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util: improve format() performance further

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Replacing the regexp and replace function with a loop improves
performance by ~60-200%.

PR-URL: https://github.com/nodejs/node/pull/5360
Reviewed-By: James M Snell <jasnell@gmail.com>
This commit is contained in:
Brian White 2016-02-22 20:47:20 -05:00 committed by Evan Lucas
parent 8d72b0d291
commit c490b8ba54
1 changed files with 47 additions and 22 deletions
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69
lib/util.js
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@ -17,7 +17,6 @@ function tryStringify(arg) {
} }
} }
const formatRegExp = /%[sdj%]/g;
exports.format = function(f) { exports.format = function(f) {
if (typeof f !== 'string') { if (typeof f !== 'string') {
const objects = new Array(arguments.length); const objects = new Array(arguments.length);
@ -27,30 +26,56 @@ exports.format = function(f) {
return objects.join(' '); return objects.join(' ');
} }
if (arguments.length === 1) return f; var argLen = arguments.length;
const len = arguments.length; if (argLen === 1) return f;
const args = new Array(len);
var i;
for (i = 0; i < len; i++) {
args[i] = arguments[i];
}
i = 1; var str = '';
var str = f.replace(formatRegExp, function(x) { var a = 1;
if (x === '%%') return '%'; var lastPos = 0;
if (i >= len) return x; for (var i = 0; i < f.length;) {
switch (x) { if (f.charCodeAt(i) === 37/*'%'*/ && i + 1 < f.length) {
case '%s': return String(args[i++]); switch (f.charCodeAt(i + 1)) {
case '%d': return Number(args[i++]); case 100: // 'd'
case '%j': return tryStringify(args[i++]); if (a >= argLen)
// falls through break;
default: if (lastPos < i)
return x; str += f.slice(lastPos, i);
str += Number(arguments[a++]);
lastPos = i = i + 2;
continue;
case 106: // 'j'
if (a >= argLen)
break;
if (lastPos < i)
str += f.slice(lastPos, i);
str += tryStringify(arguments[a++]);
lastPos = i = i + 2;
continue;
case 115: // 's'
if (a >= argLen)
break;
if (lastPos < i)
str += f.slice(lastPos, i);
str += String(arguments[a++]);
lastPos = i = i + 2;
continue;
case 37: // '%'
if (lastPos < i)
str += f.slice(lastPos, i);
str += '%';
lastPos = i = i + 2;
continue;
} }
}); }
while (i < len) { ++i;
const x = args[i++]; }
if (lastPos === 0)
str = f;
else if (lastPos < f.length)
str += f.slice(lastPos);
while (a < argLen) {
const x = arguments[a++];
if (x === null || (typeof x !== 'object' && typeof x !== 'symbol')) { if (x === null || (typeof x !== 'object' && typeof x !== 'symbol')) {
str += ' ' + x; str += ' ' + x;
} else { } else {