// Detect browser quirks that we should be aware of.

function needsDynPrefix() {
    var span = document.createElement("span");
    span.innerHTML = "<script>alert('test');</script>";
    var scripts = span.getElementsByTagName("script");
    return scripts.length == 0;
}

var dynPrefix = needsDynPrefix() ? "<span style=\"display:none\">A</span>" : "";

// Function versions of operators

function not(x) { return !x; }
function neg(x) { return -x; }

function eq(x, y) { return x == y; }
function plus(x, y) { return x + y; }
function minus(x, y) { return x - y; }
function times(x, y) { return x * y; }
function div(x, y) { return x / y; }
function divInt(x, y) { var n = x / y; return n < 0 ? Math.ceil(n) : Math.floor(n); }
function mod(x, y) { return x % y; }
function modInt(x, y) { var n = x % y; return n < 0 ? Math.ceil(n) : Math.floor(n); }
function lt(x, y) { return x < y; }
function le(x, y) { return x <= y; }

// Characters

function isLower(c) { return c >= 'a' && c <= 'z'; }
function isUpper(c) { return c >= 'A' && c <= 'Z'; }
function isAlpha(c) { return isLower(c) || isUpper(c); }
function isDigit(c) { return c >= '0' && c <= '9'; }
function isAlnum(c) { return isAlpha(c) || isDigit(c); }
function isBlank(c) { return c == ' ' || c == '\t'; }
function isSpace(c) { return isBlank(c) || c == '\r' || c == '\n'; }
function isXdigit(c) { return isDigit(c) || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F'); }
function toLower(c) { return c.toLowerCase(); }
function toUpper(c) { return c.toUpperCase(); }


// Lists

function cons(v, ls) {
    return { next : ls, data : v };
}
function rev(ls) {
    var acc = null;
    for (; ls; ls = ls.next)
        acc = cons(ls.data, acc);
    return acc;
}
function concat(ls1, ls2) {
    var acc = ls2;
    ls1 = rev(ls1);
    for (; ls1; ls1 = ls1.next)
        acc = cons(ls1.data, acc);
    return acc;
}
function member(x, ls) {
    for (; ls; ls = ls.next)
        if (ls.data == x)
            return true;
    return false;
}
function remove(x, ls) {
    var acc = null;

    for (; ls; ls = ls.next)
        if (ls.data == x)
            return concat(acc, ls.next);
        else
            acc = cons(ls.data, acc);

    return ls;
}
function union(ls1, ls2) {
    var acc = ls2;

    for (; ls1; ls1 = ls1.next)
        if (!member(ls1.data, ls2))
            acc = cons(ls1.data, acc);

    return acc;
}
function length(ls) {
    var acc = 0;

    for (; ls; ls = ls.next)
        ++acc;

    return acc;
}


// Floats

function float(n) {
    return n;
}

function trunc(n) {
    return ~~n;
}

function ceil(n) {
    return Math.ceil(n);
}

function round(n) {
    return Math.round(n);
}


// Time, represented as counts of microseconds since the epoch

function showTime(tm) {
    var newDate = new Date();
    newDate.setTime(tm / 1000);
    var r = newDate.toUTCString();
    return r;
}

function now() {
    return (new Date()).getTime() * 1000;
}

function diffInSeconds(tm1, tm2) {
    return Math.round((tm2 - tm1) / 1000000);
}

function toSeconds(tm) {
    return Math.round(tm / 1000000);
}

function addSeconds(tm, n) {
    return tm + n * 1000000;
}

function stringToTime_error(string) {
    var t = Date.parse(string);
    if (isNaN(t))
        onFail("Invalid date string: " + string);
    else
        return t * 1000;
}

function stringToTime(string) {
    try {
        var t = Date.parse(string);
        if (isNaN(t))
            return null;
        else
            return t * 1000;
    } catch (e) {
        return null;
    }
}

/*
 strftime for Javascript
 Copyright (c) 2008, Philip S Tellis <philip@bluesmoon.info>
 All rights reserved.
 
 This code is distributed under the terms of the BSD licence
 
 Redistribution and use of this software in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:

   * Redistributions of source code must retain the above copyright notice, this list of conditions
     and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright notice, this list of
     conditions and the following disclaimer in the documentation and/or other materials provided
     with the distribution.
   * The names of the contributors to this file may not be used to endorse or promote products
     derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

