initial rewrite of drawing pipeline + positioning

src/circuit.typ

@@ -9,6 +9,38 @@
 /// - length (length, ratio): Optional base unit
 /// -> none
 #let circuit(body, length: 2em) = {
-  set text(font: "Source Sans 3")
-  canvas(length: length, body)
+  let next-id = 0
+  let elements = (:)
+
+  for element in body {
+    let internal = type(element) == dictionary and "id" in element
+    let eid = if internal {element.id} else {none}
+    if eid == none {
+      while str(next-id) in elements {
+        next-id += 1
+      }
+      eid = str(next-id)
+      if internal {
+        element.id = eid
+      }
+      next-id += 1
+    }
+    elements.insert(eid, element)
+  }
+
+  for element in elements.values() {
+    if type(element) == dictionary and "pre-process" in element {
+      elements = (element.pre-process)(elements, element)
+    }
+  }
+
+  canvas(length: length, {
+    for element in elements.values() {
+      if type(element) == dictionary and "draw" in element {
+        (element.draw)(element)
+      } else {
+        (element,)
+      }
+    }
+  })
 }