roundtrip print for connect

Author: YingboMa

src/systems/abstractsystem.jl

@@ -566,7 +566,24 @@ function round_trip_expr(t, var2name)
     args = map(Base.Fix2(round_trip_expr, var2name), arguments(t))
     return :($f($(args...)))
 end
-round_trip_eq(eq, var2name) = Expr(:call, :~, round_trip_expr(eq.lhs, var2name), round_trip_expr(eq.rhs, var2name))
+
+function round_trip_eq(eq::Equation, var2name)
+    if eq.lhs isa Connection
+        syss = get_systems(eq.rhs)
+        call = Expr(:call, connect)
+        for sys in syss
+            strs = split(string(nameof(sys)), "₊")
+            s = Symbol(strs[1])
+            for st in strs[2:end]
+                s = Expr(:., s, Meta.quot(Symbol(st)))
+            end
+            push!(call.args, s)
+        end
+        call
+    else
+        Expr(:call, (~), round_trip_expr(eq.lhs, var2name), round_trip_expr(eq.rhs, var2name))
+    end
+end
 
 function push_eqs!(stmt, eqs, var2name)
     eqs_name = gensym(:eqs)

src/systems/connectors.jl

@@ -56,7 +56,9 @@ end
 
 const EMPTY_VEC = []
 
-function Base.show(io::IO, c::Connection)
+function Base.show(io::IO, ::MIME"text/plain", c::Connection)
+    # It is a bit unfortunate that the display of an array of `Equation`s won't
+    # call this.
     @unpack outers, inners = c
     if outers === nothing && inners === nothing
         print(io, "<Connection>")
@@ -124,7 +126,11 @@ isconnector(s::AbstractSystem) = has_connector_type(s) && get_connector_type(s)
 isstreamconnector(s::AbstractSystem) = isconnector(s) && get_connector_type(s) isa StreamConnector
 isstreamconnection(c::Connection) = any(isstreamconnector, c.inners) || any(isstreamconnector, c.outers)
 
-print_with_indent(n, x) = println(" " ^ n, x)
+function print_with_indent(n, x)
+    print(" " ^ n)
+    show(stdout, MIME"text/plain"(), x)
+    println()
+end
 
 function split_sys_var(var)
     var_name = string(getname(var))