More consistent library code and functions 🎄

1 files changed, 76 insertions, 0 deletions

diff --git a/src/library/maps/alignment.rs b/src/library/maps/alignment.rs
new file mode 100644
index 00000000..486c8b2e
--- /dev/null
+++ b/src/library/maps/alignment.rs
@@ -0,0 +1,76 @@
+use super::*;
+use AlignmentKey::*;
+
+/// An argument key which describes a target alignment.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum AlignmentKey {
+    Align(Alignment),
+    Left,
+    Top,
+    Right,
+    Bottom,
+}
+
+impl AlignmentKey {
+    /// The generic axis this alignment key corresponds to in the given system
+    /// of layouting axes. `None` if the alignment is generic.
+    pub fn axis(self, axes: LayoutAxes) -> Option<GenericAxis> {
+        match self {
+            Left | Right => Some(Horizontal.to_generic(axes)),
+            Top | Bottom => Some(Vertical.to_generic(axes)),
+            Align(_) => None,
+        }
+    }
+
+    /// The generic version of this alignment in the given system of layouting
+    /// axes.
+    ///
+    /// Returns an error if the alignment is invalid for the given axis.
+    pub fn to_generic(self, axes: LayoutAxes, axis: GenericAxis) -> LayoutResult<Alignment> {
+        let specific = axis.to_specific(axes);
+        let start = match axes.get(axis).is_positive() {
+            true => Origin,
+            false => End,
+        };
+
+        Ok(match (self, specific) {
+            (Align(alignment), _) => alignment,
+            (Left, Horizontal) | (Top, Vertical) => start,
+            (Right, Horizontal) | (Bottom, Vertical) => start.inv(),
+
+            _ => error!(
+                "invalid alignment `{}` for {} axis",
+                format!("{:?}", self).to_lowercase(),
+                format!("{:?}", axis).to_lowercase()
+            )
+        })
+    }
+
+    /// The specific version of this alignment in the given system of layouting
+    /// axes.
+    pub fn to_specific(self, axes: LayoutAxes, axis: SpecificAxis) -> AlignmentKey {
+        let direction = axes.get_specific(axis);
+        if let Align(alignment) = self {
+            match (direction, alignment) {
+                (LeftToRight, Origin) | (RightToLeft, End) => Left,
+                (LeftToRight, End) | (RightToLeft, Origin) => Right,
+                (TopToBottom, Origin) | (BottomToTop, End) => Top,
+                (TopToBottom, End) | (BottomToTop, Origin) => Bottom,
+                (_, Center) => self,
+            }
+        } else {
+            self
+        }
+    }
+}
+
+key!(AlignmentKey, "alignment",
+    "origin" => Align(Origin),
+    "center" => Align(Center),
+    "end"    => Align(End),
+
+    "left"   => Left,
+    "top"    => Top,
+    "right"  => Right,
+    "bottom" => Bottom,
+);