Operator token traits
| predecence(...) | explicitly set a precedence level | |
| assoc('right') | right associative (assignment, <==) | |
| assoc('list') | list associative (comma, | , &) |
| assoc('chain') | chain associative (relational ops) | |
| assoc('non') | non-associative (cmp, but, if, <=>) | |
| equiv(...) | set precedence and associativity same as existing op | |
| nullterm | term argument is optional (comma, semicolon) | |
| pasttype(...) | type of PAST->POST transformation to perform | |
| post(...) | POST instruction for this operator | |
| parsed(&sub) | regex or sub to call to parse this token |