Member function pointer in C++ for_each
I'm developing a small Virtual Machine in C++ for a school project, which should work like dc command, and is composed of a Input Output element, a Chipset, a Cpu and Ram. I'm currently working on the chipset, in which I've implemented a little parsing class in order to be able to get some Asm instructions from standard input or file, and then push this instructions to the Cpu.
The problem is: my instructions are sorted in a std::list, and I'd like to be able to push them each by each with a foreach instruction. To do that I need to be able to call 开发者_运维问答my member function "push_instruction" as the function pointer F of for_each; and I wasn't able to find the trick to do that...
Any ideas? here's my code:
/*
** Function which will supervise
** the lexing and parsing of the input (whether it's std_input or a file descriptor)
** the memory pushing of operands and operators
** and will command the execution of instructions to the Cpu
*/
void Chipset::startExecution()
{
/*
** My parsing
** Instructions
**
*/
for_each(this->_instructList.begin(), this->_instructList.end(), this->pushInstruction);
}
void Chipset::pushInstruction(instructionList* instruction)
{
if (instruction->opCode == PUSH)
this->_processor->pushOperand(instruction->value, Memory::OPERAND, Memory::BACK);
else if (instruction->opCode == ASSERT)
this->_processor->pushOperand(instruction->value, Memory::ASSERT, Memory::BACK);
else
this->_processor->pushOperation(instruction->opCode);
}
std::for_each(
_instructList.begin(),
_instructList.end(),
std::bind1st(std::mem_fun(&Chipset::pushInstruction), this));
When you can't remember the syntax for the std::bind
functions, it is sometimes easier to write a functor which just forwards to the member function:
struct PushInstruction {
PushInstruction(Chipset& self) : self(self) {}
void operator()(instructionList* instruction) {
self.pushInstruction(instruction);
}
Chipset& self;
};
std::for_each(_instructList.begin(), _instructList.end(), PushInstruction(*this));
A bit of explanation:
I define a class which, in its constructor, takes the object we want to call pushInstruction
on, and which stores a reference to the object.
Then I define an operator()
hich takes the instruction you wish to push, and calls pushInstruction
.
In the for_each
loop, I just pass this
to my constructor, creating an instance of the functor, which is passed to for_each
, which then calls operator()
on it for each element.
Use boost::bind
as,
std::for_each(/*..*/, /*..*/,
boost::bind(&Chipset::pushInstruction, this, _1));
You can bind1st
your this
pointer to obtain a functor applied on your cpu:
std::foreach( instructList.begin(), instructList.end(),
std::bind1st
( std::mem_fun( &CChipSet::pushInstruction )
, this
)
);
(Note: I deliberately left away the underscore from your _instructionList
. It's not allowed.)
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