/*! Picturefill - v3.0.1 - 2015-09-30
 * http://scottjehl.github.io/picturefill
 * Copyright (c) 2015 https://github.com/scottjehl/picturefill/blob/master/Authors.txt; Licensed MIT
 */
/*! Gecko-Picture - v1.0
 * https://github.com/scottjehl/picturefill/tree/3.0/src/plugins/gecko-picture
 * Firefox's early picture implementation (prior to FF41) is static and does
 * not react to viewport changes. This tiny module fixes this.
 */
(function (window) {
    /*jshint eqnull:true */
    var ua = navigator.userAgent;

    if (window.HTMLPictureElement && ((/ecko/).test(ua) && ua.match(/rv\:(\d+)/) && RegExp.$1 < 41)) {
        addEventListener("resize", (function () {
            var timer;

            var dummySrc = document.createElement("source");

            var fixRespimg = function (img) {
                var source, sizes;
                var picture = img.parentNode;

                if (picture.nodeName.toUpperCase() === "PICTURE") {
                    source = dummySrc.cloneNode();

                    picture.insertBefore(source, picture.firstElementChild);
                    setTimeout(function () {
                        picture.removeChild(source);
                    });
                } else if (!img._pfLastSize || img.offsetWidth > img._pfLastSize) {
                    img._pfLastSize = img.offsetWidth;
                    sizes = img.sizes;
                    img.sizes += ",100vw";
                    setTimeout(function () {
                        img.sizes = sizes;
                    });
                }
            };

            var findPictureImgs = function () {
                var i;
                var imgs = document.querySelectorAll("picture > img, img[srcset][sizes]");
                for (i = 0; i < imgs.length; i++) {
                    fixRespimg(imgs[i]);
                }
            };
            var onResize = function () {
                clearTimeout(timer);
                timer = setTimeout(findPictureImgs, 99);
            };
            var mq = window.matchMedia && matchMedia("(orientation: landscape)");
            var init = function () {
                onResize();

                if (mq && mq.addListener) {
                    mq.addListener(onResize);
                }
            };

            dummySrc.srcset = "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==";

            if (/^[c|i]|d$/.test(document.readyState || "")) {
                init();
            } else {
                document.addEventListener("DOMContentLoaded", init);
            }

            return onResize;
        })());
    }
})(window);

/*! Picturefill - v3.0.1
 * http://scottjehl.github.io/picturefill
 * Copyright (c) 2015 https://github.com/scottjehl/picturefill/blob/master/Authors.txt;
 *  License: MIT
 */

(function (window, document, undefined) {
    // Enable strict mode
    "use strict";

    // HTML shim|v it for old IE (IE9 will still need the HTML video tag workaround)
    document.createElement("picture");

    var warn, eminpx, alwaysCheckWDescriptor, evalId;
    // local object for method references and testing exposure
    var pf = {};
    var noop = function () {};
    var image = document.createElement("img");
    var getImgAttr = image.getAttribute;
    var setImgAttr = image.setAttribute;
    var removeImgAttr = image.removeAttribute;
    var docElem = document.documentElement;
    var types = {};
    var cfg = {
        //resource selection:
        algorithm: ""
    };
    var srcAttr = "data-pfsrc";
    var srcsetAttr = srcAttr + "set";
    // ua sniffing is done for undetectable img loading features,
    // to do some non crucial perf optimizations
    var ua = navigator.userAgent;
    var supportAbort = (/rident/).test(ua) || ((/ecko/).test(ua) && ua.match(/rv\:(\d+)/) && RegExp.$1 > 35);
    var curSrcProp = "currentSrc";
    var regWDesc = /\s+\+?\d+(e\d+)?w/;
    var regSize = /(\([^)]+\))?\s*(.+)/;
    var setOptions = window.picturefillCFG;
    /**
     * Shortcut property for https://w3c.github.io/webappsec/specs/mixedcontent/#restricts-mixed-content ( for easy overriding in tests )
     */
    // baseStyle also used by getEmValue (i.e.: width: 1em is important)
    var baseStyle = "position:absolute;left:0;visibility:hidden;display:block;padding:0;border:none;font-size:1em;width:1em;overflow:hidden;clip:rect(0px, 0px, 0px, 0px)";
    var fsCss = "font-size:100%!important;";
    var isVwDirty = true;

    var cssCache = {};
    var sizeLengthCache = {};
    var DPR = window.devicePixelRatio;
    var units = {
        px: 1,
        "in": 96
    };
    var anchor = document.createElement("a");
    /**
     * alreadyRun flag used for setOptions. is it true setOptions will reevaluate
     * @type {boolean}
     */
    var alreadyRun = false;

    // Reusable, non-"g" Regexes

    // (Don't use \s, to avoid matching non-breaking space.)
    var regexLeadingSpaces = /^[ \t\n\r\u000c]+/,
        regexLeadingCommasOrSpaces = /^[, \t\n\r\u000c]+/,
        regexLeadingNotSpaces = /^[^ \t\n\r\u000c]+/,
        regexTrailingCommas = /[,]+$/,
        regexNonNegativeInteger = /^\d+$/,

        // ( Positive or negative or unsigned integers or decimals, without or without exponents.
        // Must include at least one digit.
        // According to spec tests any decimal point must be followed by a digit.
        // No leading plus sign is allowed.)
        // https://html.spec.whatwg.org/multipage/infrastructure.html#valid-floating-point-number
        regexFloatingPoint = /^-?(?:[0-9]+|[0-9]*\.[0-9]+)(?:[eE][+-]?[0-9]+)?$/;

    var on = function (obj, evt, fn, capture) {
        if (obj.addEventListener) {
            obj.addEventListener(evt, fn, capture || false);
        } else if (obj.attachEvent) {
            obj.attachEvent("on" + evt, fn);
        }
    };

