port rope2 to zed2

crates/rope2/src/point.rs

@@ -0,0 +1,128 @@
+use std::{
+    cmp::Ordering,
+    ops::{Add, AddAssign, Sub},
+};
+
+#[derive(Clone, Copy, Default, Eq, PartialEq, Debug, Hash)]
+pub struct Point {
+    pub row: u32,
+    pub column: u32,
+}
+
+impl Point {
+    pub const MAX: Self = Self {
+        row: u32::MAX,
+        column: u32::MAX,
+    };
+
+    pub fn new(row: u32, column: u32) -> Self {
+        Point { row, column }
+    }
+
+    pub fn zero() -> Self {
+        Point::new(0, 0)
+    }
+
+    pub fn parse_str(s: &str) -> Self {
+        let mut point = Self::zero();
+        for (row, line) in s.split('\n').enumerate() {
+            point.row = row as u32;
+            point.column = line.len() as u32;
+        }
+        point
+    }
+
+    pub fn is_zero(&self) -> bool {
+        self.row == 0 && self.column == 0
+    }
+
+    pub fn saturating_sub(self, other: Self) -> Self {
+        if self < other {
+            Self::zero()
+        } else {
+            self - other
+        }
+    }
+}
+
+impl<'a> Add<&'a Self> for Point {
+    type Output = Point;
+
+    fn add(self, other: &'a Self) -> Self::Output {
+        self + *other
+    }
+}
+
+impl Add for Point {
+    type Output = Point;
+
+    fn add(self, other: Self) -> Self::Output {
+        if other.row == 0 {
+            Point::new(self.row, self.column + other.column)
+        } else {
+            Point::new(self.row + other.row, other.column)
+        }
+    }
+}
+
+impl<'a> Sub<&'a Self> for Point {
+    type Output = Point;
+
+    fn sub(self, other: &'a Self) -> Self::Output {
+        self - *other
+    }
+}
+
+impl Sub for Point {
+    type Output = Point;
+
+    fn sub(self, other: Self) -> Self::Output {
+        debug_assert!(other <= self);
+
+        if self.row == other.row {
+            Point::new(0, self.column - other.column)
+        } else {
+            Point::new(self.row - other.row, self.column)
+        }
+    }
+}
+
+impl<'a> AddAssign<&'a Self> for Point {
+    fn add_assign(&mut self, other: &'a Self) {
+        *self += *other;
+    }
+}
+
+impl AddAssign<Self> for Point {
+    fn add_assign(&mut self, other: Self) {
+        if other.row == 0 {
+            self.column += other.column;
+        } else {
+            self.row += other.row;
+            self.column = other.column;
+        }
+    }
+}
+
+impl PartialOrd for Point {
+    fn partial_cmp(&self, other: &Point) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Point {
+    #[cfg(target_pointer_width = "64")]
+    fn cmp(&self, other: &Point) -> Ordering {
+        let a = (self.row as usize) << 32 | self.column as usize;
+        let b = (other.row as usize) << 32 | other.column as usize;
+        a.cmp(&b)
+    }
+
+    #[cfg(target_pointer_width = "32")]
+    fn cmp(&self, other: &Point) -> Ordering {
+        match self.row.cmp(&other.row) {
+            Ordering::Equal => self.column.cmp(&other.column),
+            comparison @ _ => comparison,
+        }
+    }
+}