flow like the river

BACK_BACK/node_modules/htmlnano/lib/modules/minifyUrls.js

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+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = minifyUrls;
+
+var _relateurl = _interopRequireDefault(require("relateurl"));
+
+var _srcset = _interopRequireDefault(require("srcset"));
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+// Adopts from https://github.com/kangax/html-minifier/blob/51ce10f4daedb1de483ffbcccecc41be1c873da2/src/htmlminifier.js#L209-L221
+const tagsHaveUriValuesForAttributes = new Set(['a', 'area', 'link', 'base', 'img', 'object', 'q', 'blockquote', 'ins', 'form', 'input', 'head', 'script']);
+const tagsHasHrefAttributes = new Set(['a', 'area', 'link', 'base']);
+const attributesOfImgTagHasUriValues = new Set(['src', 'longdesc', 'usemap']);
+const attributesOfObjectTagHasUriValues = new Set(['classid', 'codebase', 'data', 'usemap']);
+
+const isUriTypeAttribute = (tag, attr) => {
+  return tagsHasHrefAttributes.has(tag) && attr === 'href' || tag === 'img' && attributesOfImgTagHasUriValues.has(attr) || tag === 'object' && attributesOfObjectTagHasUriValues.has(attr) || tag === 'q' && attr === 'cite' || tag === 'blockquote' && attr === 'cite' || (tag === 'ins' || tag === 'del') && attr === 'cite' || tag === 'form' && attr === 'action' || tag === 'input' && (attr === 'src' || attr === 'usemap') || tag === 'head' && attr === 'profile' || tag === 'script' && (attr === 'src' || attr === 'for') ||
+  /**
+   * https://html.spec.whatwg.org/#attr-source-src
+   *
+   * Although most of browsers recommend not to use "src" in <source>,
+   * but technically it does comply with HTML Standard.
+   */
+  tag === 'source' && attr === 'src';
+};
+
+const isSrcsetAttribute = (tag, attr) => {
+  return tag === 'source' && attr === 'srcset' || tag === 'img' && attr === 'srcset' || tag === 'link' && attr === 'imagesrcset';
+};
+
+const processModuleOptions = options => {
+  // FIXME!
+  // relateurl@1.0.0-alpha only supports URL while stable version (0.2.7) only supports string
+  // should convert input into URL instance after relateurl@1 is stable
+  if (typeof options === 'string') return options;
+  if (options instanceof URL) return options.toString();
+  return false;
+};
+
+const isLinkRelCanonical = ({
+  tag,
+  attrs
+}) => {
+  // Return false early for non-"link" tag
+  if (tag !== 'link') return false;
+
+  for (const [attrName, attrValue] of Object.entries(attrs)) {
+    if (attrName.toLowerCase() === 'rel' && attrValue === 'canonical') return true;
+  }
+
+  return false;
+};
+
+let relateUrlInstance;
+let STORED_URL_BASE;
+/** Convert absolute url into relative url */
+
+function minifyUrls(tree, options, moduleOptions) {
+  const urlBase = processModuleOptions(moduleOptions); // Invalid configuration, return tree directly
+
+  if (!urlBase) return tree;
+  /** Bring up a reusable RelateUrl instances (only once)
+   *
+   * STORED_URL_BASE is used to invalidate RelateUrl instances,
+   * avoiding require.cache acrossing multiple htmlnano instance with different configuration,
+   * e.g. unit tests cases.
+   */
+
+  if (!relateUrlInstance || STORED_URL_BASE !== urlBase) {
+    relateUrlInstance = new _relateurl.default(urlBase);
+    STORED_URL_BASE = urlBase;
+  }
+
+  tree.walk(node => {
+    if (!node.attrs) return node;
+    if (!node.tag) return node;
+    if (!tagsHaveUriValuesForAttributes.has(node.tag)) return node; // Prevent link[rel=canonical] being processed
+    // Can't be excluded by isUriTypeAttribute()
+
+    if (isLinkRelCanonical(node)) return node;
+
+    for (const [attrName, attrValue] of Object.entries(node.attrs)) {
+      const attrNameLower = attrName.toLowerCase();
+
+      if (isUriTypeAttribute(node.tag, attrNameLower)) {
+        // FIXME!
+        // relateurl@1.0.0-alpha only supports URL while stable version (0.2.7) only supports string
+        // the WHATWG URL API is very strict while attrValue might not be a valid URL
+        // new URL should be used, and relateUrl#relate should be wrapped in try...catch after relateurl@1 is stable
+        node.attrs[attrName] = relateUrlInstance.relate(attrValue);
+        continue;
+      }
+
+      if (isSrcsetAttribute(node.tag, attrNameLower)) {
+        try {
+          const parsedSrcset = _srcset.default.parse(attrValue);
+
+          node.attrs[attrName] = _srcset.default.stringify(parsedSrcset.map(srcset => {
+            srcset.url = relateUrlInstance.relate(srcset.url);
+            return srcset;
+          }));
+        } catch (e) {// srcset will throw an Error for invalid srcset.
+        }
+
+        continue;
+      }
+    }
+
+    return node;
+  });
+  return tree;
+}