name/value string pair.
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* @return @em true if the inert happened, @em false if not.
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*/
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bool insert(const value_type& nvpair) {
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if (map_.insert(nvpair).second) {
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update_c_arr();
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return true;
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}
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return false;
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}
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/**
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* Gets a pointer to an array of NUL-terminated C string pointer pairs.
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* This is a collection type supported by the underlying Paho C
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* library. The returned pointer is guaranteed valid so long as the
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* object is not updated. The return value may change if the object is
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* modified, so the application should not cache the return value, but
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* rather request the value when needed.
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* @return pointer to an array of NUL-terminated C string pointer pairs
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* for name/values. The array is terminated by a NULL/NULL pair.
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*/
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const MQTTAsync_nameValue* c_arr() const { return cArr_.data(); }
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};
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/////////////////////////////////////////////////////////////////////////////
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// end namespace mqtt
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}
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#endif // __mqtt_string_collection_h
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