pub fn pattern_case_expr<'d>(stmt: Statement<'d>) -> Option<Expression<'d>>Expand description
The case expression of a case ... matches statement. The bindings’
Statement::expr has no PatternCase arm, so it is the first expression
among the statement’s semantic children (slang visits the case expression
before the items); the other expression children are exactly the items’
&&& filters, which is checked. None when stmt is not a PatternCase
or the children do not have that shape.