ESM: Ported Base58, Base and BCD operations

src/core/operations/FromBase58.mjs

@@ -0,0 +1,93 @@
+/**
+ * @author tlwr [toby@toby.codes]
+ * @copyright Crown Copyright 2017
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import Utils from "../Utils";
+import OperationError from "../errors/OperationError";
+import {ALPHABET_OPTIONS} from "../lib/Base58";
+
+/**
+ * From Base58 operation
+ */
+class FromBase58 extends Operation {
+
+    /**
+     * FromBase58 constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "From Base58";
+        this.module = "Default";
+        this.description = "Base58 (similar to Base64) is a notation for encoding arbitrary byte data. It differs from Base64 by removing easily misread characters (i.e. l, I, 0 and O) to improve human readability.<br><br>This operation decodes data from an ASCII string (with an alphabet of your choosing, presets included) back into its raw form.<br><br>e.g. <code>StV1DL6CwTryKyV</code> becomes <code>hello world</code><br><br>Base58 is commonly used in cryptocurrencies (Bitcoin, Ripple, etc).";
+        this.inputType = "string";
+        this.outputType = "byteArray";
+        this.args = [
+            {
+                "name": "Alphabet",
+                "type": "editableOption",
+                "value": ALPHABET_OPTIONS
+            },
+            {
+                "name": "Remove non-alphabet chars",
+                "type": "boolean",
+                "value": true
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {byteArray}
+     */
+    run(input, args) {
+        let alphabet = args[0] || ALPHABET_OPTIONS[0].value;
+        const removeNonAlphaChars = args[1] === undefined ? true : args[1],
+            result = [0];
+
+        alphabet = Utils.expandAlphRange(alphabet).join("");
+
+        if (alphabet.length !== 58 ||
+            [].unique.call(alphabet).length !== 58) {
+            throw new OperationError("Alphabet must be of length 58");
+        }
+
+        if (input.length === 0) return [];
+
+        [].forEach.call(input, function(c, charIndex) {
+            const index = alphabet.indexOf(c);
+
+            if (index === -1) {
+                if (removeNonAlphaChars) {
+                    return;
+                } else {
+                    throw new OperationError(`Char '${c}' at position ${charIndex} not in alphabet`);
+                }
+            }
+
+            let carry = result[0] * 58 + index;
+            result[0] = carry & 0xFF;
+            carry = carry >> 8;
+
+            for (let i = 1; i < result.length; i++) {
+                carry += result[i] * 58;
+                result[i] = carry & 0xFF;
+                carry = carry >> 8;
+            }
+
+            while (carry > 0) {
+                result.push(carry & 0xFF);
+                carry = carry >> 8;
+            }
+        });
+
+        return result.reverse();
+    }
+
+}
+
+export default FromBase58;