se.py

"""
This module provides `serialize`, `is_serializable` `to_dict`, `to_tuple` and classes and functions
associated with serialization.
"""

import abc
import copy
import dataclasses
import functools
import typing
from dataclasses import dataclass, is_dataclass
from typing import Any, Callable, Dict, Iterator, List, Optional, Tuple, Type, TypeVar

import jinja2
from typing_extensions import dataclass_transform

from .compat import (
    Literal,
    SerdeError,
    SerdeSkip,
    get_origin,
    is_any,
    is_bare_dict,
    is_bare_list,
    is_bare_opt,
    is_bare_set,
    is_bare_tuple,
    is_class_var,
    is_datetime,
    is_datetime_instance,
    is_dict,
    is_enum,
    is_generic,
    is_list,
    is_literal,
    is_none,
    is_opt,
    is_primitive,
    is_set,
    is_str_serializable,
    is_str_serializable_instance,
    is_tuple,
    is_union,
    is_variable_tuple,
    iter_types,
    iter_unions,
    type_args,
    typename,
)
from .core import (
    SERDE_SCOPE,
    TO_DICT,
    TO_ITER,
    TYPE_CHECK,
    UNION_SE_PREFIX,
    DefaultTagging,
    Field,
    NoCheck,
    SerdeScope,
    Tagging,
    TypeCheck,
    add_func,
    coerce,
    conv,
    fields,
    is_instance,
    logger,
    raise_unsupported_type,
    render_type_check,
    union_func_name,
)
from .numpy import (
    is_numpy_array,
    is_numpy_datetime,
    is_numpy_scalar,
    serialize_numpy_array,
    serialize_numpy_datetime,
    serialize_numpy_scalar,
)

__all__ = ["serialize", "is_serializable", "to_dict", "to_tuple"]

# Interface of Custom serialize function.
SerializeFunc = Callable[[Type[Any], Any], Any]


def default_serializer(_cls: Type[Any], obj):
    """
    Marker function to tell serde to use the default serializer. It's used when custom serializer is specified
    at the class but you want to override a field with the default serializer.
    """


def serde_custom_class_serializer(cls: Type[Any], obj: Any, custom: SerializeFunc, default: Callable):
    try:
        return custom(cls, obj)
    except SerdeSkip:
        return default()


class Serializer(metaclass=abc.ABCMeta):
    """
    `Serializer` base class. Subclass this to customize serialize behaviour.

    See `serde.json.JsonSerializer` and `serde.msgpack.MsgPackSerializer` for example usage.
    """

    @abc.abstractclassmethod
    def serialize(cls, obj, **opts):
        raise NotImplementedError


def _make_serialize(
    cls_name: str,
    fields,
    *args,
    rename_all: Optional[str] = None,
    reuse_instances_default: bool = True,
    convert_sets_default: bool = False,
    serializer: Optional[SerializeFunc] = None,
    tagging: Tagging = DefaultTagging,
    type_check: TypeCheck = NoCheck,
    serialize_class_var: bool = False,
    **kwargs,
):
    """
    Create a serializable class programatically.
    """
    C = dataclasses.make_dataclass(cls_name, fields, *args, **kwargs)
    C = serialize(
        C,
        rename_all=rename_all,
        reuse_instances_default=reuse_instances_default,
        convert_sets_default=convert_sets_default,
        serializer=serializer,
        tagging=tagging,
        type_check=type_check,
        serialize_class_var=serialize_class_var,
        **kwargs,
    )
    return C


# The `serialize` function can call itself recursively when it needs to generate code for
# unmarked dataclasses. To avoid infinite recursion, this array remembers types for which code is
# currently being generated.
GENERATION_STACK = []


@dataclass_transform()
def serialize(
    _cls=None,
    rename_all: Optional[str] = None,
    reuse_instances_default: bool = True,
    convert_sets_default: bool = False,
    serializer: Optional[SerializeFunc] = None,
    tagging: Tagging = DefaultTagging,
    type_check: TypeCheck = NoCheck,
    serialize_class_var: bool = False,
    **kwargs,
):
    """
    A dataclass with this decorator is serializable into any of the data formats supported by pyserde.

