OrderedFloat refactor (#918)

* Move egui/util/float_ord.rs -> epaint/util/ordered_float.rs

* Implement Hash on OrderedFloat

* Generic OrderedFloat<T>; impl Hash; documentation

egui/src/util/float_ord.rs

@@ -1,64 +0,0 @@
-//! Total order on floating point types, assuming absence of NaN.
-//! Can be used for sorting, min/max computation, and other collection algorithms.
-
-use std::cmp::Ordering;
-
-/// Totally orderable floating-point value
-/// For not `f32` is supported; could be made generic if necessary.
-pub(crate) struct OrderedFloat(f32);
-
-impl Eq for OrderedFloat {}
-
-impl PartialEq<Self> for OrderedFloat {
-    #[inline]
-    fn eq(&self, other: &Self) -> bool {
-        // NaNs are considered equal (equivalent when it comes to ordering
-        if self.0.is_nan() {
-            other.0.is_nan()
-        } else {
-            self.0 == other.0
-        }
-    }
-}
-
-impl PartialOrd<Self> for OrderedFloat {
-    #[inline]
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        match self.0.partial_cmp(&other.0) {
-            Some(ord) => Some(ord),
-            None => Some(self.0.is_nan().cmp(&other.0.is_nan())),
-        }
-    }
-}
-
-impl Ord for OrderedFloat {
-    #[inline]
-    fn cmp(&self, other: &Self) -> Ordering {
-        match self.partial_cmp(other) {
-            Some(ord) => ord,
-            None => unreachable!(),
-        }
-    }
-}
-
-/// Extension trait to provide `ord` method
-pub(crate) trait FloatOrd {
-    /// Type to provide total order, useful as key in sorted contexts.
-    fn ord(self) -> OrderedFloat;
-}
-
-impl FloatOrd for f32 {
-    #[inline]
-    fn ord(self) -> OrderedFloat {
-        OrderedFloat(self)
-    }
-}
-
-// TODO ordering may break down at least significant digits due to f64 -> f32 conversion
-// Possible solutions: generic OrderedFloat<T>, always OrderedFloat(f64)
-impl FloatOrd for f64 {
-    #[inline]
-    fn ord(self) -> OrderedFloat {
-        OrderedFloat(self as f32)
-    }
-}

egui/src/util/mod.rs

@@ -2,7 +2,6 @@
 
 pub mod cache;
 pub(crate) mod fixed_cache;
-pub(crate) mod float_ord;
 mod history;
 pub mod id_type_map;
 pub mod undoer;

egui/src/widgets/plot/items/mod.rs

@@ -2,9 +2,9 @@
 
 use std::ops::RangeInclusive;
 
+use epaint::util::FloatOrd;
 use epaint::Mesh;
 
-use crate::util::float_ord::FloatOrd;
 use crate::*;
 
 use super::{PlotBounds, ScreenTransform};

egui/src/widgets/plot/mod.rs

@@ -1,9 +1,9 @@
 //! Simple plotting library.
 
-use crate::util::float_ord::FloatOrd;
 use crate::*;
-use color::Hsva;
 use epaint::ahash::AHashSet;
+use epaint::color::Hsva;
+use epaint::util::FloatOrd;
 use items::PlotItem;
 use legend::LegendWidget;
 use transform::{PlotBounds, ScreenTransform};