Add Caret/M-decode Operation

src/core/config/Categories.json

@@ -67,7 +67,8 @@
             "JSON to CSV",
             "Avro to JSON",
             "CBOR Encode",
-            "CBOR Decode"
+            "CBOR Decode",
+            "Caret/M-decode"
         ]
     },
     {

src/core/operations/CaretMdecode.mjs

@@ -0,0 +1,98 @@
+/**
+ * @author tedk [tedk@ted.do]
+ * @copyright Crown Copyright 2024
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+
+/**
+ * Caret/M-decode operation
+ *
+ * https://gist.githubusercontent.com/JaHIY/3c91bbf7bea5661e6abfbd1349ee81a2/raw/c7b480e9ff24bcb8f5287a8a8a2dcb9bf5628506/decode_m_notation.cpp
+ */
+class CaretMdecode extends Operation {
+
+    /**
+     * CaretMdecode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Caret/M-decode";
+        this.module = "Default";
+        this.description = "Decodes caret or M-encoded strings, i.e. ^M turns into a newline, M-^] turns into 0x9d. Sources such as `cat -v`.\n\nPlease be aware that when using `cat -v` ^_ (caret-underscore) will not be encoded, but represents a valid encoding (namely that of 0x1f).";
+        this.infoURL = "https://en.wikipedia.org/wiki/Caret_notation";
+        this.inputType = "string";
+        this.outputType = "byteArray";
+        this.args = [];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {byteArray}
+     */
+    run(input, args) {
+
+        const bytes = [];
+
+        let prev = "";
+
+        for (let i = 0; i < input.length; i++) {
+
+            const charCode = input.charCodeAt(i);
+            const curChar = input.charAt(i);
+
+            if (prev === "M-^") {
+                if (charCode > 63 && charCode <= 95) {
+                    bytes.push(charCode + 64);
+                } else if (charCode === 63) {
+                    bytes.push(255);
+                } else {
+                    bytes.push(77, 45, 94, charCode);
+                }
+                prev = "";
+            } else if (prev === "M-") {
+                if (curChar === "^") {
+                    prev = prev + "^";
+                } else if (charCode >= 32 && charCode <= 126) {
+                    bytes.push(charCode + 128);
+                    prev = "";
+                } else {
+                    bytes.push(77, 45, charCode);
+                    prev = "";
+                }
+            } else if (prev === "M") {
+                if (curChar === "-") {
+                    prev = prev + "-";
+                } else {
+                    bytes.push(77, charCode);
+                    prev = "";
+                }
+            } else if (prev === "^") {
+                if (charCode > 63 && charCode <= 126) {
+                    bytes.push(charCode - 64);
+                } else if (charCode === 63) {
+                    bytes.push(127);
+                } else {
+                    bytes.push(94, charCode);
+                }
+                prev = "";
+            } else {
+                if (curChar === "M") {
+                    prev = "M";
+                } else if (curChar === "^") {
+                    prev = "^";
+                } else {
+                    bytes.push(charCode);
+                }
+            }
+
+        }
+        return bytes;
+    }
+
+}
+
+export default CaretMdecode;