    >>> from datetime import datetime
    >>> from serde import serialize
    >>> from serde.json import to_json
    >>>
    >>> @serialize
    ... class Foo:
    ...     i: int
    ...     s: str
    ...     f: float
    ...     b: bool
    >>>
    >>> to_json(Foo(i=10, s='foo', f=100.0, b=True))
    '{"i":10,"s":"foo","f":100.0,"b":true}'

    #### Class Attributes

    Class attributes can be specified as arguments in the `serialize` decorator in order to customize the serialization
    behaviour of the class entirely.

    * `rename_all` attribute converts field names into the specified string case.
    The following example converts snake-case field names into camel-case names.

    >>> @serialize(rename_all = 'camelcase')
    ... class Foo:
    ...     int_field: int
    ...     str_field: str
    >>>
    >>> to_json(Foo(int_field=10, str_field='foo'))
    '{"intField":10,"strField":"foo"}'

    * `serializer` takes a custom class-level serialize function. The function applies to the all the fields
    in the class.

    >>> def serializer(cls, o):
    ...    if cls is datetime:
    ...        return o.strftime('%d/%m/%y')
    ...    else:
    ...        raise SerdeSkip()

    The first argument `cls` is a class of the field and the second argument `o` is a value of the field.
    `serializer` function will be called for every field. If you don't want to use the custom serializer
    for a certain field, raise `serde.SerdeSkip` exception, pyserde will use the default serializer for that field.

    >>> @serialize(serializer=serializer)
    ... class Foo:
    ...     i: int
    ...     dt: datetime

    This custom serializer serializes `datetime` object into the string in `MM/DD/YY` format.

    >>> to_json(Foo(10, datetime(2021, 1, 1, 0, 0, 0)))
    '{"i":10,"dt":"01/01/21"}'

    * `serialize_class_var` enables `typing.ClassVar` serialization.

    >>> @serialize(serialize_class_var=True)
    ... class Foo:
    ...     v: typing.ClassVar[int] = 10
    >>>
    >>> to_json(Foo())
    '{"v":10}'

    """

    def wrap(cls: Type[Any]):
        tagging.check()

        # If no `dataclass` found in the class, dataclassify it automatically.
        if not is_dataclass(cls):
            dataclass(cls)

        g: Dict[str, Any] = {}

        # Create a scope storage used by serde.
        # Each class should get own scope. Child classes can not share scope with parent class.
        # That's why we need the "scope.cls is not cls" check.
        scope: Optional[SerdeScope] = getattr(cls, SERDE_SCOPE, None)
        if scope is None or scope.cls is not cls:
            scope = SerdeScope(
                cls,
                reuse_instances_default=reuse_instances_default,
                convert_sets_default=convert_sets_default,
            )
            setattr(cls, SERDE_SCOPE, scope)

        # Set some globals for all generated functions
        g["cls"] = cls
        g["copy"] = copy
        g["serde_scope"] = scope
        g["SerdeError"] = SerdeError
        g["raise_unsupported_type"] = raise_unsupported_type
        g["enum_value"] = enum_value
        g["is_dataclass"] = is_dataclass
        g["typename"] = typename  # used in union functions
        g["is_instance"] = is_instance  # used in union functions
        g["to_obj"] = to_obj
        g["typing"] = typing
        g["Literal"] = Literal
        g["TypeCheck"] = TypeCheck
        g["NoCheck"] = NoCheck
        g["coerce"] = coerce
        if serialize:
            g["serde_custom_class_serializer"] = functools.partial(serde_custom_class_serializer, custom=serializer)

        # Collect types used in the generated code.
        for typ in iter_types(cls):
            # When we encounter a dataclass not marked with serialize, then also generate serialize
            # functions for it.
            if is_dataclass_without_se(typ):
                # We call serialize and not wrap to make sure that we will use the default serde
                # configuration for generating the serialization function.
                serialize(typ)

            if typ is cls or (is_primitive(typ) and not is_enum(typ)):
                continue
            g[typename(typ)] = typ

