Parsers Generators

Welcome Forums Users
We all know of course, since we are long accustomed to the use of tools and different ways to write the codes for that parsers and most famous of all are the tools lex, yacc, and alternatives to the use of the latest, which also automatically produces code such as Flex, Bison and other
Most recent such as the passage of Coco / R, which supports many languages ​​over the tools intended for a specific language, such as Beck, E, man, Lex
It is important I want to open the debate with you a discussion on the importance of these tools and their impact on efficiency, as well as your personal experiences about the use of these tools and the effect that you were special projects such tools