mpd/src/lib/dbus/ReadIter.hxx

148 lines
3.9 KiB
C++

/*
* Copyright 2007-2017 Content Management AG
* All rights reserved.
*
* author: Max Kellermann <mk@cm4all.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ODBUS_READ_ITER_HXX
#define ODBUS_READ_ITER_HXX
#include "Iter.hxx"
#include "util/Compiler.h"
#include "util/ConstBuffer.hxx"
#if GCC_OLDER_THAN(8,0)
/* switch off completely bogus shadow warnings in older GCC
versions */
#pragma GCC diagnostic ignored "-Wshadow"
#endif
namespace ODBus {
class ReadMessageIter : public MessageIter {
struct RecurseTag {};
ReadMessageIter(RecurseTag, ReadMessageIter &parent) noexcept {
dbus_message_iter_recurse(&parent.iter, &iter);
}
public:
explicit ReadMessageIter(DBusMessage &msg) noexcept {
dbus_message_iter_init(&msg, &iter);
}
bool HasNext() noexcept {
return dbus_message_iter_has_next(&iter);
}
bool Next() noexcept {
return dbus_message_iter_next(&iter);
}
int GetArgType() noexcept {
return dbus_message_iter_get_arg_type(&iter);
}
const char *GetSignature() noexcept {
return dbus_message_iter_get_signature(&iter);
}
void GetBasic(void *value) noexcept {
dbus_message_iter_get_basic(&iter, value);
}
const char *GetString() noexcept {
const char *value;
GetBasic(&value);
return value;
}
template<typename T>
ConstBuffer<T> GetFixedArray() noexcept {
void *value;
int n_elements;
dbus_message_iter_get_fixed_array(&iter, &value, &n_elements);
return {(const T *)value, size_t(n_elements)};
}
/**
* Create a new iterator which recurses into a container
* value.
*/
ReadMessageIter Recurse() noexcept {
return {RecurseTag(), *this};
}
/**
* Invoke a function for each element (including the current
* one), as long as the argument type is the specified one.
*/
template<typename F>
void ForEach(int arg_type, F &&f) {
for (; GetArgType() == arg_type; Next())
f(*this);
}
/**
* Wrapper for ForEach() which passes a recursed iterator for
* each element.
*/
template<typename F>
void ForEachRecurse(int arg_type, F &&f) {
ForEach(arg_type, [&f](auto &&i){
f(i.Recurse());
});
}
/**
* Invoke a function for each name/value pair (string/variant)
* in a dictionary (array containing #DBUS_TYPE_DICT_ENTRY).
* The function gets two parameters: the property name (as C
* string) and the variant value (as #ReadMessageIter).
*/
template<typename F>
void ForEachProperty(F &&f) {
ForEachRecurse(DBUS_TYPE_DICT_ENTRY, [&f](auto &&i){
if (i.GetArgType() != DBUS_TYPE_STRING)
return;
const char *name = i.GetString();
i.Next();
if (i.GetArgType() != DBUS_TYPE_VARIANT)
return;
f(name, i.Recurse());
});
}
};
} /* namespace ODBus */
#endif