VirtualDom.js

var _elm_lang$virtual_dom$VirtualDom_Debug$wrap;
var _elm_lang$virtual_dom$VirtualDom_Debug$wrapWithFlags;

var _elm_lang$virtual_dom$Native_VirtualDom = function() {

var STYLE_KEY = 'STYLE';
var EVENT_KEY = 'EVENT';
var ATTR_KEY = 'ATTR';
var ATTR_NS_KEY = 'ATTR_NS';

var localDoc = typeof document !== 'undefined' ? document : {};


////////////  VIRTUAL DOM NODES  ////////////


function text(string)
{
	return {
		type: 'text',
		text: string
	};
}


function node(tag)
{
	return F2(function(factList, kidList) {
		return nodeHelp(tag, factList, kidList);
	});
}


function nodeHelp(tag, factList, kidList)
{
	var organized = organizeFacts(factList);
	var namespace = organized.namespace;
	var facts = organized.facts;

	var children = [];
	var descendantsCount = 0;
	while (kidList.ctor !== '[]')
	{
		var kid = kidList._0;
		descendantsCount += (kid.descendantsCount || 0);
		children.push(kid);
		kidList = kidList._1;
	}
	descendantsCount += children.length;

	return {
		type: 'node',
		tag: tag,
		facts: facts,
		children: children,
		namespace: namespace,
		descendantsCount: descendantsCount
	};
}


function keyedNode(tag, factList, kidList)
{
	var organized = organizeFacts(factList);
	var namespace = organized.namespace;
	var facts = organized.facts;

	var children = [];
	var descendantsCount = 0;
	while (kidList.ctor !== '[]')
	{
		var kid = kidList._0;
		descendantsCount += (kid._1.descendantsCount || 0);
		children.push(kid);
		kidList = kidList._1;
	}
	descendantsCount += children.length;

	return {
		type: 'keyed-node',
		tag: tag,
		facts: facts,
		children: children,
		namespace: namespace,
		descendantsCount: descendantsCount
	};
}


function custom(factList, model, impl)
{
	var facts = organizeFacts(factList).facts;

	return {
		type: 'custom',
		facts: facts,
		model: model,
		impl: impl
	};
}


function map(tagger, node)
{
	return {
		type: 'tagger',
		tagger: tagger,
		node: node,
		descendantsCount: 1 + (node.descendantsCount || 0)
	};
}


function thunk(func, args, thunk)
{
	return {
		type: 'thunk',
		func: func,
		args: args,
		thunk: thunk,
		node: undefined
	};
}

function lazy(fn, a)
{
	return thunk(fn, [a], function() {
		return fn(a);
	});
}

function lazy2(fn, a, b)
{
	return thunk(fn, [a,b], function() {
		return A2(fn, a, b);
	});
}

function lazy3(fn, a, b, c)
{
	return thunk(fn, [a,b,c], function() {
		return A3(fn, a, b, c);
	});
}



// FACTS


function organizeFacts(factList)
{
	var namespace, facts = {};

	while (factList.ctor !== '[]')
	{
		var entry = factList._0;
		var key = entry.key;

		if (key === ATTR_KEY || key === ATTR_NS_KEY || key === EVENT_KEY)
		{
			var subFacts = facts[key] || {};
			subFacts[entry.realKey] = entry.value;
			facts[key] = subFacts;
		}
		else if (key === STYLE_KEY)
		{
			var styles = facts[key] || {};
			var styleList = entry.value;
			while (styleList.ctor !== '[]')
			{
				var style = styleList._0;
				styles[style._0] = style._1;
				styleList = styleList._1;
			}
			facts[key] = styles;
		}
		else if (key === 'namespace')
		{
			namespace = entry.value;
		}
		else if (key === 'className')
		{
			var classes = facts[key];
			facts[key] = typeof classes === 'undefined'
				? entry.value
				: classes + ' ' + entry.value;
		}
 		else
		{
			facts[key] = entry.value;
		}
		factList = factList._1;
	}

	return {
		facts: facts,
		namespace: namespace
	};
}



////////////  PROPERTIES AND ATTRIBUTES  ////////////


function style(value)
{
	return {
		key: STYLE_KEY,
		value: value
	};
}


function property(key, value)
{
	return {
		key: key,
		value: value
	};
}


function attribute(key, value)
{
	return {
		key: ATTR_KEY,
		realKey: key,
		value: value
	};
}


function attributeNS(namespace, key, value)
{
	return {
		key: ATTR_NS_KEY,
		realKey: key,
		value: {
			value: value,
			namespace: namespace
		}
	};
}


function on(name, options, decoder)
{
	return {
		key: EVENT_KEY,
		realKey: name,
		value: {
			options: options,
			decoder: decoder
		}
	};
}


function equalEvents(a, b)
{
	if (a.options !== b.options)
	{
		if (a.options.stopPropagation !== b.options.stopPropagation || a.options.preventDefault !== b.options.preventDefault)
		{
			return false;
		}
	}
	return _elm_lang$core$Native_Json.equality(a.decoder, b.decoder);
}


function mapProperty(func, property)
{
	if (property.key !== EVENT_KEY)
	{
		return property;
	}
	return on(
		property.realKey,
		property.value.options,
		A2(_elm_lang$core$Json_Decode$map, func, property.value.decoder)
	);
}