    /**
     * simple memoize function:
     */

    var memoize = function (fn) {
        var cache = {};
        return function (input) {
            if (!(input in cache)) {
                cache[ input ] = fn(input);
            }
            return cache[ input ];
        };
    };

    // UTILITY FUNCTIONS

    // Manual is faster than RegEx
    // http://jsperf.com/whitespace-character/5
    function isSpace(c) {
        return (c === "\u0020" || // space
                c === "\u0009" || // horizontal tab
                c === "\u000A" || // new line
                c === "\u000C" || // form feed
                c === "\u000D");  // carriage return
    }

    /**
     * gets a mediaquery and returns a boolean or gets a css length and returns a number
     * @param css mediaqueries or css length
     * @returns {boolean|number}
     *
     * based on: https://gist.github.com/jonathantneal/db4f77009b155f083738
     */
    var evalCSS = (function () {

        var regLength = /^([\d\.]+)(em|vw|px)$/;
        var replace = function () {
            var args = arguments, index = 0, string = args[0];
            while (++index in args) {
                string = string.replace(args[index], args[++index]);
            }
            return string;
        };

        var buildStr = memoize(function (css) {

            return "return " + replace((css || "").toLowerCase(),
                    // interpret `and`
                                       /\band\b/g, "&&",

                    // interpret `,`
                                       /,/g, "||",

                    // interpret `min-` as >=
                                       /min-([a-z-\s]+):/g, "e.$1>=",

                    // interpret `max-` as <=
                                       /max-([a-z-\s]+):/g, "e.$1<=",

                    //calc value
                                       /calc([^)]+)/g, "($1)",

                    // interpret css values
                                       /(\d+[\.]*[\d]*)([a-z]+)/g, "($1 * e.$2)",
                    //make eval less evil
                                       /^(?!(e.[a-z]|[0-9\.&=|><\+\-\*\(\)\/])).*/ig, ""
                ) + ";";
        });

        return function (css, length) {
            var parsedLength;
            if (!(css in cssCache)) {
                cssCache[css] = false;
                if (length && (parsedLength = css.match(regLength))) {
                    cssCache[css] = parsedLength[ 1 ] * units[parsedLength[ 2 ]];
                } else {
                    /*jshint evil:true */
                    try {
                        cssCache[css] = new Function("e", buildStr(css))(units);
                    } catch (e) {}
                    /*jshint evil:false */
                }
            }
            return cssCache[css];
        };
    })();

    var setResolution = function (candidate, sizesattr) {
        if (candidate.w) { // h = means height: || descriptor.type === 'h' do not handle yet...
            candidate.cWidth = pf.calcListLength(sizesattr || "100vw");
            candidate.res = candidate.w / candidate.cWidth ;
        } else {
            candidate.res = candidate.d;
        }
        return candidate;
    };

    /**
     *
     * @param opt
     */
    var picturefill = function (opt) {
        var elements, i, plen;

        var options = opt || {};

        if (options.elements && options.elements.nodeType === 1) {
            if (options.elements.nodeName.toUpperCase() === "IMG") {
                options.elements =  [options.elements];
            } else {
                options.context = options.elements;
                options.elements =  null;
            }
        }

        elements = options.elements || pf.qsa((options.context || document), (options.reevaluate || options.reselect) ? pf.sel : pf.selShort);

        if ((plen = elements.length)) {

            pf.setupRun(options);
            alreadyRun = true;

            // Loop through all elements
            for (i = 0; i < plen; i++) {
                pf.fillImg(elements[ i ], options);
            }

            pf.teardownRun(options);
        }
    };

    /**
     * outputs a warning for the developer
     * @param {message}
     * @type {Function}
     */
    warn = (window.console && console.warn) ?
        function (message) {
            console.warn(message);
        } :
        noop
    ;

    if (!(curSrcProp in image)) {
        curSrcProp = "src";
    }

    // Add support for standard mime types.
    types[ "image/jpeg" ] = true;
    types[ "image/gif" ] = true;
    types[ "image/png" ] = true;

    function detectTypeSupport(type, typeUri) {
        // based on Modernizr's lossless img-webp test
        // note: asynchronous
        var image = new window.Image();
        image.onerror = function () {
            types[ type ] = false;
            picturefill();
        };
        image.onload = function () {
            types[ type ] = image.width === 1;
            picturefill();
        };
        image.src = typeUri;
        return "pending";
    }

    // test svg support
    types[ "image/svg+xml" ] = document.implementation.hasFeature("http://wwwindow.w3.org/TR/SVG11/feature#Image", "1.1");

    /**
     * updates the internal vW property with the current viewport width in px
     */
    function updateMetrics() {

        isVwDirty = false;
        DPR = window.devicePixelRatio;
        cssCache = {};
        sizeLengthCache = {};

        pf.DPR = DPR || 1;

        units.width = Math.max(window.innerWidth || 0, docElem.clientWidth);
        units.height = Math.max(window.innerHeight || 0, docElem.clientHeight);

        units.vw = units.width / 100;
        units.vh = units.height / 100;

        evalId = [units.height, units.width, DPR].join("-");

        units.em = pf.getEmValue();
        units.rem = units.em;
    }

    function chooseLowRes(lowerValue, higherValue, dprValue, isCached) {
        var bonusFactor, tooMuch, bonus, meanDensity;

