CpcRegul is a lexical analyzer that can find and/or replace regular expressions in a text. It provides an application programming interface as well as a user interface. It is an advanced example of the Babel metacompiler.
Here, Babel is used three times at each request: firstly to analyze the regular expression, check possible syntax errors and generate a Babel definition document for this expression; secondly to compile the previous definition document and produce a compiler (in fact, one or two compilers, according to the expression); thirdly to parse the user text with this compiler and find occurrences of the regular expression. All this process is accomplished in a flash behind the screen.