////////////  RENDER  ////////////


function render(vNode, eventNode)
{
	switch (vNode.type)
	{
		case 'thunk':
			if (!vNode.node)
			{
				vNode.node = vNode.thunk();
			}
			return render(vNode.node, eventNode);

		case 'tagger':
			var subNode = vNode.node;
			var tagger = vNode.tagger;

			while (subNode.type === 'tagger')
			{
				typeof tagger !== 'object'
					? tagger = [tagger, subNode.tagger]
					: tagger.push(subNode.tagger);

				subNode = subNode.node;
			}

			var subEventRoot = { tagger: tagger, parent: eventNode };
			var domNode = render(subNode, subEventRoot);
			domNode.elm_event_node_ref = subEventRoot;
			return domNode;

		case 'text':
			return localDoc.createTextNode(vNode.text);

		case 'node':
			var domNode = vNode.namespace
				? localDoc.createElementNS(vNode.namespace, vNode.tag)
				: localDoc.createElement(vNode.tag);

			applyFacts(domNode, eventNode, vNode.facts);

			var children = vNode.children;

			for (var i = 0; i < children.length; i++)
			{
				domNode.appendChild(render(children[i], eventNode));
			}

			return domNode;

		case 'keyed-node':
			var domNode = vNode.namespace
				? localDoc.createElementNS(vNode.namespace, vNode.tag)
				: localDoc.createElement(vNode.tag);

			applyFacts(domNode, eventNode, vNode.facts);

			var children = vNode.children;

			for (var i = 0; i < children.length; i++)
			{
				domNode.appendChild(render(children[i]._1, eventNode));
			}

			return domNode;

		case 'custom':
			var domNode = vNode.impl.render(vNode.model);
			applyFacts(domNode, eventNode, vNode.facts);
			return domNode;
	}
}



////////////  APPLY FACTS  ////////////


function applyFacts(domNode, eventNode, facts)
{
	for (var key in facts)
	{
		var value = facts[key];

		switch (key)
		{
			case STYLE_KEY:
				applyStyles(domNode, value);
				break;

			case EVENT_KEY:
				applyEvents(domNode, eventNode, value);
				break;

			case ATTR_KEY:
				applyAttrs(domNode, value);
				break;

			case ATTR_NS_KEY:
				applyAttrsNS(domNode, value);
				break;

			case 'value':
				if (domNode[key] !== value)
				{
					domNode[key] = value;
				}
				break;

			default:
				domNode[key] = value;
				break;
		}
	}
}

function applyStyles(domNode, styles)
{
	var domNodeStyle = domNode.style;

	for (var key in styles)
	{
		domNodeStyle[key] = styles[key];
	}
}

function applyEvents(domNode, eventNode, events)
{
	var allHandlers = domNode.elm_handlers || {};

	for (var key in events)
	{
		var handler = allHandlers[key];
		var value = events[key];

		if (typeof value === 'undefined')
		{
			domNode.removeEventListener(key, handler);
			allHandlers[key] = undefined;
		}
		else if (typeof handler === 'undefined')
		{
			var handler = makeEventHandler(eventNode, value);
			domNode.addEventListener(key, handler);
			allHandlers[key] = handler;
		}
		else
		{
			handler.info = value;
		}
	}

	domNode.elm_handlers = allHandlers;
}

function makeEventHandler(eventNode, info)
{
	function eventHandler(event)
	{
		var info = eventHandler.info;

		var value = A2(_elm_lang$core$Native_Json.run, info.decoder, event);

		if (value.ctor === 'Ok')
		{
			var options = info.options;
			if (options.stopPropagation)
			{
				event.stopPropagation();
			}
			if (options.preventDefault)
			{
				event.preventDefault();
			}

			var message = value._0;

			var currentEventNode = eventNode;
			while (currentEventNode)
			{
				var tagger = currentEventNode.tagger;
				if (typeof tagger === 'function')
				{
					message = tagger(message);
				}
				else
				{
					for (var i = tagger.length; i--; )
					{
						message = tagger[i](message);
					}
				}
				currentEventNode = currentEventNode.parent;
			}
		}
	};

	eventHandler.info = info;

	return eventHandler;
}

function applyAttrs(domNode, attrs)
{
	for (var key in attrs)
	{
		var value = attrs[key];
		if (typeof value === 'undefined')
		{
			domNode.removeAttribute(key);
		}
		else
		{
			domNode.setAttribute(key, value);
		}
	}
}

function applyAttrsNS(domNode, nsAttrs)
{
	for (var key in nsAttrs)
	{
		var pair = nsAttrs[key];
		var namespace = pair.namespace;
		var value = pair.value;

		if (typeof value === 'undefined')
		{
			domNode.removeAttributeNS(namespace, key);
		}
		else
		{
			domNode.setAttributeNS(namespace, key, value);
		}
	}
}



////////////  DIFF  ////////////


function diff(a, b)
{
	var patches = [];
	diffHelp(a, b, patches, 0);
	return patches;
}


function makePatch(type, index, data)
{
	return {
		index: index,
		type: type,
		data: data,
		domNode: undefined,
		eventNode: undefined
	};
}


function diffHelp(a, b, patches, index)
{
	if (a === b)
	{
		return;
	}

	var aType = a.type;
	var bType = b.type;

	// Bail if you run into different types of nodes. Implies that the
	// structure has changed significantly and it's not worth a diff.
	if (aType !== bType)
	{
		patches.push(makePatch('p-redraw', index, b));
		return;
	}