        //experimental
        if (cfg.algorithm === "saveData") {
            if (lowerValue > 2.7) {
                meanDensity = dprValue + 1;
            } else {
                tooMuch = higherValue - dprValue;
                bonusFactor = Math.pow(lowerValue - 0.6, 1.5);

                bonus = tooMuch * bonusFactor;

                if (isCached) {
                    bonus += 0.1 * bonusFactor;
                }

                meanDensity = lowerValue + bonus;
            }
        } else {
            meanDensity = (dprValue > 1) ?
                Math.sqrt(lowerValue * higherValue) :
                lowerValue;
        }

        return meanDensity > dprValue;
    }

    function applyBestCandidate(img) {
        var srcSetCandidates;
        var matchingSet = pf.getSet(img);
        var evaluated = false;
        if (matchingSet !== "pending") {
            evaluated = evalId;
            if (matchingSet) {
                srcSetCandidates = pf.setRes(matchingSet);
                pf.applySetCandidate(srcSetCandidates, img);
            }
        }
        img[ pf.ns ].evaled = evaluated;
    }

    function ascendingSort(a, b) {
        return a.res - b.res;
    }

    function setSrcToCur(img, src, set) {
        var candidate;
        if (!set && src) {
            set = img[ pf.ns ].sets;
            set = set && set[set.length - 1];
        }

        candidate = getCandidateForSrc(src, set);

        if (candidate) {
            src = pf.makeUrl(src);
            img[ pf.ns ].curSrc = src;
            img[ pf.ns ].curCan = candidate;

            if (!candidate.res) {
                setResolution(candidate, candidate.set.sizes);
            }
        }
        return candidate;
    }

    function getCandidateForSrc(src, set) {
        var i, candidate, candidates;
        if (src && set) {
            candidates = pf.parseSet(set);
            src = pf.makeUrl(src);
            for (i = 0; i < candidates.length; i++) {
                if (src === pf.makeUrl(candidates[ i ].url)) {
                    candidate = candidates[ i ];
                    break;
                }
            }
        }
        return candidate;
    }

    function getAllSourceElements(picture, candidates) {
        var i, len, source, srcset;

        // SPEC mismatch intended for size and perf:
        // actually only source elements preceding the img should be used
        // also note: don't use qsa here, because IE8 sometimes doesn't like source as the key part in a selector
        var sources = picture.getElementsByTagName("source");

        for (i = 0, len = sources.length; i < len; i++) {
            source = sources[ i ];
            source[ pf.ns ] = true;
            srcset = source.getAttribute("srcset");

            // if source does not have a srcset attribute, skip
            if (srcset) {
                candidates.push({
                    srcset: srcset,
                    media: source.getAttribute("media"),
                    type: source.getAttribute("type"),
                    sizes: source.getAttribute("sizes")
                });
            }
        }
    }

    /**
     * Srcset Parser
     * By Alex Bell |  MIT License
     *
     * @returns Array [{url: _, d: _, w: _, h:_, set:_(????)}, ...]
     *
     * Based super duper closely on the reference algorithm at:
     * https://html.spec.whatwg.org/multipage/embedded-content.html#parse-a-srcset-attribute
     */

    // 1. Let input be the value passed to this algorithm.
    // (TO-DO : Explain what "set" argument is here. Maybe choose a more
    // descriptive & more searchable name.  Since passing the "set" in really has
    // nothing to do with parsing proper, I would prefer this assignment eventually
    // go in an external fn.)
    function parseSrcset(input, set) {

        function collectCharacters(regEx) {
            var chars,
                match = regEx.exec(input.substring(pos));
            if (match) {
                chars = match[ 0 ];
                pos += chars.length;
                return chars;
            }
        }

        var inputLength = input.length,
            url,
            descriptors,
            currentDescriptor,
            state,
            c,

            // 2. Let position be a pointer into input, initially pointing at the start
            //    of the string.
            pos = 0,

            // 3. Let candidates be an initially empty source set.
            candidates = [];

        /**
         * Adds descriptor properties to a candidate, pushes to the candidates array
         * @return undefined
         */
        // (Declared outside of the while loop so that it's only created once.
        // (This fn is defined before it is used, in order to pass JSHINT.
        // Unfortunately this breaks the sequencing of the spec comments. :/ )
        function parseDescriptors() {

            // 9. Descriptor parser: Let error be no.
            var pError = false,

                // 10. Let width be absent.
                // 11. Let density be absent.
                // 12. Let future-compat-h be absent. (We're implementing it now as h)
                w, d, h, i,
                candidate = {},
                desc, lastChar, value, intVal, floatVal;

            // 13. For each descriptor in descriptors, run the appropriate set of steps
            // from the following list:
            for (i = 0 ; i < descriptors.length; i++) {
                desc = descriptors[ i ];

                lastChar = desc[ desc.length - 1 ];
                value = desc.substring(0, desc.length - 1);
                intVal = parseInt(value, 10);
                floatVal = parseFloat(value);

                // If the descriptor consists of a valid non-negative integer followed by
                // a U+0077 LATIN SMALL LETTER W character
                if (regexNonNegativeInteger.test(value) && (lastChar === "w")) {

                    // If width and density are not both absent, then let error be yes.
                    if (w || d) {
                        pError = true;
                    }

                    // Apply the rules for parsing non-negative integers to the descriptor.
                    // If the result is zero, let error be yes.
                    // Otherwise, let width be the result.
                    if (intVal === 0) {
                        pError = true;
                    } else {
                        w = intVal;
                    }

                                        // If the descriptor consists of a valid floating-point number followed by
                                        // a U+0078 LATIN SMALL LETTER X character
                } else if (regexFloatingPoint.test(value) && (lastChar === "x")) {

                    // If width, density and future-compat-h are not all absent, then let error
                    // be yes.
                    if (w || d || h) {
                        pError = true;
                    }

                    // Apply the rules for parsing floating-point number values to the descriptor.
                    // If the result is less than zero, let error be yes. Otherwise, let density
                    // be the result.
                    if (floatVal < 0) {
                        pError = true;
                    } else {
                        d = floatVal;
                    }

                                        // If the descriptor consists of a valid non-negative integer followed by
                                        // a U+0068 LATIN SMALL LETTER H character
                } else if (regexNonNegativeInteger.test(value) && (lastChar === "h")) {

                    // If height and density are not both absent, then let error be yes.
                    if (h || d) {
                        pError = true;
                    }

