Question

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Division/RegExp conflict while tokenizing Javascript

I’m writing a JS lexer for fun and there’s just one piece that’s missing: the part that can chew in regexes.

Take for instance the following valid JS piece of code: /ab+c/;

How can a JS lexer know whether it’s dealing with a regex or with
[Operator('/'), Identifier('ab'), Operator('+'), Identifier('c'), Operator('/'), Semicolon] ?

Answer 1

You would need to implement a Lexical grammar which included parsing regex. According to ECMA Script documenation, “A RegExp grammar for ECMAScript is given in 15.10“:

"The form and functionality of regular expressions is modeled 
after the regular expression facility in the Perl 5 programming language."

See also: ECMAScript Lexical Conventions