        # render all union functions
        for union in iter_unions(cls):
            union_args = type_args(union)
            union_key = union_func_name(UNION_SE_PREFIX, union_args)
            add_func(scope, union_key, render_union_func(cls, union_args, tagging), g)
            scope.union_se_args[union_key] = union_args

        for f in sefields(cls, serialize_class_var):
            if f.skip_if:
                g[f.skip_if.name] = f.skip_if
            if f.serializer:
                g[f.serializer.name] = f.serializer

        add_func(scope, TO_ITER, render_to_tuple(cls, serializer, type_check, serialize_class_var), g)
        add_func(scope, TO_DICT, render_to_dict(cls, rename_all, serializer, type_check, serialize_class_var), g)
        add_func(scope, TYPE_CHECK, render_type_check(cls), g)

        logger.debug(f"{typename(cls)}: {SERDE_SCOPE} {scope}")

        return cls

    if _cls is None:
        return wrap  # type: ignore

    if _cls in GENERATION_STACK:
        return _cls

    GENERATION_STACK.append(_cls)
    try:
        return wrap(_cls)
    finally:
        GENERATION_STACK.pop()


def is_serializable(instance_or_class: Any) -> bool:
    """
    Test if an instance or class is serializable.

    >>> @serialize
    ... class Foo:
    ...     pass

    Testing `Foo` class object returns `True`.
    >>> is_serializable(Foo)
    True

    Testing `Foo` object laso returns `True`.
    >>> is_serializable(Foo())
    True
    """
    return hasattr(instance_or_class, SERDE_SCOPE)


def is_dataclass_without_se(cls: Type[Any]) -> bool:
    if not dataclasses.is_dataclass(cls):
        return False
    if not hasattr(cls, SERDE_SCOPE):
        return True
    scope: Optional[SerdeScope] = getattr(cls, SERDE_SCOPE)
    return TO_DICT not in scope.funcs


def to_obj(o, named: bool, reuse_instances: bool, convert_sets: bool, c: Optional[Type[Any]] = None):
    def serializable_to_obj(object):
        serde_scope: SerdeScope = getattr(object, SERDE_SCOPE)
        func_name = TO_DICT if named else TO_ITER
        return serde_scope.funcs[func_name](object, reuse_instances=reuse_instances, convert_sets=convert_sets)

    try:
        thisfunc = functools.partial(
            to_obj,
            named=named,
            reuse_instances=reuse_instances,
            convert_sets=convert_sets,
        )
        if o is None:
            return None
        if is_dataclass_without_se(o):
            serialize(type(o))
            return serializable_to_obj(o)
        if is_serializable(o):
            return serializable_to_obj(o)
        elif isinstance(o, list):
            return [thisfunc(e) for e in o]
        elif isinstance(o, tuple):
            return tuple(thisfunc(e) for e in o)
        elif isinstance(o, set):
            return [thisfunc(e) for e in o]
        elif isinstance(o, dict):
            return {k: thisfunc(v) for k, v in o.items()}
        elif is_str_serializable_instance(o):
            return str(o)
        elif is_datetime_instance(o):
            return o.isoformat()

        return o

    except Exception as e:
        raise SerdeError(e)


def astuple(v: Any) -> Tuple[Any, ...]:
    """
    Serialize object into tuple.
    """
    return to_tuple(v, reuse_instances=False, convert_sets=False)


def to_tuple(o, reuse_instances: bool = ..., convert_sets: bool = ...) -> Tuple[Any, ...]:
    """
    Serialize object into tuple.