	// Now we know that both nodes are the same type.
	switch (bType)
	{
		case 'thunk':
			var aArgs = a.args;
			var bArgs = b.args;
			var i = aArgs.length;
			var same = a.func === b.func && i === bArgs.length;
			while (same && i--)
			{
				same = aArgs[i] === bArgs[i];
			}
			if (same)
			{
				b.node = a.node;
				return;
			}
			b.node = b.thunk();
			var subPatches = [];
			diffHelp(a.node, b.node, subPatches, 0);
			if (subPatches.length > 0)
			{
				patches.push(makePatch('p-thunk', index, subPatches));
			}
			return;

		case 'tagger':
			// gather nested taggers
			var aTaggers = a.tagger;
			var bTaggers = b.tagger;
			var nesting = false;

			var aSubNode = a.node;
			while (aSubNode.type === 'tagger')
			{
				nesting = true;

				typeof aTaggers !== 'object'
					? aTaggers = [aTaggers, aSubNode.tagger]
					: aTaggers.push(aSubNode.tagger);

				aSubNode = aSubNode.node;
			}

			var bSubNode = b.node;
			while (bSubNode.type === 'tagger')
			{
				nesting = true;

				typeof bTaggers !== 'object'
					? bTaggers = [bTaggers, bSubNode.tagger]
					: bTaggers.push(bSubNode.tagger);

				bSubNode = bSubNode.node;
			}

			// Just bail if different numbers of taggers. This implies the
			// structure of the virtual DOM has changed.
			if (nesting && aTaggers.length !== bTaggers.length)
			{
				patches.push(makePatch('p-redraw', index, b));
				return;
			}

			// check if taggers are "the same"
			if (nesting ? !pairwiseRefEqual(aTaggers, bTaggers) : aTaggers !== bTaggers)
			{
				patches.push(makePatch('p-tagger', index, bTaggers));
			}

			// diff everything below the taggers
			diffHelp(aSubNode, bSubNode, patches, index + 1);
			return;

		case 'text':
			if (a.text !== b.text)
			{
				patches.push(makePatch('p-text', index, b.text));
				return;
			}

			return;

		case 'node':
			// Bail if obvious indicators have changed. Implies more serious
			// structural changes such that it's not worth it to diff.
			if (a.tag !== b.tag || a.namespace !== b.namespace)
			{
				patches.push(makePatch('p-redraw', index, b));
				return;
			}

			var factsDiff = diffFacts(a.facts, b.facts);

			if (typeof factsDiff !== 'undefined')
			{
				patches.push(makePatch('p-facts', index, factsDiff));
			}

			diffChildren(a, b, patches, index);
			return;

		case 'keyed-node':
			// Bail if obvious indicators have changed. Implies more serious
			// structural changes such that it's not worth it to diff.
			if (a.tag !== b.tag || a.namespace !== b.namespace)
			{
				patches.push(makePatch('p-redraw', index, b));
				return;
			}

			var factsDiff = diffFacts(a.facts, b.facts);

			if (typeof factsDiff !== 'undefined')
			{
				patches.push(makePatch('p-facts', index, factsDiff));
			}

			diffKeyedChildren(a, b, patches, index);
			return;

		case 'custom':
			if (a.impl !== b.impl)
			{
				patches.push(makePatch('p-redraw', index, b));
				return;
			}

			var factsDiff = diffFacts(a.facts, b.facts);
			if (typeof factsDiff !== 'undefined')
			{
				patches.push(makePatch('p-facts', index, factsDiff));
			}

			var patch = b.impl.diff(a,b);
			if (patch)
			{
				patches.push(makePatch('p-custom', index, patch));
				return;
			}

			return;
	}
}


// assumes the incoming arrays are the same length
function pairwiseRefEqual(as, bs)
{
	for (var i = 0; i < as.length; i++)
	{
		if (as[i] !== bs[i])
		{
			return false;
		}
	}

	return true;
}


// TODO Instead of creating a new diff object, it's possible to just test if
// there *is* a diff. During the actual patch, do the diff again and make the
// modifications directly. This way, there's no new allocations. Worth it?
function diffFacts(a, b, category)
{
	var diff;

	// look for changes and removals
	for (var aKey in a)
	{
		if (aKey === STYLE_KEY || aKey === EVENT_KEY || aKey === ATTR_KEY || aKey === ATTR_NS_KEY)
		{
			var subDiff = diffFacts(a[aKey], b[aKey] || {}, aKey);
			if (subDiff)
			{
				diff = diff || {};
				diff[aKey] = subDiff;
			}
			continue;
		}

		// remove if not in the new facts
		if (!(aKey in b))
		{
			diff = diff || {};
			diff[aKey] =
				(typeof category === 'undefined')
					? (typeof a[aKey] === 'string' ? '' : null)
					:
				(category === STYLE_KEY)
					? ''
					:
				(category === EVENT_KEY || category === ATTR_KEY)
					? undefined
					:
				{ namespace: a[aKey].namespace, value: undefined };

			continue;
		}

		var aValue = a[aKey];
		var bValue = b[aKey];

		// reference equal, so don't worry about it
		if (aValue === bValue && aKey !== 'value'
			|| category === EVENT_KEY && equalEvents(aValue, bValue))
		{
			continue;
		}

		diff = diff || {};
		diff[aKey] = bValue;
	}

	// add new stuff
	for (var bKey in b)
	{
		if (!(bKey in a))
		{
			diff = diff || {};
			diff[bKey] = b[bKey];
		}
	}

	return diff;
}


function diffChildren(aParent, bParent, patches, rootIndex)
{
	var aChildren = aParent.children;
	var bChildren = bParent.children;

	var aLen = aChildren.length;
	var bLen = bChildren.length;

