zhipuzi_pos_windows/include/mqtt/properties.h

/////////////////////////////////////////////////////////////////////////////
/// @file properties.h
/// Declaration of MQTT properties class
/// @date July 7, 2019
/// @author Frank Pagliughi
/////////////////////////////////////////////////////////////////////////////

/*******************************************************************************
 * Copyright (c) 2019-2024 Frank Pagliughi <fpagliughi@mindspring.com>
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v20.html
 * and the Eclipse Distribution License is available at
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Frank Pagliughi - initial implementation and documentation
 *******************************************************************************/

#ifndef __mqtt_properties_h
#define __mqtt_properties_h

extern "C" {
#include "MQTTProperties.h"
}

#include <initializer_list>
#include <iostream>
#include <map>
#include <stdexcept>
#include <string_view>
#include <tuple>
#include <typeinfo>

#include "mqtt/buffer_ref.h"
#include "mqtt/exception.h"
#include "mqtt/platform.h"
#include "mqtt/types.h"

namespace mqtt {

/** A pair of strings as a tuple. */
using string_pair = std::tuple<string, string>;

/////////////////////////////////////////////////////////////////////////////

/**
 * A single MQTT v5 property.
 */
class property
{
    /** The underlying Paho C property struct. */
    MQTTProperty prop_;

    // Make a deep copy of the property struct into this one.
    // For string properties, this allocates memory and copied the string(s)
    void copy(const MQTTProperty& other);

    friend class properties;
    property() {}

public:
    /**
     * The integer codes for the different v5 properties.
     */
    enum code {
        PAYLOAD_FORMAT_INDICATOR = 1,
        MESSAGE_EXPIRY_INTERVAL = 2,
        CONTENT_TYPE = 3,
        RESPONSE_TOPIC = 8,
        CORRELATION_DATA = 9,
        SUBSCRIPTION_IDENTIFIER = 11,
        SESSION_EXPIRY_INTERVAL = 17,
        ASSIGNED_CLIENT_IDENTIFIER = 18,
        SERVER_KEEP_ALIVE = 19,
        AUTHENTICATION_METHOD = 21,
        AUTHENTICATION_DATA = 22,
        REQUEST_PROBLEM_INFORMATION = 23,
        WILL_DELAY_INTERVAL = 24,
        REQUEST_RESPONSE_INFORMATION = 25,
        RESPONSE_INFORMATION = 26,
        SERVER_REFERENCE = 28,
        REASON_STRING = 31,
        RECEIVE_MAXIMUM = 33,
        TOPIC_ALIAS_MAXIMUM = 34,
        TOPIC_ALIAS = 35,
        MAXIMUM_QOS = 36,
        RETAIN_AVAILABLE = 37,
        USER_PROPERTY = 38,
        MAXIMUM_PACKET_SIZE = 39,
        WILDCARD_SUBSCRIPTION_AVAILABLE = 40,
        SUBSCRIPTION_IDENTIFIERS_AVAILABLE = 41,
        SHARED_SUBSCRIPTION_AVAILABLE = 42
    };

    /** The names of the different types of properties */
    PAHO_MQTTPP_EXPORT static const std::map<code, std::string_view> TYPE_NAME;

