> Generating the tree is trivial. If by "generating the tree" you mean generating definitions for the AST data structures, this is nontrivial enough that yacc

> Generating the tree is trivial. If by "generating the tree" you mean generating definitions for the AST data structures, this is nontrivial enough that yacc does not do it. > The lexer is part of the parser. Again, yacc (a parser generator) does not include a lexer generator; that requires a second package such as lex. > A pretty printer is not part of a compiler. A pretty-printer for the IR or target language is an important part of a compiler, as one needs to render the output in a form that some other tool (e.g., an assembler) can accept. A pretty-printer for the source language also comes in handy. > The rest you have to do by hand. What you have to do by hand is to write a function from the source AST to the target AST (i.e., a compiler backend). langcc generates the whole frontend, not just the parser.