    >>> @serialize
    ... class Foo:
    ...     i: int
    ...     s: str = 'foo'
    ...     f: float = 100.0
    ...     b: bool = True
    >>>
    >>> to_tuple(Foo(i=10))
    (10, 'foo', 100.0, True)

    You can pass any type supported by pyserde. For example,

    >>> lst = [Foo(i=10), Foo(i=20)]
    >>> to_tuple(lst)
    [(10, 'foo', 100.0, True), (20, 'foo', 100.0, True)]
    """
    return to_obj(o, named=False, reuse_instances=reuse_instances, convert_sets=convert_sets)


def asdict(v: Any) -> Dict[Any, Any]:
    """
    Serialize object into dictionary.
    """
    return to_dict(v, reuse_instances=False, convert_sets=False)


def to_dict(o, reuse_instances: bool = ..., convert_sets: bool = ...) -> Dict[Any, Any]:
    """
    Serialize object into dictionary.

    >>> @serialize
    ... class Foo:
    ...     i: int
    ...     s: str = 'foo'
    ...     f: float = 100.0
    ...     b: bool = True
    >>>
    >>> to_dict(Foo(i=10))
    {'i': 10, 's': 'foo', 'f': 100.0, 'b': True}

    You can pass any type supported by pyserde. For example,

    >>> lst = [Foo(i=10), Foo(i=20)]
    >>> to_dict(lst)
    [{'i': 10, 's': 'foo', 'f': 100.0, 'b': True}, {'i': 20, 's': 'foo', 'f': 100.0, 'b': True}]
    """
    return to_obj(o, named=True, reuse_instances=reuse_instances, convert_sets=convert_sets)


@dataclass
class SeField(Field):
    """
    Field class for serialization.
    """

    parent: Optional["SeField"] = None

    @property
    def varname(self) -> str:
        """
        Get variable name in the generated code e.g. obj.a.b
        """
        var = self.parent.varname if self.parent else None
        if var:
            return f"{var}.{self.name}"
        else:
            if self.name is None:
                raise SerdeError("Field name is None.")
            return self.name

    def __getitem__(self, n: int) -> "SeField":
        typ = type_args(self.type)[n]
        return SeField(typ, name=None)


def sefields(cls: Type[Any], serialize_class_var: bool = False) -> Iterator[SeField]:
    """
    Iterate fields for serialization.
    """
    for f in fields(SeField, cls, serialize_class_var=serialize_class_var):
        f.parent = SeField(None, "obj")  # type: ignore
        yield f


def render_to_tuple(
    cls: Type[Any],
    custom: Optional[SerializeFunc] = None,
    type_check: TypeCheck = NoCheck,
    serialize_class_var: bool = False,
) -> str:
    template = """
def {{func}}(obj, reuse_instances = {{serde_scope.reuse_instances_default}},
             convert_sets = {{serde_scope.convert_sets_default}}):
  if reuse_instances is Ellipsis:
    reuse_instances = {{serde_scope.reuse_instances_default}}
  if convert_sets is Ellipsis:
    convert_sets = {{serde_scope.convert_sets_default}}

  if not is_dataclass(obj):
    return copy.deepcopy(obj)

  {% if type_check.is_strict() %}
  obj.__serde__.funcs['typecheck'](obj)
  {% endif %}

  return (
  {% for f in fields -%}
  {% if not f.skip|default(False) %}
  {{f|rvalue()}},
  {% endif -%}
  {% endfor -%}
  )
    """

    renderer = Renderer(
        TO_ITER, custom, suppress_coerce=(not type_check.is_coerce()), serialize_class_var=serialize_class_var
    )
    env = jinja2.Environment(loader=jinja2.DictLoader({"iter": template}))
    env.filters.update({"rvalue": renderer.render})
    return env.get_template("iter").render(
        func=TO_ITER,
        serde_scope=getattr(cls, SERDE_SCOPE),
        fields=sefields(cls, serialize_class_var),
        type_check=type_check,
    )


def render_to_dict(
    cls: Type[Any],
    case: Optional[str] = None,
    custom: Optional[SerializeFunc] = None,
    type_check: TypeCheck = NoCheck,
    serialize_class_var: bool = False,
) -> str:
    template = """
def {{func}}(obj, reuse_instances = {{serde_scope.reuse_instances_default}},
             convert_sets = {{serde_scope.convert_sets_default}}):
  if reuse_instances is Ellipsis:
    reuse_instances = {{serde_scope.reuse_instances_default}}
  if convert_sets is Ellipsis:
    convert_sets = {{serde_scope.convert_sets_default}}

  if not is_dataclass(obj):
    return copy.deepcopy(obj)

