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For what do people use parser generators, besides writing new programming languages? I'm very curious to know about the use cases.

• e12e 11y ago
  The sibling comment alludes to parsing calendar events (possibly .ical files). In general you need it for any kind of (de)serialization -- and as the recent java deserialization bug[1] (along with similar bugs in python, ruby) illustrates -- even in a mature language, "common practice" might not be "best practice" (everyone should've known that the various uses of blind deserialization was a bad idea -- but that doesn't really matter after the fact -- lots of high-profile libraries were completely broken). So "just use a library" might not be possible. Any time you take native objects/data and persist them, or marshal them, you need a parser -- or a parser library. That might mean reading some CSV, parsing some XML, reading some YAML, JSON or what-not. Then there's configuration that does more than set some variables, like for Nginx, Apache (web server), etc. One might want to have a short-hand for defining templates -- either for general meta-programming, or just to generate a layout-language (eg: html, css). If you're doing markdown (or markdown-like) processing, you might want to have some assurances that that's all that code can do -- generate html. Or you might want do meta-programming on some higher level, like generating interfaces for some java-beans based on a CSV structure. For more on meta-programming in Java, I recommend (the now slightly dated: http://www.amazon.com/Program-Generators-Java-Craig-Cleaveland/dp/0130258784 http://www.amazon.com/Program-Generators-Java-Craig-Cleavela... ). It's a shame he didn't name it as he claims he considered in the foreword: "Program Generators for Fun and Profit!". And finally there's "real" programming languages - full blown DSLs of some kind. Perhaps in an effort to represent some kind of business logic (eg: authorization based on group membership, roles and time of day) in a language that is "safe" -- has no side-effects. [1] http://fishbowl.pastiche.org/2015/11/09/java_serialization_bug/ http://fishbowl.pastiche.org/2015/11/09/java_serialization_b... http://blog.codeclimate.com/blog/2013/01/10/rails-remote-code-execution-vulnerability-explained/ http://blog.codeclimate.com/blog/2013/01/10/rails-remote-cod...
• Blackthorn 11y ago
  They should be used anywhere you receive input for a defined protocol, rather than writing your own ad-hoc implementation. Security is much, much better that way.
• YorickPeterse 11y ago
  I used one to parse XML/HTML, CSS selectors, and XPath expressions. Parser generator in question is https://github.com/YorickPeterse/ruby-ll https://github.com/YorickPeterse/ruby-ll which is an LL(1) parser generator in Ruby. Example grammars: https://github.com/YorickPeterse/oga/blob/master/lib/oga/css/parser.rll https://github.com/YorickPeterse/oga/blob/master/lib/oga/css... https://github.com/YorickPeterse/oga/blob/master/lib/oga/xml/parser.rll https://github.com/YorickPeterse/oga/blob/master/lib/oga/xml... https://github.com/YorickPeterse/oga/blob/master/lib/oga/xpath/parser.rll https://github.com/YorickPeterse/oga/blob/master/lib/oga/xpa...