	// FIGURE OUT IF THERE ARE INSERTS OR REMOVALS

	if (aLen > bLen)
	{
		patches.push(makePatch('p-remove-last', rootIndex, aLen - bLen));
	}
	else if (aLen < bLen)
	{
		patches.push(makePatch('p-append', rootIndex, bChildren.slice(aLen)));
	}

	// PAIRWISE DIFF EVERYTHING ELSE

	var index = rootIndex;
	var minLen = aLen < bLen ? aLen : bLen;
	for (var i = 0; i < minLen; i++)
	{
		index++;
		var aChild = aChildren[i];
		diffHelp(aChild, bChildren[i], patches, index);
		index += aChild.descendantsCount || 0;
	}
}



////////////  KEYED DIFF  ////////////


function diffKeyedChildren(aParent, bParent, patches, rootIndex)
{
	var localPatches = [];

	var changes = {}; // Dict String Entry
	var inserts = []; // Array { index : Int, entry : Entry }
	// type Entry = { tag : String, vnode : VNode, index : Int, data : _ }

	var aChildren = aParent.children;
	var bChildren = bParent.children;
	var aLen = aChildren.length;
	var bLen = bChildren.length;
	var aIndex = 0;
	var bIndex = 0;

	var index = rootIndex;

	while (aIndex < aLen && bIndex < bLen)
	{
		var a = aChildren[aIndex];
		var b = bChildren[bIndex];

		var aKey = a._0;
		var bKey = b._0;
		var aNode = a._1;
		var bNode = b._1;

		// check if keys match

		if (aKey === bKey)
		{
			index++;
			diffHelp(aNode, bNode, localPatches, index);
			index += aNode.descendantsCount || 0;

			aIndex++;
			bIndex++;
			continue;
		}

		// look ahead 1 to detect insertions and removals.

		var aLookAhead = aIndex + 1 < aLen;
		var bLookAhead = bIndex + 1 < bLen;

		if (aLookAhead)
		{
			var aNext = aChildren[aIndex + 1];
			var aNextKey = aNext._0;
			var aNextNode = aNext._1;
			var oldMatch = bKey === aNextKey;
		}

		if (bLookAhead)
		{
			var bNext = bChildren[bIndex + 1];
			var bNextKey = bNext._0;
			var bNextNode = bNext._1;
			var newMatch = aKey === bNextKey;
		}


		// swap a and b
		if (aLookAhead && bLookAhead && newMatch && oldMatch)
		{
			index++;
			diffHelp(aNode, bNextNode, localPatches, index);
			insertNode(changes, localPatches, aKey, bNode, bIndex, inserts);
			index += aNode.descendantsCount || 0;

			index++;
			removeNode(changes, localPatches, aKey, aNextNode, index);
			index += aNextNode.descendantsCount || 0;

			aIndex += 2;
			bIndex += 2;
			continue;
		}

		// insert b
		if (bLookAhead && newMatch)
		{
			index++;
			insertNode(changes, localPatches, bKey, bNode, bIndex, inserts);
			diffHelp(aNode, bNextNode, localPatches, index);
			index += aNode.descendantsCount || 0;

			aIndex += 1;
			bIndex += 2;
			continue;
		}

		// remove a
		if (aLookAhead && oldMatch)
		{
			index++;
			removeNode(changes, localPatches, aKey, aNode, index);
			index += aNode.descendantsCount || 0;

			index++;
			diffHelp(aNextNode, bNode, localPatches, index);
			index += aNextNode.descendantsCount || 0;

			aIndex += 2;
			bIndex += 1;
			continue;
		}

		// remove a, insert b
		if (aLookAhead && bLookAhead && aNextKey === bNextKey)
		{
			index++;
			removeNode(changes, localPatches, aKey, aNode, index);
			insertNode(changes, localPatches, bKey, bNode, bIndex, inserts);
			index += aNode.descendantsCount || 0;

			index++;
			diffHelp(aNextNode, bNextNode, localPatches, index);
			index += aNextNode.descendantsCount || 0;

			aIndex += 2;
			bIndex += 2;
			continue;
		}

		break;
	}

	// eat up any remaining nodes with removeNode and insertNode

	while (aIndex < aLen)
	{
		index++;
		var a = aChildren[aIndex];
		var aNode = a._1;
		removeNode(changes, localPatches, a._0, aNode, index);
		index += aNode.descendantsCount || 0;
		aIndex++;
	}

	var endInserts;
	while (bIndex < bLen)
	{
		endInserts = endInserts || [];
		var b = bChildren[bIndex];
		insertNode(changes, localPatches, b._0, b._1, undefined, endInserts);
		bIndex++;
	}

	if (localPatches.length > 0 || inserts.length > 0 || typeof endInserts !== 'undefined')
	{
		patches.push(makePatch('p-reorder', rootIndex, {
			patches: localPatches,
			inserts: inserts,
			endInserts: endInserts
		}));
	}
}



////////////  CHANGES FROM KEYED DIFF  ////////////


var POSTFIX = '_elmW6BL';


function insertNode(changes, localPatches, key, vnode, bIndex, inserts)
{
	var entry = changes[key];