                    // Apply the rules for parsing non-negative integers to the descriptor.
                    // If the result is zero, let error be yes. Otherwise, let future-compat-h
                    // be the result.
                    if (intVal === 0) {
                        pError = true;
                    } else {
                        h = intVal;
                    }

                                        // Anything else, Let error be yes.
                } else {
                    pError = true;
                }
            } // (close step 13 for loop)

            // 15. If error is still no, then append a new image source to candidates whose
            // URL is url, associated with a width width if not absent and a pixel
            // density density if not absent. Otherwise, there is a parse error.
            if (!pError) {
                candidate.url = url;

                if (w) {
                    candidate.w = w;
                }
                if (d) {
                    candidate.d = d;
                }
                if (h) {
                    candidate.h = h;
                }
                if (!h && !d && !w) {
                    candidate.d = 1;
                }
                if (candidate.d === 1) {
                    set.has1x = true;
                }
                candidate.set = set;

                candidates.push(candidate);
            }
        } // (close parseDescriptors fn)

        /**
         * Tokenizes descriptor properties prior to parsing
         * Returns undefined.
         * (Again, this fn is defined before it is used, in order to pass JSHINT.
         * Unfortunately this breaks the logical sequencing of the spec comments. :/ )
         */
        function tokenize() {

            // 8.1. Descriptor tokeniser: Skip whitespace
            collectCharacters(regexLeadingSpaces);

            // 8.2. Let current descriptor be the empty string.
            currentDescriptor = "";

            // 8.3. Let state be in descriptor.
            state = "in descriptor";

            while (true) {

                // 8.4. Let c be the character at position.
                c = input.charAt(pos);

                //  Do the following depending on the value of state.
                //  For the purpose of this step, "EOF" is a special character representing
                //  that position is past the end of input.

                // In descriptor
                if (state === "in descriptor") {
                    // Do the following, depending on the value of c:

                    // Space character
                    // If current descriptor is not empty, append current descriptor to
                    // descriptors and let current descriptor be the empty string.
                    // Set state to after descriptor.
                    if (isSpace(c)) {
                        if (currentDescriptor) {
                            descriptors.push(currentDescriptor);
                            currentDescriptor = "";
                            state = "after descriptor";
                        }

                        // U+002C COMMA (,)
                        // Advance position to the next character in input. If current descriptor
                        // is not empty, append current descriptor to descriptors. Jump to the step
                        // labeled descriptor parser.
                    } else if (c === ",") {
                        pos += 1;
                        if (currentDescriptor) {
                            descriptors.push(currentDescriptor);
                        }
                        parseDescriptors();
                        return;

                        // U+0028 LEFT PARENTHESIS (()
                        // Append c to current descriptor. Set state to in parens.
                    } else if (c === "\u0028") {
                        currentDescriptor = currentDescriptor + c;
                        state = "in parens";

                        // EOF
                        // If current descriptor is not empty, append current descriptor to
                        // descriptors. Jump to the step labeled descriptor parser.
                    } else if (c === "") {
                        if (currentDescriptor) {
                            descriptors.push(currentDescriptor);
                        }
                        parseDescriptors();
                        return;

                        // Anything else
                        // Append c to current descriptor.
                    } else {
                        currentDescriptor = currentDescriptor + c;
                    }
                    // (end "in descriptor"

                    // In parens
                } else if (state === "in parens") {

                    // U+0029 RIGHT PARENTHESIS ())
                    // Append c to current descriptor. Set state to in descriptor.
                    if (c === ")") {
                        currentDescriptor = currentDescriptor + c;
                        state = "in descriptor";

                        // EOF
                        // Append current descriptor to descriptors. Jump to the step labeled
                        // descriptor parser.
                    } else if (c === "") {
                        descriptors.push(currentDescriptor);
                        parseDescriptors();
                        return;

                        // Anything else
                        // Append c to current descriptor.
                    } else {
                        currentDescriptor = currentDescriptor + c;
                    }

                    // After descriptor
                } else if (state === "after descriptor") {

                    // Do the following, depending on the value of c:
                    // Space character: Stay in this state.
                    if (isSpace(c)) {

                        // EOF: Jump to the step labeled descriptor parser.
                    } else if (c === "") {
                        parseDescriptors();
                        return;

                        // Anything else
                        // Set state to in descriptor. Set position to the previous character in input.
                    } else {
                        state = "in descriptor";
                        pos -= 1;

                    }
                }

                // Advance position to the next character in input.
                pos += 1;

                // Repeat this step.
            } // (close while true loop)
        }

        // 4. Splitting loop: Collect a sequence of characters that are space
        //    characters or U+002C COMMA characters. If any U+002C COMMA characters
        //    were collected, that is a parse error.
        while (true) {
            collectCharacters(regexLeadingCommasOrSpaces);

            // 5. If position is past the end of input, return candidates and abort these steps.
            if (pos >= inputLength) {
                return candidates; // (we're done, this is the sole return path)
            }

            // 6. Collect a sequence of characters that are not space characters,
            //    and let that be url.
            url = collectCharacters(regexLeadingNotSpaces);

            // 7. Let descriptors be a new empty list.
            descriptors = [];

            // 8. If url ends with a U+002C COMMA character (,), follow these substeps:
            //		(1). Remove all trailing U+002C COMMA characters from url. If this removed
            //         more than one character, that is a parse error.
            if (url.slice(-1) === ",") {
                url = url.replace(regexTrailingCommas, "");
                // (Jump ahead to step 9 to skip tokenization and just push the candidate).
                parseDescriptors();

                //	Otherwise, follow these substeps:
            } else {
                tokenize();
            } // (close else of step 8)

            // 16. Return to the step labeled splitting loop.
        } // (Close of big while loop.)
    }

