blossom/application/text/linked_list.js

Modern, Cross-Platform Application Framework

/*!
 * JavaScript LinkedList
 *
 * Licensed under the new BSD License.
 * Copyright 2008-2009, Bram Stein
 * All rights reserved.
 */

sc_require('text/object');

function LinkedList() {
  this.head = null;
  this.tail = null;
  this.listSize = 0;
}
(function () {
  Object.extend(LinkedList, {
    Node: function (data) {
      this.prev = null;
      this.next = null;
      this.data = data;    
    }
  });

  Object.extend(LinkedList.Node.prototype, {
    toString: function () {
      return this.data.toString();
    }
  });

  function isLinked(list, node) {
    return !((node && node.prev === null && node.next === null && list.tail !== node && list.head !== node) || list.isEmpty());
  }

  Object.extend(LinkedList.prototype, {
    size: function () {
      return this.listSize;
    },

    isEmpty: function () {
      return this.listSize === 0;
    },

    first: function () {
      return this.head;
    },

    last: function () {
      return this.last;
    },

    toString: function () {
      return this.toArray().toString();
    },

    toArray: function () {
      var node = this.head,
        result = [];
      while (node !== null) {
        result.push(node);
        node = node.next;
      }
      return result;
    },

    // Note that modifying the list during
    // iteration is not safe.
    forEach: function (fun) {
      var node = this.head;
      while (node !== null) {
        fun(node);
        node = node.next;
      }
    },  

    contains: function (n) {
      var node = this.head;
      if (!isLinked(this, n)) {
        return false;
      }
      while (node !== null) {
        if (node === n) {
          return true;
        }
        node = node.next;
      }
      return false;
    },

    at: function (i) {
      var node = this.head, index = 0;

      if (i >= this.listLength || i < 0) {
        return null;
      }

      while (node !== null) {
        if (i === index) {
          return node;
        }
        node = node.next;
        index += 1;
      }
      return null;
    },

    insertAfter: function (node, newNode) {
      if (!isLinked(this, node)) {
        return this;
      }
      newNode.prev = node;
      newNode.next = node.next;
      if (node.next === null) {
        this.tail = newNode;
      } else {
        node.next.prev = newNode;
      }
      node.next = newNode;
      this.listSize += 1;
      return this;
    },

    insertBefore: function (node, newNode) {
      if (!isLinked(this, node)) {
        return this;
      }
      newNode.prev = node.prev;
      newNode.next = node;
      if (node.prev === null) {
        this.head = newNode;
      } else {
        node.prev.next = newNode;
      }
      node.prev = newNode;
      this.listSize += 1;
      return this;
    },

    push: function (node) {
      if (this.head === null) {
        this.unshift(node);
      } else {
        this.insertAfter(this.tail, node);
      }
      return this;
    },

    unshift: function (node) {
      if (this.head === null) {
        this.head = node;
        this.tail = node;
        node.prev = null;
        node.next = null;
        this.listSize += 1;
      } else {
        this.insertBefore(this.head, node);
      }
      return this;
    },

    remove: function (node) {
      if (!isLinked(this, node)) {
        return this;
      }
      if (node.prev === null) {
        this.head = node.next;
      } else {
        node.prev.next = node.next;
      }
      if (node.next === null) {
        this.tail = node.prev;
      } else {
        node.next.prev = node.prev;
      }
      this.listSize -= 1;
      return this;
    },

    pop: function () {
      var node = this.tail;
      this.tail.prev.next = null;
      this.tail = this.tail.prev;
      this.listSize -= 1;
      node.prev = null;
      node.next = null;
      return node;
    },

    shift: function () {
      var node = this.head;
      this.head.next.prev = null;
      this.head = this.head.next;
      this.listSize -= 1;
      node.prev = null;
      node.next = null;
      return node;
    }
  });
}());