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module: simpler shebang function
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This simplifies the shebang function significantly. Before, it was
optimized for two characters input. Any module actually parsed should
however have more characters than just the shebang.
The performance stays the same as before.

PR-URL: #26266
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
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BridgeAR authored and addaleax committed Mar 1, 2019
1 parent 0c8e9ee commit 2a66cd3
Showing 1 changed file with 11 additions and 32 deletions.
43 changes: 11 additions & 32 deletions lib/internal/modules/cjs/helpers.js
Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,6 @@ const path = require('path');
const { pathToFileURL } = require('internal/url');
const { URL } = require('url');

const {
CHAR_LINE_FEED,
CHAR_CARRIAGE_RETURN,
CHAR_EXCLAMATION_MARK,
CHAR_HASH,
} = require('internal/constants');

// Invoke with makeRequireFunction(module) where |module| is the Module object
// to use as the context for the require() function.
function makeRequireFunction(mod) {
Expand Down Expand Up @@ -67,31 +60,17 @@ function stripBOM(content) {
*/
function stripShebang(content) {
// Remove shebang
var contLen = content.length;
if (contLen >= 2) {
if (content.charCodeAt(0) === CHAR_HASH &&
content.charCodeAt(1) === CHAR_EXCLAMATION_MARK) {
if (contLen === 2) {
// Exact match
content = '';
} else {
// Find end of shebang line and slice it off
var i = 2;
for (; i < contLen; ++i) {
var code = content.charCodeAt(i);
if (code === CHAR_LINE_FEED || code === CHAR_CARRIAGE_RETURN)
break;
}
if (i === contLen)
content = '';
else {
// Note that this actually includes the newline character(s) in the
// new output. This duplicates the behavior of the regular expression
// that was previously used to replace the shebang line
content = content.slice(i);
}
}
}
if (content.charAt(0) === '#' && content.charAt(1) === '!') {
// Find end of shebang line and slice it off
let index = content.indexOf('\n', 2);
if (index === -1)
return '';
if (content.charAt(index - 1) === '\r')
index--;
// Note that this actually includes the newline character(s) in the
// new output. This duplicates the behavior of the regular expression
// that was previously used to replace the shebang line.
content = content.slice(index);
}
return content;
}
Expand Down

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