add proptests to some layout ops

output/src/area.rs

@@ -38,29 +38,29 @@ pub trait Area<N: Coordinate>: From<[N;4]> + Debug + Copy {
         [self.x(), self.y(), self.w(), h]
     }
     #[inline] fn x2 (&self) -> N {
-        self.x() + self.w()
+        self.x().plus(self.w())
     }
     #[inline] fn y2 (&self) -> N {
-        self.y() + self.h()
+        self.y().plus(self.h())
     }
     #[inline] fn lrtb (&self) -> [N;4] {
         [self.x(), self.x2(), self.y(), self.y2()]
     }
     #[inline] fn center (&self) -> [N;2] {
-        [self.x() + self.w()/2.into(), self.y() + self.h()/2.into()]
+        [self.x().plus(self.w()/2.into()), self.y().plus(self.h()/2.into())]
     }
 
     #[inline] fn center_x (&self, n: N) -> [N;4] {
         let [x, y, w, h] = self.xywh();
-        [(x + w / 2.into()).minus(n / 2.into()), y + h / 2.into(), n, 1.into()]
+        [(x.plus(w / 2.into())).minus(n / 2.into()), y.plus(h / 2.into()), n, 1.into()]
     }
     #[inline] fn center_y (&self, n: N) -> [N;4] {
         let [x, y, w, h] = self.xywh();
-        [x + w / 2.into(), (y + h / 2.into()).minus(n / 2.into()), 1.into(), n]
+        [x.plus(w / 2.into()), (y + h / 2.into()).minus(n / 2.into()), 1.into(), n]
     }
     #[inline] fn center_xy (&self, [n, m]: [N;2]) -> [N;4] {
         let [x, y, w, h] = self.xywh();
-        [(x + w / 2.into()).minus(n / 2.into()), (y + h / 2.into()).minus(m / 2.into()), n, m]
+        [(x.plus(w / 2.into())).minus(n / 2.into()), (y.plus(h / 2.into())).minus(m / 2.into()), n, m]
     }
 
     #[inline] fn centered (&self) -> [N;2] {

output/src/coordinate.rs

@@ -1,7 +1,11 @@
 use std::fmt::{Debug, Display};
 use std::ops::{Add, Sub, Mul, Div};
 
-impl Coordinate for u16 {}
+impl Coordinate for u16 {
+    #[inline] fn plus (self, other: Self) -> Self {
+        self.saturating_add(other)
+    }
+}
 
 /// A linear coordinate.
 pub trait Coordinate: Send + Sync + Copy
@@ -15,6 +19,7 @@ pub trait Coordinate: Send + Sync + Copy
     + Into<usize>
     + Into<f64>
 {
+    #[inline] fn zero () -> Self { 0.into() }
     #[inline] fn minus (self, other: Self) -> Self {
         if self >= other {
             self - other
@@ -22,7 +27,5 @@ pub trait Coordinate: Send + Sync + Copy
             0.into()
         }
     }
-    #[inline] fn zero () -> Self {
-        0.into()
-    }
+    fn plus (self, other: Self) -> Self;
 }