    /*
     * Sizes Parser
     *
     * By Alex Bell |  MIT License
     *
     * Non-strict but accurate and lightweight JS Parser for the string value <img sizes="here">
     *
     * Reference algorithm at:
     * https://html.spec.whatwg.org/multipage/embedded-content.html#parse-a-sizes-attribute
     *
     * Most comments are copied in directly from the spec
     * (except for comments in parens).
     *
     * Grammar is:
     * <source-size-list> = <source-size># [ , <source-size-value> ]? | <source-size-value>
     * <source-size> = <media-condition> <source-size-value>
     * <source-size-value> = <length>
     * http://www.w3.org/html/wg/drafts/html/master/embedded-content.html#attr-img-sizes
     *
     * E.g. "(max-width: 30em) 100vw, (max-width: 50em) 70vw, 100vw"
     * or "(min-width: 30em), calc(30vw - 15px)" or just "30vw"
     *
     * Returns the first valid <css-length> with a media condition that evaluates to true,
     * or "100vw" if all valid media conditions evaluate to false.
     */

    function parseSizes(strValue) {

        // (Percentage CSS lengths are not allowed in this case, to avoid confusion:
        // https://html.spec.whatwg.org/multipage/embedded-content.html#valid-source-size-list
        // CSS allows a single optional plus or minus sign:
        // http://www.w3.org/TR/CSS2/syndata.html#numbers
        // CSS is ASCII case-insensitive:
        // http://www.w3.org/TR/CSS2/syndata.html#characters )
        // Spec allows exponential notation for <number> type:
        // http://dev.w3.org/csswg/css-values/#numbers
        var regexCssLengthWithUnits = /^(?:[+-]?[0-9]+|[0-9]*\.[0-9]+)(?:[eE][+-]?[0-9]+)?(?:ch|cm|em|ex|in|mm|pc|pt|px|rem|vh|vmin|vmax|vw)$/i;

        // (This is a quick and lenient test. Because of optional unlimited-depth internal
        // grouping parens and strict spacing rules, this could get very complicated.)
        var regexCssCalc = /^calc\((?:[0-9a-z \.\+\-\*\/\(\)]+)\)$/i;

        var i;
        var unparsedSizesList;
        var unparsedSizesListLength;
        var unparsedSize;
        var lastComponentValue;
        var size;

        // UTILITY FUNCTIONS

        //  (Toy CSS parser. The goals here are:
        //  1) expansive test coverage without the weight of a full CSS parser.
        //  2) Avoiding regex wherever convenient.
        //  Quick tests: http://jsfiddle.net/gtntL4gr/3/
        //  Returns an array of arrays.)
        function parseComponentValues(str) {
            var chrctr;
            var component = "";
            var componentArray = [];
            var listArray = [];
            var parenDepth = 0;
            var pos = 0;
            var inComment = false;

            function pushComponent() {
                if (component) {
                    componentArray.push(component);
                    component = "";
                }
            }

            function pushComponentArray() {
                if (componentArray[0]) {
                    listArray.push(componentArray);
                    componentArray = [];
                }
            }

            // (Loop forwards from the beginning of the string.)
            while (true) {
                chrctr = str.charAt(pos);

                if (chrctr === "") { // ( End of string reached.)
                    pushComponent();
                    pushComponentArray();
                    return listArray;
                } else if (inComment) {
                    if ((chrctr === "*") && (str[pos + 1] === "/")) { // (At end of a comment.)
                        inComment = false;
                        pos += 2;
                        pushComponent();
                        continue;
                    } else {
                        pos += 1; // (Skip all characters inside comments.)
                        continue;
                    }
                } else if (isSpace(chrctr)) {
                    // (If previous character in loop was also a space, or if
                    // at the beginning of the string, do not add space char to
                    // component.)
                    if ((str.charAt(pos - 1) && isSpace(str.charAt(pos - 1))) || !component) {
                        pos += 1;
                        continue;
                    } else if (parenDepth === 0) {
                        pushComponent();
                        pos += 1;
                        continue;
                    } else {
                        // (Replace any space character with a plain space for legibility.)
                        chrctr = " ";
                    }
                } else if (chrctr === "(") {
                    parenDepth += 1;
                } else if (chrctr === ")") {
                    parenDepth -= 1;
                } else if (chrctr === ",") {
                    pushComponent();
                    pushComponentArray();
                    pos += 1;
                    continue;
                } else if ((chrctr === "/") && (str.charAt(pos + 1) === "*")) {
                    inComment = true;
                    pos += 2;
                    continue;
                }

                component = component + chrctr;
                pos += 1;
            }
        }

        function isValidNonNegativeSourceSizeValue(s) {
            if (regexCssLengthWithUnits.test(s) && (parseFloat(s) >= 0)) {
                return true;
            }
            if (regexCssCalc.test(s)) {
                return true;
            }
            // ( http://www.w3.org/TR/CSS2/syndata.html#numbers says:
            // "-0 is equivalent to 0 and is not a negative number." which means that
            // unitless zero and unitless negative zero must be accepted as special cases.)
            if ((s === "0") || (s === "-0") || (s === "+0")) {
                return true;
            }
            return false;
        }

        // When asked to parse a sizes attribute from an element, parse a
        // comma-separated list of component values from the value of the element's
        // sizes attribute (or the empty string, if the attribute is absent), and let
        // unparsed sizes list be the result.
        // http://dev.w3.org/csswg/css-syntax/#parse-comma-separated-list-of-component-values

        unparsedSizesList = parseComponentValues(strValue);
        unparsedSizesListLength = unparsedSizesList.length;

        // For each unparsed size in unparsed sizes list:
        for (i = 0; i < unparsedSizesListLength; i++) {
            unparsedSize = unparsedSizesList[i];

            // 1. Remove all consecutive <whitespace-token>s from the end of unparsed size.
            // ( parseComponentValues() already omits spaces outside of parens. )

            // If unparsed size is now empty, that is a parse error; continue to the next
            // iteration of this algorithm.
            // ( parseComponentValues() won't push an empty array. )

