Require help learning how to decompose class into policies
Below is a class that is suppose to represent a segment of memory or a
contents of a binary image (e.g. ELF executable). I have started to read
Modern C++ Design and thought the best way to ensure I was understanding
the chapter on policy classes was to attempt to apply them to my project.
I understand the general concept of policies but I lack the knowledge and
wisdom of how to identify them in an existing project. So I figured to get
an existing class and start from there.
Some notes about the code:
- Tracing: The following statement is only activate if the ./configure
script was run with --enable-debug. Otherwise its compiled out by
the compiler. If debugging is enabled AND the trace level of the
library was set to TraceLevel::DETAIL or higher then the message
will appear.
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::swap" );
- Assert: The following statement will perform either a throw an exception
which performs a typical abort after finding a false expression,
reporting where in the code the assert happened along with a descriptive message.
Otherwise a developer can provide another exception which can take a different
approach to terminating the program.
Assert::bool_check ( size != 0, "Size of memory map is zero." );
My first thoughts where to make the Asserts into a policy. Second place could be the to_String
function. One way of printing could be a indented string with spaces or another method writing the content
of the class as a XML string. Any help is appreciated.
Stephen
----------------------
HEADER
----------------------
#ifndef MEMORY_MAP_H_
#define MEMORY_MAP_H_
#include <boost/shared_ptr.hpp>
#include <iostream>
#include <iomanip>
#include <vector>
#include <map>
#include <boost/enable_shared_from_this.hpp>
#include "Data_Types.h"
namespace libreverse { namespace data_container {
class Memory_Map : public boost::enable_shared_from_this<Memory_Map>
{
public:
/**
* \brief Set up a blank memory map of a set size
*
* \param size Size of memory map to allocate
*
* \param base_address The memory address of the first byte
*
* \pre size has a value of 0 or more
*
* \pre base_address has a value of 0 or more
*
* \post Size of memory map has been set to the value of the
* input variable 'size'
*
* \post Base addres of the memory map has been set to the
* value of the input variable 'base_address' or the default
* value of zero
*/
explicit Memory_Map ( boost::uint32_t size,
boost::uint32_t base_address = 0 );
/**
* \brief Set up a memory map of a set size with the contents
* of the input file stream.
*
* \param input_ref Input file stream where data is stored.
*
* \param base_address The memory address of the first byte
*
* \pre size has a value of 0 or more
*
* \pre base_address has a value of 0 or more
*
* \post Size of memory map has been set to the value of the
* size of the input file stream.
*
* \post Base addres of the memory map has been set to the
* value of the input variable 'base_address' or the default
* value of zero
*/
explicit Memory_Map ( std::ifstream& input_ref,
boost::uint32_t base_address = 0 );
/**
* \brief Copy constructor
*
* \pre The input reference is a fully initialized Memory_Map
*
* \post The output Memory_Map is a deep copy of the input
*/
explicit Memory_Map ( Memory_Map const& rhs );
virtual ~Memory_Map();
/**
* \brief assignment operator
*
* This function handles copying the rhs reference even if the rhs
* is a reference to this object.
*
* \pre The input reference is a fully initialized Memory_Map
*
* \post The output Memory_Map is a deep copy of the input
*/
Memory_Map& operator= ( Memory_Map const& rhs );
/**
* \brief assignment operator
*
* \pre The input reference is a fully initialized Memory_Map
*
* \post The output Memory_Map is a deep copy of the input
*/
void swap ( Memory_Map& rhs );
/**
* \brief Adjust the pointer into the memory to the location
* specified in by the address.
*
* \post The present position is set to the new location.
*/
boost::int8_t address_Seek ( boost::uint32_t address );
/**
* \brief Adjust the pointer into the memory to the location
* specified in by the index.
*
* \post The present position is set to the new location.
*/
template <typename Offset_Type>
boost::int8_t
index_Seek ( Offset_Type offset )
{
if ( offset > m_data.size() - 1 )
{
std::cerr << "The offset given, " << offset
<< " is invalid. Its pointing to a "
<< std::endl
<< "memory location outside of space "
<< "allocated to"
<< std::endl
<< "this Memory Map. ("
<< m_data.size() << ")"
<< std::endl;
return data_types::Memory_Map::OUT_OF_RANGE;
}
m_present_pos = offset;
return data_types::Memory_Map::SUCCESS;
}
/**
* \brief Read 'length' units of data from this Memory Map.
