gitolite/doc/extras/regex.mkd

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2012-03-16 02:54:47 +01:00
# extremely brief regex overview
Regexes are powerful. Gitolite uses that power as much as it can. If you
can't handle that power, hire someone who can and become a manager.
That said, here's a very quick overview of the highlights.
`^` and `$` are called "anchors". They anchor the match to the beginning and
end of the string respectively.
^foo matches any string starting with 'foo'
foo$ matches any string ending with 'foo'
^foo$ matches exact string 'foo'.
To be precise, the last one is "any string starting and ending with *the same*
'foo'". "foofoo" does not match.
`[0-9]` is an example of a character class; it matches any single digit.
`[a-z]` matches any lower case alpha, and `[0-9a-f]` is the range of hex
characters. You should now guess what `[a-zA-Z0-9_]` does.
`.` (the period) is special -- it matches any character. If you want to match
an actual period, you need to say `\.`.
`*`, `?`, and `+` are quantifiers. They apply to the previous token. `a*`
means "zero or more 'a' characters". Similarly `a+` means "one or more", and
`a?` means "zero or one".
As a result, `.*` means "any number (including zero) of any character".
The previous token need not be a single character; you can use parens to make
it longer. `(foo)+` matches one or more "foo", (like "foo", "foofoo",
"foofoofoo", etc.)