To Python bytes

src/core/config/Categories.json

@@ -53,7 +53,8 @@
             "To MessagePack",
             "From MessagePack",
             "To Braille",
-            "From Braille"
+            "From Braille",
+            "To Python bytes"
         ]
     },
     {

src/core/operations/ToPythonBytes.mjs

@@ -0,0 +1,85 @@
+/**
+ * @author edouard hinard []
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import OperationError from "../errors/OperationError";
+
+/**
+ * To Python bytes operation
+ */
+class ToPythonBytes extends Operation {
+
+    /**
+     * ToPythonBytes constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "To Python bytes";
+        this.module = "Default";
+        this.description = "Converts the input data to Python bytes literal.<br><br>e.g. 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 = [];
+    }
+
+    /**
+     * @param {ArrayBuffer} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        let data = new Uint8Array(input);
+        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 ToPythonBytes;