Macro calyx_ir::build_assignments

macro_rules! build_assignments {
    (@base $builder:expr;
     $dst_node:ident[$dst_port:expr] = ? $src_node:ident[$src_port:expr]) => { ... };
    (@base $builder:expr;
     $dst_node:ident[$dst_port:expr] =
        $guard:ident ?
        $src_node:ident[$src_port:expr]) => { ... };
    ($builder:expr;
     $($dst_node:ident[$dst_port:expr] =
         $($guard:ident)? ?
         $src_node:ident[$src_port:expr];)*) => { ... };
}

Build guarded assignment statements and return a vector containing them.

The macro accepts two forms:

build_assignments!(builder;
    group["go"] = ? signal_on["out"]; // no guard
    fsm["in"] = guard ? add["out"];
)

Note: Guards used in the assignments are cloned.