  {% if type_check.is_strict() %}
  obj.__serde__.funcs['typecheck'](obj)
  {% endif %}

  res = {}
  {% for f in fields -%}
  {% if not f.skip -%}
    {% if f.skip_if -%}
  if not {{f.skip_if.name}}({{f|rvalue}}):
    {{f|lvalue}} = {{f|rvalue}}
    {% else -%}
  {{f|lvalue}} = {{f|rvalue}}
    {% endif -%}
  {% endif %}

  {% endfor -%}
  return res
    """
    renderer = Renderer(TO_DICT, custom, suppress_coerce=(not type_check.is_coerce()))
    lrenderer = LRenderer(case, serialize_class_var)
    env = jinja2.Environment(loader=jinja2.DictLoader({"dict": template}))
    env.filters.update({"rvalue": renderer.render})
    env.filters.update({"lvalue": lrenderer.render})
    env.filters.update({"case": functools.partial(conv, case=case)})
    return env.get_template("dict").render(
        func=TO_DICT,
        serde_scope=getattr(cls, SERDE_SCOPE),
        fields=sefields(cls, serialize_class_var),
        type_check=type_check,
    )


def render_union_func(cls: Type[Any], union_args: List[Type[Any]], tagging: Tagging = DefaultTagging) -> str:
    """
    Render function that serializes a field with union type.
    """
    template = """
def {{func}}(obj, reuse_instances, convert_sets):
  union_args = serde_scope.union_se_args['{{func}}']

  {% for t in union_args %}
  if is_instance(obj, union_args[{{loop.index0}}]):
    {% if tagging.is_external() and is_taggable(t) %}
    return {"{{t|typename}}": {{t|arg|rvalue}}}

    {% elif tagging.is_internal() and is_taggable(t) %}
    res = {{t|arg|rvalue}}
    res["{{tagging.tag}}"] = "{{t|typename}}"
    return res

    {% elif tagging.is_adjacent() and is_taggable(t) %}
    res = {"{{tagging.content}}": {{t|arg|rvalue}}}
    res["{{tagging.tag}}"] = "{{t|typename}}"
    return res

    {% else %}
    return {{t|arg|rvalue}}
    {% endif %}
  {% endfor %}
  raise SerdeError("Can not serialize " + repr(obj) + " of type " + typename(type(obj)) + " for {{union_name}}")
    """
    union_name = f"Union[{', '.join([typename(a) for a in union_args])}]"

    renderer = Renderer(TO_DICT, suppress_coerce=True)
    env = jinja2.Environment(loader=jinja2.DictLoader({"dict": template}))
    env.filters.update({"arg": lambda x: SeField(x, "obj")})
    env.filters.update({"rvalue": renderer.render})
    env.filters.update({"typename": typename})
    return env.get_template("dict").render(
        func=union_func_name(UNION_SE_PREFIX, union_args),
        serde_scope=getattr(cls, SERDE_SCOPE),
        union_args=union_args,
        union_name=union_name,
        tagging=tagging,
        is_taggable=Tagging.is_taggable,
    )


@dataclass
class LRenderer:
    """
    Render lvalue for various types.
    """

    case: Optional[str]
    serialize_class_var: bool = False

    def render(self, arg: SeField) -> str:
        """
        Render lvalue
        """
        if is_dataclass(arg.type) and arg.flatten:
            return self.flatten(arg)
        else:
            return f'res["{arg.conv_name(self.case)}"]'

    def flatten(self, arg: SeField) -> str:
        """
        Render field with flatten attribute.
        """
        flattened = []
        for f in sefields(arg.type, self.serialize_class_var):
            flattened.append(self.render(f))
        return ", ".join(flattened)


