1 /**@constructor*/

     2 function ChainNode(object, link) {

     3 	this.value = object;

     4 	this.link = link; // describes this node's relationship to the previous node

     5 }

     6 

     7 /**@constructor*/

     8 function Chain(valueLinks) {

     9 	this.nodes = [];

    10 	this.cursor = -1;

    11 	

    12 	if (valueLinks && valueLinks.length > 0) {

    13 		this.push(valueLinks[0], "//");

    14 		for (var i = 1, l = valueLinks.length; i < l; i+=2) {

    15 			this.push(valueLinks[i+1], valueLinks[i]);

    16 		}

    17 	}

    18 }

    19 

    20 Chain.prototype.push = function(o, link) {

    21 	if (this.nodes.length > 0 && link) this.nodes.push(new ChainNode(o, link));

    22 	else this.nodes.push(new ChainNode(o));

    23 }

    24 

    25 Chain.prototype.unshift = function(o, link) {

    26 	if (this.nodes.length > 0 && link) this.nodes[0].link = link;

    27 	this.nodes.unshift(new ChainNode(o));

    28 	this.cursor++;

    29 }

    30 

    31 Chain.prototype.get = function() {

    32 	if (this.cursor < 0 || this.cursor > this.nodes.length-1) return null;

    33 	return this.nodes[this.cursor];

    34 }

    35 

    36 Chain.prototype.first = function() {

    37 	this.cursor = 0;

    38 	return this.get();

    39 }

    40 

    41 Chain.prototype.last = function() {

    42 	this.cursor = this.nodes.length-1;

    43 	return this.get();

    44 }

    45 

    46 Chain.prototype.next = function() {

    47 	this.cursor++;

    48 	return this.get();

    49 }

    50 

    51 Chain.prototype.prev = function() {

    52 	this.cursor--;

    53 	return this.get();

    54 }

    55 

    56 Chain.prototype.toString = function() {

    57 	var string = "";

    58 	for (var i = 0, l = this.nodes.length; i < l; i++) {

    59 		if (this.nodes[i].link) string += " -("+this.nodes[i].link+")-> ";

    60 		string += this.nodes[i].value.toString();

    61 	}

    62 	return string;

    63 }

    64 

    65 Chain.prototype.joinLeft = function() {

    66 	var result = "";

    67 	for (var i = 0, l = this.cursor; i < l; i++) {

    68 		if (result && this.nodes[i].link) result += this.nodes[i].link;

    69 		result += this.nodes[i].value.toString();

    70 	}

    71 	return result;

    72 }

    73 

    74 

    75 /* USAGE:

    76 

    77 var path = "one/two/three.four/five-six";

    78 var pathChain = new Chain(path.split(/([\/.-])/));

    79 print(pathChain);

    80 

    81 var lineage = new Chain();

    82 lineage.push("Port");

    83 lineage.push("Les", "son");

    84 lineage.push("Dawn", "daughter");

    85 lineage.unshift("Purdie", "son");

    86 

    87 print(lineage);

    88 

    89 // walk left

    90 for (var node = lineage.last(); node !== null; node = lineage.prev()) {

    91 	print("< "+node.value);

    92 }

    93 

    94 // walk right

    95 var node = lineage.first()

    96 while (node !== null) {

    97 	print(node.value);

    98 	node = lineage.next();

    99 	if (node && node.link) print("had a "+node.link+" named");

   100 }

   101 

   102 */