@vue/component-compiler-utils/dist/templateCompilerModules/srcset.js

"use strict";
// vue compiler module for transforming `img:srcset` to a number of `require`s
Object.defineProperty(exports, "__esModule", { value: true });
const utils_1 = require("./utils");
exports.default = (transformAssetUrlsOptions) => ({
    postTransformNode: (node) => {
        transform(node, transformAssetUrlsOptions);
    }
});
// http://w3c.github.io/html/semantics-embedded-content.html#ref-for-image-candidate-string-5
const escapedSpaceCharacters = /( |\\t|\\n|\\f|\\r)+/g;
function transform(node, transformAssetUrlsOptions) {
    const tags = ['img', 'source'];
    if (tags.indexOf(node.tag) !== -1 && node.attrs) {
        node.attrs.forEach(attr => {
            if (attr.name === 'srcset') {
                // same logic as in transform-require.js
                const value = attr.value;
                const isStatic = value.charAt(0) === '"' && value.charAt(value.length - 1) === '"';
                if (!isStatic) {
                    return;
                }
                const imageCandidates = value
                    .substr(1, value.length - 2)
                    .split(',')
                    .map(s => {
                    // The attribute value arrives here with all whitespace, except
                    // normal spaces, represented by escape sequences
                    const [url, descriptor] = s
                        .replace(escapedSpaceCharacters, ' ')
                        .trim()
                        .split(' ', 2);
                    return {
                        require: utils_1.urlToRequire(url, transformAssetUrlsOptions),
                        descriptor
                    };
                });
                // "require(url1)"
                // "require(url1) 1x"
                // "require(url1), require(url2)"
                // "require(url1), require(url2) 2x"
                // "require(url1) 1x, require(url2)"
                // "require(url1) 1x, require(url2) 2x"
                const code = imageCandidates
                    .map(({ require, descriptor }) => `${require} + "${descriptor ? ' ' + descriptor : ''}, " + `)
                    .join('')
                    .slice(0, -6)
                    .concat('"')
                    .replace(/ \+ ""$/, '');
                attr.value = code;
            }
        });
    }
}