added support for loading dictionary structure

gallery/test.typ

@@ -25,4 +25,106 @@ structures:
 ```)
 #schema.render(test-raw, config: config.config(
   full-page: true
+))
+
+#let test-typ = schema.load((
+  structures: (
+    main: (
+      bits: 32,
+      ranges: (
+        "31-28": (name: "cond"),
+        "27": (name: "0"),
+        "26": (name: "1"),
+        "25": (name: "I"),
+        "24": (
+          name: "P",
+          description: "pre / post indexing bit",
+          values: (
+            "0": "post, add offset after transfer",
+            "1": "pre, add offset before transfer"
+          )
+        ),
+        "23": (
+          name: "U",
+          description: "up / down bit",
+          values: (
+            "0": "down, subtract offset from base",
+            "1": "up, addition offset to base"
+          )
+        ),
+        "22": (
+          name: "B",
+          description: "byte / word bit",
+          values: (
+            "0": "transfer word quantity",
+            "1": "transfer byte quantity"
+          )
+        ),
+        "21": (
+          name: "W",
+          description: "write-back bit",
+          values: (
+            "0": "no write-back",
+            "1": "write address into base"
+          )
+        ),
+        "20": (
+          name: "L",
+          description: "load / store bit",
+          values: (
+            "0": "store to memory",
+            "1": "load from memory"
+          )
+        ),
+        "19-16": (
+          name: "Rn",
+          description: "base register"
+        ),
+        "15-12": (
+          name: "Rd",
+          description: "source / destination register"
+        ),
+        "11-0": (
+          name: "offset",
+          depends-on: "25",
+          values: (
+            "0": (
+              description: "offset is an immediate value",
+              structure: "immediateOffset"
+            ),
+            "1": (
+              description: "offset is a register",
+              structure: "registerOffset"
+            )
+          )
+        )
+      )
+    ),
+    immediateOffset: (
+      bits: 12,
+      ranges: (
+        "11-0": (
+          name: "12-bit immediate offset",
+          description: "unsigned number"
+        )
+      )
+    ),
+    registerOffset: (
+      bits: 12,
+      ranges: (
+        "11-4": (
+          name: "shift",
+          description: "shift applied to Rm"
+        ),
+        "3-0": (
+          name: "Rm",
+          description: "offset register"
+        )
+      )
+    )
+  )
+))
+
+#schema.render(test-typ, config: config.config(
+  full-page: true
 ))