[antlr-interest] Regular Expression vs CFG

Randall R Schulz rschulz at sonic.net
Mon Mar 5 18:34:13 PST 2007


On Monday 05 March 2007 18:29, Dennis Katumalla wrote:
> Can someone give me a simple example where a regular expression alone
> (using java.util.regex) is not sufficient to parse a SQL statement
> and requires specification of a full grammar?

The mere fact that there are balanced and nested constructs (e.g., 
parenthesized sub-expressions) is enough to tell you that no finite 
automaton alone can recognize the language. Such constructs demand a 
push-down automaton of some sort.

> Thanks in advance.
> Dennis

Randall Schulz

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