Index operator overloads for Mat

mino/src/matrix.rs

@@ -36,11 +36,6 @@ impl Mat {
 
     pub const EMPTY: &'static Self = Self::new(&[]);
 
-    #[inline]
-    const fn data(&self) -> &[u16] {
-        &self.0
-    }
-
     /// Returns the number of columns in the matrix. This always returns `COLUMNS`.
     #[inline]
     pub const fn cols(&self) -> i16 {
@@ -51,17 +46,13 @@ impl Mat {
     #[inline]
     pub const fn rows(&self) -> i16 {
         // XXX(iitalics): this is guarunteed not to wrap, since we check len in `new`.
-        self.data().len() as i16
+        self.0.len() as i16
     }
 
     /// Returns true if the cells in row `y` selected by `mask` match the pattern `test`.
     #[inline]
     pub fn test_row(&self, y: i16, mask: u16, test: u16) -> bool {
-        let bits = match usize::try_from(y) {
-            Ok(i) => self.data().get(i).copied().unwrap_or(EMPTY_ROW),
-            Err(_) => FULL_ROW,
-        };
-        (bits & mask) == test
+        (self[y] & mask) == test
     }
 
     /// Returns true if the cell at `(x,y)` is occupied.
@@ -75,6 +66,33 @@ impl Mat {
     }
 }
 
+impl core::ops::Index<i16> for Mat {
+    type Output = u16;
+    fn index(&self, y: i16) -> &u16 {
+        if y < 0 {
+            &FULL_ROW
+        } else {
+            self.0.get(y as usize).unwrap_or(&EMPTY_ROW)
+        }
+    }
+}
+
+impl core::ops::Index<core::ops::RangeTo<i16>> for Mat {
+    type Output = [u16];
+    fn index(&self, r: core::ops::RangeTo<i16>) -> &[u16] {
+        let y = core::cmp::max(r.end, 0);
+        let y = core::cmp::min(y as usize, self.0.len());
+        &self.0[..y]
+    }
+}
+
+impl core::ops::Index<core::ops::RangeFull> for Mat {
+    type Output = [u16];
+    fn index(&self, _: core::ops::RangeFull) -> &[u16] {
+        &self.0
+    }
+}
+
 impl core::fmt::Debug for Mat {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "mat!{{")?;
@@ -170,12 +188,13 @@ where
     ///
     /// Panics if the buffer space cannot fit the rows of `mat`.
     pub fn copy_from(&mut self, mat: &Mat) {
-        let data = self.buffer.as_mut();
-        if mat.data().len() > data.len() {
+        let mat_data = &mat[..];
+        let buf_data = self.buffer.as_mut();
+        if mat_data.len() > buf_data.len() {
             panic!("matrix cannot fit in available buffer space");
         }
-        self.rows = mat.rows() as usize;
-        data[..self.rows].copy_from_slice(mat.data());
+        self.rows = mat_data.len();
+        buf_data[..self.rows].copy_from_slice(mat_data);
     }
 
     pub fn fill_row(&mut self, y: i16, mask: u16) {
@@ -184,14 +203,14 @@ where
             return;
         }
         let y = y as usize;
-        let data = self.buffer.as_mut();
+        let buf_data = self.buffer.as_mut();
         while y >= self.rows {
-            *data
+            *buf_data
                 .get_mut(self.rows)
                 .expect("y should be within available buffer space") = EMPTY_ROW;
             self.rows += 1;
         }
-        data[y] |= mask;
+        buf_data[y] |= mask;
     }
 
     /// Fills in the cell at the given (x,y) coordinate. Adds new rows to the top of the