This will be used as a parameter of id.shortest*() methods. For now, only
decimal literal is supported, and there's no unary negate operator.
"0"-prefix is disallowed because it looks like an octal number.
I don't think we would want multiple integer types in the template language,
so I chose i64 as the integer type of reasonable width.
Before, "f()" was parsed as a function call with one empty argument. In
practice, this change means "if(divergent,,false_template)" is no longer
valid.
Suppose "template" is a sequence of "term"s, it makes more sense to handle
an empty sequence there. It might be even better to disallow empty template
other than the top-level one.
A "list" is a sequence of more than one "term" nodes, so it shouldn't contain
a single parenthesized node.
Also, a parenthesized "term" rule wasn't handled.
A method call is typically parsed as (obj.meth)(), not as obj.(meth()),
but the latter is good enough for our needs. It's unlikely we'll add a
first-class function support.
.into_inner().next().unwrap() mess will be cleaned up by the next commit.
Let's acknowledge everyone's contributions by replacing "Google LLC"
in the copyright header by "The Jujutsu Authors". If I understand
correctly, it won't have any legal effect, but maybe it still helps
reduce concerns from contributors (though I haven't heard any
concerns).
Google employees can read about Google's policy at
go/releasing/contributions#copyright.
