Lists

Author: Carlos Green

Chapter3/chap3_1.js

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+function List() {
+  this.listSize = 0; // number of elements
+  this.pos = 0; // current position in list
+  this.length = length; // returns the number of elements in list
+  this.clear = clear; // clears all elements from list
+  this.toString = toString; // returns string representation of list
+  this.getElement = getElement; // returns element at current position
+  this.insert = insert; // Inserts new element to the end of list
+  this.append = append; // adds new element to end of list
+  this.remove = remove; // removes element from list
+  this.front = front; // sets current position to first element list
+  this.end = end; // sets current position to last element of list
+  this.prev = prev; // moves current position to last element of list
+  this.next = next; // moves current position forward one element
+  this.currPos = currPos; // returns the current position in list
+  this.moveTo = moveTo; // moves the current position to specified position
+  this.dataStore = [];
+  this.find = find;
+  this.contains = contains;
+}
+
+// adds new element to end of list
+function append(element) {
+  this.dataStore[this.listSize++] = element;
+}
+
+function find(element) {
+  for (var i = 0; i < this.dataStore.length; ++i) {
+    if (this.dataStore[i] == element) {
+      return i;
+    }
+  }
+  return -1;
+}
+
+// removes element from list
+function remove(element) {
+  var foundAt = this.find(element);
+  if (foundAt > -1) {
+    this.dataStore.splice(foundAt, 1);
+    --this.listSize;
+    return true;
+  }
+  return false;
+}
+
+// returns the number of elements in list
+function length() {
+  return this.listSize;
+}
+
+// returns string representation of list
+function toString() {
+  return this.dataStore;
+}
+
+// Inserts new element to the end of list
+function insert(element, after) {
+  var insertPos = this.find(after);
+  if (insertPos > -1) {
+    this.dataStore.splice(insertPos + 1, 0, element);
+    ++this.listSize;
+    return true;
+  }
+  return false;
+}
+
+// clears all elements from list
+function clear() {
+  delete this.dataStore;
+  this.dataStore = [];
+  this.listSize = this.pos = 0;
+}
+
+function contains(element) {
+  for (var i = 0; i < this.dataStore.length; ++i) {
+    if (this.dataStore[i] === element) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// sets current position to first element list
+function front() {
+  this.pos = 0;
+}
+
+// sets current position to last element of list
+function end() {
+  this.pos = this.listSize - 1;
+}
+
+// moves current position to last element of list
+function prev() {
+  if (this.pos > 0) {
+    --this.pos;
+  }
+}
+
+// moves current position forward one element
+function next() {
+  if (this.pos < this.listSize - 1) {
+    ++this.pos;
+  }
+}
+
+// returns the current position in list
+function currPos() {
+  return this.pos;
+}
+
+// moves the current position to specified position
+function moveTo(position) {
+  this.pos = position;
+}
+
+// returns element at current position
+function getElement() {
+  return this.dataStore[this.pos];
+}
+
+var names = new List();
+
+names.append('Clayton');
+names.append('Raymond');
+names.append('Cynthia');
+names.append('Jennifer');
+names.append('Bryan');
+names.append('Danny');
+
+names.front();
+
+console.log(names.toString(), 'toString');
+
+names.remove('Raymond');
+
+names.next();
+
+console.log(names.getElement(), 'getElement');
+
+names.next();
+names.next();
+names.prev();
+
+console.log(names.getElement(), 'getElement');
+
+console.log(names.toString(), 'toString');