From 47e8bd5f4f57617840055244cbb935d9f75d25c5 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Mon, 25 Jul 2022 15:06:04 +0200
Subject: [PATCH] Introduce `MultiBuffer::clip_offset_utf16`

---
 crates/editor/src/multi_buffer.rs | 19 +++++++++++++++++++
 crates/text/src/text.rs           |  4 ++++
 2 files changed, 23 insertions(+)

diff --git a/crates/editor/src/multi_buffer.rs b/crates/editor/src/multi_buffer.rs
index 71d0053e56..78d7e94ae5 100644
--- a/crates/editor/src/multi_buffer.rs
+++ b/crates/editor/src/multi_buffer.rs
@@ -1692,6 +1692,25 @@ impl MultiBufferSnapshot {
         *cursor.start() + overshoot
     }
 
+    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
+        if let Some((_, _, buffer)) = self.as_singleton() {
+            return buffer.clip_offset_utf16(offset, bias);
+        }
+
+        let mut cursor = self.excerpts.cursor::<OffsetUtf16>();
+        cursor.seek(&offset, Bias::Right, &());
+        let overshoot = if let Some(excerpt) = cursor.item() {
+            let excerpt_start = excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
+            let buffer_offset = excerpt
+                .buffer
+                .clip_offset_utf16(excerpt_start + (offset - cursor.start()), bias);
+            OffsetUtf16(buffer_offset.0.saturating_sub(excerpt_start.0))
+        } else {
+            OffsetUtf16(0)
+        };
+        *cursor.start() + overshoot
+    }
+
     pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
         if let Some((_, _, buffer)) = self.as_singleton() {
             return buffer.clip_point_utf16(point, bias);
diff --git a/crates/text/src/text.rs b/crates/text/src/text.rs
index 1e56439fcc..7da77b22ff 100644
--- a/crates/text/src/text.rs
+++ b/crates/text/src/text.rs
@@ -1901,6 +1901,10 @@ impl BufferSnapshot {
         self.visible_text.clip_point(point, bias)
     }
 
+    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
+        self.visible_text.clip_offset_utf16(offset, bias)
+    }
+
     pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
         self.visible_text.clip_point_utf16(point, bias)
     }