/* d.o transcode * v. 0.2 released 2010-05-09 * docs @ http://code.drostie.org/library/transcode * * This function was written by Chris Drost of drostie.org, and he hereby dedicates it into the * public domain: it has no copyright. It is provided with NO WARRANTIES OF ANY KIND. * I do humbly request that you provide me some sort of credit if you use it; but I leave that * choice up to you. */ "use strict"; /*global d */ /*jslint white: true, onevar: true, undef: true, nomen: true, eqeqeq: true, plusplus: true, newcap: true, immed: true, strict: true, bitwise: false, regexp: false */ d.o.library({ name: "d.o transcode", version: "0.2", docs: "http://code.drostie.org/d.o/transcode", depends: [], fn: function (lib) { var lib64, regex, hexify, // utility methods transform_lib, // the currently defined transforms error, validate; // error-throwing methods. // simple error-handling functions error = function (message, meta) { switch (typeof meta) { case "undefined": break; case "number": case "string": message += ": " + meta; break; default: message += ": (see error.meta)"; break; } var v = new SyntaxError(message); v.meta = meta; throw v; }; validate = function (condition, message, meta) { if (! condition) { error(message, meta); } }; // utilities used in the transform_lib lib64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; hexify = function (array) { for (var i = 0; i < array.length; i += 1) { array[i] = array[i].toString(16); if (array[i].length === 1) { array[i] = "0" + array[i]; } } }; regex = { b64: /^[a-z0-9+\/]*(|=|==)$/i, equals: /[=]/g, hex_check: /[^a-f0-9]/i, whitespace: /[\n\s]+/g }; transform_lib = { "array": { "base64": function (bytes) { var padding, output, i, n; output = ""; padding = 3 - bytes.length % 3; padding = padding === 3 ? 0 : padding; while (bytes.length % 3 !== 0) { bytes.push(0); } for (i = 0; i < bytes.length; i += 3) { n = 65536 * bytes[i] + 256 * bytes[i + 1] + bytes[i + 2]; output += lib64.charAt(n >>> 18); output += lib64.charAt((n >>> 12) % 64); output += lib64.charAt((n >>> 6) % 64); output += lib64.charAt(n % 64); } output = output.substring(0, output.length - padding); output += "==".substring(0, padding); return output; }, "hex": function (bytes) { return hexify(bytes).join(""); }, "utf-8": function (bytes) { try { var encoded = "%" + hexify(bytes).join("%"); return decodeURIComponent(encoded); } catch (e) { error("Invalid utf-8 sequences", bytes); } }, "utf-16le": function (bytes) { validate(bytes.length % 2 === 0, "Invalid byte length for UTF-16", bytes.length); var i, output; output = ""; for (i = 0; i < bytes.length; i += 2) { output += String.fromCharCode(bytes[i] + 256 * bytes[i + 1]); } return output; }, "utf-16be": function (bytes) { validate(bytes.length % 2 === 0, "Invalid byte length for UTF-16", bytes.length); var i, output; output = ""; for (i = 0; i < bytes.length; i += 2) { output += String.fromCharCode(256 * bytes[i] + bytes[i + 1]); } return output; }, "utf-16": function (bytes) { validate(bytes.length > 2, "No UTF-16 byte-order marker", bytes); var bom = hexify(bytes.splice(0, 2)).join(" "); switch (bom) { case "ff fe": return transform_lib.array["utf-16le"](bytes); case "fe ff": return transform_lib.array["utf-16be"](bytes.slice(2)); default: bom = "0x" + bom.replace(" ", ", 0x"); throw error("Invalid UTF-16 byte-order marker", bom); } } }, "string": { "base64": function (string) { var array, padding, c, i; string = string.replace(regex.whitespace, ""); function code(i) { return lib64.indexOf(string.charAt(i)); } padding = regex.b64.exec(string); validate(string.length % 4 === 0 && padding !== null, "Invalid base64 string", string); padding = padding[1].length; string = string.replace(regex.equals, "A"); array = []; for (i = 0; i < string.length; i += 4) { c = 262144 * code(i) + 4096 * code(i + 1) + 64 * code(i + 2) + code(i + 3); array.push(c >>> 16); array.push((c & 0xFF00) >>> 8); array.push(c & 0xFF); } for (i = 0; i < padding; i += 1) { array.pop(); } return array; }, "hex": function (string) { string = string.replace(regex.whitespace, ""); validate(regex.hex_check.exec(string) === null, "Invalid characters in hex string"); validate(string.length % 2 === 0, "Hex string must be a multiple of 2 chars in length."); var array, i; array = []; for (i = 0; i < string.length; i += 2) { array.push(parseInt(string.substr(i, 2), 16)); } return array; }, "utf-8": function (string) { var array, i, j, s, preprocess; array = []; // we normalize the array entries by prepending a fake null preprocess = encodeURIComponent("00" + string).split("%"); for (i = 0; i < preprocess.length; i += 1) { s = preprocess[i]; array.push(parseInt(s.substring(0, 2), 16)); for (j = 2; j < s.length; j += 1) { array.push(s.charCodeAt(j)); } } return array.slice(1); //skip the fake null }, "utf-16le": function (string) { var array, i, c; array = []; for (i = 0; i < string.length; i += 1) { c = string.charCodeAt(i); array.push(c % 256); array.push(c >> 8); } return array; }, "utf-16be": function (string) { var array, i, c; array = []; for (i = 0; i < string.length; i += 1) { c = string.charCodeAt(i); array.push(c >> 8); array.push(c % 256); } return array; }, "utf-16": function (string) { return [255, 254].concat( transform_lib.string['utf-16le'](string) ); } } }; lib.transcode = function (source) { var i, n, transform, t; if (source instanceof Array) { // duplicate the array and validate that it contains bytes. source = source.slice(0); for (i = 0; i < source.length; i += 1) { n = source[i] - 0; validate(n % 1 === 0 && n >= 0 && n < 256, "Not a byte", n); } } else if (typeof source !== 'string') { error("Invalid input", source); } for (i = 1; i < arguments.length; i += 1) { // get the transform name transform = arguments[i]; validate(typeof transform === 'string', "Transform literals must be string literals", transform); transform = transform.toLowerCase(); // get the library that handles this type of source object t = source instanceof Array ? "array" : "string"; t = transform_lib[t]; // validate that the library knows what to do here: validate(t.hasOwnProperty(transform), "No such transform registered", transform); transform = t[transform]; // the source for the next step is transform(source). source = transform(source); } return source; }; } });