Date.ext = {};
Date.ext.util = {};
Date.ext.util.xPad=function(x, pad, r)
{
	if(typeof(r) == 'undefined')
	{
		r=10;
	}
	for( ; parseInt(x, 10)<r && r>1; r/=10)
		x = pad.toString() + x;
	return x.toString();
};
Date.prototype.locale = 'en-US';
if(document.getElementsByTagName('html') && document.getElementsByTagName('html')[0].lang)
{
	Date.prototype.locale = document.getElementsByTagName('html')[0].lang;
}
Date.ext.locales = { };
Date.ext.locales.en = {
	a: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
	A: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
	b: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
	B: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
	c: '%a %d %b %Y %T %Z',
	p: ['AM', 'PM'],
	P: ['am', 'pm'],
	x: '%d/%m/%y',
	X: '%T'
};
Date.ext.locales['en-US'] = Date.ext.locales.en;
Date.ext.locales['en-US'].c = '%a %d %b %Y %r %Z';
Date.ext.locales['en-US'].x = '%D';
Date.ext.locales['en-US'].X = '%r';
Date.ext.locales['en-GB'] = Date.ext.locales.en;
Date.ext.locales['en-AU'] = Date.ext.locales['en-GB'];
Date.ext.formats = {
	a: function(d) { return Date.ext.locales[d.locale].a[d.getDay()]; },
	A: function(d) { return Date.ext.locales[d.locale].A[d.getDay()]; },
	b: function(d) { return Date.ext.locales[d.locale].b[d.getMonth()]; },
	B: function(d) { return Date.ext.locales[d.locale].B[d.getMonth()]; },
	c: 'toLocaleString',
	C: function(d) { return Date.ext.util.xPad(parseInt(d.getFullYear()/100, 10), 0); },
	d: ['getDate', '0'],
	e: ['getDate', ' '],
	g: function(d) { return Date.ext.util.xPad(parseInt(Date.ext.util.G(d)/100, 10), 0); },
	G: function(d) {
			var y = d.getFullYear();
			var V = parseInt(Date.ext.formats.V(d), 10);
			var W = parseInt(Date.ext.formats.W(d), 10);

			if(W > V) {
				y++;
			} else if(W===0 && V>=52) {
				y--;
			}

			return y;
		},
	H: ['getHours', '0'],
	I: function(d) { var I=d.getHours()%12; return Date.ext.util.xPad(I===0?12:I, 0); },
	j: function(d) {
			var ms = d - new Date('' + d.getFullYear() + '/1/1 GMT');
			ms += d.getTimezoneOffset()*60000;
			var doy = parseInt(ms/60000/60/24, 10)+1;
			return Date.ext.util.xPad(doy, 0, 100);
		},
	m: function(d) { return Date.ext.util.xPad(d.getMonth()+1, 0); },
	M: ['getMinutes', '0'],
	p: function(d) { return Date.ext.locales[d.locale].p[d.getHours() >= 12 ? 1 : 0 ]; },
	P: function(d) { return Date.ext.locales[d.locale].P[d.getHours() >= 12 ? 1 : 0 ]; },
	S: ['getSeconds', '0'],
	u: function(d) { var dow = d.getDay(); return dow===0?7:dow; },
	U: function(d) {
			var doy = parseInt(Date.ext.formats.j(d), 10);
			var rdow = 6-d.getDay();
			var woy = parseInt((doy+rdow)/7, 10);
			return Date.ext.util.xPad(woy, 0);
		},
	V: function(d) {
			var woy = parseInt(Date.ext.formats.W(d), 10);
			var dow1_1 = (new Date('' + d.getFullYear() + '/1/1')).getDay();
			var idow = woy + (dow1_1 > 4 || dow1_1 <= 1 ? 0 : 1);
			if(idow == 53 && (new Date('' + d.getFullYear() + '/12/31')).getDay() < 4)
			{
				idow = 1;
			}
			else if(idow === 0)
			{
				idow = Date.ext.formats.V(new Date('' + (d.getFullYear()-1) + '/12/31'));
			}

			return Date.ext.util.xPad(idow, 0);
		},
	w: 'getDay',
	W: function(d) {
			var doy = parseInt(Date.ext.formats.j(d), 10);
			var rdow = 7-Date.ext.formats.u(d);
			var woy = parseInt((doy+rdow)/7, 10);
			return Date.ext.util.xPad(woy, 0, 10);
		},
	y: function(d) { return Date.ext.util.xPad(d.getFullYear()%100, 0); },
	Y: 'getFullYear',
	z: function(d) {
			var o = d.getTimezoneOffset();
			var H = Date.ext.util.xPad(parseInt(Math.abs(o/60), 10), 0);
			var M = Date.ext.util.xPad(o%60, 0);
			return (o>0?'-':'+') + H + M;
		},
	Z: function(d) { return d.toString().replace(/^.*\(([^)]+)\)$/, '$1'); },
	'%': function(d) { return '%'; }
};
Date.ext.aggregates = {
	c: 'locale',
	D: '%m/%d/%y',
	h: '%b',
	n: '\n',
	r: '%I:%M:%S %p',
	R: '%H:%M',
	t: '\t',
	T: '%H:%M:%S',
	x: 'locale',
	X: 'locale'
};
Date.ext.aggregates.z = Date.ext.formats.z(new Date());
Date.ext.aggregates.Z = Date.ext.formats.Z(new Date());
Date.ext.unsupported = { };
function strftime(fmt, thisTime)
{
    var thisDate = new Date();
    thisDate.setTime(thisTime / 1000);

    if(!(thisDate.locale in Date.ext.locales))
    {
	if(thisDate.locale.replace(/-[a-zA-Z]+$/, '') in Date.ext.locales)
	{
	    thisDate.locale = thisDate.locale.replace(/-[a-zA-Z]+$/, '');
	}
	else
	{
	    thisDate.locale = 'en-US';
	}
    }

    var d = thisDate;
    while(fmt.match(/%[cDhnrRtTxXzZ]/))
    {
	fmt = fmt.replace(/%([cDhnrRtTxXzZ])/g, function(m0, m1)
        {
	    var f = Date.ext.aggregates[m1];
	    return (f == 'locale' ? Date.ext.locales[d.locale][m1] : f);
	});
    }

    var str = fmt.replace(/%([aAbBCdegGHIjmMpPSuUVwWyY%])/g, function(m0, m1) 
    {
	var f = Date.ext.formats[m1];
	if(typeof(f) == 'string') {
	    return d[f]();
	} else if(typeof(f) == 'function') {
	    return f.call(d, d);
	} else if(typeof(f) == 'object' && typeof(f[0]) == 'string') {
	    return Date.ext.util.xPad(d[f[0]](), f[1]);
	} else {
	    return m1;
	}
    });
    d=null;
    return str;
};

