Regular Expression Transformations to Extend Regular LanguagesJ P RobsonDa LuzMartin Musicante
Under section 4D of the OfficialLanguagesOrdinance (Cap. 5), the Secretary for Justice may make formal alterations to the text of an Ordinance in one officiallanguagetoachieve consistency between a word, expression or phrase with another word, expression or phrase where both such words, expression...
We've defined an alphabet, we've defined a language -- a language which looks suspiciously like the expressions we've been using to talkabout languages. Next time we'll do something insanely clever to bridge the gap between strings in the regular expression language and ...
the text using only a fixed amount of memory. Newer regular expression facilities (notably Perl and those languages that have copied it) have added many new operators and escape sequences. These changes make the regular expressions more concise, and sometimes more cryptic, but not more powerful....
(regexp, RE) One of the wild card patterns used by Perl and other languages, following Unix utilities such as grep, sed, and awk and editors such as vi and Emacs. Regular expressions use conventions similar to but more elaborate than those described under glob. A regular expression is a ...
If you don’t get how that all works yet, don’t worry: I’ll explain the whole expression a little at a time in this chapter. If you will just follow the examples (and those throughout the book, for that matter), writing regular expressions will soon become second nature to you. ...
regular expression syntax provides a powerful tool for pattern matching in strings. regular expressions (regex) use a combination of characters and special symbols to define patterns that match specific sequences of characters. for example, the regex pattern "^[a-za-z]+$" matches strings ...
If we can reason about the limits of a DFA then we can determine whether a machine with finite storage is buff enough to recognize any interesting languages. Today's machine recognizes a regular language, and that's a start.Next time, we'll add a little magic to a DFA....
These are "equivalent" in the sense that each defines precisely the same family of regular languages. Moreover, there exist algorithms for transforming any regular expression, finite automaton or regular grammar into an equivalent language description belonging to either of the other two classes. ...
For some languages though, we can build and analyze devices which recognize them - that is, when given a string and a language, a device can tell you whether or not the string is a member of the language. To do that, we're going to need a way to describe langu...