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buffer: speed up Buffer.isEncoding() method #5256

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buffer: speed up Buffer.isEncoding() method #5256

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43 changes: 43 additions & 0 deletions benchmark/buffers/buffer-is-encoding.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,43 @@
'use strict';

const common = require('../common.js');

const bench = common.createBenchmark(main, {
encoding: [ 'hex',
'utf8',
'utf-8',
'ascii',
'binary',
'base64',
'ucs2',
'ucs-2',
'utf16le',
'utf-16le',
'HEX',
'UTF8',
'UTF-8',
'ASCII',
'BINARY',
'BASE64',
'UCS2',
'UCS-2',
'UTF16LE',
'UTF-16LE',
'utf9',
'utf-7',
'utf17le',
'utf-17le',
'Unicode-FTW',
'new gnu gun'
]
});

function main(conf) {
var encoding = conf.encoding;
bench.start();
var n = 1024 * 1024;
for (let i = 0; i < n; i++) {
Buffer.isEncoding(encoding);
}
bench.end(n);
}
145 changes: 124 additions & 21 deletions lib/buffer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -185,30 +185,133 @@ Buffer.compare = function compare(a, b) {


Buffer.isEncoding = function(encoding) {
var loweredCase = false;
for (;;) {
switch (encoding) {
case 'hex':
case 'utf8':
case 'utf-8':
case 'ascii':
case 'binary':
case 'base64':
case 'ucs2':
case 'ucs-2':
case 'utf16le':
case 'utf-16le':
if (typeof encoding !== 'string')
encoding = '' + encoding;

// only allow:
// 'hex', 'utf8', 'utf-8', 'ascii', 'binary', 'base64',
// 'ucs2', 'ucs-2', 'utf16le', 'utf-16le'

switch (encoding.length) {
case 3: // hex
var code0 = encoding.charCodeAt(0);
var code1 = encoding.charCodeAt(1);
var code2 = encoding.charCodeAt(2);
if ((code0 === 72 || code0 === 104) && // h, H
(code1 === 69 || code1 === 101) && // e, E
(code2 === 88 || code2 === 120)) { // x, X
return true;

default:
if (loweredCase)
return false;
encoding = ('' + encoding).toLowerCase();
loweredCase = true;
}
}

break;
case 4: // utf8/ucs2
var code0 = encoding.charCodeAt(0);
var code1 = encoding.charCodeAt(1);
var code2 = encoding.charCodeAt(2);
var code3 = encoding.charCodeAt(3);
if ((code0 === 85 || code0 === 117)) { // u, U
if ((code1 === 84 || code1 === 116) && // t, T
(code2 === 70 || code2 === 102) && // f, F
code3 === 56) { // 8
return true;
} else if ((code1 === 67 || code1 === 99) && // c, C
(code2 === 83 || code2 === 115) && // s, S
code3 === 50) { // 2
return true;
}
}
break;
case 5: // utf-8/ucs-2/ascii
var code0 = encoding.charCodeAt(0);
var code1 = encoding.charCodeAt(1);
var code2 = encoding.charCodeAt(2);
var code3 = encoding.charCodeAt(3);
var code4 = encoding.charCodeAt(4);
if ((code0 === 85 || code0 === 117)) { // u, U
if ((code1 === 84 || code1 === 116) && // t, T
(code2 === 70 || code2 === 102) && // f, F
code3 === 45 && // -
code4 === 56) { // 8
return true;
} else if ((code1 === 67 || code1 === 99) && // c, C
(code2 === 83 || code2 === 115) && // s, S
code3 === 45 && // -
code4 === 50) { // 2
return true;
}
} else if ((code0 === 65 || code0 === 97) && // a, A
(code1 === 83 || code1 === 115) && // s, S
(code2 === 67 || code2 === 99) && // c, C
(code3 === 73 || code3 === 105) && // i, I
(code4 === 73 || code4 === 105)) { // i, I
return true;
}
break;
case 6: // binary/base64
var code0 = encoding.charCodeAt(0);
var code1 = encoding.charCodeAt(1);
var code2 = encoding.charCodeAt(2);
var code3 = encoding.charCodeAt(3);
var code4 = encoding.charCodeAt(4);
var code5 = encoding.charCodeAt(5);
if ((code0 === 66 || code0 === 98)) { // b, B
if ((code1 === 73 || code1 === 105) && // i, I
(code2 === 78 || code2 === 110) && // n, N
(code3 === 65 || code3 === 97) && // a, A
(code4 === 82 || code4 === 114) && // r, R
(code5 === 89 || code5 === 121)) { // y, Y
return true;
} else if ((code1 === 65 || code1 === 97) && // a, A
(code2 === 83 || code2 === 115) && // s, S
(code3 === 69 || code3 === 101) && // e, E
code4 === 54 && // 6
code5 === 52) { // 4
return true;
}
}
break;
case 7: // utf16le
var code0 = encoding.charCodeAt(0);
var code1 = encoding.charCodeAt(1);
var code2 = encoding.charCodeAt(2);
var code3 = encoding.charCodeAt(3);
var code4 = encoding.charCodeAt(4);
var code5 = encoding.charCodeAt(5);
var code6 = encoding.charCodeAt(6);
if ((code0 === 85 || code0 === 117) && // u, U
(code1 === 84 || code1 === 116) && // t, T
(code2 === 70 || code2 === 102) && // f, F
code3 === 49 && // 1
code4 === 54 && // 6
(code5 === 76 || code5 === 108) && // l, L
(code6 === 69 || code6 === 101)) { // e, E
return true;
}
break;
case 8: // utf-16le
var code0 = encoding.charCodeAt(0);
var code1 = encoding.charCodeAt(1);
var code2 = encoding.charCodeAt(2);
var code3 = encoding.charCodeAt(3);
var code4 = encoding.charCodeAt(4);
var code5 = encoding.charCodeAt(5);
var code6 = encoding.charCodeAt(6);
var code7 = encoding.charCodeAt(7);
if ((code0 === 85 || code0 === 117) && // u, U
(code1 === 84 || code1 === 116) && // t, T
(code2 === 70 || code2 === 102) && // f, F
code3 === 45 && // -
code4 === 49 && // 1
code5 === 54 && // 6
(code6 === 76 || code6 === 108) && // l, L
(code7 === 69 || code7 === 101)) { // e, E
return true;
}
break;
}
};

return false;
};

Buffer.concat = function(list, length) {
if (!Array.isArray(list))
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7 changes: 5 additions & 2 deletions test/parallel/test-buffer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -998,14 +998,17 @@ Buffer(Buffer(0), 0, 0);
'ucs-2',
'utf16le',
'utf-16le' ].forEach(function(enc) {
assert.equal(Buffer.isEncoding(enc), true);
assert.equal(Buffer.isEncoding(enc), true, `${enc} should be an encoding`);
});

[ 'utf9',
'utf-7',
'utf17le',
'utf-17le',
'Unicode-FTW',
'new gnu gun' ].forEach(function(enc) {
assert.equal(Buffer.isEncoding(enc), false);
assert.equal(Buffer.isEncoding(enc), false,
`${enc} should not an encoding`);
});


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