    /**
     * Create a numeric property.
     * This can be a byte, or 2-byte, 4-byte, or variable byte integer.
     * @param c The property code
     * @param val The integer value for the property
     */
    property(code c, int32_t val);
    /**
     * Create a numeric property.
     * This can be a byte, or 2-byte, 4-byte, or variable byte integer.
     * @param c The property code
     * @param val The integer value for the property
     */
    property(code c, uint32_t val) : property(c, int32_t(val)) {}
    /**
     * Create a string or binary property.
     * @param c The property code
     * @param val The value for the property
     */
    property(code c, string_ref val);
    /**
     * Create a string pair property.
     * @param c The property code
     * @param name The string name for the property
     * @param val The string value for the property
     */
    property(code c, string_ref name, string_ref val);
    /**
     * Creates a property from a C struct.
     * @param cprop A C struct for a property list.
     */
    explicit property(const MQTTProperty& cprop) { copy(cprop); }
    /**
     * Moves a C struct into this property list.
     * This takes ownership of any memory that the C struct is holding.
     * @param cprop A C struct for a property list.
     */
    explicit property(MQTTProperty&& cprop) : prop_(cprop) {
        memset(&cprop, 0, sizeof(MQTTProperty));
    }
    /**
     * Copy constructor
     * @param other The other property to copy into this one.
     */
    property(const property& other) { copy(other.prop_); }
    /**
     * Move constructor.
     * @param other The other property that is moved into this one.
     */
    property(property&& other);
    /**
     * Destructor
     */
    ~property();
    /**
     * Copy assignment.
     * @param rhs Another property list to copy into this one.
     * @return A reference to this object.
     */
    property& operator=(const property& rhs);
    /**
     * Move assignment.
     * @param rhs Another property list to move into this one.
     * @return A reference to this object.
     */
    property& operator=(property&& rhs);
    /**
     * Gets the underlying C property struct.
     * @return A const reference to the underlying C property
     *  	   struct.
     */
    const MQTTProperty& c_struct() const { return prop_; }
    /**
     * Gets the property type (identifier).
     * @return The code for the property type.
     */
    code type() const { return code(prop_.identifier); }
    /**
     * Gets a printable name for the property type.
     * @return A printable name for the property type.
     */
    std::string_view type_name() const;
    /**
     * Gets the typeid for the value contained in the property.
     * @return The typeid for the value contained in the property.
     */
    const std::type_info& value_type_id();
};

std::ostream& operator<<(std::ostream& os, const property& prop);

/**
 * Extracts the value from the property as the specified type.
 * @return The value from the property as the specified type.
 */
template <typename T>
inline T get(const property&) {
    throw bad_cast();
}

/**
 * Extracts the value from the property as an unsigned 8-bit integer.
 * @return The value from the property as an unsigned 8-bit integer.
 */
template <>
inline uint8_t get<uint8_t>(const property& prop) {
    return uint8_t(prop.c_struct().value.byte);
}

/**
 * Extracts the value from the property as an unsigned 16-bit integer.
 * @return The value from the property as an unsigned 16-bit integer.
 */
template <>
inline uint16_t get<uint16_t>(const property& prop) {
    return uint16_t(prop.c_struct().value.integer2);
}

/**
 * Extracts the value from the property as a signed 16-bit integer.
 * @return The value from the property as a signed 16-bit integer.
 * @deprecated All integer properties are unsigned. Use
 *  		   `get<uint16_t>()`
 */
template <>
[[deprecated("Integer properties are unsigned. Use get<uint16_t>()")]] inline int16_t
get<int16_t>(const property& prop) {
    return int16_t(prop.c_struct().value.integer2);
}

/**
 * Extracts the value from the property as an unsigned 32-bit integer.
 * @return The value from the property as an unsigned 32-bit integer.
 */
template <>
inline uint32_t get<uint32_t>(const property& prop) {
    return uint32_t(prop.c_struct().value.integer4);
}

/**
 * Extracts the value from the property as a signed 32-bit integer.
 * @return The value from the property as a signed 32-bit integer.
 * @deprecated All integer properties are unsigned. Use
 *  		   `get<uint32_t>()`
 */
template <>
[[deprecated("Integer properties are unsigned. Use get<uint32_t>()")]] inline int32_t
get<int32_t>(const property& prop) {
    return int32_t(prop.c_struct().value.integer4);
}

/**
 * Extracts the value from the property as a string.
 * @return The value from the property as a string.
 */
template <>
inline string get<string>(const property& prop) {
    return (!prop.c_struct().value.data.data)
               ? string()
               : string(prop.c_struct().value.data.data, prop.c_struct().value.data.len);
}

