Add a function to escape strings for use in regular expressions #29643
Conversation
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Regexen and state machines are equivalent, of course, but I guess your objection goes beyond that. However, look at (e.g.) the Python implementation – it just uses straight-up character substitution: |
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I think the travis failure is unrelated -- maybe some temporary network issue since the failing tests are related to Sockets? We've been using a slightly simpler version (almost exactly what Python does) in an internal project without issues for a while. Are there any other inputs we should test this with? I threw a few strings containing metacharacters at it as well as some strange stuff from BLoNS and it seems to be working. |
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Hey guys, what's holding this up? It seems to have had popular demand, and I found myself re-implementing this myself lately. Also, wouldn't a better name be |
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Needs to be rebased (it's quite conflicted at this point) and reviewed. Although note that a different escaping approach was used in #23422 and we should probably use the same approach for this kind of functionality. |
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It's about 20 lines of code, include documentation, it should be fairly easy to merge or just rewrite. I would do it myself, but I don't know much about Julia's conventions yet (but I'm willing to do it with guidance). |
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It seems it might need to be replaced, if it is to conform to #23422? |
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There’s also the issue I mentioned with my original code: We might not want to use |
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| ## escaping ## | ||
| """ | ||
| regex_escape(s::AbstractString) |
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Probably better call this escape_regex, for consistency with escape_string?
| The `regex_escape` function allows you to escape a string for use in constructing a regular | ||
| expression. All whitespace and PCRE metacharacters are escaped. | ||
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| ```julia-repl |
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I think #31989 is further along now, I'll close this PR in favor of that |
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One disadvantage of dropping this for #31989 is that we no longer cover the original functionality, of producing a string where regex stuff is escaped. It only covers the cases where you want a fully formed regex, which isn’t what I needed, and which isn’t what other languages do. The new functionality of composing regexen etc. helps, of course, but there may still be cases where you’ll want to simply escape the various character sequences without actually producing a regex object, in which case you’d have to reimplement this. |
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@mlhetland Good point -- I should have looked more closely at that PR. |
| ``` | ||
| """ | ||
| function regex_escape(s::AbstractString) | ||
| res = replace(s, r"([()[\]{}?*+\-|^\$\\.&~#\s=!<>|:])" => s"\\\1") |
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why =!<>|: (which aren't in the python list)?
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I believe my original was based on PHP, but adding some precautionary characters from Python, and escaping whitespace.
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(But I haven’t looked at wrap_string. Documenting that might be a reasonable alternative. 🤷♂️)
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(My comments end with this version, BTW.)
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Seems like wrap_string uses the Perl strategy (with \Q)? I just thought that was overkill, but given that it’s already used, that might be the way to go, dropping this version. (Just my two cents.)
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Any updates on this? Very short function, but nontrivial to get it right. |
This uses the implementation from @mlhetland that was mentioned in #6124.