Auto pairs selection (#1254)

* use auto pairs with selections

Previously, the auto pairs code was converting the user selection into
its cursor form, and setting the transaction's selection to that cursor.
This has the effect of destroying the user's selection if they type a
pair character that gets auto completed.

This fixes the code to work with the user's selection, inserting auto
pairs where appropriate, but either keeping or extending the user's
selection.

* use movement::Direction instead of bool

* assume 0-width cursor is forward

1 files changed, 20 insertions, 0 deletions

diff --git a/helix-core/src/selection.rs b/helix-core/src/selection.rs
index 116a1c7c..884c98ac 100644
--- a/helix-core/src/selection.rs
+++ b/helix-core/src/selection.rs
@@ -7,6 +7,7 @@ use crate::{
         ensure_grapheme_boundary_next, ensure_grapheme_boundary_prev, next_grapheme_boundary,
         prev_grapheme_boundary,
     },
+    movement::Direction,
     Assoc, ChangeSet, RopeSlice,
 };
 use smallvec::{smallvec, SmallVec};
@@ -82,6 +83,13 @@ impl Range {
         std::cmp::max(self.anchor, self.head)
     }
 
+    /// Total length of the range.
+    #[inline]
+    #[must_use]
+    pub fn len(&self) -> usize {
+        self.to() - self.from()
+    }
+
     /// The (inclusive) range of lines that the range overlaps.
     #[inline]
     #[must_use]
@@ -102,6 +110,18 @@ impl Range {
         self.anchor == self.head
     }
 
+    /// `Direction::Backward` when head < anchor.
+    /// `Direction::Backward` otherwise.
+    #[inline]
+    #[must_use]
+    pub fn direction(&self) -> Direction {
+        if self.head < self.anchor {
+            Direction::Backward
+        } else {
+            Direction::Forward
+        }
+    }
+
     /// Check two ranges for overlap.
     #[must_use]
     pub fn overlaps(&self, other: &Self) -> bool {