ch17pc1.cpp

#include "linked_list.hpp"

int main(int args, const char* argv[]) {
  linked_list<int> foo;

  foo.append(1);
  foo.append(2);
  foo.insert(3);

  foo.remove(2);

  return 0;
}

linked_list.cpp

#include "linked_list.hpp"

template<class T>
linked_list<T>::linked_list() : head(NULL) { }

template<class T>
linked_list<T>::~linked_list() {
  node * curr = head;
  if (curr == NULL) { return; }
  while (curr->next != NULL) { curr = curr->next; }
  while (curr != NULL) {
    curr = curr-> prev;
    delete curr;
  }
}

template<class T>
linked_list<T>::node::node() : next(NULL), prev(NULL) { }

template<class T>
linked_list<T>::node::node(T t, node * prev, node * next) : data(t), next(next), prev(prev) { }

template<class T>
void linked_list<T>::append(T t) {
  if (head == NULL) {
    head = new node(t, NULL, NULL);
  } else {
    node * curr = head;
    while (curr->next != NULL) { curr = curr->next; }
    curr->next = new node(t, curr, NULL);
  }
}

template<class T>
void linked_list<T>::insert(T t) {
  if (head == NULL) {
    append(t);
  } else {
    head = new node(t, NULL, head);
    head->next->prev = head;
  }
}

template<class T>
void linked_list<T>::remove(T t) {
  if (head == NULL) { return; }
  node * curr = head;
  while (curr->next != NULL && curr->data != t) { curr = curr-> next; }
  if (curr->data == t) {
    if (curr == head) {
      head = curr->next;
      head->prev = NULL;
      delete curr;
    } else {
      curr->prev->next = curr->next;
      if (curr->next != NULL) { curr->next->prev = curr->prev; }
      delete curr; /* lawl */
    }
  }
}

linked_list.hpp

#include <cstddef>
#include <memory>

#ifndef __LINKED_LIST_HPP__
#define __LINKED_LIST_HPP__

template<class T>
class linked_list {
private:
  struct node {
    T data;
    node * next;
    node * prev;
    node();
    node(T data, node * prev,node * next);
  };
  node * head;
public:
  linked_list();
  ~linked_list();

  void append(T);
  void insert(T);
  void remove(T);
};

#endif

Makefile

# Chris Miller ([email protected]), CS124
# Copyright (C) 2014 Chris Miller.  Aw richts pitten by.
# Academic endorsement.  This code is not licensed for commercial use.
# 20140404, Chapter 17 Programming Challenge 1

CXX=clang++
CXXFLAGS=-std=c++11 -stdlib=libc++ -Wall
SOURCES=ch17pc1.cpp linked_list.cpp
OBJECTS=$(SOURCES:.cpp=.o)
EXECUTABLE=ch17pc1

all: $(SOURCES) $(EXECUTABLE)

$(EXECUTABLE): $(OBJECTS)
	$(CXX) $(OBJECTS) -o $@

.cpp.o:
	$(CXX) $(CXXFLAGS) -c $< -o $@

clean:
	rm -fv $(EXECUTABLE) $(OBJECTS)