@dataclass
class Renderer:
    """
    Render rvalue for code generation.
    """

    func: str
    custom: Optional[SerializeFunc] = None  # Custom class level serializer.
    suppress_coerce: bool = False
    """ Suppress type coercing because generated union serializer has its own type checking """
    serialize_class_var: bool = False

    def render(self, arg: SeField) -> str:
        """
        Render rvalue

        >>> from typing import Tuple
        >>> Renderer(TO_ITER).render(SeField(int, 'i'))
        'coerce(int, i)'

        >>> Renderer(TO_ITER).render(SeField(List[int], 'l'))
        '[coerce(int, v) for v in l]'

        >>> @serialize
        ... @dataclass(unsafe_hash=True)
        ... class Foo:
        ...    val: int
        >>> Renderer(TO_ITER).render(SeField(Foo, 'foo'))
        "foo.__serde__.funcs['to_iter'](foo, reuse_instances=reuse_instances, convert_sets=convert_sets)"

        >>> Renderer(TO_ITER).render(SeField(List[Foo], 'foo'))
        "[v.__serde__.funcs['to_iter'](v, reuse_instances=reuse_instances, convert_sets=convert_sets) for v in foo]"

        >>> Renderer(TO_ITER).render(SeField(Dict[str, Foo], 'foo'))
        "{coerce(str, k): v.__serde__.funcs['to_iter'](v, reuse_instances=reuse_instances, \
convert_sets=convert_sets) for k, v in foo.items()}"

        >>> Renderer(TO_ITER).render(SeField(Dict[Foo, Foo], 'foo'))
        "{k.__serde__.funcs['to_iter'](k, reuse_instances=reuse_instances, \
convert_sets=convert_sets): v.__serde__.funcs['to_iter'](v, reuse_instances=reuse_instances, \
convert_sets=convert_sets) for k, v in foo.items()}"

        >>> Renderer(TO_ITER).render(SeField(Tuple[str, Foo, int], 'foo'))
        "(coerce(str, foo[0]), foo[1].__serde__.funcs['to_iter'](foo[1], reuse_instances=reuse_instances, \
convert_sets=convert_sets), coerce(int, foo[2]),)"
        """
        if arg.serializer and arg.serializer.inner is not default_serializer:
            res = self.custom_field_serializer(arg)
        elif is_dataclass(arg.type):
            res = self.dataclass(arg)
        elif is_opt(arg.type):
            res = self.opt(arg)
        elif is_list(arg.type):
            res = self.list(arg)
        elif is_set(arg.type):
            res = self.set(arg)
        elif is_dict(arg.type):
            res = self.dict(arg)
        elif is_tuple(arg.type):
            res = self.tuple(arg)
        elif is_enum(arg.type):
            res = self.enum(arg)
        elif is_numpy_datetime(arg.type):
            res = serialize_numpy_datetime(arg)
        elif is_numpy_scalar(arg.type):
            res = serialize_numpy_scalar(arg)
        elif is_numpy_array(arg.type):
            res = serialize_numpy_array(arg)
        elif is_primitive(arg.type):
            res = self.primitive(arg)
        elif is_union(arg.type):
            res = self.union_func(arg)
        elif is_str_serializable(arg.type):
            res = f"{arg.varname} if reuse_instances else {self.string(arg)}"
        elif is_datetime(arg.type):
            res = f"{arg.varname} if reuse_instances else {arg.varname}.isoformat()"
        elif is_none(arg.type):
            res = "None"
        elif is_any(arg.type) or isinstance(arg.type, TypeVar):
            res = f"to_obj({arg.varname}, True, False, False)"
        elif is_generic(arg.type):
            origin = get_origin(arg.type)
            assert origin
            arg.type = origin
            res = self.render(arg)
        elif is_literal(arg.type):
            res = self.literal(arg)
        elif is_class_var(arg.type):
            arg.type = type_args(arg.type)[0]
            res = self.render(arg)
        else:
            res = f"raise_unsupported_type({arg.varname})"

