Cache all top-level calls to filterByTypes (~7% runtime reduction).

lib/cache.js

@@ -2,14 +2,69 @@
 
 "use strict";
 
+const helpers = require("../helpers");
+const { filterByTypes } = require("../helpers/micromark.cjs");
+
+/** @type {Map<string, object>} */
 const map = new Map();
+// eslint-disable-next-line no-undef-init
+let params = undefined;
 
-module.exports.set = (keyValuePairs) => {
-  for (const [ key, value ] of Object.entries(keyValuePairs)) {
-    map.set(key, value);
+/**
+ * Initializes (resets) the cache.
+ *
+ * @param {import("./markdownlint").RuleParams} [p] Rule parameters object.
+ * @returns {void}
+ */
+function initialize(p) {
+  map.clear();
+  params = p;
+}
+
+/**
+ * Gets a cached object value - computes it and caches it.
+ *
+ * @param {string} name Cache object name.
+ * @param {Function} getValue Getter for object value.
+ * @returns {Object} Object value.
+ */
+function getCached(name, getValue) {
+  if (map.has(name)) {
+    return map.get(name);
   }
-};
-module.exports.clear = () => map.clear();
+  const value = getValue();
+  map.set(name, value);
+  return value;
+}
 
-module.exports.referenceLinkImageData =
-  () => map.get("referenceLinkImageData");
+/**
+ * Filters a list of Micromark tokens by type and caches the result.
+ *
+ * @param {import("./markdownlint").MicromarkTokenType[]} types Types to allow.
+ * @param {boolean} [htmlFlow] Whether to include htmlFlow content.
+ * @returns {import("./markdownlint").MicromarkToken[]} Filtered tokens.
+ */
+function filterByTypesCached(types, htmlFlow) {
+  return getCached(
+    types.join("|"),
+    () => filterByTypes(params.parsers.micromark.tokens, types, htmlFlow)
+  );
+}
+
+/**
+ * Gets a reference link and image data object.
+ *
+ * @returns {Object} Reference link and image data object.
+ */
+function getReferenceLinkImageData() {
+  return getCached(
+    getReferenceLinkImageData.name,
+    () => helpers.getReferenceLinkImageData(params.parsers.micromark.tokens)
+  );
+}
+
+module.exports = {
+  initialize,
+  filterByTypesCached,
+  getReferenceLinkImageData
+};