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1. C++ Assignment Help
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2. Problem 1: C++ Linked List Library (cpplist)
Your job is now to refactor your C code from the second assignment and produce a much more
flexible library with similar functionality– and this time in C++. Download the zipped folder provided in
the file cpplist.zip as a basis of your program and take a look at the existing code.
• Write your implementation code in .cpp files in the src/ directory; feel free to add more header
cpphomeworkhelp.com
Problem
files as needed in the include/ directory.
•GRADER INFO.txtis a file for the grader (don’t edit!) containing PROG: cpplist,
LANG: C++
As before: you should submit a zipped folder using the same directory structure as
the provided zip file. We’ve added a section in the Makefile for your convenience: if
you type make zip in the same folder as your project, a zip file containing all of your
code and the required headers will be constructed in the project directory and you
can upload that to the grader.
We are provided a header file describing the interface for the List data structure. Look
in the file list.h
to find the functionality required of the other functions, which you will write.
II Forward declaration of applyIreduce types class
ApplyFunction;
class ReduceFunction;

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int value( size t pos ) const;?
• What is a forward declaration?
• Why is there a function int& value( size t pos ); as well as a function
class List {
II ... put whatever private data members you need here II can
also add any private member functions you'd like
public: List();
-List();
size t length() const; int& value( size t
pos );
int value( size t pos ) const; void append( int
value ); void deleteAll( int value );
void insertBefore( int value, int before ); void apply(
const ApplyFunction &interface );
int reduce( const ReduceFunction &interface ) const; void
print() const;
};
II ..etc
Some questions to ask yourself for understanding:

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• Why don’t we include the headers apply.h and reduce.h here?
You’llfind those two other header files containing definitions for yourApplyFunctionand
ReduceFunction
classes, shown here:
#include "list.h"
class ReduceFunction { protected:
virtual int function( int x, int y ) const = 0; public:
int reduce( const List &list ) const; virtual int
identity() const = 0; virtual -ReduceFunction() {}
};
II An example ReduceFunction
class SumReduce : public ReduceFunction { int function(
int x, int y ) const;
public: SumReduce() {}
-SumReduce() {}
int identity() const { return 0; }
};
and then in the source code file:

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#include "list.h" #include "reduce.h"
II This works fine, but iterating over a list like this is II fairly slow. See
if you can speed it up!
int ReduceFunction::reduce( const List &list ) const { int result =
identity();
for( size t p = 0; p < list.length(); ++p ) { result = function(
result, list.value( p ) );
}
return result;
}
int SumReduce::function( int x, int y ) const { return x + y;
}
Input/Output Format
Not applicable; your library will be compiled into a testing suite, your implemented functions will be
called by the program, and the behavior checked for correctness. For example, here is a potential test:
#include "list.h" int main() {
int N = 5;
II you'll need to write a copy constructor II to be able to do
this (see Lecture 5) auto list = List{};

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for( int i = 0; i < N; ++i ) { list.append( i );
}
list.print(); return 0;
}
Upon calling this function, the code outputs
{ 0 -> 1 -> 2 -> 3 -> 4 }
or whatever your formatted output from list.print() is made to look like. You are strongly encour
aged to write your own tests in test.cpp so that you can try out your implementation code before
submitting it to the online grader.
Best Practices
The problem is only worth 500/1000 points when you submit; the rest of the grade will be based
on how well your code follows C++ best practices and object-oriented programming principles.
See a list of those here. The rubric for the other 500 points is as follows.
• +500 points: Code is eminently readable, follows best practices, highly efficient, well
structured, and extensible.