output/src/op_transform.rs

@@ -139,8 +139,7 @@ transform_xy!("fill/x" "fill/y" "fill/xy" |self: Fill, to|{
         X(_)  => [x0, y, wmax, h],
         Y(_)  => [x, y0, w, hmax],
         XY(_) => [x0, y0, wmax, hmax],
-    }.into()
-});
+    }.into() });
 transform_xy_unit!("fixed/x" "fixed/y" "fixed/xy"|self: Fixed, area|{
     let [x, y, w, h] = area.xywh();
     let fixed_area = match self {
@@ -154,8 +153,7 @@ transform_xy_unit!("fixed/x" "fixed/y" "fixed/xy"|self: Fixed, area|{
         Self::Y(fh, _) => [x, y, w, *fh],
         Self::XY(fw, fh, _) => [x, y, *fw, *fh],
     };
-    fixed_area
-});
+    fixed_area });
 transform_xy_unit!("min/x" "min/y" "min/xy"|self: Min, area|{
     let area = Render::layout(&self.content(), area);
     match self {
@@ -175,24 +173,60 @@ transform_xy_unit!("shrink/x" "shrink/y" "shrink/xy"|self: Shrink, area|Render::
     [area.x(), area.y(), area.w().minus(self.dx()), area.h().minus(self.dy())].into()));
 transform_xy_unit!("expand/x" "expand/y" "expand/xy"|self: Expand, area|Render::layout(
     &self.content(),
-    [area.x(), area.y(), area.w() + self.dx(), area.h() + self.dy()].into()));
+    [area.x(), area.y(), area.w().plus(self.dx()), area.h().plus(self.dy())].into()));
 transform_xy_unit!("push/x" "push/y" "push/xy"|self: Push, area|{
     let area = Render::layout(&self.content(), area);
-    [area.x() + self.dx(), area.y() + self.dy(), area.w(), area.h()]
-});
+    [area.x().plus(self.dx()), area.y().plus(self.dy()), area.w(), area.h()] });
 transform_xy_unit!("pull/x" "pull/y" "pull/xy"|self: Pull, area|{
     let area = Render::layout(&self.content(), area);
-    [area.x().minus(self.dx()), area.y().minus(self.dy()), area.w(), area.h()]
-});
+    [area.x().minus(self.dx()), area.y().minus(self.dy()), area.w(), area.h()] });
 transform_xy_unit!("margin/x" "margin/y" "margin/xy"|self: Margin, area|{
     let area = Render::layout(&self.content(), area);
     let dx = self.dx();
     let dy = self.dy();
-    [area.x().minus(dx), area.y().minus(dy), area.w() + dy + dy, area.h() + dy + dy]
-});
+    [area.x().minus(dx), area.y().minus(dy), area.w().plus(dy.plus(dy)), area.h().plus(dy.plus(dy))] });
 transform_xy_unit!("padding/x" "padding/y" "padding/xy"|self: Padding, area|{
     let area = Render::layout(&self.content(), area);
     let dx = self.dx();
     let dy = self.dy();
-    [area.x() + dx, area.y() + dy, area.w().minus(dy + dy), area.h().minus(dy + dy), ]
-});
+    [area.x().plus(dx), area.y().plus(dy), area.w().minus(dy.plus(dy)), area.h().minus(dy.plus(dy)), ] });
+
+#[cfg(test)] mod test_op_transform {
+    use super::*;
+    use proptest::prelude::*;
+    use proptest::option::of;
+    macro_rules! test_op_transform {
+        ($fn:ident, $Op:ident) => {
+            proptest! {
+                #[test] fn $fn (
+                    op_x in of(u16::MIN..u16::MAX),
+                    op_y in of(u16::MIN..u16::MAX),
+                    content in "\\PC*",
+                    x in u16::MIN..u16::MAX,
+                    y in u16::MIN..u16::MAX,
+                    w in u16::MIN..u16::MAX,
+                    h in u16::MIN..u16::MAX,
+                ) {
+                    if let Some(op) = match (op_x, op_y) {
+                        (Some(x), Some(y)) => Some($Op::xy(x, y, content)),
+                        (Some(x), None)    => Some($Op::x(x, content)),
+                        (Some(y), None)    => Some($Op::y(y, content)),
+                        _ => None
+                    } {
+                        assert_eq!(Content::layout(&op, [x, y, w, h]),
+                                   Render::layout(&op,  [x, y, w, h]));
+                    }
+                }
+            }
+        }
+    }
+    test_op_transform!(test_op_fixed,   Fixed);
+    test_op_transform!(test_op_min,     Min);
+    test_op_transform!(test_op_max,     Max);
+    test_op_transform!(test_op_push,    Push);
+    test_op_transform!(test_op_pull,    Pull);
+    test_op_transform!(test_op_shrink,  Shrink);
+    test_op_transform!(test_op_expand,  Expand);
+    test_op_transform!(test_op_margin,  Margin);
+    test_op_transform!(test_op_padding, Padding);
+}