Package: ask-orex
ASK-OrexASK-Orex is a package designed to simplify regular expressions in Python. It provides a high-level interface for constructing and working with regular expressions, making it easier and more intuitive to use.The package is heavily inspired by Richy Cotton'srebuspackage for theRlanguage.InstallationYou can install Orex using pip:pipinstallask-orexTo use Orex, import theask-orexpackage into your Python script:importask_orexasoxCreating regular expressionsThe easiest regular expression is just a literal string to be found.s='Hello World'pattern=ox.literal('Hello')pattern.is_match(s)TrueOrex regular expressions are extended by simply using a+.
A slightly more useful example is to find a hex colourpattern=ox.literal('#')+ox.HEXDIGIT+ox.HEXDIGIT+\ox.HEXDIGIT+ox.HEXDIGIT+ox.HEXDIGIT+ox.HEXDIGITs_hex='This package is #a83232 hot'pattern.is_match(s_hex)Truepattern.findall(s_hex)['#a83232']On the other hands_nonhex='Just a twitter handle: #Red123'pattern.is_match(s_nonhex)Falsepattern.findall(s_nonhex)[]Clearly, the pattern is somewhat burdensome. We can alternatively write it like thispattern=ox.literal('#')+ox.repeat(ox.HEXDIGIT,6)orpattern=ox.literal('#')+ox.n_or_more(ox.HEXDIGIT,min=6,max=6)SubpatternsMost oforexfunctions accept other regular expressions as characters.Say we want to find a regex to parse emails. We can define first all email allowed charactersallowed_characters=ox.character_class(ox.ALNUM+ox.DASH+'_'+ox.DOT)whereox.ALNUMare just all letters and numbers. Note that the_is just used as a string.
In Orex it is okay to use strings as part of the pattern, unless they are at the start, where we useox.literalto show python that we mean pattern business. Whenever we want to use the.or_explicitly, it is best to useox.DOTorox.DASH, since.and-can have a special meaning in regular expression.Next we defineuser_name=ox.one_or_more(allowed_characters)domain_name=ox.one_or_more(allowed_characters)extension=ox.n_or_more(ox.ALPHA,2,4)email_pattern=user_name+'@'+domain_name+ox.DOT+extensionemail='captainspamalot@funnyspammail.com'And indeedemail_pattern.is_match(email)TrueCapturingIf we want to extract the individual components of a match, we have to capture them first.
Using the email example above, we can just change the code toemail_pattern =  ox.capture(user_name) + '@' + ox.capture(domain_name) \
                + ox.DOT + ox.capture(extension)email_pattern.findall(email)returns[('captainspamalot', 'funnyspammail', 'com')]Handy indeed! We can also name the individual components for even easier extractionemail_pattern=ox.capture(user_name,'user')\+'@'+ox.capture(domain_name,'domain')\+ox.DOT+ox.capture(extension,'ext')We can now use thegroup_dictmethod for even easier accessemail_pattern.group_dict(email){'user': 'captainspamalot', 'domain': 'funnyspammail', 'ext': 'com'}Capturing has another benefit, namely that we can use it to find repeated patterns with theox.backreferencefunctiontag_name=ox.one_or_more(allowed_characters)content=ox.one_or_more(ox.ANY_CHAR)tag_pattern=ox.literal('<')+ox.capture(tag_name,'tag')+'>'\+ox.capture(content,'content')+'</'+ox.backreference(name='tag')+'>'message='<name>Sir Snakington</name>'tag_pattern.group_dict(message){'tag': 'name', 'content': 'Sir Snakington'}Back references can also be used to substitute patterns, though here the named backreference does not work. Instead, the backrefence uses the index of the reference in the pattern.tag_pattern=ox.literal('<')+ox.capture(tag_name)+'>'+ox.capture(content)+'</'+ox.backreference(1)+'>'replace_pattern=ox.literal('<')+ox.backreference(2)+'>'+ox.backreference(1)+ox.literal('<')+ox.backreference(2)+'>'tag_pattern.sub(message,replace_pattern)'<Sir Snakington>name<Sir Snakington>'