dsn: add loading of assignments of pins to nets

src/dsn/de.rs

@@ -611,7 +611,12 @@ impl<'de, 'a> SeqAccess<'de> for StructFields<'a, 'de> {
         // TODO explain this part of empty option detection
         if let Some(lookahead) = self.de.next_name_lookahead() {
             if lookahead != self.fields[self.current_field] {
-                self.de.next_option_empty_hint = true;
+                if lookahead + "s" != self.fields[self.current_field] {
+                    self.de.next_option_empty_hint = true;
+                }
+                else {
+                    self.de.next_option_empty_hint = false;
+                }
             } else {
                 self.de.next_option_empty_hint = false;
             }

src/dsn/structure.rs

@@ -171,9 +171,24 @@ pub struct Attach(pub bool);
 #[derive(Deserialize, Debug)]
 #[serde(rename = "network")]
 pub struct Network {
+    pub nets: Option<Vec<NetPinAssignments>>,
     pub classes: Vec<Class>,
 }
 
+#[derive(Deserialize, Debug)]
+#[serde(rename = "net")]
+// dsn names this "net", but it's a structure unrelated to "net" in wiring or elsewhere
+pub struct NetPinAssignments {
+    pub net: String,
+    pub pins: Vec<Pins>,
+}
+
+#[derive(Deserialize, Debug)]
+#[serde(rename = "pins")]
+pub struct Pins {
+    pub ids: Vec<String>,
+}
+
 #[derive(Deserialize, Debug)]
 #[serde(rename = "class")]
 pub struct Class {