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• +400 points: Code is easy to follow, only a few small violations of best practices, and
extensible.
• +300 points: Adecent refactoring effort, no egregiously bad practices, might be difficult to
extend.
• +200 points: Some refactoring effort, lots of violations of best practices, not very
extensible
• +100 points: Minor refactorings/improvements, little effort to follow best practices.
• +0 points: No effort to refactor or improve code (basically direct copy of HW#2)

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Look in list.h for a sense of the structure of the solution. The big idea to speed up the
reduce/apply functions while also giving users a nice way to iterate over the items in the list is to
create an "iterator" type within our class. Users will be able to write code similar to the STL:
// Print out every item in the list for( List::iterator it = list.begin(); it != list.end(); ++it ) {
std::cout < < *it << "n"; }
To speed up our "append" function, the List class will also store a pointer to the very last element
in the current list.
Directory structure:
•GRADER_INFO.txt
•include
•apply.h
•list.h
•list_node.h
•reduce.h
•Makefile
•src
•apply.cpp
•list.cpp
•list_iterator.cpp
•list_node.cpp
•reduce.cpp
•test.cpp
Solutions

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Here are the contents of apply.h:
#ifndef _6S096_CPPLIST_APPLY_H
#define _6S096_CPPLIST_APPLY_H
#include "list.h" class ApplyFunction {
protected:
virtual int function( int x ) const = 0;
public:
void apply( List &list ) const;
virtual ~ApplyFunction() {}
};
// An example ApplyFunction (see apply.cpp)
class SquareApply : public ApplyFunction { int
function( int x ) const;
};
#endif // _6S096_CPPLIST_APPLY_H
Here are the contents of list.h:
#ifndef _6S096_CPPLIST_H
#define _6S096_CPPLIST_H

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#include <cstddef>
#include <stdexcept>
class ApplyFunction;
class ReduceFunction;
class ListNode;
class List
{ size_t _length;
ListNode *_begin;
ListNode *_back;
public: // Can use outside as List::iterator type
class iterator { // Making List a friend class means we'll be able to access
// the private _node pointer data within the scope of List.
friend class List;
ListNode *_node;
public:
iterator( ListNode *theNode );
iterator& operator++();
int& operator*();

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#include <cstddef>
#include <stdexcept>
class ApplyFunction;
class ReduceFunction;
class ListNode;
bool operator==( const iterator &rhs );
bool operator!=( const iterator &rhs ); }; //
Can use outside as List::const_iterator type
class const_iterator {
// Again, this is basically the only situation you should
// be using the keyword 'friend'
friend class List;
ListNode *_node;
public:
const_iterator( ListNode *theNode );
const_iterator& operator++();
const int& operator*(); bool operator==( const const_iterator &rhs );
bool operator!=( const const_iterator &rhs );
};
List(); List( const List &list );
List& operator=( const List &list )
; ~List(); size_t length()const; int& value( size_t pos )

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; int value( size_t pos ) const;
bool empty() const;
iterator begin();
const_iterator begin() const;
iterator back();
const;
iterator back();
const_iterator back()
const; iterator end();
const_iterator end()
const;
iterator find( iterator s, iterator t, int needle );
void append( int theValue );
void deleteAll( int theValue );
void insertBefore( int theValue, int before );
void insert( iterator pos, int theValue );
void apply( const ApplyFunction &interface );
int reduce( const ReduceFunction &interface ) const;
void print() const;
void clear();
private: ListNode* node( iterator it ) { return it._node;
}
ListNode* node( const_iterator it ) { return it._node;
} };
class ListOutOfBounds :

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#ifndef _6S096_CPPLIST_NODE_H
#define _6S096_CPPLIST_NODE_H
class ListNode
{ int _value; ListNode *_next;
ListNode( const ListNode & ) = delete;
ListNode& operator=( const ListNode & ) = delete;
public:
ListNode();
ListNode( int theValue );
~ListNode();
int& value();
int value() const; ListNode* next();
void insertAfter( ListNode *before );
void setNext( ListNode *nextNode );
static void deleteNext( ListNode *before );
static void deleteSection( ListNode *before,
ListNode *after );
static ListNode* create( int theValue = 0 ); };
public std::range_error
{
public:
explicit ListOutOfBounds() : std::range_error( "List
index out of bounds" ) {} };
#endif // _6S096_CPPLIST_H
Here are the contents of list_node.h:

14. cpphomeworkhelp.com
#endif // _6S096_CPPLIST_NODE_H
Here are the contents of reduce.h:
#ifndef _6S096_CPPLIST_REDUCE_H
#define _6S096_CPPLIST_REDUCE_H
#include "list.h"
class ReduceFunction {
protected:
virtual int function( int x, int y ) const = 0;
public:
int reduce( const List &list )
const; virtual int identity() const = 0;
virtual ~ReduceFunction() {} };
// An example ReduceFunction
class SumReduce :
public ReduceFunction
{ int function( int x, int y ) const;
public:
SumReduce()
{} ~SumReduce() {}
int identity() const { return 0; } }; // Another ReduceFunction
class ProductReduce :
public ReduceFunction { int function( int x, int y )
const;
public:
ProductReduce() {}
~ProductReduce() {}

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iint identity() const { return 1; } };
#endif // _6S096_CPPLIST_REDUCE_H
Here is the source code file apply.cpp:
#include "list.h" #include "apply.h"
void
ApplyFunction::apply( List &list )
const
{ for( auto it = list.begin(); it != list.end(); ++it ) {
*it = function( *it );
}
}
int SquareApply::function( int x ) const {
return x * x; }
Here is the source code file list.cpp:
#include "list.h"
#include "list_node.h"
#include "apply.h"
#include "reduce.h"
#include <iostream>
List::List() : _length{0}, _begin{
nullptr }, _back{ nullptr } {}
List::List(
const List &list ) : _length{0}, _begin{nullptr}, _back{

16. cpphomeworkhelp.com
nullptr} {
for( auto it = list.begin(); it != list.end(); ++it )
{ append( *it );
}
}
List& List::operator=( const List &list ) {
if( this != &list ) { clear();
for( auto it = list.begin(); it != list.end(); ++it ) { append( *it ); } }
return *this;
} List::~List() { clear(); }
} } return *this; }
List::~List() { clear(); } size_t List::length() const {
return _length; } int& List::value( size_t pos ) { auto it = begin();
for( size_t i = 0; i < pos && it != end(); ++it, ++i );
if( it == end() ) {
throw ListOutOfBounds(); }
return *it; } int List::value( size_t pos )
const { auto it = begin();
for( size_t i = 0; i < pos && it != end(); ++it, ++i );
if( it == end() ) {
Throw
void List::append( int theValue )
{ auto *newNode = ListNode::create( theValue );
if( empty() ) {

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newNode->setNext( _back );
_begin = newNode;
} else
{ newNode->insertAfter( _back );
}
_back = newNode;
++_length;
}
void List::deleteAll( int theValue ) {
if( !empty() ) {
// Delete from the front
while( _begin->value() == theValue && _begin != _back ) {
auto *newBegin = _begin->next(); delete _begin; _begin =
newBegin; --_
length; }
auto *p = _begin;
if( _begin != _back ) {
// Normal deletion from interior of list
for( ; p->next() != _back; )
{ if( p->next()->value() == theValue )
{ ListNode::deleteNext( p ); --
_length; } else {
p = p->next();
}
}

18. cpphomeworkhelp.com
// Deleting the last item
if( _back->value() == theValue ) {
ListNode::deleteNext( p ); _
back = p;
--_length; }
} else if( _begin->value() == theValue )
{
// Deal with the case where we deleted the whole list _
begin = _back = nullptr; _
length = 0;
}
}
}
List::iterator List::find( iterator s, iterator t, int needle ) {
for( auto it = s; it != t; ++it ) {
if( *it == needle )
{ return it;
}
} return t; }
void List::insert( iterator pos, int theValue ) {
auto *posPtr = node( pos );
auto *newNode = ListNode::create( theValue );
newNode->insertAfter( posPtr ); ++_length; }
void List::insertBefore( int theValue, int before ) {
if( !empty() ) {