	// never seen this key before
	if (typeof entry === 'undefined')
	{
		entry = {
			tag: 'insert',
			vnode: vnode,
			index: bIndex,
			data: undefined
		};

		inserts.push({ index: bIndex, entry: entry });
		changes[key] = entry;

		return;
	}

	// this key was removed earlier, a match!
	if (entry.tag === 'remove')
	{
		inserts.push({ index: bIndex, entry: entry });

		entry.tag = 'move';
		var subPatches = [];
		diffHelp(entry.vnode, vnode, subPatches, entry.index);
		entry.index = bIndex;
		entry.data.data = {
			patches: subPatches,
			entry: entry
		};

		return;
	}

	// this key has already been inserted or moved, a duplicate!
	insertNode(changes, localPatches, key + POSTFIX, vnode, bIndex, inserts);
}


function removeNode(changes, localPatches, key, vnode, index)
{
	var entry = changes[key];

	// never seen this key before
	if (typeof entry === 'undefined')
	{
		var patch = makePatch('p-remove', index, undefined);
		localPatches.push(patch);

		changes[key] = {
			tag: 'remove',
			vnode: vnode,
			index: index,
			data: patch
		};

		return;
	}

	// this key was inserted earlier, a match!
	if (entry.tag === 'insert')
	{
		entry.tag = 'move';
		var subPatches = [];
		diffHelp(vnode, entry.vnode, subPatches, index);

		var patch = makePatch('p-remove', index, {
			patches: subPatches,
			entry: entry
		});
		localPatches.push(patch);

		return;
	}

	// this key has already been removed or moved, a duplicate!
	removeNode(changes, localPatches, key + POSTFIX, vnode, index);
}



////////////  ADD DOM NODES  ////////////
//
// Each DOM node has an "index" assigned in order of traversal. It is important
// to minimize our crawl over the actual DOM, so these indexes (along with the
// descendantsCount of virtual nodes) let us skip touching entire subtrees of
// the DOM if we know there are no patches there.


function addDomNodes(domNode, vNode, patches, eventNode)
{
	addDomNodesHelp(domNode, vNode, patches, 0, 0, vNode.descendantsCount, eventNode);
}


// assumes `patches` is non-empty and indexes increase monotonically.
function addDomNodesHelp(domNode, vNode, patches, i, low, high, eventNode)
{
	var patch = patches[i];
	var index = patch.index;

	while (index === low)
	{
		var patchType = patch.type;

		if (patchType === 'p-thunk')
		{
			addDomNodes(domNode, vNode.node, patch.data, eventNode);
		}
		else if (patchType === 'p-reorder')
		{
			patch.domNode = domNode;
			patch.eventNode = eventNode;

			var subPatches = patch.data.patches;
			if (subPatches.length > 0)
			{
				addDomNodesHelp(domNode, vNode, subPatches, 0, low, high, eventNode);
			}
		}
		else if (patchType === 'p-remove')
		{
			patch.domNode = domNode;
			patch.eventNode = eventNode;

			var data = patch.data;
			if (typeof data !== 'undefined')
			{
				data.entry.data = domNode;
				var subPatches = data.patches;
				if (subPatches.length > 0)
				{
					addDomNodesHelp(domNode, vNode, subPatches, 0, low, high, eventNode);
				}
			}
		}
		else
		{
			patch.domNode = domNode;
			patch.eventNode = eventNode;
		}

		i++;

		if (!(patch = patches[i]) || (index = patch.index) > high)
		{
			return i;
		}
	}

	switch (vNode.type)
	{
		case 'tagger':
			var subNode = vNode.node;

			while (subNode.type === "tagger")
			{
				subNode = subNode.node;
			}

			return addDomNodesHelp(domNode, subNode, patches, i, low + 1, high, domNode.elm_event_node_ref);

		case 'node':
			var vChildren = vNode.children;
			var childNodes = domNode.childNodes;
			for (var j = 0; j < vChildren.length; j++)
			{
				low++;
				var vChild = vChildren[j];
				var nextLow = low + (vChild.descendantsCount || 0);
				if (low <= index && index <= nextLow)
				{
					i = addDomNodesHelp(childNodes[j], vChild, patches, i, low, nextLow, eventNode);
					if (!(patch = patches[i]) || (index = patch.index) > high)
					{
						return i;
					}
				}
				low = nextLow;
			}
			return i;

		case 'keyed-node':
			var vChildren = vNode.children;
			var childNodes = domNode.childNodes;
			for (var j = 0; j < vChildren.length; j++)
			{
				low++;
				var vChild = vChildren[j]._1;
				var nextLow = low + (vChild.descendantsCount || 0);
				if (low <= index && index <= nextLow)
				{
					i = addDomNodesHelp(childNodes[j], vChild, patches, i, low, nextLow, eventNode);
					if (!(patch = patches[i]) || (index = patch.index) > high)
					{
						return i;
					}
				}
				low = nextLow;
			}
			return i;

		case 'text':
		case 'thunk':
			throw new Error('should never traverse `text` or `thunk` nodes like this');
	}
}



