ESM: Ported HTML, Unicode, Quoted Printable and Endian operations

src/core/operations/UnescapeUnicodeCharacters.mjs

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+/**
+ * @author n1474335 [n1474335@gmail.com]
+ * @copyright Crown Copyright 2016
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import Utils from "../Utils";
+
+/**
+ * Unescape Unicode Characters operation
+ */
+class UnescapeUnicodeCharacters extends Operation {
+
+    /**
+     * UnescapeUnicodeCharacters constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Unescape Unicode Characters";
+        this.module = "Default";
+        this.description = "Converts unicode-escaped character notation back into raw characters.<br><br>Supports the prefixes:<ul><li><code>\\u</code></li><li><code>%u</code></li><li><code>U+</code></li></ul>e.g. <code>\\u03c3\\u03bf\\u03c5</code> becomes <code>σου</code>";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                "name": "Prefix",
+                "type": "option",
+                "value": ["\\u", "%u", "U+"]
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const prefix = prefixToRegex[args[0]],
+            regex = new RegExp(prefix+"([a-f\\d]{4})", "ig");
+        let output = "",
+            m,
+            i = 0;
+
+        while ((m = regex.exec(input))) {
+            // Add up to match
+            output += input.slice(i, m.index);
+            i = m.index;
+
+            // Add match
+            output += Utils.chr(parseInt(m[1], 16));
+
+            i = regex.lastIndex;
+        }
+
+        // Add all after final match
+        output += input.slice(i, input.length);
+
+        return output;
+    }
+
+}
+
+/**
+ * Lookup table to add prefixes to unicode delimiters so that they can be used in a regex.
+ */
+const prefixToRegex = {
+    "\\u": "\\\\u",
+    "%u": "%u",
+    "U+": "U\\+"
+};
+
+export default UnescapeUnicodeCharacters;