// End of code from Philip S Tellis


// Error handling

function whine(msg) {
    alert(msg);
    throw msg;
}

function pf(loc) {
    throw ("Pattern match failure (" + loc + ")");
}

var lameDuck = false;

function runHandlers(kind, ls, arg) {
    if (!lameDuck) {
        if (ls == null)
            alert(kind + ": " + arg);
        for (; ls; ls = ls.next)
            try {
                exec({c:"a", f:{c:"a", f:ls.data, x:{c:"c", v:arg}}, x:{c:"c", v:null}});
            } catch (v) { }
    }
}

var errorHandlers = null;

function onError(f) {
    errorHandlers = cons(f, errorHandlers);
}

function er(s) {
    runHandlers("Error", errorHandlers, s);
    throw {uw_error: s};
}

var failHandlers = null;

function onFail(f) {
    failHandlers = cons(f, failHandlers);
}

function doExn(v) {
    if (v == null || v.uw_error == null) {
        var s = (v == null ? "null" : v.message ? v.message : v.toString());
        if (v != null && v.fileName && v.lineNumber)
            s += " (" + v.fileName + ":" + v.lineNumber + ")";
        runHandlers("Fail", failHandlers, s);
    }
}

var disconnectHandlers = null;

function flift(f) {
    return {c: "c", v:{env:cons(f,null), body:{c:"v", n:1}}};
}

function onDisconnect(f) {
    disconnectHandlers = cons(flift(f), disconnectHandlers);
}

function discon() {
    runHandlers("Disconnect", disconnectHandlers, null);
}

var connectHandlers = null;

function onConnectFail(f) {
    connectHandlers = cons(flift(f), connectHandlers);
}

function conn() {
    runHandlers("Connect", connectHandlers, null);
}

var serverHandlers = null;

function onServerError(f) {
    serverHandlers = cons(f, serverHandlers);
}

function servErr(s) {
    window.setTimeout(function () { runHandlers("Server", serverHandlers, s); }, 0);
}

// Key events

var uw_event = null;

function kc() {
    return window.event ? event.keyCode : (uw_event ? uw_event.which : 0);
}

// Document events

function uw_handler(name, f) {
    var old = document[name];
    if (old == undefined)
        document[name] = function(event) { uw_event = event; execF(f); };
    else
        document[name] = function(event) { uw_event = event; old(); execF(f); };
}

function uw_onClick(f) {
    uw_handler("onclick", f);
}

function uw_onDblclick(f) {
    uw_handler("ondblclick", f);
}

function uw_onMousedown(f) {
    uw_handler("onmousedown", f);
}

function uw_onMouseup(f) {
    uw_handler("onmouseup", f);
}

function uw_keyHandler(name, f) {
    var old = document[name];
    if (old == undefined)
        document[name] = function(event) { uw_event = event; execF(execF(f, kc())); };
    else
        document[name] = function(event) { uw_event = event; old(); execF(execF(f, kc())); };
}

function uw_onKeydown(f) {
    uw_keyHandler("onkeydown", f);
}

function uw_onKeypress(f) {
    uw_keyHandler("onkeypress", f);
}

function uw_onKeyup(f) {
    uw_keyHandler("onkeyup", f);
}

// Cancelling of further event processing

function uw_preventDefault() {
    var e = window.event ? window.event : uw_event;
    e.returnValue = false;
    if (e.preventDefault) e.preventDefault();
}

function uw_stopPropagation() {
    var e = window.event ? window.event : uw_event;
    e.cancelBubble = true;
    if (e.stopPropagation) e.stopPropagation();
}

// Embedding closures in XML strings

function cs(f) {
    return {closure: f};
}

function isWeird(v) {
    return v.closure != null || v.cat1 != null;
}

function cat(s1, s2) {
    if (isWeird(s1) || isWeird(s2))
        return {cat1: s1, cat2: s2};
    else
        return s1 + s2;
}

var closures = [];
var freeClosures = null;

function newClosure(f) {
    var n;
    if (freeClosures == null) {
        n = closures.length;
    } else {
        n = freeClosures.data;
        freeClosures = freeClosures.next;
    }
    closures[n] = f;
    return n;
}

function freeClosure(n) {
    closures[n] = null;
    freeClosures = cons(n, freeClosures);
}

function cr(n) {
    return closures[n];
}

function flatten(cls, tr) {
    if (tr.cat1 != null)
        return flatten(cls, tr.cat1) + flatten(cls, tr.cat2);
    else if (tr.closure != null) {
        var cl = newClosure(tr.closure);
        cls.v = cons(cl, cls.v);
        return "cr(" + cl + ")";
    } else
        return tr;
}

function flattenLocal(s) {
    var cls = {v : null};
    var r = flatten(cls, s);
    for (cl = cls.v; cl != null; cl = cl.next)
        freeClosure(cl.data);
    return r;
}



