Method _tuple_schema

pydantic/_internal/_generate_schema.py:1674–1702

Generate schema for a Tuple, e.g. `tuple[int, str]` or `tuple[int, ...]`.

(self, tuple_type: Any)

        return parameter_schema

    def _tuple_schema(self, tuple_type: Any) -> core_schema.CoreSchema:
        """Generate schema for a Tuple, e.g. `tuple[int, str]` or `tuple[int, ...]`."""
        # TODO: do we really need to resolve type vars here?
        typevars_map = get_standard_typevars_map(tuple_type)
        params = self._get_args_resolving_forward_refs(tuple_type)

        if typevars_map and params:
            params = tuple(replace_types(param, typevars_map) for param in params)

        # NOTE: subtle difference: `tuple[()]` gives `params=()`, whereas `typing.Tuple[()]` gives `params=((),)`
        # This is only true for <3.11, on Python 3.11+ `typing.Tuple[()]` gives `params=()`
        if not params:
            if tuple_type in TUPLE_TYPES:
                return core_schema.tuple_schema([core_schema.any_schema()], variadic_item_index=0)
            else:
                # special case for `tuple[()]` which means `tuple[]` - an empty tuple
                return core_schema.tuple_schema([])
        elif params[-1] is Ellipsis:
            if len(params) == 2:
                return core_schema.tuple_schema([self.generate_schema(params[0])], variadic_item_index=0)
            else:
                # TODO: something like https://github.com/pydantic/pydantic/issues/5952
                raise ValueError('Variable tuples can only have one type')
        elif len(params) == 1 and params[0] == ():
            # special case for `tuple[()]` which means `tuple[]` - an empty tuple
            # NOTE: This conditional can be removed when we drop support for Python 3.10.
            return core_schema.tuple_schema([])
        else:
            return core_schema.tuple_schema([self.generate_schema(param) for param in params])

    def _type_schema(self) -> core_schema.CoreSchema:
        return core_schema.custom_error_schema(