other: add additional clamping functions on numeric types (#1324)

* other: add additional clamping functions on numeric types

* add tests and replace one usage

src/components/data_table.rs

@@ -21,6 +21,8 @@ pub use data_type::*;
 pub mod sortable;
 pub use sortable::*;
 
+use crate::utils::gen_util::ClampExt;
+
 /// A [`DataTable`] is a component that displays data in a tabular form.
 ///
 /// Note that [`DataTable`] takes a generic type `S`, bounded by [`SortType`]. This controls whether this table
@@ -120,7 +122,7 @@ impl<DataType: DataToCell<H>, H: ColumnHeader, S: SortType, C: DataTableColumn<H
     /// Updates the scroll position to a selected index.
     #[allow(clippy::comparison_chain)]
     pub fn set_position(&mut self, new_index: usize) {
-        let new_index = new_index.clamp(0, self.data.len().saturating_sub(1));
+        let new_index = new_index.clamp_upper(self.data.len().saturating_sub(1));
         if self.state.current_index < new_index {
             self.state.scroll_direction = ScrollDirection::Down;
         } else if self.state.current_index > new_index {

src/utils/gen_util.rs

@@ -186,6 +186,43 @@ macro_rules! multi_eq_ignore_ascii_case {
     };
 }
 
+/// A trait for additional clamping functions on numeric types.
+pub trait ClampExt {
+    /// Restrict a value by a lower bound. If the current value is _lower_ than `lower_bound`,
+    /// it will be set to `_lower_bound`.
+    fn clamp_lower(&self, lower_bound: Self) -> Self;
+
+    /// Restrict a value by an upper bound. If the current value is _greater_ than `upper_bound`,
+    /// it will be set to `upper_bound`.
+    fn clamp_upper(&self, upper_bound: Self) -> Self;
+}
+
+macro_rules! clamp_num_impl {
+    ( $($NumType:ty),+ $(,)? ) => {
+        $(
+            impl ClampExt for $NumType {
+                fn clamp_lower(&self, lower_bound: Self) -> Self {
+                    if *self < lower_bound {
+                        lower_bound
+                    } else {
+                        *self
+                    }
+                }
+
+                fn clamp_upper(&self, upper_bound: Self) -> Self {
+                    if *self > upper_bound {
+                        upper_bound
+                    } else {
+                        *self
+                    }
+                }
+            }
+        )*
+    };
+}
+
+clamp_num_impl!(u8, u16, u32, u64, usize);
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -209,7 +246,7 @@ mod test {
     }
 
     #[test]
-    fn test_truncate() {
+    fn test_truncate_str() {
         let cpu_header = "CPU(c)▲";
 
         assert_eq!(
@@ -232,7 +269,7 @@ mod test {
     }
 
     #[test]
-    fn test_truncate_cjk() {
+    fn truncate_cjk() {
         let cjk = "施氏食獅史";
 
         assert_eq!(
@@ -255,7 +292,7 @@ mod test {
     }
 
     #[test]
-    fn test_truncate_mixed() {
+    fn truncate_mixed() {
         let test = "Test (施氏食獅史) Test";
 
         assert_eq!(
@@ -288,7 +325,7 @@ mod test {
     }
 
     #[test]
-    fn test_truncate_flags() {
+    fn truncate_flags() {
         let flag = "🇨🇦";
         assert_eq!(truncate_str(flag, 3_usize), flag);
         assert_eq!(truncate_str(flag, 2_usize), flag);
@@ -331,7 +368,7 @@ mod test {
 
     /// This might not be the best way to handle it, but this at least tests that it doesn't crash...
     #[test]
-    fn test_truncate_hindi() {
+    fn truncate_hindi() {
         // cSpell:disable
         let test = "हिन्दी";
         assert_eq!(truncate_str(test, 10_usize), test);
@@ -346,7 +383,7 @@ mod test {
     }
 
     #[test]
-    fn test_truncate_emoji() {
+    fn truncate_emoji() {
         let heart = "❤️";
         assert_eq!(truncate_str(heart, 2_usize), heart);
         assert_eq!(truncate_str(heart, 1_usize), heart);
@@ -396,4 +433,28 @@ mod test {
             "multi non-matching should fail"
         );
     }
+
+    #[test]
+    fn test_clamp_upper() {
+        let val: usize = 100;
+        assert_eq!(val.clamp_upper(150), 100);
+
+        let val: usize = 100;
+        assert_eq!(val.clamp_upper(100), 100);
+
+        let val: usize = 100;
+        assert_eq!(val.clamp_upper(50), 50);
+    }
+
+    #[test]
+    fn test_clamp_lower() {
+        let val: usize = 100;
+        assert_eq!(val.clamp_lower(150), 150);
+
+        let val: usize = 100;
+        assert_eq!(val.clamp_lower(100), 100);
+
+        let val: usize = 100;
+        assert_eq!(val.clamp_lower(50), 100);
+    }
 }