// Dynamic tree management

function populate(node) {
    var s = node.signal;
    var oldSources = node.sources;
    try {
        var sr = execF(s, null);
        var newSources = sr._sources;

        for (var sp = oldSources; sp; sp = sp.next)
            if (!member(sp.data, newSources))
                sp.data.dyns = remove(node, sp.data.dyns);

        for (var sp = newSources; sp; sp = sp.next)
            if (!member(sp.data, oldSources))
                sp.data.dyns = cons(node, sp.data.dyns);

        node.sources = newSources;
        node.recreate(sr._data);
    } catch (v) {
        doExn(v);
    }
}

function sc(v) {
    return {data : v, dyns : null};
}
function sv(s, v) {
    if (s.data != v) {
        s.data = v;

        for (var ls = s.dyns; ls; ls = ls.next)
            if (!ls.dead)
                populate(ls.data);
    }
}
function sg(s) {
    return s.data;
}

function ss(s) {
    return {env:cons(s, null), body:{c:"r", l:
            cons({n:"sources", v:{c:"c", v:cons(s, null)}},
                 cons({n:"data", v:{c:"f", f:sg, a:cons({c:"v", n:1}, null)}}, null))}};
}
function sr(v) {
    return {env:null, body:{c:"c", v:{_sources : null, _data : v}}};
}
function sb(x,y) {
    return {env:cons(y,cons(x,null)),
            body:{c:"=",
                e1:{c:"a", f:{c:"v", n:2}, x:{c:"c", v:null}},
                e2:{c:"=",
                    e1:{c:"a",
                        f:{c:"a", f:{c:"v", n:2}, x:{c:".", r:{c:"v", n:0}, f:"data"}},
                        x:{c:"c", v:null}},
                    e2:{c:"r", l:cons(
                                      {n:"sources", v:{c:"f", f:union, a:cons({c:".", r:{c:"v", n:1}, f:"sources"},
                                                                              cons({c:".", r:{c:"v", n:0}, f:"sources"}, null))}},
                                      cons({n:"data", v:{c:".", r:{c:"v", n:0}, f:"data"}}, null))}}}};
}
function scur(s) {
    return execF(s, null)._data;
}

function lastParent() {
    var pos = document.body;

    while (pos.lastChild && pos.lastChild.nodeType == 1)
        pos = pos.lastChild;

    pos = pos.parentNode;

    return pos;
}

function parent() {
    return thisScript ? thisScript.parentNode : lastParent();
}

function addNode(node) {
    if (thisScript)
        thisScript.parentNode.replaceChild(node, thisScript);
    else
        lastParent().appendChild(node);
}

var thisScript = null;

function runScripts(node) {
    if (node.getElementsByTagName) {
        var savedScript = thisScript;

        var scripts = node.getElementsByTagName("script"), scriptsCopy = [];
        var len = scripts.length;
        for (var i = 0; i < len; ++i)
            scriptsCopy[i] = scripts[i];
        for (var i = 0; i < len; ++i) {
            thisScript = scriptsCopy[i];

            try {
                eval(thisScript.text);
            } catch (v) {
                doExn(v);
            }
            if (thisScript.parentNode)
                thisScript.parentNode.removeChild(thisScript);
        }

        thisScript = savedScript;
    }
}


// Dynamic tree entry points

function killScript(scr) {
    scr.dead = true;
    for (var ls = scr.sources; ls; ls = ls.next)
        ls.data.dyns = remove(scr, ls.data.dyns);
    for (var ls = scr.closures; ls; ls = ls.next)
        freeClosure(ls.data);
}

// Sometimes we wind up with tables that contain <script>s outside the single <tbody>.
// To avoid dealing with that case, we normalize by moving <script>s into <tbody>.
function normalizeTable(table) {
    var orig = table;

    var script, next;

    while (table.tagName != "TABLE")
        table = table.parentNode;

    for (var tbody = table.firstChild; tbody; tbody = tbody.nextSibling) {
        if (tbody.tagName == "TBODY") {
            for (script = table.firstChild; script && script != tbody; script = next) {
                next = script.nextSibling;

                tbody.insertBefore(script, tbody.firstChild);
            }

            return;
        }
    }

    var tbody = document.createElement("tbody");
    for (script = table.firstChild; script; script = next) {
        next = script.nextSibling;

        tbody.insertBefore(script, tbody.firstChild);
    }
    table.appendChild(tbody);
}

function dyn(pnode, s) {
    var x = document.createElement("script");
    x.dead = false;
    x.signal = s;
    x.sources = null;
    x.closures = null;

    var firstChild = null;

    x.recreate = function(v) {
        for (var ls = x.closures; ls; ls = ls.next)
            freeClosure(ls.data);

        var next;
        for (var child = firstChild; child && child != x; child = next) {
            next = child.nextSibling;

            killScript(child);
            if (child.getElementsByTagName) {
                var arr = child.getElementsByTagName("script");
                for (var i = 0; i < arr.length; ++i)
                    killScript(arr[i]);
            }

