* Expose lexer item types
We have generally agreed to expose AST types / values that are necessary
to make sense of the AST outside of the promql package. Currently the
`UnaryExpr`, `BinaryExpr`, and `AggregateExpr` AST nodes store the lexer
item type to indicate the operator type, but since the individual item
types aren't exposed, an external user of the package cannot determine
the operator type. So this PR exposes them.
Although not all item types are required to make sense of the AST (some
are really only used in the lexer), I decided to expose them all here to
be somewhat more consistent. Another option would be to not use lexer
item types at all in AST nodes.
The concrete motivation is my work on the PromQL->Flux transpiler, but
this ought to be useful for other cases as well.
Signed-off-by: Julius Volz <julius.volz@gmail.com>
* Fix item type names in tests
Signed-off-by: Julius Volz <julius.volz@gmail.com>