*
* The read data will be placed into the destination startin
* at the beginning.
*
* \pre The destination pointer is initialized.
*
* \pre Read length is non-zero
*
* \post The present position is set to the new location.
*/
boost::int8_t read ( data_types::Memory_Map::pointer_t dest_addr_ptr,
boost::uint32_t length );
/**
* \brief This copies from the src_ptr to the local Memory
* Map. It is assumed that the local Memory Map has been
* adjusted to the position where data will be store. It is
* also assumed that the src_ptr has been adjusted to the
* position where we will start reading data.
*
* \pre The destination pointer is initialized.
*
* \pre Read length is non-zero
*
* \post The present position is set to the new location.
*/
boost::int8_t copy ( data_types::Memory_Map::ptr_t src_ptr,
boost::uint32_t length );
/**
* \brief This produces a new Memory Map containing a subset
* of the parent map. It is assumed that the parent Memory Map
* has been adjusted to the position where we will start
* reading data.
*
* \pre Present Position of the pointer into the data will not
* go past the boundary with the given length.
*
* \pre Length is non-zero
*/
std::pair <data_types::Memory_Map::ptr_t, boost::int8_t>
subset ( boost::uint32_t length );
data_types::Memory_Map::iterator begin();
data_types::Memory_Map::const_iterator begin() const;
data_types::Memory_Map::const_iterator end() const;
boost::uint32_t get_Present_Position_Value (void) const;
data_types::Memory_Map::const_iterator get_Present_Position (void) const;
boost::uint32_t get_Present_Position_Address (void) const;
boost::uint32_t get_Previous_Position_Value (void) const;
data_types::Memory_Map::const_iterator get_Previous_Position (void) const;
boost::uint32_t get_Previous_Position_Address (void) const;
boost::uint32_t const size (void) const;
std::string to_String (void) const;
bool operator== ( Memory_Map& rhs_ref ) const;
bool allocate_Range ( boost::uint32_t address, boost::uint32_t size );
private:
Memory_Map();
data_types::Memory_Map::Values_t m_data;
boost::uint32_t m_present_pos; // Present index
boost::uint32_t m_previous_pos; // Previous index
boost::uint32_t m_base_address;
};
} /* namespace data_types */
} /* namespace libreverse */
#endif /* MEMORY_MAP_H_ */
--------------------
SOURCE
---------------------
#include "Memory_Map.h"
#include <sstream>
#include <fstream>
#include <boost/format.hpp>
#include "libreverse/Trace.h"
#include "libreverse/Assert.h"
using namespace libreverse::api;
using namespace libreverse::assert;
using namespace libreverse::trace;
namespace libreverse { namespace data_container {
template < template<class> class CheckingPolicy >
Memory_Map::Memory_Map ()
: m_data (),
m_present_pos ( 0 ),
m_previous_pos ( 0 ),
m_base_address ( 0 )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map constructor" );
}
Memory_Map::Memory_Map ( boost::uint32_t size,
boost::uint32_t base_address )
: m_data ( size, 0 ),
m_present_pos ( 0 ),
m_previous_pos ( 0 ),
m_base_address ( base_address )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map constructor (uint32,uint32)" );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DATA,
boost::str ( boost::format ( "paramaters: size = 0x%1X base address = 0x%2X")
% size
% base_address ) );
Assert::bool_check ( size != 0, "Size of memory map is zero." );
Assert::bool_check ( ( m_data.size() == size ), "Size of the image data array is not equal to the requested size." );
Assert::bool_check ( ( m_base_address == base_address ), "Base address of image is not equal to the requested address.");
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map constructor (uint32,uint32)" );
}
Memory_Map::Memory_Map ( std::ifstream& input_ref,
boost::uint32_t base_address )
: m_present_pos ( 0 ),
m_previous_pos ( 0 ),
m_base_address ( base_address )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map constructor (ifstream,uint32)" );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DATA,
boost::str ( boost::format ( "paramaters: ifstream = 0x%1X base address = 0x%2X")
% &input_ref
% base_address ) );
Assert::bool_check ( input_ref.good(), "Input file stream is not ready for I/O operations." );
char byte = 0;
while ( !input_ref.eof() )
{
input_ref.read ( &byte, sizeof(byte) );
m_data.push_back ( byte );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DATA,
boost::str ( boost::format (" byte: 0x%1X" )
% static_cast<boost::uint16_t>(byte) ) );
}
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DATA,
boost::str ( boost::format (" data size: 0x%1d" ) % m_data.size() ) );
input_ref.clear();