19. cpphomeworkhelp.com
if( _begin->value() == before )
{ auto *newNode = ListNode::create(
theValue );
newNode->setNext( _begin ); _begin =
newNode;
++_length; }
else { auto *p = _begin;
for( ; p != _back && p->next()->value() !=
before; p = p->next() );
if( p != _back && p->next()->value() ==
before ) {
auto *newNode = ListNode::create( theValue );
newNode->insertAfter( p );
++_length;
}
}
}
}
void List::apply(
const ApplyFunction &interface ) {
interface.apply( *this ); } int List::reduce(
const ReduceFunction &interface ) const {
return interface.reduce( *this ); }
void List::print()

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const { std::cout << "{ ";
for( auto it = begin(); it != back(); ++it ) {
std::cout << *it << " -> "; }
if( !empty() ) {
std::cout << *back() << " "; }
std::cout << "}n"; }
void List::clear() {
for( auto *p = _begin; p != nullptr; ) {
auto *p_next = p->next();
delete p; p = p_next; } _length = 0;
_begin = nullptr; _
back = nullptr;
}
Here is the source code file list_iterator.cpp:
#include "list.h" #include "list_node.h" List::iterator::iterator( ListNode *theNode ) :
_node{theNode} {} List::iterator& List::iterator::operator++() { _node = _node-
>next(); return *this; }
int& List::iterator::operator*() { return _node->value(); } bool
List::iterator::operator==( const iterator &rhs ) { return _node == rhs._node; } bool
List::iterator::operator!=( const iterator &rhs ) { return _node != rhs._node; }
List::const_iterator::const_iterator( ListNode *theNode ) : _node{theNode} {}
List::const_iterator& List::const_iterator::operator++() { _node = _node->next(); return
*this; } const int& List::const_iterator::operator*() { return _node->value(); } bool
List::const_iterator::operator==( const const_iterator &rhs ) { return _node ==
rhs._node; } bool List::const_iterator::operator!=(

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const const_iterator &rhs ) {
return _node != rhs._node;
}
Here is the source code file list_node.cpp:
#include "list_node.h"
ListNode::ListNode() :
_value{0}, _next{nullptr} {} ListNode::ListNode( int theValue ) :
_value{theValue}, _next{nullptr} {} ListNode::~ListNode() {} int&
ListNode::value() { return _value; } int ListNode::value(){const { return _value;
} ListNode* ListNode::next() { return _next; } void ListNode::insertAfter(
ListNode *before ) { _next = before->next(); before->_next = this;
}
void ListNode::setNext( ListNode *nextNode ) { _next = nextNode; } void
ListNode::deleteNext( ListNode *before ) { auto *after = before->next()->next();
delete before->next(); before->_next = after; } void ListNode::deleteSection(
ListNode *before, ListNode *after ) { auto *deleteFront = before->next(); while(
deleteFront != after ) { auto *nextDelete = deleteFront->next(); delete deleteFront;
deleteFront = nextDelete; } } ListNode* ListNode::create( int theValue ) { return
new ListNode{ theValue }; }
Here is the source code file reduce.cpp:
#include "list.h" #include "reduce.h" int ReduceFunction::reduce(const List &list )
const { int result = identity(); for( auto it = list.begin(); it != list.end(); ++it ) {
result = function( result, *it ); } return result; }

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int SumReduce::function( int x, int y ) const { return x + y; }
int ProductReduce::function(int x, int y ) const { return x * y; }
Below is the output using the test data:
cpplist: 1: OK [0.004 seconds] OK!
2: OK [0.005 seconds] OK!
3: OK [0.005 seconds] OK!
4: OK [0.009 seconds] OK!
5: OK [0.006 seconds] OK!
6: OK [0.308 seconds] OK!
7: OK [0.053 seconds] OK!
8: OK [0.007 seconds] OK!
9: OK [0.005 seconds] OK!
10: OK [0.742 seconds] OK!