Hi Folks,
Is there a way ask a regex if it matches any part of a string? matches: wants an exact match, and matchesPrefix: clearly only matches a prefix. The best I found was to abuse matchesIn: and check the size of the response, but this is not very clean.
Does anybody know if there is a better way?
normalize: url | normal re | ... re := '[^/]+/../' asRegex. [ (re matchesIn: normal) notEmpty ] whileTrue: [ normal := re copy: normal replacingMatchesWith: '' ]. ^ normal
Here I am collapsing ".." navigations within a URL against parent directories, as long as there is such a match. But copy:replacingMatchesWith: considers submatches, whereas matches: does not. Bummer.
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A second question: I would like to strip a string prefix if it matches. Since this is a literal string, I should not need regexes. But I cannot find a nice existing method to do this. With regexes I must escape all special regex chars:
localize: url "remove prefix if url is for this website" self aliasesAsRegexes do: [ :re | (re matchesPrefix: url) ifTrue: [ ^ re copy: url replacingMatchesWith: '' ] ]. ^ url
This is supposed to delete all known aliases for a given web site from the start of a url to turn them into local urls.
aliasesAsRegexes aliasesAsRegexes ifNil: [ aliasesAsRegexes := aliases collect: [:alias | alias := '/' asRegex copy: alias replacingMatchesWith: '/'. alias := '~' asRegex copy: alias replacingMatchesWith: '~'. alias := ':' asRegex copy: alias replacingMatchesWith: ':'. alias := '.' asRegex copy: alias replacingMatchesWith: '.'. alias asRegex ]]. ^ aliasesAsRegexes
Bleh! I am ashamed to have to write such crappy code.
The Method Finder did not find me a cool method to do this:
'abra' . 'abracadabra' . 'cadabra'
Thanks for any hints.
- on
Hi Oscar,
Oscar Nierstrasz wrote:
Hi Folks,
Is there a way ask a regex if it matches any part of a string? matches: wants an exact match, and matchesPrefix: clearly only matches a prefix. The best I found was to abuse matchesIn: and check the size of the response, but this is not very clean.
Have a look at #search: as I think this will help you.
A second question: I would like to strip a string prefix if it matches. Since this is a literal string, I should not need regexes. But I cannot find a nice existing method to do this. With regexes I must escape all special regex chars:
I can't think of anything off the top of my head but the great thing about smalltalk is you can easily add what you need. For example, you could use #beginsWith: when adding a method to String.
copyReplacePrefix: prefix with: replacement self beginsWith: prefix ifTrue: [^ replacement , (self copyFrom: prefix size to: self size)] ^ self
Then you will be able to do:
'abracadabra' copyReplacePrefix: 'abra' with: ''
Next step would be to write a few unit tests and then attach both as to an enhancement request at http://bugs.squeak.org.
aliasesAsRegexes aliasesAsRegexes ifNil: [ aliasesAsRegexes := aliases collect: [:alias | alias := '/' asRegex copy: alias replacingMatchesWith: '/'. alias := '~' asRegex copy: alias replacingMatchesWith: '~'. alias := ':' asRegex copy: alias replacingMatchesWith: ':'. alias := '.' asRegex copy: alias replacingMatchesWith: '.'. alias asRegex ]]. ^ aliasesAsRegexes
I don't think /, ~ or : have any special meaning so why do you need to escape them? Even if you did, a better way might be to do:
alias copyWithRegex: '[/~:.]' matchesTranslatedUsing: [:ea | '' , ea]
But if you're just replacing '.' then you can use:
alias copyReplaceAll: '.' with: '.'
Hope this helps.
Zulq
beginners@lists.squeakfoundation.org
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Oscar Nierstrasz -
Zulq Alam