            // 2. If the last component value in unparsed size is a valid non-negative
            // <source-size-value>, let size be its value and remove the component value
            // from unparsed size. Any CSS function other than the calc() function is
            // invalid. Otherwise, there is a parse error; continue to the next iteration
            // of this algorithm.
            // http://dev.w3.org/csswg/css-syntax/#parse-component-value
            lastComponentValue = unparsedSize[unparsedSize.length - 1];

            if (isValidNonNegativeSourceSizeValue(lastComponentValue)) {
                size = lastComponentValue;
                unparsedSize.pop();
            } else {
                continue;
            }

            // 3. Remove all consecutive <whitespace-token>s from the end of unparsed
            // size. If unparsed size is now empty, return size and exit this algorithm.
            // If this was not the last item in unparsed sizes list, that is a parse error.
            if (unparsedSize.length === 0) {
                return size;
            }

            // 4. Parse the remaining component values in unparsed size as a
            // <media-condition>. If it does not parse correctly, or it does parse
            // correctly but the <media-condition> evaluates to false, continue to the
            // next iteration of this algorithm.
            // (Parsing all possible compound media conditions in JS is heavy, complicated,
            // and the payoff is unclear. Is there ever an situation where the
            // media condition parses incorrectly but still somehow evaluates to true?
            // Can we just rely on the browser/polyfill to do it?)
            unparsedSize = unparsedSize.join(" ");
            if (!(pf.matchesMedia(unparsedSize))) {
                continue;
            }

            // 5. Return size and exit this algorithm.
            return size;
        }

        // If the above algorithm exhausts unparsed sizes list without returning a
        // size value, return 100vw.
        return "100vw";
    }

    // namespace
    pf.ns = ("pf" + new Date().getTime()).substr(0, 9);

    // srcset support test
    pf.supSrcset = "srcset" in image;
    pf.supSizes = "sizes" in image;
    pf.supPicture = !!window.HTMLPictureElement;

    if (pf.supSrcset && pf.supPicture && !pf.supSizes) {
        (function (image2) {
            image.srcset = "data:,a";
            image2.src = "data:,a";
            pf.supSrcset = image.complete === image2.complete;
            pf.supPicture = pf.supSrcset && pf.supPicture;
        })(document.createElement("img"));
    }

    // using pf.qsa instead of dom traversing does scale much better,
    // especially on sites mixing responsive and non-responsive images
    pf.selShort = "picture>img,img[srcset]";
    pf.sel = pf.selShort;
    pf.cfg = cfg;

    if (pf.supSrcset) {
        pf.sel += ",img[" + srcsetAttr + "]";
    }

    /**
     * Shortcut property for `devicePixelRatio` ( for easy overriding in tests )
     */
    pf.DPR = (DPR  || 1);
    pf.u = units;

    // container of supported mime types that one might need to qualify before using
    pf.types =  types;

    alwaysCheckWDescriptor = pf.supSrcset && !pf.supSizes;

    pf.setSize = noop;

    /**
     * Gets a string and returns the absolute URL
     * @param src
     * @returns {String} absolute URL
     */

    pf.makeUrl = memoize(function (src) {
        anchor.href = src;
        return anchor.href;
    });

    /**
     * Gets a DOM element or document and a selctor and returns the found matches
     * Can be extended with jQuery/Sizzle for IE7 support
     * @param context
     * @param sel
     * @returns {NodeList}
     */
    pf.qsa = function (context, sel) {
        return context.querySelectorAll(sel);
    };

    /**
     * Shortcut method for matchMedia ( for easy overriding in tests )
     * wether native or pf.mMQ is used will be decided lazy on first call
     * @returns {boolean}
     */
    pf.matchesMedia = function () {
        if (window.matchMedia && (matchMedia("(min-width: 0.1em)") || {}).matches) {
            pf.matchesMedia = function (media) {
                return !media || (matchMedia(media).matches);
            };
        } else {
            pf.matchesMedia = pf.mMQ;
        }

        return pf.matchesMedia.apply(this, arguments);
    };

    /**
     * A simplified matchMedia implementation for IE8 and IE9
     * handles only min-width/max-width with px or em values
     * @param media
     * @returns {boolean}
     */
    pf.mMQ = function (media) {
        return media ? evalCSS(media) : true;
    };

    /**
     * Returns the calculated length in css pixel from the given sourceSizeValue
     * http://dev.w3.org/csswg/css-values-3/#length-value
     * intended Spec mismatches:
     * * Does not check for invalid use of CSS functions
     * * Does handle a computed length of 0 the same as a negative and therefore invalid value
     * @param sourceSizeValue
     * @returns {Number}
     */
    pf.calcLength = function (sourceSizeValue) {

        var value = evalCSS(sourceSizeValue, true) || false;
        if (value < 0) {
            value = false;
        }

        return value;
    };

    /**
     * Takes a type string and checks if its supported
     */

    pf.supportsType = function (type) {
        return (type) ? types[ type ] : true;
    };

    /**
     * Parses a sourceSize into mediaCondition (media) and sourceSizeValue (length)
     * @param sourceSizeStr
     * @returns {*}
     */
    pf.parseSize = memoize(function (sourceSizeStr) {
        var match = (sourceSizeStr || "").match(regSize);
        return {
            media: match && match[1],
            length: match && match[2]
        };
    });

    pf.parseSet = function (set) {
        if (!set.cands) {
            set.cands = parseSrcset(set.srcset, set);
        }
        return set.cands;
    };

    /**
     * returns 1em in css px for html/body default size
     * function taken from respondjs
     * @returns {*|number}
     */
    pf.getEmValue = function () {
        var body;
        if (!eminpx && (body = document.body)) {
            var div = document.createElement("div"),
                originalHTMLCSS = docElem.style.cssText,
                originalBodyCSS = body.style.cssText;

            div.style.cssText = baseStyle;

            // 1em in a media query is the value of the default font size of the browser
            // reset docElem and body to ensure the correct value is returned
            docElem.style.cssText = fsCss;
            body.style.cssText = fsCss;

            body.appendChild(div);
            eminpx = div.offsetWidth;
            body.removeChild(div);