input_ref.seekg ( std::ios_base::beg );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map constructor (ifstream,uint32)" );
}
Memory_Map::Memory_Map ( Memory_Map const& rhs )
: boost::enable_shared_from_this<Memory_Map>(rhs),
m_data ( rhs.m_data.size() ),
m_present_pos ( rhs.m_present_pos ),
m_previous_pos ( rhs.m_previous_pos )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map copy constructor" );
std::copy ( rhs.m_data.begin(),
rhs.m_data.end(),
m_data.begin() );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map copy constructor" );
}
Memory_Map::~Memory_Map ()
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Memory_Map destructor called" );
}
boost::int8_t
Memory_Map::read ( data_types::Memory_Map::pointer_t dest_addr_ptr,
boost::uint32_t length )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::read" );
assert ( dest_addr_ptr != 0 );
assert ( length != 0 );
if ( m_present_pos + length > m_data.size() )
{
Trace::write_Trace
( TraceArea::DATA_CONTAINERS,
TraceLevel::ERROR,
boost::str(boost::format("Present Position: %d") %
m_present_pos) );
Trace::write_Trace
( TraceArea::DATA_CONTAINERS,
TraceLevel::ERROR,
boost::str(boost::format("Input read length: %d") %
length) );
Trace::write_Trace
( TraceArea::DATA_CONTAINERS,
TraceLevel::ERROR,
boost::str(boost::format("Data size: %d") %
m_data.size()) );
Trace::write_Trace
( TraceArea::DATA_CONTAINERS,
TraceLevel::ERROR,
boost::str(boost::format("The resulting pointer is invalid. %d + %d > %d")
% m_present_pos
% length
% m_data.size() ) );
Trace::write_Trace
( TraceArea::DATA_CONTAINERS,
TraceLevel::ERROR,
"Its pointing to a memory location out side of space allocated to this Memory Map.");
return data_types::Memory_Map::INVALID_INDEX;
}
data_types::Memory_Map::Values_t::const_iterator pos = m_data.begin();
std::copy ( pos + m_present_pos,
pos + m_present_pos + length,
dest_addr_ptr );
m_previous_pos = m_present_pos;
m_present_pos += length;
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map::read" );
return data_types::Memory_Map::SUCCESS;
}
data_types::Memory_Map::iterator
Memory_Map::begin()
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::begin" );
return m_data.begin();
}
data_types::Memory_Map::const_iterator
Memory_Map::begin() const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::begin (const)" );
return m_data.begin();
}
data_types::Memory_Map::const_iterator
Memory_Map::end() const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::end (const)" );
return m_data.end();
}
boost::uint32_t
Memory_Map::get_Present_Position_Value (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::get_Present_Position_Value" );
return m_present_pos;
}
data_types::Memory_Map::const_iterator
Memory_Map::get_Present_Position (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::get_Present_Position" );
return m_data.begin() + m_present_pos;
}
boost::uint32_t
Memory_Map::get_Present_Position_Address (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::get_Present_Position_Address" );
boost::uint32_t position_address = m_base_address + m_present_pos;
return position_address;
}
boost::uint32_t
Memory_Map::get_Previous_Position_Value (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::get_Previous_Position_Value" );
return m_previous_pos;
}
data_types::Memory_Map::const_iterator
Memory_Map::get_Previous_Position (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::get_Previous_Position" );
return m_data.begin() + m_previous_pos;
}
boost::uint32_t
Memory_Map::get_Previous_Position_Address (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::get_Previous_Position_Address" );
boost::uint32_t position_address = m_base_address + m_previous_pos;
return position_address;
}
boost::uint32_t const
Memory_Map::size (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::size" );
return m_data.size();
}
boost::int8_t
Memory_Map::copy ( data_types::Memory_Map::ptr_t src_ptr,
boost::uint32_t length )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::copy" );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DATA,
boost::str ( boost::format ("parameters: src_ptr address = 0x%1p length=0x%2X (%3d)" )
% src_ptr.get()
% length
% length ) );
assert ( src_ptr.get() != 0 );
assert ( length != 0 );
// Off the end check
if ( m_present_pos + length > m_data.size() )
{
Trace::write_Trace
( TraceArea::DATA_CONTAINERS,
TraceLevel::ERROR,
boost::str(boost::format("The present position
pointer will be invalid if we write from the present\nposition with the
given length. It will cause an segfault. Recheck the value\ngiven for
length (%d) or check the setting of the present position.")
