[feature request] Expose libregex's parsing/compiling internals #29
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Should be closed - see #23 |
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So I've gotten more requests to do this and I'm also somewhat interested in it myself. Regex parsing is not easy and it has uses beyond the matching supported in crate. @alexcrichton I know you were kind of down on this last time we talked about it, but what if we split the parsing into its own separate crate? (In this repository.) That way, we can keep the main |
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Creating a separate crate for the parser sounds like a great idea to me! |
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I'm currently working on this in the |
This commit introduces a new `regex-syntax` crate that provides a regular expression parser and an abstract syntax for regular expressions. As part of this effort, the parser has been rewritten and has grown a substantial number of tests. The `regex` crate itself hasn't changed too much. I opted for the smallest possible delta to get it working with the new regex AST. In most cases, this simplified code because it no longer has to deal with unwieldy flags. (Instead, flag information is baked into the AST.) Here is a list of public facing non-breaking changes: * A new `regex-syntax` crate with a parser, regex AST and lots of tests. This closes #29 and fixes #84. * A new flag, `x`, has been added. This allows one to write regexes with insignificant whitespace and comments. * Repetition operators can now be directly applied to zero-width matches. e.g., `\b+` was previously not allowed but now works. Note that one could always write `(\b)+` previously. This change is mostly about lifting an arbitrary restriction. And a list of breaking changes: * A new `Regex::with_size_limit` constructor function, that allows one to tweak the limit on the size of a compiled regex. This fixes #67. The new method isn't a breaking change, but regexes that exceed the size limit (set to 10MB by default) will no longer compile. To fix, simply call `Regex::with_size_limit` with a bigger limit. * Capture group names cannot start with a number. This is a breaking change because regexes that previously compiled (e.g., `(?P<1a>.)`) will now return an error. This fixes #69. * The `regex::Error` type has been changed to reflect the better error reporting in the `regex-syntax` crate, and a new error for limiting regexes to a certain size. This is a breaking change. Most folks just call `unwrap()` on `Regex::new`, so I expect this to have minimal impact. Closes #29, #67, #69, #79, #84. [breaking-change]
Thursday Nov 06, 2014 at 19:54 GMT
For earlier discussion, see rust-lang/rust#18710
This issue was labelled with: in the Rust repository
I was looking at implementing something similar to this - a trigram-index-aided search. I'd rather not reproduce the code necessary to parse the regex, considering it already lives in libregex. It'd be nice if the parsing/compiling was exposed for use - perhaps similar to how Go does it with their
regexpandregexp/syntaxpackages.cc @BurntSushi
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