Add $ref and $defs support to json schema converter

llama_cpp/llama_grammar.py

@@ -1399,6 +1399,7 @@ class SchemaConverter:
     def __init__(self, prop_order):
         self._prop_order = prop_order
         self._rules = {"space": SPACE_RULE}
+        self._defs = {}
 
     def _format_literal(self, literal):
         escaped = GRAMMAR_LITERAL_ESCAPE_RE.sub(
@@ -1422,6 +1423,11 @@ class SchemaConverter:
         schema_type = schema.get("type")
         rule_name = name or "root"
 
+        if "$defs" in schema:
+            # add defs to self._defs for later inlining
+            for def_name, def_schema in schema["$defs"].items():
+                self._defs[def_name] = def_schema
+
         if "oneOf" in schema or "anyOf" in schema:
             rule = " | ".join(
                 (
@@ -1471,6 +1477,14 @@ class SchemaConverter:
             )
             return self._add_rule(rule_name, rule)
 
+        elif "$ref" in schema:
+            ref = schema["$ref"]
+            assert ref.startswith("#/$defs/"), f"Unrecognized schema: {schema}"
+            # inline $defs
+            def_name = ref[len("#/$defs/") :]
+            def_schema = self._defs[def_name]
+            return self.visit(def_schema, f'{name}{"-" if name else ""}{def_name}')
+
         else:
             assert schema_type in PRIMITIVE_RULES, f"Unrecognized schema: {schema}"
             return self._add_rule(