% length ) );
return data_types::Memory_Map::OUT_OF_RANGE;
}
std::copy ( src_ptr->get_Present_Position(),
src_ptr->get_Present_Position() + length,
m_data.begin() + m_present_pos );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map::copy" );
return data_types::Memory_Map::SUCCESS;
}
std::pair<data_types::Memory_Map::ptr_t, boost::int8_t>
Memory_Map::subset ( boost::uint32_t length )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::subset" );
assert ( length != 0 );
data_types::Memory_Map::ptr_t result_ptr
( new Memory_Map ( length,
this->get_Present_Position_Address() ) );
/*
* There is something wrong with the m_data. Its
*/
boost::int8_t result =
result_ptr->copy ( this->shared_from_this(), length );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map::subset" );
return std::make_pair ( result_ptr , result );
}
std::string
Memory_Map::to_String (void) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::to_String" );
std::stringstream output;
std::stringstream char_output;
output << "----------------------------------------" << std::endl;
boost::uint8_t byte_counter = 0;
for ( boost::uint32_t index = 0;
index < m_data.size();
++index )
{
if ( byte_counter == 0 )
{
output << boost::format("%1X: ") % ( m_base_address + index );
}
output << boost::format("%1X") %
boost::io::group ( std::hex,
std::setw(2),
std::setfill('0'),
static_cast<boost::uint16_t>(m_data[index]));
if ( ( m_data[index] > 0x1F ) &&
( m_data[index] < 0x7F ) )
{
char_output << boost::format("%1c") % m_data[index];
}
else
{
char_output << ".";
}
if ( ( byte_counter == 3 ) ||
( byte_counter == 7 ) ||
( byte_counter == 11 ) )
{
output << " ";
byte_counter++;
}
else if ( byte_counter != 15 )
{
output << " ";
byte_counter++;
}
else
{
byte_counter = 0;
output << " " << char_output.str();
char_output.str("");
output << std::endl;
}
}
if ( byte_counter != 15 )
{
for ( ;
byte_counter <= 15;
byte_counter++ )
{
output << " ";
char_output << ".";
if ( ( byte_counter == 3 ) ||
( byte_counter == 7 ) ||
( byte_counter == 11 ) )
{
output << " ";
}
else if ( byte_counter != 15 )
{
output << " ";
}
else
{
output << " " << char_output.str();
output << std::endl;
}
}
}
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map::to_String" );
return output.str();
}
bool
Memory_Map::operator== ( Memory_Map& rhs_ref ) const
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Inside Memory_Map::operator== (equality)" );
return ( m_data == rhs_ref.m_data );
}
boost::int8_t
Memory_Map::address_Seek ( boost::uint32_t address )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::address_Seek" );
// If index is outside the range of the map
if ( ( address < m_base_address ) ||
( address > m_base_address + m_data.size() ) )
{
std::cerr << "The address given, "
<< boost::format("%1X") % address
<< " is invalid. Its pointing to a "
<< std::endl
<< "memory location outside of space "
<< "allocated to"
<< std::endl
<< "this Memory Map. (";
std::cerr << boost::format("%1X") % m_base_address << " - ";
std::cerr << boost::format("%1X") % ( m_base_address + m_data.size() ) << ")"
<< std::endl;
return data_types::Memory_Map::OUT_OF_RANGE;
}
m_previous_pos = m_present_pos;
m_present_pos = address - m_base_address;
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map::address_Seek" );
return data_types::Memory_Map::SUCCESS;
}
Memory_Map&
Memory_Map::operator= ( Memory_Map const& rhs )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::operator= (assignment)" );
Memory_Map temp ( rhs );
swap ( temp );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map::operator= (assignment)" );
return *this;
}
void
Memory_Map::swap ( Memory_Map& rhs )
{
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Entering Memory_Map::swap" );
std::swap ( m_data, rhs.m_data );
Trace::write_Trace ( TraceArea::DATA_CONTAINERS,
TraceLevel::DETAIL,
"Exiting Memory_Map::swap" );
}
} /* Namespace data_types */
} /* namespace libreverse */