Make BlockMap unit test pass with 2d coordinates

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/buffer/src/point.rs

@@ -23,6 +23,15 @@ impl Point {
         Point::new(0, 0)
     }
 
+    pub fn from_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
     }

crates/buffer/src/rope.rs

@@ -3,7 +3,7 @@ use crate::PointUtf16;
 use super::Point;
 use arrayvec::ArrayString;
 use smallvec::SmallVec;
-use std::{cmp, fmt, ops::Range, str};
+use std::{cmp, fmt, mem, ops::Range, str};
 use sum_tree::{Bias, Dimension, SumTree};
 
 #[cfg(test)]
@@ -89,6 +89,21 @@ impl Rope {
         self.check_invariants();
     }
 
+    pub fn push_front(&mut self, text: &str) {
+        let suffix = mem::replace(self, Rope::from(text));
+        self.append(suffix);
+    }
+
+    pub fn starts_with(&self, text: &str) -> bool {
+        self.chunks().flat_map(|c| c.bytes()).eq(text.bytes())
+    }
+
+    pub fn ends_with(&self, text: &str) -> bool {
+        self.reversed_chunks_in_range(0..self.len())
+            .flat_map(|c| c.bytes().rev())
+            .eq(text.bytes().rev())
+    }
+
     fn check_invariants(&self) {
         #[cfg(test)]
         {