buffer: optimize Buffer.byteLength

Buffer.byteLength is important for speed because it is called whenever a
new Buffer is created from a string.

This commit optimizes Buffer.byteLength execution by:
- moving base64 length calculation into JS-land, which is now much
  faster
- remove redundant code and streamline the UTF8 length calculation

It also adds a benchmark and better tests.

PR-URL: https://github.com/nodejs/io.js/pull/1713
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

1 files changed, 46 insertions, 0 deletions

diff --git a/test/parallel/test-buffer-bytelength.js b/test/parallel/test-buffer-bytelength.js
new file mode 100644
index 0000000000..c136c62808
--- /dev/null
+++ b/test/parallel/test-buffer-bytelength.js
@@ -0,0 +1,46 @@
+'use strict';
+
+var common = require('../common');
+var assert = require('assert');
+var Buffer = require('buffer').Buffer;
+
+// coerce values to string
+assert.equal(Buffer.byteLength(32, 'raw'), 2);
+assert.equal(Buffer.byteLength(NaN, 'utf8'), 3);
+assert.equal(Buffer.byteLength({}, 'raws'), 15);
+assert.equal(Buffer.byteLength(), 9);
+
+// special case: zero length string
+assert.equal(Buffer.byteLength('', 'ascii'), 0);
+assert.equal(Buffer.byteLength('', 'HeX'), 0);
+
+// utf8
+assert.equal(Buffer.byteLength('∑éllö wørl∂!', 'utf-8'), 19);
+assert.equal(Buffer.byteLength('κλμνξο', 'utf8'), 12);
+assert.equal(Buffer.byteLength('挵挶挷挸挹', 'utf-8'), 15);
+assert.equal(Buffer.byteLength('𠝹𠱓𠱸', 'UTF8'), 12);
+// without an encoding, utf8 should be assumed
+assert.equal(Buffer.byteLength('hey there'), 9);
+assert.equal(Buffer.byteLength('𠱸挶νξ#xx :)'), 17);
+assert.equal(Buffer.byteLength('hello world', ''), 11);
+// it should also be assumed with unrecognized encoding
+assert.equal(Buffer.byteLength('hello world', 'abc'), 11);
+assert.equal(Buffer.byteLength('ßœ∑≈', 'unkn0wn enc0ding'), 10);
+
+// base64
+assert.equal(Buffer.byteLength('aGVsbG8gd29ybGQ=', 'base64'), 11);
+assert.equal(Buffer.byteLength('bm9kZS5qcyByb2NrcyE=', 'base64'), 14);
+assert.equal(Buffer.byteLength('aGkk', 'base64'), 3);
+assert.equal(Buffer.byteLength('bHNrZGZsa3NqZmtsc2xrZmFqc2RsZmtqcw==',
+    'base64'), 25);
+// special padding
+assert.equal(Buffer.byteLength('aaa=', 'base64'), 2);
+assert.equal(Buffer.byteLength('aaaa==', 'base64'), 3);
+
+assert.equal(Buffer.byteLength('Il était tué'), 14);
+assert.equal(Buffer.byteLength('Il était tué', 'utf8'), 14);
+assert.equal(Buffer.byteLength('Il était tué', 'ascii'), 12);
+assert.equal(Buffer.byteLength('Il était tué', 'binary'), 12);
+['ucs2', 'ucs-2', 'utf16le', 'utf-16le'].forEach(function(encoding) {
+  assert.equal(24, Buffer.byteLength('Il était tué', encoding));
+});