Pangram checker: Difference between revisions

Txr has two regex engines and compilers. This type of regex is handled by derivatives, which means doing symbolic computing on an abstract syntax representation of the regex. This generates garbage as it goes. Only a single additional call to the OS to get 4096 bytes of memory is made while matching the regex, as shown the <code>strace</code> output below. The derivative method does not run into any combinatorial explosion of memory.