/**
 * Extracts the value from the property as a pair of strings.
 * @return The value from the property as a pair of strings.
 */
template <>
inline string_pair get<string_pair>(const property& prop) {
    string name =
        (!prop.c_struct().value.data.data)
            ? string()
            : string(prop.c_struct().value.data.data, prop.c_struct().value.data.len);

    string value =
        (!prop.c_struct().value.value.data)
            ? string()
            : string(prop.c_struct().value.value.data, prop.c_struct().value.value.len);

    return std::make_tuple(std::move(name), std::move(value));
}

/////////////////////////////////////////////////////////////////////////////

/**
 * MQTT v5 property list.
 *
 * A collection of properties that can be added to outgoing packets or
 * retrieved from incoming packets.
 */
class properties
{
    /** The default C struct */
    static constexpr MQTTProperties DFLT_C_STRUCT MQTTProperties_initializer;

    /** The underlying C properties struct */
    MQTTProperties props_{DFLT_C_STRUCT};

    template <typename T>
    friend T get(const properties& props, property::code propid, size_t idx);

    template <typename T>
    friend T get(const properties& props, property::code propid);

public:
    /** A const iterator for the properties list */
    class const_iterator
    {
        const MQTTProperty* curr_;
        mutable property prop_;

        friend properties;
        const_iterator(const MQTTProperty* curr) : curr_{curr} {}

    public:
        /**
         * Gets a reference to the current value.
         * @return A reference to the current value.
         */
        const property& operator*() const {
            prop_ = property{*curr_};
            return prop_;
        }
        /**
         * Postfix increment operator.
         * @return An iterator pointing to the previous matching item.
         */
        const_iterator operator++(int) noexcept {
            auto tmp = *this;
            curr_++;
            return tmp;
        }
        /**
         * Prefix increment operator.
         * @return An iterator pointing to the next matching item.
         */
        const_iterator& operator++() noexcept {
            ++curr_;
            return *this;
        }
        /**
         * Compares two iterators to see if they don't refer to the same
         * node.
         *
         * @param other The other iterator to compare against this one.
         * @return @em true if they don't match, @em false if they do
         */
        bool operator!=(const const_iterator& other) const noexcept {
            return curr_ != other.curr_;
        }
    };

