On Mon, Mar 20, 2017 at 9:19 AM, Dmitry Soshnikov < [email protected]> wrote:
> > On Mon, Mar 20, 2017 at 8:36 AM Jason Orendorff <[email protected]> > wrote: > >> The second approach, hands down. >> >> 1. With the first approach, you're setting up a situation where it's very >> easy to write buggy analysis code: if you forget to check `re.quantifier` >> anywhere, your code will run, but you have a bug. Much easier to only have >> to check `re.type`. >> >> 2. If you have a regexp `re` and you want to programmatically build a >> regexp that matches one or more repetitions of it, it's much easier to >> write `{type: '+', expression: re}` than to have to examine `re.quantifier` >> and (if it's already present) figure out how to modify it. >> >> 3. With the first approach, you don't have to represent `(?:)` group in >> the AST at all (rather like how Esprima drops redundant parentheses). With >> the latter, I think you have to, because it's possible for a single regexp >> "node" to have multiple quantifiers: `/(?:\d{4,6})?/` >> >> To me this is not even a question. >> > > Jason, thanks; all good points! And I came to similar conclusions while > was experimenting. Wanted to double-check, thanks for confirming. > > OK, I added docs and specs for AST node types, which can also be a good learning material: https://www.npmjs.com/package/regexp-tree#ast-nodes-specification Any feedback is welcome! Parsing regexes is fun :) with this you realize that these are completely valid regexp patterns: ``` /^^^^$$$/.test(''); // true /$^/.test(''); // true /[---]/.test('-'); // true, a range from '-' to '-'! /[-]/.test('-'); // true ``` Dmitry
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
