generalization: 'To Byte String Literal'. Python implemented. More to come...

src/core/operations/ToByteStringLiteral.mjs

@@ -0,0 +1,106 @@
+/**
+ * @author edouard hinard []
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+
+const LANGUAGES = {
+    "Python": "python",
+};
+
+/**
+ * To Byte String Literal operation
+ */
+class ToByteStringLiteral extends Operation {
+
+    /**
+     * ToByteStringLiteral constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "To Byte String Literal";
+        this.module = "Default";
+        this.description = "Converts the input data to byte string literal in common languages.<br><br>e.g. for python, the UTF-8 encoded string <code>ça ma couté 20€</code> becomes <code>b'\\xc3\\xa7a ma cout\\xc3\\xa9 20\\xe2\\x82\\xac'</code>";
+        this.infoURL = "https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals";
+        this.inputType = "ArrayBuffer" ;
+        this.outputType = "string";
+        this.args = [
+            {
+                "name": "Language",
+                "type": "option",
+                "value": Object.keys(LANGUAGES)
+            },
+        ];
+    }
+
+    /**
+     * @param {ArrayBuffer} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const data = new Uint8Array(input);
+        const language = args[0];
+        if (language === "python") {
+            return this.python(data);
+        }
+        return "";
+    }
+
+    /**
+     * @param {Uint8Array} data
+     * @returns {string}
+     */
+    python(data) {
+        if (!data) return "b''";
+
+        // First pass to decide which quote to use
+        //  single quote is prefered
+        let onlySingleQuote = false;
+        for (let i = 0; i < data.length; i++) {
+            if (data[i] === 0x22) { // 0x22 <-> "
+                onlySingleQuote = false;
+                break;
+            }
+            if (data[i] === 0x27) { // 0x27 <-> '
+                onlySingleQuote = true;
+            }
+        }
+        let singleQuoted = true;
+        if (onlySingleQuote) {
+            singleQuoted = false;
+        }
+
+        // Second pass to convert byte array in Python bytes literal
+        let output = "";
+        for (let i = 0; i < data.length; i++) {
+            if (data[i] === 0x09) {
+                output += "\\t";
+            } else if (data[i] === 0x0a) {
+                output += "\\n";
+            } else if (data[i] === 0x0d) {
+                output += "\\r";
+            } else if (data[i] === 0x22 && !singleQuoted) {
+                output += '\\"';
+            } else if (data[i] === 0x27 && singleQuoted) {
+                output += "\\'";
+            } else if (data[i] === 0x5c) {
+                output += "\\";
+            } else if (data[i] < 0x20 || data[i] > 0x7e) {
+                output += "\\x" + data[i].toString(16).padStart(2, 0);
+            } else {
+                output += String.fromCharCode(data[i]);
+            }
+        }
+        if (singleQuoted) {
+            return "b'" + output + "'";
+        } else {
+            return 'b"' + output + '"';
+        }
+    }
+}
+
+export default ToByteStringLiteral;