            if (child.parentNode)
                child.parentNode.removeChild(child);
        }

        var cls = {v : null};
        var html = flatten(cls, v);
        if (pnode != "table" && pnode != "tr")
            html = dynPrefix + html;
        x.closures = cls.v;

        if (pnode == "table") {
            normalizeTable(x.parentNode);

            var dummy = document.createElement("body");
            dummy.innerHTML = "<table>" + html + "</table>";
            runScripts(dummy);
            var table = x.parentNode;

            if (table) {
                firstChild = null;
                var tbody;

                var arr = dummy.getElementsByTagName("tbody");

                var tbody;
                if (arr.length > 0 && arr[0].parentNode == dummy.firstChild) {
                    tbody = arr[0];
                    var next;
                    for (var node = dummy.firstChild.firstChild; node; node = next) {
                        next = node.nextSibling;

                        if (node.tagName != "TBODY")
                            tbody.appendChild(node);
                    }
                } else
                    tbody = dummy.firstChild;

                var next;
                firstChild = document.createElement("script");
                table.insertBefore(firstChild, x);
                for (var node = tbody.firstChild; node; node = next) {
                    next = node.nextSibling;
                    table.insertBefore(node, x);
                }
            }
        } else if (pnode == "tr") {
            var dummy = document.createElement("body");
            dummy.innerHTML = "<table><tr>" + html + "</tr></table>";
            runScripts(dummy);
            var table = x.parentNode;

            if (table) {
                var arr = dummy.getElementsByTagName("tr");
                firstChild = null;
                var tr;
                if (arr.length > 0 && table != null)
                    tr = arr[0];
                else
                    tr = dummy.firstChild;

                var next;
                firstChild = document.createElement("script");
                table.insertBefore(firstChild, x);
                for (var node = tr.firstChild; node; node = next) {
                    next = node.nextSibling;
                    table.insertBefore(node, x);
                }
            }
        } else {
            firstChild = document.createElement("span");
            firstChild.innerHTML = html;
            runScripts(firstChild);
            if (x.parentNode)
                x.parentNode.insertBefore(firstChild, x);
        }
    };

    addNode(x);
    populate(x);
}

function input(x, s, recreate, type, name) {
    if (name) x.name = name;
    if (type) x.type = type;
    x.dead = false;
    x.signal = ss(s);
    x.sources = null;
    x.recreate = recreate(x);
    addNode(x);
    populate(x);

    return x;
}

function inp(s, name) {
    var x = input(document.createElement("input"), s,
                  function(x) { return function(v) { if (x.value != v) x.value = v; }; }, null, name);
    x.value = s.data;
    x.onkeyup = x.oninput = x.onchange = x.onpropertychange = function() { sv(s, x.value) };

    return x;
}

function selectValue(x) {
    if (x.options.length == 0)
        return "";
    else
        return x.options[x.selectedIndex].value;
}

function setSelectValue(x, v) {
  for (var i = 0; i < x.options.length; ++i) {
      if(x.options[i].value == v) {
          x.selectedIndex = i;
          return;
      }
  }
}

function sel(s, content) {
    var dummy = document.createElement("span");
    dummy.innerHTML = "<select>" + content + "</select>";
    var x = input(dummy.firstChild, s, function(x) { return function(v) { if (selectValue(x) != v) setSelectValue(x, v); }; });

    for (var i = 0; i < x.options.length; ++i) {
        if (x.options[i].value == "")
            x.options[i].value = x.options[i].text;
        else
            x.options[i].value = x.options[i].value.substring(1);
    }

    setSelectValue(x, s.data);
    if (selectValue(x) != s.data)
        sv(s, selectValue(x));
    x.onchange = function() { sv(s, selectValue(x)) };

    return x;
}

function chk(s) {
    var x = input(document.createElement("input"), s,
                  function(x) { return function(v) { if (x.checked != v) x.checked = v; }; }, "checkbox");
    x.defaultChecked = x.checked = s.data;
    x.onclick = x.onkeyup = x.oninput = x.onchange = x.onpropertychange = function() { sv(s, x.checked) };

    return x;
}

function tbx(s) {
    var x = input(document.createElement("textarea"), s,
                  function(x) { return function(v) { if (x.innerHTML != v) x.innerHTML = v; }; });
    x.innerHTML = s.data;
    x.onkeyup = x.oninput = x.onchange = x.onpropertychange = function() { sv(s, x.value) };

    return x;
}

function addOnChange(x, f) {
    var old = x.onchange;
    if (old == null)
        x.onchange = f;
    else
        x.onchange = function() { old(); f(); };
}

function addOnKeyUp(x, f) {
    var old = x.onkeyup;
    if (old == null)
        x.onkeyup = f;
    else
        x.onkeyup = function(x) { old(x); f(x); };
}


