flatten workspace into 1 crate

src/space/cond.rs

@@ -0,0 +1,65 @@
+use crate::*;
+
+pub enum Cond<E: Engine, A: Render<E>, B: Render<E>> {
+    _Unused(E),
+    When(bool, A),
+    Either(bool, A, B)
+}
+
+impl<E: Engine, R: Render<E>> LayoutCond<E> for R {}
+
+pub trait LayoutCond<E: Engine>: Render<E> + Sized {
+    fn when (self, cond: bool) -> If<E, Self> {
+        If(Default::default(), cond, self)
+    }
+    fn or <B: Render<E>> (self, cond: bool, other: B) -> Either<E, Self, B> {
+        Either(Default::default(), cond, self, other)
+    }
+}
+
+impl<E: Engine> LayoutCondStatic<E> for E {}
+
+pub trait LayoutCondStatic<E: Engine> {
+    fn either <A: Render<E>, B: Render<E>> (
+        condition: bool,
+        a: A,
+        b: B,
+    ) -> Either<E, A, B> {
+        Either(Default::default(), condition, a, b)
+    }
+}
+
+/// Render widget if predicate is true
+pub struct If<E: Engine, A: Render<E>>(PhantomData<E>, bool, A);
+
+impl<E: Engine, A: Render<E>> Render<E> for If<E, A> {
+    fn min_size (&self, to: E::Size) -> Perhaps<E::Size> {
+        if self.1 {
+            return self.2.min_size(to)
+        }
+        Ok(None)
+    }
+    fn render (&self, to: &mut E::Output) -> Usually<()> {
+        if self.1 {
+            return self.2.render(to)
+        }
+        Ok(())
+    }
+}
+
+/// Render widget A if predicate is true, otherwise widget B
+pub struct Either<E: Engine, A: Render<E>, B: Render<E>>(
+    PhantomData<E>,
+    bool,
+    A,
+    B,
+);
+
+impl<E: Engine, A: Render<E>, B: Render<E>> Render<E> for Either<E, A, B> {
+    fn min_size (&self, to: E::Size) -> Perhaps<E::Size> {
+        if self.1 { self.2.min_size(to) } else { self.3.min_size(to) }
+    }
+    fn render (&self, to: &mut E::Output) -> Usually<()> {
+        if self.1 { self.2.render(to) } else { self.3.render(to) }
+    }
+}