regex operators

> Hi David, > 2 weeks ago Hartmut Holzgraefe had similar idea : > switch ($data, "preg_match") { > case '/foo.*?bar/i' : /* computation here */ > break; > } > > > The second argument is a callback. > > Andrey > > David Sklar wrote: > >> I was thinking about adding one or two regex-related features to the >> engine: >> >> 1. "preg_case": this would behave just like case but instead of doing >> an >> equality comparison, would match against a regular expression, e.g. >> >> switch($data) { >> preg_case '/^\d{5}(-\d{4})?$/': >> print "US Postal Code"; >> break; >> preg_case '/^[a-z]\d[a-z] ?\d[a-z]\d$/i'; >> print "Canadian Postal Code"; >> break; >> default: >> print "something else!"; >> } >> >> Where should any captured subpatterns go? >> >> 2. A regex match operator that returns an array containing >> subpatterns. If >> there is no match against the regex, then an empty array (or just >> false?) >> would be returned. >> >> if ($data =~ '/^(\d{5})(-\d{4})?$/') { >> print "The whole postal code is $data[0]."; >> print "The first five digits is $data[1]."; >> if ($data[2]) { print "The ZIP+4 is $data[2].";} >> } >> >> Some issues with adding these features: >> >> - It creates an engine dependency on the PCRE library. >> - There would have to be some new opcodes and parser tokens >> - Ideally the code that implements these operators could share as >> much as >> possible with what's already been done in the PCRE extension -- is >> that >> possible? >> >> Comments? >> >> Thanks, >> David >> >> > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > >

> David Sklar wrote: > >> I was thinking about adding one or two regex-related features to the >> engine: >> >> 1. "preg_case": this would behave just like case but instead of doing an >> equality comparison, would match against a regular expression, e.g. >> >> switch($data) { >> preg_case '/^\d{5}(-\d{4})?$/': >> print "US Postal Code"; >> break; >> preg_case '/^[a-z]\d[a-z] ?\d[a-z]\d$/i'; >> print "Canadian Postal Code"; >> break; >> default: >> print "something else!"; >> } >> > > i've started to play with a more general way to handle this: > > switch(mixed data [, callback compare_function])

> > { > ... > > "compare_function" would default to the functionality of the > "==" operator to show the current behavior > > "compare_function" will be called with two parameters: > the switch expression and the case value and should > return true if both match, false otherwise > > as a special case "compare_function" should also accept > "===" > > this way we do not have to add new keywords and are not > limited to preg expresions here, > possible uses not possible now would include: > > switch($foobar, "===") { > case false: ... > case 0: ... > case '': ... > > switch($foobar, "preg_match") { > case '/^\d{5}$/': ... > case '/(foo)?bar/': ... > > switch($foobar, "fnmatch") { > case '*.gif': ... > case '*.jpg': ... > > switch($foober, "my_custom_function") { > ... > > switch($foobar, array($this, "compare_function") { > ... > > > >

> This should also be BC if you just pass one string.

> * Thus wrote David Sklar (sklar@sklar.com): > > I was thinking about adding one or two regex-related features to the

> > > > 1. "preg_case": this would behave just like case but instead of doing an > > equality comparison, would match against a regular expression, e.g. > > > > switch($data) { > > preg_case '/^\d{5}(-\d{4})?$/': > > print "US Postal Code"; > > break; > > preg_case '/^[a-z]\d[a-z] ?\d[a-z]\d$/i'; > > print "Canadian Postal Code"; > > break; > > default: > > print "something else!"; > > } > [...] > > > > Some issues with adding these features: > > > > - It creates an engine dependency on the PCRE library. > > - There would have to be some new opcodes and parser tokens > > - Ideally the code that implements these operators could share as much

> > possible with what's already been done in the PCRE extension -- is that > > possible? > > I'm thinking a more viable solution would be to do something like: > > mixed preg_match ( mixed pattern, string subject [, array matches [, int

> > if pattern is an array, preg_match will cycle through each one till > a match is made; returns the index of the array passed (that > matched) or false if not found.