diff --git a/htpy/__init__.py b/htpy/__init__.py
index 4001d92..143c424 100644
--- a/htpy/__init__.py
+++ b/htpy/__init__.py
@@ -109,7 +109,45 @@ def _attrs_string(attrs: dict[str, Attribute]) -> str:
return " " + result
-def iter_node(x: Node) -> Iterator[str]:
+T = t.TypeVar("T")
+
+
+class ContextProvider(t.Generic[T]):
+ def __init__(self, context: Context[T], value: T, children_func: Callable[[], Node]) -> None:
+ self.context = context
+ self.value = value
+ self.children_func = children_func
+
+ def __iter__(self) -> Iterator[str]:
+ return iter_node(self)
+
+ def __str__(self) -> str:
+ return "".join(self)
+
+
+class ContextUse(t.Generic[T]):
+ def __init__(self, context: Context[T], children_func: Callable[[T], Node]):
+ self.context = context
+ self.children_func = children_func
+
+
+class Context(t.Generic[T]):
+ def __init__(self, default: T) -> None:
+ self.default = default
+
+ def provide(self, value: T, children_func: Callable[[], Node]) -> ContextProvider[T]:
+ return ContextProvider(self, value, children_func)
+
+ def use(self, children_func: Callable[[T], Node]) -> ContextUse[T]:
+ return ContextUse(self, children_func)
+
+
+ContextDict: t.TypeAlias = dict[t.Any, t.Any]
+
+
+def iter_node(x: Node, ctx: ContextDict | None = None) -> Iterator[str]:
+ _ctx: ContextDict = ctx or {}
+
while not isinstance(x, BaseElement) and callable(x):
x = x()
@@ -123,12 +161,16 @@ def iter_node(x: Node) -> Iterator[str]:
return
if isinstance(x, BaseElement):
- yield from x
+ yield from x.iter_context(_ctx)
+ elif isinstance(x, ContextProvider):
+ yield from iter_node(x.children_func(), {**_ctx, x.context: x.value})
+ elif isinstance(x, ContextUse):
+ yield from iter_node(x.children_func(_ctx.get(x.context, x.context.default)), _ctx)
elif isinstance(x, str | _HasHtml):
yield str(_escape(x))
elif isinstance(x, Iterable): # pyright: ignore [reportUnnecessaryIsInstance]
for child in x:
- yield from iter_node(child)
+ yield from iter_node(child, _ctx)
else:
raise ValueError(f"{x!r} is not a valid child element")
@@ -201,8 +243,11 @@ def __call__(self: BaseElementSelf, *args: t.Any, **kwargs: t.Any) -> BaseElemen
)
def __iter__(self) -> Iterator[str]:
+ return self.iter_context({})
+
+ def iter_context(self, ctx: dict[Context, t.Any]) -> Iterator[str]:
yield f"<{self._name}{_attrs_string(self._attrs)}>"
- yield from iter_node(self._children)
+ yield from iter_node(self._children, ctx)
yield f""
def __repr__(self) -> str:
@@ -221,13 +266,13 @@ def __getitem__(self: ElementSelf, children: Node) -> ElementSelf:
class HTMLElement(Element):
- def __iter__(self) -> Iterator[str]:
+ def iter_context(self, ctx: dict[Context, t.Any]) -> Iterator[str]:
yield ""
- yield from super().__iter__()
+ yield from super().iter_context(ctx)
class VoidElement(BaseElement):
- def __iter__(self) -> Iterator[str]:
+ def iter_context(self, ctx: dict[Context, t.Any]) -> Iterator[str]:
yield f"<{self._name}{_attrs_string(self._attrs)}>"
@@ -248,7 +293,15 @@ def __html__(self) -> str: ...
_ClassNamesDict: t.TypeAlias = dict[str, bool]
_ClassNames: t.TypeAlias = Iterable[str | None | bool | _ClassNamesDict] | _ClassNamesDict
Node: t.TypeAlias = (
- None | bool | str | BaseElement | _HasHtml | Iterable["Node"] | Callable[[], "Node"]
+ None
+ | bool
+ | str
+ | BaseElement
+ | _HasHtml
+ | Iterable["Node"]
+ | Callable[[], "Node"]
+ | ContextProvider[t.Any]
+ | ContextUse[t.Any]
)
Attribute: t.TypeAlias = None | bool | str | _HasHtml | _ClassNames
diff --git a/tests/test_context.py b/tests/test_context.py
new file mode 100644
index 0000000..1f1045b
--- /dev/null
+++ b/tests/test_context.py
@@ -0,0 +1,15 @@
+from htpy import Context, div
+
+
+def test_context_default() -> None:
+ theme: Context[str] = Context("light")
+
+ result = div[theme.use(lambda value: f"My theme is {value}")]
+ assert str(result) == "My theme is light
"
+
+
+def test_context_provider() -> None:
+ theme = Context("light")
+
+ result = theme.provide("dark", lambda: div[theme.use(lambda value: f"My theme is {value}")])
+ assert str(result) == "My theme is dark
"