Add IATA code type

docs/reference/types.md

@@ -5,6 +5,7 @@ Outlines provides custom Pydantic types so you can focus on your use case rather
 - Using `outlines.types.ZipCode` will generate valid US Zip(+4) codes.
 - Using `outlines.types.PhoneNumber` will generate valid US phone numbers.
 - Using `outlines.types.ISBN` will generate ISBNs. Note that there is no guarantee that the [check digit](https://en.wikipedia.org/wiki/ISBN#Check_digits) will be correct.
+- Using `outlines.types.airports.IATA` will generate valid airport IATA codes.
 
 You can use these types in Pydantic schemas for JSON-structured generation:
 

outlines/fsm/types.py

@@ -1,5 +1,6 @@
 import datetime
-from typing import Protocol, Tuple, Type, Union
+from enum import EnumMeta
+from typing import Any, Protocol, Tuple, Type
 
 from typing_extensions import _AnnotatedAlias, get_args
 
@@ -12,9 +13,7 @@
 
 
 class FormatFunction(Protocol):
-    def __call__(
-        self, sequence: str
-    ) -> Union[int, float, bool, datetime.date, datetime.time, datetime.datetime]:
+    def __call__(self, sequence: str) -> Any:
         ...
 
 
@@ -24,8 +23,17 @@ def python_types_to_regex(python_type: Type) -> Tuple[str, FormatFunction]:
         json_schema = get_args(python_type)[1].json_schema
         type_class = get_args(python_type)[0]
 
-        regex_str = json_schema["pattern"]
-        format_fn = lambda x: type_class(x)
+        custom_regex_str = json_schema["pattern"]
+
+        def custom_format_fn(sequence: str) -> Any:
+            return type_class(sequence)
+
+        return custom_regex_str, custom_format_fn
+
+    if isinstance(python_type, EnumMeta):
+        values = python_type.__members__.keys()
+        regex_str = "(" + "|".join(values) + ")"
+        format_fn = lambda x: str(x)
 
         return regex_str, format_fn
 

outlines/types/__init__.py

@@ -1,3 +1,4 @@
 from .isbn import ISBN
 from .phone_numbers import PhoneNumber
 from .zip_codes import ZipCode
+from . import airports

outlines/types/airports.py

@@ -0,0 +1,16 @@
+"""Generate valid airport codes."""
+from enum import Enum
+
+try:
+    from pyairports.airports import AIRPORT_LIST
+except ImportError:
+    raise ImportError(
+        'The `airports` module requires "pyairports" to be installed. You can install it with "pip install pyairports"'
+    )
+
+
+AIRPORT_IATA_LIST = list(
+    {(airport[3], airport[3]) for airport in AIRPORT_LIST if airport[3] != ""}
+)
+
+IATA = Enum("Airport", AIRPORT_IATA_LIST)  # type:ignore

pyproject.toml

@@ -126,6 +126,7 @@ module = [
     "vllm.*",
     "uvicorn.*",
     "fastapi.*",
+    "pyairports.*",
 ]
 ignore_missing_imports = true
 

tests/test_types.py

@@ -26,7 +26,7 @@
         (types.ISBN, "0-596-52068-9", True),
     ],
 )
-def test_phone_number(custom_type, test_string, should_match):
+def test_type_regex(custom_type, test_string, should_match):
     class Model(BaseModel):
         attr: custom_type
 
@@ -40,3 +40,28 @@ class Model(BaseModel):
     assert isinstance(format_fn(1), str)
     does_match = re.match(regex_str, test_string) is not None
     assert does_match is should_match
+
+
+@pytest.mark.parametrize(
+    "custom_type,test_string,should_match",
+    [
+        (types.airports.IATA, "CDG", True),
+        (types.airports.IATA, "XXX", False),
+    ],
+)
+def test_type_enum(custom_type, test_string, should_match):
+
+    type_name = custom_type.__name__
+
+    class Model(BaseModel):
+        attr: custom_type
+
+    schema = Model.model_json_schema()
+    assert isinstance(schema["$defs"][type_name]["enum"], list)
+    does_match = test_string in schema["$defs"][type_name]["enum"]
+    assert does_match is should_match
+
+    regex_str, format_fn = python_types_to_regex(custom_type)
+    assert isinstance(format_fn(1), str)
+    does_match = re.match(regex_str, test_string) is not None
+    assert does_match is should_match