We have an "ANTLR 2 Bashing" list so we can try to fix stuff that we don't like, but we also need a list of stuff we like so as not to break a good "recipe." :)

Terence Parr

• Human readable code; i.e., I like recursive-descent parsers
• ANTLR is mostly understandable in its fundamental structure / behavior
• k>1 is good
• Predicates add power to LL
• ANTLR code is easy to fold into applications for the most part
• ANTLR generates parsers in multiple languages
• Simple annotations can tell antlr how to make ASTs
• Tree parsers
• consistent syntax among lexer, parser, tree parser
• LL(k) based lexers (this is a love hate thing)
• TokenStreams
• Exceptions for error handling

John Mitchell

• Readability of the generated code.
• Syntactic and semantic predicates.
• Permissive licensing.
• This mailing list and the people that make it so valuable.
• All of the people who have contributed so many grammars, etc.

Loring Craymer

• Actions are invoked in a civilized manner.
• ANTLR-style trees are an aid to language transformation.
• Labels, rule arguments, and return values help with semantic processing.
• Encapsulating generated code in classes is very clean.

Monty Zukowski

• Human readable code. Still the best way to learn what is going on inside.
• Solid theoretical basis. Way beyond your typical LL parser generator.
• Does smart things for k>1. So many possibly cool tools limit themselves to LL(1) and ignore real problems.

Robin Debreuil

• It actually works - this is not a minor consideration. Works very well in fact, and all of it.
• It is simple enough that you can get useful work done within a few days, and pursue the finer points over time.
• Cross platform (C++, C# versions), and cross OS (java based)
• It is free to use, and to modify little things to suit your specific needs (er, I think!)
• The grammar markup is consistant - a few concepts will generally apply the same way in different situations (eg, ! applies to a rule, a choice, a subrule, a Token - similar with labels etc.)
• The ability to insert native code anywhere, and actually see what it is up to (in a grok-able context) in the output.
• The syntax and concepts are similar across Lexer, Parser, and Tree walker
• The generated code is easy to understand, conceptually as well, so it isn't a 'magic' blackbox step.
• There is a lot of underlying prewritten goodness that can help you out, at your option. Nothing is forced on you.
• You have near total control over what the generated tree looks like, and things like hetrogeneous trees are not an all or nothing option.
• It is complete across stages - eg. it isn't a lexer with a parser quickly tacked on, so one program, one set of concepts, no gluing chunks together.
• Documentation is quite good for those just starting out, with plenty of sample files.
• LL(k)
• It is similar enough to ebnf etc. that such documents remain very useful
• Grammars are easy to read, navigate and modify (as opposed to say regular expressions etc). Doing things like moving a task from the Lexer to the Parser is trivial.
• Option to use it as a (uber) filter is great
• Multiple contributors are welcomed, feedback is solicited, improvment is ongoing
• The 'culture' around the program is very generous, encouraging and smart - and tolerant of newcomers :).
• There is a great mailing list (filled with the above people) with a searchable archives.
• There is a central up to date site with the latest news, tutorials, grammars, and oh yes, that picture. Mostly it all comes down to that picture.

Sriram Srinivasan

• Readable generated code. I'm uncomfortable with tools that do things for me in ways I don't understand.
• Readable code makes it easy to profile a parser.
• Recursive descent parsing feels intuitive to me. k > 1 makes it practical
• Passing parameters and results is so simple.
• The civility and approachablility of the people working on and with it.
• Open liicensing scheme, no scary copyrights.
• Predicates
• Similar scheme for scanning characters, tokens, trees.
• Written in java. It is a pleasure to build a 3rd party product with

  jikes *.java */*.java */*/*.java
  

  Try compiling Flex or Bison for windows.
• Token stream pipelines.
• Lots of people use it, so no effort spent in evangelization within your own company.

Matthew Ford

• I like the Java base