Proper way to resolve ANTLR lexer rule ambiguities?

Question

Please see the source code available at: https://gist.github.com/1684022.

I've got two tokens defined:

ID  :   ('a'..'z' | 'A'..'Z') ('0'..'9' | 'a'..'z' | 'A'..'Z' | ' ')*;

PITCH   
    :   (('A'|'a') '#'?)
    |   (('B'|'b') '#'?) 
    |   (('C'|'c') '#'?);

Obviously, the letter "A" would be an ambiguity.

I further define:

note    :   PITCH;
name    :   ID;
main    :   name ':' note '\n'?

Now, if I enter "A:A" as input to the parser, I always get an error. Either the parser expects PITCH or ID depending on whether ID or PITCH is defined first:

mismatched input 'A' expecting ID

What is the proper way to resolve this so that it works as intended?

---

As is described, although it makes intuitive sense how the parsing should work, ANTLR doesn't do the "right thing". That is, even though the main rule says a name/ID should come first, the lexer seems to be ignorant of this and identifies "A" as a PITCH because it follows the "longest match"/"which comes first" rule rather than the more reasonable "what the rule says" rule.

Is the only solution to fake/hack it by matching both ID and PITCH, and then recombining them later as dasblinkenlight says?

Answer 1

Here is how I would re-factor this grammar to make it work:

ID  :   (('a'..'z' | 'A'..'Z') ('0'..'9' | 'a'..'z' | 'A'..'Z' | ' ')+)
    |   ('d'..'z' | 'D'..'Z');

PITCH : 'a'..'c' | 'A'..'C';

SHARP : '#';

note    :   PITCH SHARP?;

name    :   ID | PITCH;

main    :   name ':' note '\n'? EOF

This separates long names from one-character pitch names, which get "reunited" in the parser. Also the "sharp" token gets its own name, and gets recognized in the parser as an optional token.