Hello all! I have some questions about antlr3 with tree grammar in C target. I have almost done my interpretor (functions, variables, boolean and math expressions ok) and i have kept the most difficult statements for the end (like if, switch, etc.) 1) I would like interpreting a simple loop statement: repeat: ^(REPEAT DIGIT stmt); I've seen many examples but nothing about the tree walker (only a topic here with the macros MARK() / REWIND(m) + @init / @after but not working (i've antlr errors: "unexpected node at offset 0")). How can i interpret this statement in C? 2) Same question with a simple if statement: if: ^(IF condition stmt elseifstmt* elsestmt?); The problem is to skip the statement if the condition is false and test the other elseif/else statements. 3) I have some statements which can stop the script (like "break" or "exit"). How can i interrupt the tree walker and skip the following tokens? 4) When a lexer or parser error is detected, antlr returns an error. But i would like to make my homemade error messages. How can i have the line number where parser crashed? Ask me if you want more details. Thanks you very much (and i apologize for my poor english)