// Basic string operations

function eh(x) {
    if (x == null)
        return "NULL";
    else
        return x.split("&").join("&amp;").split("<").join("&lt;").split(">").join("&gt;");
}

function ts(x) { return x.toString() }
function bs(b) { return (b ? "True" : "False") }

function id(x) { return x; }
function sub(s, i) { return s.charAt(i); }
function suf(s, i) { return s.substring(i); }
function slen(s) { return s.length; }
function sidx(s, ch) {
    var r = s.indexOf(ch);
    if (r == -1)
        return null;
    else
        return r;
}
function sspn(s, chs) {
    for (var i = 0; i < s.length; ++i)
        if (chs.indexOf(s.charAt(i)) != -1)
            return i;

    return null;
}
function schr(s, ch) {
    var r = s.indexOf(ch);
    if (r == -1)
        return null;
    else
        return s.substring(r);
}
function ssub(s, start, len) {
    return s.substring(start, start+len);
}

function pi(s) {
    var r = parseInt(s);
    if (r.toString() == s)
        return r;
    else
        er("Can't parse int: " + s);
}

function pfl(s) {
    var r = parseFloat(s);
    if (r.toString() == s)
        return r;
    else
        er("Can't parse float: " + s);
}

function pio(s) {
    var r = parseInt(s);
    if (r.toString() == s)
        return r;
    else
        return null;
}

function pflo(s) {
    var r = parseFloat(s);
    if (r.toString() == s)
        return r;
    else
        return null;
}

function uf(s) {
    if (s.length == 0)
        return "_";
    s = s.replace(new RegExp ("\\.", "g"), ".2E");
    return (s.charAt(0) == '_' ? "_" : "") + encodeURIComponent(s).replace(new RegExp ("%", "g"), ".");
}

function uu(s) {
    if (s.length > 0 && s.charAt(0) == '_') {
        s = s.substring(1);
    } else if (s.length >= 3 && (s.charAt(0) == '%' || s.charAt(0) == '.')
               && s.charAt(1) == '5' && (s.charAt(2) == 'f' || s.charAt(2) == 'F'))
        s = s.substring(3);
    s = s.replace(new RegExp ("\\+", "g"), " ");
    s = s.replace(new RegExp ("\\.", "g"), "%");
    return decodeURIComponent(s);
}

function atr(s) {
    return s.replace(new RegExp ("\"", "g"), "&quot;").replace(new RegExp ("&", "g"), "&amp;")
        }

function ub(b) {
    return b ? "1" : "0";
}

function uul(getToken, getData) {
    var tok = getToken();
    if (tok == "Nil") {
        return null;
    } else if (tok == "Cons") {
        var d = getData();
        var l = uul(getToken, getData);
        return {_1:d, _2:l};
    } else
        whine("Can't unmarshal list (" + tok + ")");
}

function strcmp(str1, str2) {
    return ((str1 == str2) ? 0 : ((str1 > str2) ? 1 : -1));
}


// Remote calls

var client_id = null;
var client_pass = 0;
var url_prefix = "/";
var timeout = 60;
var isPost = false;

function getXHR(uri)
{
    try {
        return new XMLHttpRequest();
    } catch (e) {
        try {
            return new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
            try {
                return new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {
                whine("Your browser doesn't seem to support AJAX.");
            }
        }
    }
}

var sig = null;

var unloading = false, inFlight = null;

function unload() {
    unloading = true;

    for (; inFlight; inFlight = inFlight.next) {
        inFlight.data.abort();
    }
}

function requestUri(xhr, uri, needsSig) {
    if (unloading)
        return;

    xhr.open("POST", uri, true);
    xhr.setRequestHeader("Content-type", "text/plain");
    try {
        xhr.setRequestHeader("Content-length", "0");
        xhr.setRequestHeader("Connection", "close");
    } catch (e) { }

    if (client_id != null) {
        xhr.setRequestHeader("UrWeb-Client", client_id.toString());
        xhr.setRequestHeader("UrWeb-Pass", client_pass.toString());
    }

    if (needsSig) {
        if (sig == null)
            whine("Missing cookie signature!");

        xhr.setRequestHeader("UrWeb-Sig", sig);
    }

    inFlight = cons(xhr, inFlight);
    xhr.send(null);
}

function xhrFinished(xhr) {
    xhr.abort();
    inFlight = remove(xhr, inFlight);
}

function unurlify(parse, s) {
    return parse(s);
}

function redirect(s) {
    window.location = s;
}

function rc(prefix, uri, parse, k, needsSig) {
    uri = cat(prefix, uri);
    uri = flattenLocal(uri);
    var xhr = getXHR();

    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4) {
            var isok = false;

            try {
                if (xhr.status == 200)
                    isok = true;
            } catch (e) { }

            if (isok) {
                var lines = xhr.responseText.split("\n");
                if (lines.length != 2)
                    whine("Bad RPC response lines");

                eval(lines[0]);

                try {
                    k(parse(lines[1]));
                } catch (v) {
                    doExn(v);
                }
            } else {
                conn();
            }

            xhrFinished(xhr);
        }
    };

    requestUri(xhr, uri, needsSig);
}

function path_join(s1, s2) {
    if (s1.length > 0 && s1.charAt(s1.length-1) == '/')
        return s1 + s2;
    else
        return s1 + "/" + s2;
}

var channels = [];

function newQueue() {
    return { front : null, back : null };
}
function enqueue(q, v) {
    if (q.front == null) {
        q.front = cons(v, null);
        q.back = q.front;
    } else {
        var node = cons(v, null);
        q.back.next = node;
        q.back = node;
    }
}
function dequeue(q) {
    if (q.front == null)
        return null;
    else {
        var r = q.front.data;
        q.front = q.front.next;
        if (q.front == null)
            q.back = null;
        return r;
    }
}

