WIP

zed/src/editor/movement.rs

@@ -0,0 +1,60 @@
+use super::{DisplayMap, DisplayPoint};
+use crate::app::AppContext;
+use anyhow::Result;
+use std::cmp;
+
+pub fn left(map: &DisplayMap, mut point: DisplayPoint, app: &AppContext) -> Result<DisplayPoint> {
+    if point.column() > 0 {
+        *point.column_mut() -= 1;
+    } else if point.row() > 0 {
+        *point.row_mut() -= 1;
+        *point.column_mut() = map.line_len(point.row(), app)?;
+    }
+    Ok(point)
+}
+
+pub fn right(map: &DisplayMap, mut point: DisplayPoint, app: &AppContext) -> Result<DisplayPoint> {
+    let max_column = map.line_len(point.row(), app).unwrap();
+    if point.column() < max_column {
+        *point.column_mut() += 1;
+    } else if point.row() < map.max_point(app).row() {
+        *point.row_mut() += 1;
+        *point.column_mut() = 0;
+    }
+    Ok(point)
+}
+
+pub fn up(
+    map: &DisplayMap,
+    mut point: DisplayPoint,
+    goal_column: Option<u32>,
+    app: &AppContext,
+) -> Result<(DisplayPoint, Option<u32>)> {
+    let goal_column = goal_column.or(Some(point.column()));
+    if point.row() > 0 {
+        *point.row_mut() -= 1;
+        *point.column_mut() = cmp::min(goal_column.unwrap(), map.line_len(point.row(), app)?);
+    } else {
+        point = DisplayPoint::new(0, 0);
+    }
+
+    Ok((point, goal_column))
+}
+
+pub fn down(
+    map: &DisplayMap,
+    mut point: DisplayPoint,
+    goal_column: Option<u32>,
+    app: &AppContext,
+) -> Result<(DisplayPoint, Option<u32>)> {
+    let goal_column = goal_column.or(Some(point.column()));
+    let max_point = map.max_point(app);
+    if point.row() < max_point.row() {
+        *point.row_mut() += 1;
+        *point.column_mut() = cmp::min(goal_column.unwrap(), map.line_len(point.row(), app)?)
+    } else {
+        point = max_point;
+    }
+
+    Ok((point, goal_column))
+}