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url: reduce deplicated codes in autoEscapeStr #18613

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url: reduce deplicated codes in autoEscapeStr #18613

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url: reduce deplicated codes in `autoEscapeStr`
starkwang Feb 7, 2018
ba9427c
[squash]fix performance regression
starkwang Feb 7, 2018
943d3a9
add benchmark
starkwang Feb 7, 2018
9db55c5
use array
starkwang Feb 7, 2018
2b82afc
use dense array
starkwang Feb 22, 2018
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[squash]fix performance regression
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@starkwang
starkwang committed Feb 7, 2018
commit ba9427c9555be90122e2ea054218b0562458ce09
38 changes: 26 additions & 12 deletions lib/url.js
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Original file line number Diff line number Diff line change
Expand Up @@ -442,25 +442,39 @@ function validateHostname(self, rest, hostname) {
// Automatically escape all delimiters and unwise characters from RFC 2396.
// Also escape single quotes in case of an XSS attack.
// Return the escaped string.
const escapedCharacters = {
'\t': '%09', '\n': '%0A', '\r': '%0D', ' ': '%20',
'"': '%22', '\'': '%27', '<': '%3C', '>': '%3E',
'\\': '%5C', '^': '%5E', '`': '%60', '{': '%7B',
'|': '%7C', '}': '%7D'
const escapedCharacterCodes = {
9: '%09', 10: '%0A', 13: '%0D', 32: '%20',
34: '%22', 39: '%27', 60: '%3C', 62: '%3E',
92: '%5C', 94: '%5E', 96: '%60', 123: '%7B',
124: '%7C', 125: '%7D'
};
function autoEscapeStr(rest) {
var escaped = '';
var lastEscapedPos = 0;
for (var i = 0; i < rest.length; ++i) {
// Manual switching is faster than using a Map/Object.
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@joyeecheung joyeecheung Feb 7, 2018 •
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Isn't the whole point of having these switch statements to avoid the overhead of accessing a Map/object? (although that looks quite Crankshaftscript-ish so I doubt if the comment here still holds)...if we are going to access an object anyway, then the switch statements can just be replaced with something like const code = escapedCharacterCodes[rest.charCodeAt(i)]; if (code)..., and this comment can be removed.

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That's exactly what I do in the first commit, but it causes ~10% performance regression in url.parse.

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@bmeurer Would you be interested in taking a look at this?

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Intuitively I'd suggest to go with an array instead of an object literal. Did you try with an array?

// `escaped` contains substring up to the last escaped character.
var escapedChar = escapedCharacters[rest[i]];
if (escapedChar) {
// Concat if there are ordinary characters in the middle.
if (i > lastEscapedPos)
escaped += rest.slice(lastEscapedPos, i);
escaped += escapedChar;
lastEscapedPos = i + 1;
var code = rest.charCodeAt(i);
switch (code) {
case 9: // '\t'
case 10: // '\n'
case 13: // '\r'
case 32: // ' '
case 34: // '"'
case 39: // '\''
case 60: // '<'
case 62: // '>'
case 92: // '\\'
case 94: // '^'
case 96: // '`'
case 123: // '{'
case 124: // '|'
case 125: // '}'
// Concat if there are ordinary characters in the middle.
if (i > lastEscapedPos)
escaped += rest.slice(lastEscapedPos, i);
escaped += escapedCharacterCodes[code];
lastEscapedPos = i + 1;
}
}
if (lastEscapedPos === 0) // Nothing has been escaped.
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