Menu
Over the years, "regex" pattern matching has been getting more and more powerful to the point where I wonder: is it really just context-sensitive-grammar matching? Is it a variation/extension of context-free-grammar matching? Where is it right now and why don't we just call it that instead of the old, restrictive "regular expression"?
933
Regular Expressions are capable of describing the syntax of Tokens. Any syntactic construct that can be described by Regular Expression can also be described by the Context free grammar.
The difference between regular expression and context free grammar is that the regular expressions help to describe all the strings of a regular language while the context free grammar helps to define all possible strings of a context free language.
Programming languages, for example, are context-free grammars — a compiler reads your code to make sure it conforms to specific rules and informs you of any errors.
We also talk about a specialized form of a grammar called a regular expression. In addition to being used for specification and parsing, regular expressions are a widely-used tool for many string-processing tasks that need to disassemble a string, extract information from it, or transform it.
In particular backreferences to capturing parentheses make regular expressions more complex than regular, context-free, or context-sensitive grammars. The name is simply historically grown (as many words). See also this section in Wikipedia and this explanation with an example from Perl.
106
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