    /**
     * Default constructor.
     * Creates an empty properties list.
     */
    properties() {}
    /**
     * Copy constructor.
     * @param other The property list to copy.
     */
    properties(const properties& other) : props_(::MQTTProperties_copy(&other.props_)) {}
    /**
     * Move constructor.
     * @param other The property list to move to this one.
     */
    properties(properties&& other) : props_(other.props_) {
        std::memset(&other.props_, 0, sizeof(MQTTProperties));
    }
    /**
     * Creates a list of properties from a C struct.
     * @param cprops The c struct of properties
     */
    properties(const MQTTProperties& cprops) { props_ = ::MQTTProperties_copy(&cprops); }
    /**
     * Constructs from a list of property objects.
     * @param props An initializer list of property objects.
     */
    properties(std::initializer_list<property> props);
    /**
     * Destructor.
     */
    ~properties() { ::MQTTProperties_free(&props_); }
    /**
     * Gets a reference to the underlying C properties structure.
     * @return A const reference to the underlying C properties structure.
     */
    const MQTTProperties& c_struct() const { return props_; }
    /**
     * Copy assignment.
     * @param rhs The other property list to copy into this one
     * @return A reference to this object.
     */
    properties& operator=(const properties& rhs);
    /**
     * Move assignment.
     * @param rhs The property list to move to this one.
     * @return A reference to this object.
     */
    properties& operator=(properties&& rhs);
    /**
     * Determines if the property list is empty.
     * @return @em true if there are no properties in the list, @em false if
     *  	   the list contains any items.
     */
    bool empty() const { return props_.count == 0; }
    /**
     * Gets the property at the specified index in the collection.
     * @param i The index
     * @return The property at the specified index.
     */
    const property operator[](size_t i) const { return property{props_.array[i]}; }
    /**
     * Gets the property at the specified index in the collection.
     * @param i The index
     * @return The property at the specified index.
     */
    const property at(size_t i) const {
        if (i < size_t(props_.count))
            return property{props_.array[i]};
        throw std::out_of_range{"property index"};
    }
    /**
     * Gets the numbers of property items in the list.
     * @return The number of property items in the list.
     */
    size_t size() const { return size_t(props_.count); }
    /**
     * Gets a const iterator to the full collection of properties.
     * @return A const iterator to the full collection of properties.
     */
    const_iterator begin() const { return const_iterator{props_.array}; }
    /**
     * Gets a const iterator to the full collection of properties.
     * @return A const iterator to the full collection of properties.
     */
    const_iterator cbegin() const { return begin(); }
    /**
     * Gets a const iterator to the end of the collection of properties.
     * @return A const iterator to the end of collection of properties.
     */
    const_iterator end() const { return const_iterator{props_.array + size()}; }
    /**
     * Gets a const iterator to the end of the collection of properties.
     * @return A const iterator to the end of collection of properties.
     */
    const_iterator cend() const { return end(); }
    /**
     * Adds a property to the list.
     * @param prop The property to add to the list.
     */
    void add(const property& prop) { ::MQTTProperties_add(&props_, &prop.c_struct()); }
    /**
     * Removes all the items from the property list.
     */
    void clear() { ::MQTTProperties_free(&props_); }
    /**
     * Determines if the list contains a specific property.
     * @param propid The property ID (code).
     * @return @em true if the list contains the property, @em false if not.
     */
    bool contains(property::code propid) const {
        return ::MQTTProperties_hasProperty(
                   const_cast<MQTTProperties*>(&props_), MQTTPropertyCodes(propid)
               ) != 0;
    }
    /**
     * Get the number of properties in the list with the specified property
     * ID.
     *
     * Most properties can exist only once. User properties and subscription
     * ID's can exist more than once.
     *
     * @param propid The property ID (code).
     * @return The number of properties in the list with the specified ID.
     */
    size_t count(property::code propid) const {
        return size_t(
            ::MQTTProperties_propertyCount(
                const_cast<MQTTProperties*>(&props_), MQTTPropertyCodes(propid)
            )
        );
    }
    /**
     * Gets the property with the specified ID.
     *
     * @param propid The property ID (code).
     * @param idx Which instance of the property to retrieve, if there are
     *  		  more than one.
     * @return The requested property
     */
    property get(property::code propid, size_t idx = 0) const;
};

// --------------------------------------------------------------------------

/**
 * Retrieves a single value from a property list for when there may be
 * multiple identical property ID's.
 * @tparam T The type of the value to retrieve
 * @param props The property list
 * @param propid The property ID code for the desired value.
 * @param idx Index of the desired property ID
 * @return The requested value of type T
 */
template <typename T>
inline T get(const properties& props, property::code propid, size_t idx) {
    MQTTProperty* prop = MQTTProperties_getPropertyAt(
        const_cast<MQTTProperties*>(&props.c_struct()), MQTTPropertyCodes(propid), int(idx)
    );
    if (!prop)
        throw bad_cast();

    return get<T>(property(*prop));
}

/**
 * Retrieves a single value from a property list.
 * @tparam T The type of the value to retrieve
 * @param props The property list
 * @param propid The property ID code for the desired value.
 * @return The requested value of type T
 */
template <typename T>
inline T get(const properties& props, property::code propid) {
    return get<T>(props, propid, 0);
}

/////////////////////////////////////////////////////////////////////////////
}  // namespace mqtt

#endif  // __mqtt_properties_h