            //also update eminpx before returning
            eminpx = parseFloat(eminpx, 10);

            // restore the original values
            docElem.style.cssText = originalHTMLCSS;
            body.style.cssText = originalBodyCSS;

        }
        return eminpx || 16;
    };

    /**
     * Takes a string of sizes and returns the width in pixels as a number
     */
    pf.calcListLength = function (sourceSizeListStr) {
        // Split up source size list, ie ( max-width: 30em ) 100%, ( max-width: 50em ) 50%, 33%
        //
        //                           or (min-width:30em) calc(30% - 15px)
        if (!(sourceSizeListStr in sizeLengthCache) || cfg.uT) {
            var winningLength = pf.calcLength(parseSizes(sourceSizeListStr));

            sizeLengthCache[ sourceSizeListStr ] = !winningLength ? units.width : winningLength;
        }

        return sizeLengthCache[ sourceSizeListStr ];
    };

    /**
     * Takes a candidate object with a srcset property in the form of url/
     * ex. "images/pic-medium.png 1x, images/pic-medium-2x.png 2x" or
     *     "images/pic-medium.png 400w, images/pic-medium-2x.png 800w" or
     *     "images/pic-small.png"
     * Get an array of image candidates in the form of
     *      {url: "/foo/bar.png", resolution: 1}
     * where resolution is http://dev.w3.org/csswg/css-values-3/#resolution-value
     * If sizes is specified, res is calculated
     */
    pf.setRes = function (set) {
        var candidates;
        if (set) {

            candidates = pf.parseSet(set);

            for (var i = 0, len = candidates.length; i < len; i++) {
                setResolution(candidates[ i ], set.sizes);
            }
        }
        return candidates;
    };

    pf.setRes.res = setResolution;

    pf.applySetCandidate = function (candidates, img) {
        if (!candidates.length) {
            return;
        }
        var candidate,
            i,
            j,
            length,
            bestCandidate,
            curSrc,
            curCan,
            candidateSrc,
            abortCurSrc;

        var imageData = img[ pf.ns ];
        var dpr = pf.DPR;

        curSrc = imageData.curSrc || img[curSrcProp];

        curCan = imageData.curCan || setSrcToCur(img, curSrc, candidates[0].set);

        // if we have a current source, we might either become lazy or give this source some advantage
        if (curCan && curCan.set === candidates[ 0 ].set) {

            // if browser can abort image request and the image has a higher pixel density than needed
            // and this image isn't downloaded yet, we skip next part and try to save bandwidth
            abortCurSrc = (supportAbort && !img.complete && curCan.res - 0.1 > dpr);

            if (!abortCurSrc) {
                curCan.cached = true;

                // if current candidate is "best", "better" or "okay",
                // set it to bestCandidate
                if (curCan.res >= dpr) {
                    bestCandidate = curCan;
                }
            }
        }

        if (!bestCandidate) {

            candidates.sort(ascendingSort);

            length = candidates.length;
            bestCandidate = candidates[ length - 1 ];

            for (i = 0; i < length; i++) {
                candidate = candidates[ i ];
                if (candidate.res >= dpr) {
                    j = i - 1;

                    // we have found the perfect candidate,
                    // but let's improve this a little bit with some assumptions ;-)
                    if (candidates[ j ] &&
                        (abortCurSrc || curSrc !== pf.makeUrl(candidate.url)) &&
                        chooseLowRes(candidates[ j ].res, candidate.res, dpr, candidates[ j ].cached)) {

                        bestCandidate = candidates[ j ];

                    } else {
                        bestCandidate = candidate;
                    }
                    break;
                }
            }
        }

        if (bestCandidate) {

            candidateSrc = pf.makeUrl(bestCandidate.url);

            imageData.curSrc = candidateSrc;
            imageData.curCan = bestCandidate;

            if (candidateSrc !== curSrc) {
                pf.setSrc(img, bestCandidate);
            }
            pf.setSize(img);
        }
    };

    pf.setSrc = function (img, bestCandidate) {
        var origWidth;
        img.src = bestCandidate.url;

        // although this is a specific Safari issue, we don't want to take too much different code paths
        if (bestCandidate.set.type === "image/svg+xml") {
            origWidth = img.style.width;
            img.style.width = (img.offsetWidth + 1) + "px";

            // next line only should trigger a repaint
            // if... is only done to trick dead code removal
            if (img.offsetWidth + 1) {
                img.style.width = origWidth;
            }
        }
    };

    pf.getSet = function (img) {
        var i, set, supportsType;
        var match = false;
        var sets = img [ pf.ns ].sets;

        for (i = 0; i < sets.length && !match; i++) {
            set = sets[i];

            if (!set.srcset || !pf.matchesMedia(set.media) || !(supportsType = pf.supportsType(set.type))) {
                continue;
            }

            if (supportsType === "pending") {
                set = supportsType;
            }

            match = set;
            break;
        }

        return match;
    };

    pf.parseSets = function (element, parent, options) {
        var srcsetAttribute, imageSet, isWDescripor, srcsetParsed;

        var hasPicture = parent && parent.nodeName.toUpperCase() === "PICTURE";
        var imageData = element[ pf.ns ];

        if (imageData.src === undefined || options.src) {
            imageData.src = getImgAttr.call(element, "src");
            if (imageData.src) {
                setImgAttr.call(element, srcAttr, imageData.src);
            } else {
                removeImgAttr.call(element, srcAttr);
            }
        }

        if (imageData.srcset === undefined || options.srcset || !pf.supSrcset || element.srcset) {
            srcsetAttribute = getImgAttr.call(element, "srcset");
            imageData.srcset = srcsetAttribute;
            srcsetParsed = true;
        }

        imageData.sets = [];

        if (hasPicture) {
            imageData.pic = true;
            getAllSourceElements(parent, imageData.sets);
        }

        if (imageData.srcset) {
            imageSet = {
                srcset: imageData.srcset,
                sizes: getImgAttr.call(element, "sizes")
            };

            imageData.sets.push(imageSet);

            isWDescripor = (alwaysCheckWDescriptor || imageData.src) && regWDesc.test(imageData.srcset || "");