////////////  APPLY PATCHES  ////////////


function applyPatches(rootDomNode, oldVirtualNode, patches, eventNode)
{
	if (patches.length === 0)
	{
		return rootDomNode;
	}

	addDomNodes(rootDomNode, oldVirtualNode, patches, eventNode);
	return applyPatchesHelp(rootDomNode, patches);
}

function applyPatchesHelp(rootDomNode, patches)
{
	for (var i = 0; i < patches.length; i++)
	{
		var patch = patches[i];
		var localDomNode = patch.domNode
		var newNode = applyPatch(localDomNode, patch);
		if (localDomNode === rootDomNode)
		{
			rootDomNode = newNode;
		}
	}
	return rootDomNode;
}

function applyPatch(domNode, patch)
{
	switch (patch.type)
	{
		case 'p-redraw':
			return applyPatchRedraw(domNode, patch.data, patch.eventNode);

		case 'p-facts':
			applyFacts(domNode, patch.eventNode, patch.data);
			return domNode;

		case 'p-text':
			domNode.replaceData(0, domNode.length, patch.data);
			return domNode;

		case 'p-thunk':
			return applyPatchesHelp(domNode, patch.data);

		case 'p-tagger':
			if (typeof domNode.elm_event_node_ref !== 'undefined')
			{
				domNode.elm_event_node_ref.tagger = patch.data;
			}
			else
			{
				domNode.elm_event_node_ref = { tagger: patch.data, parent: patch.eventNode };
			}
			return domNode;

		case 'p-remove-last':
			var i = patch.data;
			while (i--)
			{
				domNode.removeChild(domNode.lastChild);
			}
			return domNode;

		case 'p-append':
			var newNodes = patch.data;
			for (var i = 0; i < newNodes.length; i++)
			{
				domNode.appendChild(render(newNodes[i], patch.eventNode));
			}
			return domNode;

		case 'p-remove':
			var data = patch.data;
			if (typeof data === 'undefined')
			{
				domNode.parentNode.removeChild(domNode);
				return domNode;
			}
			var entry = data.entry;
			if (typeof entry.index !== 'undefined')
			{
				domNode.parentNode.removeChild(domNode);
			}
			entry.data = applyPatchesHelp(domNode, data.patches);
			return domNode;

		case 'p-reorder':
			return applyPatchReorder(domNode, patch);

		case 'p-custom':
			var impl = patch.data;
			return impl.applyPatch(domNode, impl.data);

		default:
			throw new Error('Ran into an unknown patch!');
	}
}


function applyPatchRedraw(domNode, vNode, eventNode)
{
	var parentNode = domNode.parentNode;
	var newNode = render(vNode, eventNode);

	if (typeof newNode.elm_event_node_ref === 'undefined')
	{
		newNode.elm_event_node_ref = domNode.elm_event_node_ref;
	}

	if (parentNode && newNode !== domNode)
	{
		parentNode.replaceChild(newNode, domNode);
	}
	return newNode;
}


function applyPatchReorder(domNode, patch)
{
	var data = patch.data;

	// remove end inserts
	var frag = applyPatchReorderEndInsertsHelp(data.endInserts, patch);

	// removals
	domNode = applyPatchesHelp(domNode, data.patches);

	// inserts
	var inserts = data.inserts;
	for (var i = 0; i < inserts.length; i++)
	{
		var insert = inserts[i];
		var entry = insert.entry;
		var node = entry.tag === 'move'
			? entry.data
			: render(entry.vnode, patch.eventNode);
		domNode.insertBefore(node, domNode.childNodes[insert.index]);
	}

	// add end inserts
	if (typeof frag !== 'undefined')
	{
		domNode.appendChild(frag);
	}

	return domNode;
}


function applyPatchReorderEndInsertsHelp(endInserts, patch)
{
	if (typeof endInserts === 'undefined')
	{
		return;
	}

	var frag = localDoc.createDocumentFragment();
	for (var i = 0; i < endInserts.length; i++)
	{
		var insert = endInserts[i];
		var entry = insert.entry;
		frag.appendChild(entry.tag === 'move'
			? entry.data
			: render(entry.vnode, patch.eventNode)
		);
	}
	return frag;
}


// PROGRAMS

var program = makeProgram(checkNoFlags);
var programWithFlags = makeProgram(checkYesFlags);

function makeProgram(flagChecker)
{
	return F2(function(debugWrap, impl)
	{
		return function(flagDecoder)
		{
			return function(object, moduleName, debugMetadata)
			{
				var checker = flagChecker(flagDecoder, moduleName);
				if (typeof debugMetadata === 'undefined')
				{
					normalSetup(impl, object, moduleName, checker);
				}
				else
				{
					debugSetup(A2(debugWrap, debugMetadata, impl), object, moduleName, checker);
				}
			};
		};
	});
}

function staticProgram(vNode)
{
	var nothing = _elm_lang$core$Native_Utils.Tuple2(
		_elm_lang$core$Native_Utils.Tuple0,
		_elm_lang$core$Platform_Cmd$none
	);
	return A2(program, _elm_lang$virtual_dom$VirtualDom_Debug$wrap, {
		init: nothing,
		view: function() { return vNode; },
		update: F2(function() { return nothing; }),
		subscriptions: function() { return _elm_lang$core$Platform_Sub$none; }
	})();
}


// FLAG CHECKERS

function checkNoFlags(flagDecoder, moduleName)
{
	return function(init, flags, domNode)
	{
		if (typeof flags === 'undefined')
		{
			return init;
		}

		var errorMessage =
			'The `' + moduleName + '` module does not need flags.\n'
			+ 'Initialize it with no arguments and you should be all set!';

		crash(errorMessage, domNode);
	};
}

function checkYesFlags(flagDecoder, moduleName)
{
	return function(init, flags, domNode)
	{
		if (typeof flagDecoder === 'undefined')
		{
			var errorMessage =
				'Are you trying to sneak a Never value into Elm? Trickster!\n'
				+ 'It looks like ' + moduleName + '.main is defined with `programWithFlags` but has type `Program Never`.\n'
				+ 'Use `program` instead if you do not want flags.'

