Show me the actual regex implementation that escapes special characters.

The actual regex implementation is in [index.js:L9-L10]:

return string
	.replace(/[|\\{}()[\]^$+*?.]/g, '\\$&')
	.replace(/-/g, '\\x2d');

This implementation uses two sequential regex replacements:

1. First replace (/[|\\{}()[\]^$+*?.]/g): Escapes the characters | \ { } ( ) [ ] ^ $ + * ? . by prefixing them with a backslash (\\$&). This handles most RegExp special characters.

2. Second replace (/-/g → '\\x2d'): Escapes the hyphen - using hex escape notation (\x2d) instead of a simple backslash. According to the comment in [index.js:L7-L8], this approach is used "when the simpler form would be disallowed by Unicode patterns' stricter grammar."

The tests in [test.js:L11-L14] confirm this special handling for hyphens to maintain compatibility with PCRE and the Unicode flag.

FOLLOW_UPS:

• Why does the hyphen use hex escape instead of backslash?
• Which characters are considered RegExp special characters?
• How does this handle Unicode characters like emoji?