function newChannel() {
    return { msgs : newQueue(), listeners : newQueue() };
}

function listener() {
    var uri = path_join(url_prefix, ".msgs");
    var xhr = getXHR();
    var tid, orsc, onTimeout;

    var connect = function () {
        xhr.onreadystatechange = orsc;
        tid = window.setTimeout(onTimeout, timeout * 500);
        requestUri(xhr, uri, false);
    }

    orsc = function() {
        if (xhr.readyState == 4) {
            window.clearTimeout(tid);

            var isok = false;

            try {
                if (xhr.status == 200)
                    isok = true;
            } catch (e) { }

            if (isok) {
                var text = xhr.responseText;
                if (text == "")
                    return;
                var lines = text.split("\n");

                if (lines.length == 1 && lines[0] == "R") {
                    lameDuck = true;

                    if (isPost)
                        history.back();
                    else
                        location.reload();

                    return;
                }

                if (lines.length < 2) {
                    discon();
                    return;
                }

                var messageReader = function(i) {
                    if (i+1 >= lines.length) {
                        xhrFinished(xhr);
                        connect();
                    }
                    else {
                        var chn = lines[i];
                        var msg = lines[i+1];

                        if (chn == "E") {
                            eval(msg);
                            window.setTimeout(function() { messageReader(i+2); }, 0);
                        } else {
                            if (chn < 0)
                                whine("Out-of-bounds channel in message from remote server");

                            var ch;

                            if (chn >= channels.length || channels[chn] == null) {
                                ch = newChannel();
                                channels[chn] = ch;
                            } else
                                ch = channels[chn];

                            var listener = dequeue(ch.listeners);
                            if (listener == null) {
                                enqueue(ch.msgs, msg);
                            } else {
                                try {
                                    listener(msg);
                                } catch (v) {
                                    doExn(v);
                                }
                            }

                            messageReader(i+2);
                        }
                    }
                }

                messageReader(0);
            }
            else {
                try {
                    if (xhr.status != 0)
                        servErr("Error querying remote server for messages: " + xhr.status);
                } catch (e) { }
            }
        }
    };

    onTimeout = function() {
        xhrFinished(xhr);
        connect();
    };

    connect();
}

function rv(chn, parse, k) {
    if (chn == null)
        return;

    if (chn < 0)
        whine("Out-of-bounds channel receive");

    var ch;

    if (chn >= channels.length || channels[chn] == null) {
        ch = newChannel();
        channels[chn] = ch;
    } else
        ch = channels[chn];

    var msg = dequeue(ch.msgs);
    if (msg == null) {
        enqueue(ch.listeners, function(msg) { k(parse(msg)); });
    } else {
        try {
            k(parse(msg));
        } catch (v) {
            doExn(v);
        }
    }
}

function sl(ms, k) {
    window.setTimeout(function() { k(null); }, ms);
}

function sp(e) {
    execF(e, null);
}


// The Ur interpreter

var urfuncs = [];

function lookup(env, n) {
    while (env != null) {
        if (n == 0)
            return env.data;
        else {
            --n;
            env = env.next;
        }
    }

    whine("Out-of-bounds Ur variable reference");
}

function execP(env, p, v) {
    switch (p.c) {
    case "w":
        return env;
    case "v":
        return cons(v, env);
    case "c":
        if (v == p.v)
            return env;
        else
            return false;
    case "s":
        if (v == null)
            return false;
        else
            return execP(env, p.p, p.n ? v.v : v);
    case "1":
        if (v.n != p.n)
            return false;
        else
            return execP(env, p.p, v.v);
    case "r":
        for (var fs = p.l; fs != null; fs = fs.next) {
            env = execP(env, fs.data.p, v["_" + fs.data.n]);
            if (env == false)
                return false;
        }
        return env;
    default:
        whine("Unknown Ur pattern kind" + p.c);
    }
}

function exec0(env, e) {
    return exec1(env, null, e);
}

function exec1(env, stack, e) {
    var stack, usedK = false;

    var saveEnv = function() {
        if (stack.next != null && stack.next.data.c != "<")
            stack = cons({c: "<", env: env}, stack.next);
        else
            stack = stack.next;
    };

    while (true) {
        switch (e.c) {
        case "c":
            var v = e.v;
            if (stack == null)
                return v;
            var fr = stack.data;

            switch (fr.c) {
            case "s":
                e = {c: "c", v: {v: v}};
                stack = stack.next;
                break;
            case "1":
                e = {c: "c", v: {n: fr.n, v: v}};
                stack = stack.next;
                break;
            case "f":
                fr.args[fr.pos++] = v;
                if (fr.a == null) {
                    var res;
                    stack = stack.next;

                    if (fr.f.apply)
                        res = fr.f.apply(null, fr.args);
                    else if (fr.args.length == 0)
                        res = fr.f();
                    else if (fr.args.length == 1)
                        res = fr.f(fr.args[0]);
                    else if (fr.args.length == 2)
                        res = fr.f(fr.args[0], fr.args[1]);
                    else if (fr.args.length == 3)
                        res = fr.f(fr.args[0], fr.args[1], fr.args[2]);
                    else if (fr.args.length == 4)
                        res = fr.f(fr.args[0], fr.args[1], fr.args[2], fr.args[3]);
                    else if (fr.args.length == 5)
                        res = fr.f(fr.args[0], fr.args[1], fr.args[2], fr.args[3], fr.args[4]);
                    else
                        whine("Native function has " + fr.args.length + " args, but there is no special case for that count.");

