feat: implement base64 utility functions atob/btoa, taken implementations from core-js

Author: Xmader

python/pythonmonkey/__init__.py

@@ -6,5 +6,6 @@
 import importlib.metadata
 __version__= importlib.metadata.version(__name__)
 
-# Load the module by default to make `console` globally available
+# Load the module by default to make `console`/`atob`/`btoa` globally available
 require("console")
+require("base64")

python/pythonmonkey/builtin_modules/base64.js

@@ -0,0 +1,93 @@
+/**
+ * @file     base64.js
+ * @author   Tom Tang <[email protected]>
+ * @date     May 2023
+ */
+
+/*!
+ * Modified from https://github.com/zloirock/core-js/blob/44cf9e8/packages/core-js/modules/web.atob.js and
+ *               https://github.com/zloirock/core-js/blob/44cf9e8/packages/core-js/modules/web.btoa.js
+ * core-js
+ * MIT License, Copyright (c) 2014-2023 Denis Pushkarev
+ */
+
+var uncurryThis = function (fn) {
+  // Modified from https://github.com/zloirock/core-js/blob/44cf9e8/packages/core-js/internals/
+  return function () {
+    return Function.prototype.call.apply(fn, arguments);
+  };
+};
+var toString = (arg) => String(arg);
+var hasOwn = Object.hasOwn;
+
+// Taken from https://github.com/zloirock/core-js/blob/44cf9e8/packages/core-js/internals/validate-arguments-length.js
+function validateArgumentsLength(passed, required) {
+  if (passed < required) throw TypeError('Not enough arguments');
+  return passed;
+};
+
+// Taken from https://github.com/zloirock/core-js/blob/44cf9e8/packages/core-js/internals/base64-map.js
+var itoc = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
+var ctoi = {};
+for (var index = 0; index < 66; index++) ctoi[itoc.charAt(index)] = index;
+
+var disallowed = /[^\d+/a-z]/i;
+var whitespaces = /[\t\n\f\r ]+/g;
+var finalEq = /[=]{1,2}$/;
+
+var fromCharCode = String.fromCharCode;
+var charAt = uncurryThis(''.charAt);
+var charCodeAt = uncurryThis(''.charCodeAt);
+var replace = uncurryThis(''.replace);
+var exec = uncurryThis(disallowed.exec);
+
+function atob(data) {
+  validateArgumentsLength(arguments.length, 1);
+  var string = replace(toString(data), whitespaces, '');
+  var output = '';
+  var position = 0;
+  var bc = 0;
+  var chr, bs = 0;
+  if (string.length % 4 == 0) {
+    string = replace(string, finalEq, '');
+  }
+  if (string.length % 4 == 1 || exec(disallowed, string)) {
+    // throw new (getBuiltIn('DOMException'))('The string is not correctly encoded', 'InvalidCharacterError');
+    throw new Error('InvalidCharacterError: The string is not correctly encoded');
+  }
+  while (chr = charAt(string, position++)) {
+    if (hasOwn(ctoi, chr)) {
+      bs = bc % 4 ? bs * 64 + ctoi[chr] : ctoi[chr];
+      if (bc++ % 4) output += fromCharCode(255 & bs >> (-2 * bc & 6));
+    }
+  } return output;
+}
+
+function btoa(data) {
+  validateArgumentsLength(arguments.length, 1);
+  var string = toString(data);
+  var output = '';
+  var position = 0;
+  var map = itoc;
+  var block = 0, charCode;
+  while (charAt(string, position) || (map = '=', position % 1)) {
+    charCode = charCodeAt(string, position += 3 / 4);
+    if (charCode > 0xFF) {
+      // throw new (getBuiltIn('DOMException'))('The string contains characters outside of the Latin1 range', 'InvalidCharacterError');
+      throw new Error('InvalidCharacterError: The string contains characters outside of the Latin1 range');
+    }
+    block = block << 8 | charCode;
+    output += charAt(map, 63 & block >> 8 - position % 1 * 8);
+  } return output;
+}
+
+// Make `atob`/`btoa` globally available
+if (!globalThis["atob"]) {
+  globalThis["atob"] = atob;
+}
+if (!globalThis["btoa"]) {
+  globalThis["btoa"] = btoa;
+}
+
+exports.atob = atob;
+exports.btoa = btoa;