            // add normal src as candidate, if source has no w descriptor
            if (!isWDescripor && imageData.src && !getCandidateForSrc(imageData.src, imageSet) && !imageSet.has1x) {
                imageSet.srcset += ", " + imageData.src;
                imageSet.cands.push({
                    url: imageData.src,
                    d: 1,
                    set: imageSet
                });
            }

        } else if (imageData.src) {
            imageData.sets.push({
                srcset: imageData.src,
                sizes: null
            });
        }

        imageData.curCan = null;
        imageData.curSrc = undefined;

        // if img has picture or the srcset was removed or has a srcset and does not support srcset at all
        // or has a w descriptor (and does not support sizes) set support to false to evaluate
        imageData.supported = !(hasPicture || (imageSet && !pf.supSrcset) || isWDescripor);

        if (srcsetParsed && pf.supSrcset && !imageData.supported) {
            if (srcsetAttribute) {
                setImgAttr.call(element, srcsetAttr, srcsetAttribute);
                element.srcset = "";
            } else {
                removeImgAttr.call(element, srcsetAttr);
            }
        }

        if (imageData.supported && !imageData.srcset && ((!imageData.src && element.src) ||  element.src !== pf.makeUrl(imageData.src))) {
            if (imageData.src === null) {
                element.removeAttribute("src");
            } else {
                element.src = imageData.src;
            }
        }

        imageData.parsed = true;
    };

    pf.fillImg = function (element, options) {
        var imageData;
        var extreme = options.reselect || options.reevaluate;

        // expando for caching data on the img
        if (!element[ pf.ns ]) {
            element[ pf.ns ] = {};
        }

        imageData = element[ pf.ns ];

        // if the element has already been evaluated, skip it
        // unless `options.reevaluate` is set to true ( this, for example,
        // is set to true when running `picturefill` on `resize` ).
        if (!extreme && imageData.evaled === evalId) {
            return;
        }

        if (!imageData.parsed || options.reevaluate) {
            pf.parseSets(element, element.parentNode, options);
        }

        if (!imageData.supported) {
            applyBestCandidate(element);
        } else {
            imageData.evaled = evalId;
        }
    };

    pf.setupRun = function () {
        if (!alreadyRun || isVwDirty || (DPR !== window.devicePixelRatio)) {
            updateMetrics();
        }
    };

    // If picture is supported, well, that's awesome.
    if (pf.supPicture) {
        picturefill = noop;
        pf.fillImg = noop;
    } else {

        // Set up picture polyfill by polling the document
        (function () {
            var isDomReady;
            var regReady = window.attachEvent ? /d$|^c/ : /d$|^c|^i/;

            var run = function () {
                var readyState = document.readyState || "";

                timerId = setTimeout(run, readyState === "loading" ? 200 :  999);
                if (document.body) {
                    pf.fillImgs();
                    isDomReady = isDomReady || regReady.test(readyState);
                    if (isDomReady) {
                        clearTimeout(timerId);
                    }

                }
            };

            var timerId = setTimeout(run, document.body ? 9 : 99);

            // Also attach picturefill on resize and readystatechange
            // http://modernjavascript.blogspot.com/2013/08/building-better-debounce.html
            var debounce = function (func, wait) {
                var timeout, timestamp;
                var later = function () {
                    var last = (new Date()) - timestamp;

                    if (last < wait) {
                        timeout = setTimeout(later, wait - last);
                    } else {
                        timeout = null;
                        func();
                    }
                };

                return function () {
                    timestamp = new Date();

                    if (!timeout) {
                        timeout = setTimeout(later, wait);
                    }
                };
            };
            var lastClientWidth = docElem.clientHeight;
            var onResize = function () {
                isVwDirty = Math.max(window.innerWidth || 0, docElem.clientWidth) !== units.width || docElem.clientHeight !== lastClientWidth;
                lastClientWidth = docElem.clientHeight;
                if (isVwDirty) {
                    pf.fillImgs();
                }
            };

            on(window, "resize", debounce(onResize, 99));
            on(document, "readystatechange", run);
        })();
    }

    pf.picturefill = picturefill;
    //use this internally for easy monkey patching/performance testing
    pf.fillImgs = picturefill;
    pf.teardownRun = noop;

    /* expose methods for testing */
    picturefill._ = pf;

    window.picturefillCFG = {
        pf: pf,
        push: function (args) {
            var name = args.shift();
            if (typeof pf[name] === "function") {
                pf[name].apply(pf, args);
            } else {
                cfg[name] = args[0];
                if (alreadyRun) {
                    pf.fillImgs({ reselect: true });
                }
            }
        }
    };

    while (setOptions && setOptions.length) {
        window.picturefillCFG.push(setOptions.shift());
    }

    /* expose picturefill */
    window.picturefill = picturefill;

    /* expose picturefill */
    if (typeof module === "object" && typeof module.exports === "object") {
        // CommonJS, just export
        module.exports = picturefill;
    } else if (typeof define === "function" && define.amd) {
        // AMD support
        define("picturefill", function () {
            return picturefill;
        });
    }

    // IE8 evals this sync, so it must be the last thing we do
    if (!pf.supPicture) {
        types[ "image/webp" ] = detectTypeSupport("image/webp", "data:image/webp;base64,UklGRkoAAABXRUJQVlA4WAoAAAAQAAAAAAAAAAAAQUxQSAwAAAABBxAR/Q9ERP8DAABWUDggGAAAADABAJ0BKgEAAQADADQlpAADcAD++/1QAA==");
    }

})(window, document);