                    e = {c: "c", v: res};
                    if (usedK) return null;
                } else {
                    e = fr.a.data;
                    fr.a = fr.a.next;
                }
                break;
            case "a1":
                e = fr.x;
                stack = cons({c: "a2", f: v}, stack.next);
                break;
            case "a2":
                if (fr.f == null)
                    whine("Ur: applying null function");
                else if (fr.f.body) {
                    saveEnv();
                    env = cons(v, fr.f.env);
                    e = fr.f.body;
                } else {
                    e = {c: "c", v: fr.f(v)};
                    stack = stack.next;
                }
                break;
            case "<":
                env = fr.env;
                stack = stack.next;
                break;
            case "r":
                fr.fs["_" + fr.n] = v;
                if (fr.l == null) {
                    e = {c: "c", v: fr.fs};
                    stack = stack.next;
                } else {
                    fr.n = fr.l.data.n;
                    e = fr.l.data.v;
                    fr.l = fr.l.next;
                }
                break;
            case ".":
                e = {c: "c", v: v["_" + fr.f]};
                stack = stack.next;
                break;
            case ";":
                e = fr.e2;
                stack = stack.next;
                break;
            case "=":
                saveEnv();
                env = cons(v, env);
                e = fr.e2;
                break;
            case "m":
                var ps;
                for (ps = fr.p; ps != null; ps = ps.next) {
                    var r = execP(env, ps.data.p, v);
                    if (r != false) {
                        saveEnv();
                        env = r;
                        e = ps.data.b;
                        break;
                    }
                }
                if (ps == null)
                    whine("Match failure in Ur interpretation");
                break;
            default:
                whine("Unknown Ur continuation kind " + fr.c);
            }

            break;
        case "v":
            e = {c: "c", v: lookup(env, e.n)};
            break;
        case "n":
            var idx = e.n;
            e = urfuncs[idx];
            if (e.c == "t")
                e = urfuncs[idx] = eval("(" + e.f + ")");
            break;
        case "s":
            stack = cons({c: "s"}, stack);
            e = e.v;
            break;
        case "1":
            stack = cons({c: "1", n: e.n}, stack);
            e = e.v;
            break;
        case "f":
            if (e.a == null)
                e = {c: "c", v: (eval(e.f))()};
            else {
                var args = [];
                stack = cons({c: "f", f: eval(e.f), args: args, pos: 0, a: e.a.next}, stack);
                if (!e.a.data.c) alert("[2] fr.f = " + e.f + "; 0 = " + e.a.data);
                e = e.a.data;
            }
            break;
        case "l":
            e = {c: "c", v: {env: env, body: e.b}};
            break;
        case "a":
            stack = cons({c: "a1", x: e.x}, stack);
            e = e.f;
            break;
        case "r":
            if (e.l == null)
                whine("Empty Ur record in interpretation");
            var fs = {};
            stack = cons({c: "r", n: e.l.data.n, fs: fs, l: e.l.next}, stack);
            e = e.l.data.v;
            break;
        case ".":
            stack = cons({c: ".", f: e.f}, stack);
            e = e.r;
            break;
        case ";":
            stack = cons({c: ";", e2: e.e2}, stack);
            e = e.e1;
            break;
        case "=":
            stack = cons({c: "=", e2: e.e2}, stack);
            e = e.e1;
            break;
        case "m":
            stack = cons({c: "m", p: e.p}, stack);
            e = e.e;
            break;
        case "e":
            e = {c: "c", v: cs({c: "wc", env: env, body: e.e})};
            break;
        case "wc":
            env = e.env;
            e = e.body;
            break;
        case "K":
            { var savedStack = stack.next, savedEnv = env;
                e = {c: "c", v: function(v) { return exec1(savedEnv, savedStack, {c: "c", v: v}); } };}
            usedK = true;
            break;
        default:
            whine("Unknown Ur expression kind " + e.c);
        }
    }
}

function execD(e) {
    return exec0(null, e);
}

function exec(e) {
    var r = exec0(null, e);

    if (r != null && r.body != null)
        return function(v) { return exec0(cons(v, r.env), r.body); };
    else
        return r;
}

function execF(f, x) {
    return exec0(cons(x, f.env), f.body);
}


// Wrappers

function confrm(s) {
    return confirm(s) ? true : false;
}


// URL blessing

var urlRules = null;

function checkUrl(s) {
    for (var r = urlRules; r; r = r.next) {
        var ru = r.data;
        if (ru.prefix ? s.indexOf(ru.pattern) == 0 : s == ru.pattern)
            return ru.allow ? s : null;
    }

    return null;
}

function bless(s) {
    u = checkUrl(s);
    if (u == null)
        er("Disallowed URL: " + s);
    return u;
}


// ID generation

var nextId = 0;

function fresh() {
    return (--nextId).toString();
}


// App-specific code