			crash(errorMessage, domNode);
		}

		var result = A2(_elm_lang$core$Native_Json.run, flagDecoder, flags);
		if (result.ctor === 'Ok')
		{
			return init(result._0);
		}

		var errorMessage =
			'Trying to initialize the `' + moduleName + '` module with an unexpected flag.\n'
			+ 'I tried to convert it to an Elm value, but ran into this problem:\n\n'
			+ result._0;

		crash(errorMessage, domNode);
	};
}

function crash(errorMessage, domNode)
{
	if (domNode)
	{
		domNode.innerHTML =
			'<div style="padding-left:1em;">'
			+ '<h2 style="font-weight:normal;"><b>Oops!</b> Something went wrong when starting your Elm program.</h2>'
			+ '<pre style="padding-left:1em;">' + errorMessage + '</pre>'
			+ '</div>';
	}

	throw new Error(errorMessage);
}


//  NORMAL SETUP

function normalSetup(impl, object, moduleName, flagChecker)
{
	object['embed'] = function embed(node, flags)
	{
		while (node.lastChild)
		{
			node.removeChild(node.lastChild);
		}

		return _elm_lang$core$Native_Platform.initialize(
			flagChecker(impl.init, flags, node),
			impl.update,
			impl.subscriptions,
			normalRenderer(node, impl.view)
		);
	};

	object['fullscreen'] = function fullscreen(flags)
	{
		return _elm_lang$core$Native_Platform.initialize(
			flagChecker(impl.init, flags, document.body),
			impl.update,
			impl.subscriptions,
			normalRenderer(document.body, impl.view)
		);
	};
}

function normalRenderer(parentNode, view)
{
	return function(tagger, initialModel)
	{
		var eventNode = { tagger: tagger, parent: undefined };
		var initialVirtualNode = view(initialModel);
		var domNode = render(initialVirtualNode, eventNode);
		parentNode.appendChild(domNode);
		return makeStepper(domNode, view, initialVirtualNode, eventNode);
	};
}


// STEPPER

var rAF =
	typeof requestAnimationFrame !== 'undefined'
		? requestAnimationFrame
		: function(callback) { setTimeout(callback, 1000 / 60); };

function makeStepper(domNode, view, initialVirtualNode, eventNode)
{
	var state = 'NO_REQUEST';
	var currNode = initialVirtualNode;
	var nextModel;

	function updateIfNeeded()
	{
		switch (state)
		{
			case 'NO_REQUEST':
				throw new Error(
					'Unexpected draw callback.\n' +
					'Please report this to <https://github.com/elm-lang/virtual-dom/issues>.'
				);

			case 'PENDING_REQUEST':
				rAF(updateIfNeeded);
				state = 'EXTRA_REQUEST';

				var nextNode = view(nextModel);
				var patches = diff(currNode, nextNode);
				domNode = applyPatches(domNode, currNode, patches, eventNode);
				currNode = nextNode;

				return;

			case 'EXTRA_REQUEST':
				state = 'NO_REQUEST';
				return;
		}
	}

	return function stepper(model)
	{
		if (state === 'NO_REQUEST')
		{
			rAF(updateIfNeeded);
		}
		state = 'PENDING_REQUEST';
		nextModel = model;
	};
}


// DEBUG SETUP

function debugSetup(impl, object, moduleName, flagChecker)
{
	object['fullscreen'] = function fullscreen(flags)
	{
		var popoutRef = { doc: undefined };
		return _elm_lang$core$Native_Platform.initialize(
			flagChecker(impl.init, flags, document.body),
			impl.update(scrollTask(popoutRef)),
			impl.subscriptions,
			debugRenderer(moduleName, document.body, popoutRef, impl.view, impl.viewIn, impl.viewOut)
		);
	};

	object['embed'] = function fullscreen(node, flags)
	{
		var popoutRef = { doc: undefined };
		return _elm_lang$core$Native_Platform.initialize(
			flagChecker(impl.init, flags, node),
			impl.update(scrollTask(popoutRef)),
			impl.subscriptions,
			debugRenderer(moduleName, node, popoutRef, impl.view, impl.viewIn, impl.viewOut)
		);
	};
}

function scrollTask(popoutRef)
{
	return _elm_lang$core$Native_Scheduler.nativeBinding(function(callback)
	{
		var doc = popoutRef.doc;
		if (doc)
		{
			var msgs = doc.getElementsByClassName('debugger-sidebar-messages')[0];
			if (msgs)
			{
				msgs.scrollTop = msgs.scrollHeight;
			}
		}
		callback(_elm_lang$core$Native_Scheduler.succeed(_elm_lang$core$Native_Utils.Tuple0));
	});
}


function debugRenderer(moduleName, parentNode, popoutRef, view, viewIn, viewOut)
{
	return function(tagger, initialModel)
	{
		var appEventNode = { tagger: tagger, parent: undefined };
		var eventNode = { tagger: tagger, parent: undefined };

		// make normal stepper
		var appVirtualNode = view(initialModel);
		var appNode = render(appVirtualNode, appEventNode);
		parentNode.appendChild(appNode);
		var appStepper = makeStepper(appNode, view, appVirtualNode, appEventNode);

		// make overlay stepper
		var overVirtualNode = viewIn(initialModel)._1;
		var overNode = render(overVirtualNode, eventNode);
		parentNode.appendChild(overNode);
		var wrappedViewIn = wrapViewIn(appEventNode, overNode, viewIn);
		var overStepper = makeStepper(overNode, wrappedViewIn, overVirtualNode, eventNode);

