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util: improve getStringWidth performance #33674

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util: improve getStringWidth performance #33674

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util: improve getStringWidth performance 
This makes sure the common path does not normalize the input string.
It's only required for characters that are outside of the ASCII range.

Signed-off-by: Ruben Bridgewater <ruben@bridgewater.de>
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@BridgeAR
BridgeAR committed May 31, 2020
commit 5e1fe3fa3d234e2417cf2606071350f1dbb03a47
16 changes: 6 additions & 10 deletions lib/internal/util/inspect.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1960,13 +1960,6 @@ function formatWithOptionsInternal(inspectOptions, ...args) {
return str;
}

function prepareStringForGetStringWidth(str, removeControlChars) {
str = str.normalize('NFC');
if (removeControlChars)
str = stripVTControlCharacters(str);
return str;
}

if (internalBinding('config').hasIntl) {
const icu = internalBinding('icu');
// icu.getStringWidth(string, ambiguousAsFullWidth, expandEmojiSequence)
Expand All @@ -1977,13 +1970,14 @@ if (internalBinding('config').hasIntl) {
getStringWidth = function getStringWidth(str, removeControlChars = true) {
let width = 0;

str = prepareStringForGetStringWidth(str, removeControlChars);
if (removeControlChars)
str = stripVTControlCharacters(str);
for (let i = 0; i < str.length; i++) {
// Try to avoid calling into C++ by first handling the ASCII portion of
// the string. If it is fully ASCII, we skip the C++ part.
const code = str.charCodeAt(i);
if (code >= 127) {
width += icu.getStringWidth(str.slice(i));
width += icu.getStringWidth(str.slice(i).normalize('NFC'));
break;
}
width += code >= 32 ? 1 : 0;
Expand All @@ -1997,7 +1991,9 @@ if (internalBinding('config').hasIntl) {
getStringWidth = function getStringWidth(str, removeControlChars = true) {
let width = 0;

str = prepareStringForGetStringWidth(str, removeControlChars);
if (removeControlChars)
str = stripVTControlCharacters(str);
str = str.normalize('NFC');
for (const char of str) {
const code = char.codePointAt(0);
if (isFullWidthCodePoint(code)) {
Expand Down