        # Custom field serializer overrides custom class serializer.
        if self.custom and not arg.serializer:
            return f"serde_custom_class_serializer({typename(arg.type)}, {arg.varname}, default=lambda: {res})"
        else:
            return res

    def custom_field_serializer(self, arg: SeField) -> str:
        """
        Render rvalue for the field with custom serializer.
        """
        assert arg.serializer
        return f"{arg.serializer.name}({arg.varname})"

    def dataclass(self, arg: SeField) -> str:
        """
        Render rvalue for dataclass.
        """
        if arg.flatten:
            flattened = []
            for f in sefields(arg.type, self.serialize_class_var):
                f.parent = arg  # type: ignore
                flattened.append(self.render(f))  # type: ignore
            return ", ".join(flattened)
        else:
            return (
                f"{arg.varname}.{SERDE_SCOPE}.funcs['{self.func}']({arg.varname},"
                " reuse_instances=reuse_instances, convert_sets=convert_sets)"
            )

    def opt(self, arg: SeField) -> str:
        """
        Render rvalue for optional.
        """
        if is_bare_opt(arg.type):
            return f"{arg.varname} if {arg.varname} is not None else None"
        else:
            inner = arg[0]
            inner.name = arg.varname
            return f"({self.render(inner)}) if {arg.varname} is not None else None"

    def list(self, arg: SeField) -> str:
        """
        Render rvalue for list.
        """
        if is_bare_list(arg.type):
            return arg.varname
        else:
            earg = arg[0]
            earg.name = "v"
            return f"[{self.render(earg)} for v in {arg.varname}]"

    def set(self, arg: SeField) -> str:
        """
        Render rvalue for set.
        """
        if is_bare_set(arg.type):
            return f"list({arg.varname}) if convert_sets else {arg.varname}"
        else:
            earg = arg[0]
            earg.name = "v"
            return (
                f"[{self.render(earg)} for v in {arg.varname}] "
                f"if convert_sets else set({self.render(earg)} for v in {arg.varname})"
            )

    def tuple(self, arg: SeField) -> str:
        """
        Render rvalue for tuple.
        """
        if is_bare_tuple(arg.type) or is_variable_tuple(arg.type):
            return arg.varname
        else:
            rvalues = []
            for i, _ in enumerate(type_args(arg.type)):
                r = arg[i]
                r.name = f"{arg.varname}[{i}]"
                rvalues.append(self.render(r))
            return f"({', '.join(rvalues)},)"  # trailing , is required for single element tuples

    def dict(self, arg: SeField) -> str:
        """
        Render rvalue for dict.
        """
        if is_bare_dict(arg.type):
            return arg.varname
        else:
            karg = arg[0]
            karg.name = "k"
            varg = arg[1]
            varg.name = "v"
            return f"{{{self.render(karg)}: {self.render(varg)} for k, v in {arg.varname}.items()}}"

    def enum(self, arg: SeField) -> str:
        return f"enum_value({typename(arg.type)}, {arg.varname})"

    def primitive(self, arg: SeField) -> str:
        """
        Render rvalue for primitives.
        """
        typ = typename(arg.type)
        var = arg.varname
        if self.suppress_coerce:
            return var
        else:
            return f'coerce({typ}, {var})'

    def string(self, arg: SeField) -> str:
        return f"str({arg.varname})"

    def union_func(self, arg: SeField) -> str:
        func_name = union_func_name(UNION_SE_PREFIX, type_args(arg.type))
        return f"serde_scope.funcs['{func_name}']({arg.varname}, reuse_instances, convert_sets)"

    def literal(self, arg: SeField) -> str:
        return f"{arg.varname}"


def enum_value(cls: Any, e: Any) -> Any:
    """
    Helper function to get value from enum or enum compatible value.
    """
    if is_enum(e):
        v = e.value
        # Recursively get value of Nested enum.
        if is_enum(v):
            return enum_value(v.__class__, v)
        else:
            return v
    else:
        return cls(e).value