		// make debugger stepper
		var debugStepper = makeDebugStepper(initialModel, viewOut, eventNode, parentNode, moduleName, popoutRef);

		return function stepper(model)
		{
			appStepper(model);
			overStepper(model);
			debugStepper(model);
		}
	};
}

function makeDebugStepper(initialModel, view, eventNode, parentNode, moduleName, popoutRef)
{
	var curr;
	var domNode;

	return function stepper(model)
	{
		if (!model.isDebuggerOpen)
		{
			return;
		}

		if (!popoutRef.doc)
		{
			curr = view(model);
			domNode = openDebugWindow(moduleName, popoutRef, curr, eventNode);
			return;
		}

		// switch to document of popout
		localDoc = popoutRef.doc;

		var next = view(model);
		var patches = diff(curr, next);
		domNode = applyPatches(domNode, curr, patches, eventNode);
		curr = next;

		// switch back to normal document
		localDoc = document;
	};
}

function openDebugWindow(moduleName, popoutRef, virtualNode, eventNode)
{
	var w = 900;
	var h = 360;
	var x = screen.width - w;
	var y = screen.height - h;
	var debugWindow = window.open('', '', 'width=' + w + ',height=' + h + ',left=' + x + ',top=' + y);

	// switch to window document
	localDoc = debugWindow.document;

	popoutRef.doc = localDoc;
	localDoc.title = 'Debugger - ' + moduleName;
	localDoc.body.style.margin = '0';
	localDoc.body.style.padding = '0';
	var domNode = render(virtualNode, eventNode);
	localDoc.body.appendChild(domNode);

	localDoc.addEventListener('keydown', function(event) {
		if (event.metaKey && event.which === 82)
		{
			window.location.reload();
		}
		if (event.which === 38)
		{
			eventNode.tagger({ ctor: 'Up' });
			event.preventDefault();
		}
		if (event.which === 40)
		{
			eventNode.tagger({ ctor: 'Down' });
			event.preventDefault();
		}
	});

	function close()
	{
		popoutRef.doc = undefined;
		debugWindow.close();
	}
	window.addEventListener('unload', close);
	debugWindow.addEventListener('unload', function() {
		popoutRef.doc = undefined;
		window.removeEventListener('unload', close);
		eventNode.tagger({ ctor: 'Close' });
	});

	// switch back to the normal document
	localDoc = document;

	return domNode;
}


// BLOCK EVENTS

function wrapViewIn(appEventNode, overlayNode, viewIn)
{
	var ignorer = makeIgnorer(overlayNode);
	var blocking = 'Normal';
	var overflow;

	var normalTagger = appEventNode.tagger;
	var blockTagger = function() {};

	return function(model)
	{
		var tuple = viewIn(model);
		var newBlocking = tuple._0.ctor;
		appEventNode.tagger = newBlocking === 'Normal' ? normalTagger : blockTagger;
		if (blocking !== newBlocking)
		{
			traverse('removeEventListener', ignorer, blocking);
			traverse('addEventListener', ignorer, newBlocking);

			if (blocking === 'Normal')
			{
				overflow = document.body.style.overflow;
				document.body.style.overflow = 'hidden';
			}

			if (newBlocking === 'Normal')
			{
				document.body.style.overflow = overflow;
			}

			blocking = newBlocking;
		}
		return tuple._1;
	}
}

function traverse(verbEventListener, ignorer, blocking)
{
	switch(blocking)
	{
		case 'Normal':
			return;

		case 'Pause':
			return traverseHelp(verbEventListener, ignorer, mostEvents);

		case 'Message':
			return traverseHelp(verbEventListener, ignorer, allEvents);
	}
}

function traverseHelp(verbEventListener, handler, eventNames)
{
	for (var i = 0; i < eventNames.length; i++)
	{
		document.body[verbEventListener](eventNames[i], handler, true);
	}
}

function makeIgnorer(overlayNode)
{
	return function(event)
	{
		if (event.type === 'keydown' && event.metaKey && event.which === 82)
		{
			return;
		}

		var isScroll = event.type === 'scroll' || event.type === 'wheel';

		var node = event.target;
		while (node !== null)
		{
			if (node.className === 'elm-overlay-message-details' && isScroll)
			{
				return;
			}

			if (node === overlayNode && !isScroll)
			{
				return;
			}
			node = node.parentNode;
		}

		event.stopPropagation();
		event.preventDefault();
	}
}

var mostEvents = [
	'click', 'dblclick', 'mousemove',
	'mouseup', 'mousedown', 'mouseenter', 'mouseleave',
	'touchstart', 'touchend', 'touchcancel', 'touchmove',
	'pointerdown', 'pointerup', 'pointerover', 'pointerout',
	'pointerenter', 'pointerleave', 'pointermove', 'pointercancel',
	'dragstart', 'drag', 'dragend', 'dragenter', 'dragover', 'dragleave', 'drop',
	'keyup', 'keydown', 'keypress',
	'input', 'change',
	'focus', 'blur'
];

var allEvents = mostEvents.concat('wheel', 'scroll');


return {
	node: node,
	text: text,
	custom: custom,
	map: F2(map),

	on: F3(on),
	style: style,
	property: F2(property),
	attribute: F2(attribute),
	attributeNS: F3(attributeNS),
	mapProperty: F2(mapProperty),

	lazy: F2(lazy),
	lazy2: F3(lazy2),
	lazy3: F4(lazy3),
	keyedNode: F3(keyedNode),

	program: program,
	programWithFlags: programWithFlags,
	staticProgram: staticProgram
};

}();