Tokenizer makes negative lookbehind regex invalid

[towc]

changing the keywordMapper rule from [a-zA-Z_][a-zA-Z0-9_$]*\\b to (?<!\\s*\\.)([a-zA-Z_][a-zA-Z0-9_$]*)(?!\\s*\\.) in the pgSQL mode in https://ace.c9.io/tool/mode_creator.html tells you that the compiled regex is invalid, in chrome.

The (?<!\\s*\\.) is being transformed into (?:?<!\\s*\\.)

What I'm trying to achieve is to not get the second select in select xyz.select from s3.xyz" highlighted as a keyword, while maintaining s3as an identifier, rather than being split into an identifiersand numerical constant3`.

For now, I think I'll patch the tokenizer locally, to not mangle the lookbehind

[towc]

It seems all that's needed is to replace [:=!] with [:=!<] in https://github.com/ajaxorg/ace/blob/master/lib/ace/tokenizer.js#L179