fixup folding ranges for "lineFoldingOnly" clients #2033

1 files changed, 49 insertions, 14 deletions

diff --git a/crates/ra_lsp_server/src/conv.rs b/crates/ra_lsp_server/src/conv.rs
index 1318a1738..173580dee 100644
--- a/crates/ra_lsp_server/src/conv.rs
+++ b/crates/ra_lsp_server/src/conv.rs
@@ -227,22 +227,57 @@ impl ConvWith<(&LineIndex, LineEndings)> for &AtomTextEdit {
     }
 }
 
-impl ConvWith<&LineIndex> for Fold {
+pub(crate) struct FoldConvCtx<'a> {
+    pub(crate) text: &'a str,
+    pub(crate) line_index: &'a LineIndex,
+    pub(crate) line_folding_only: bool,
+}
+
+impl ConvWith<&FoldConvCtx<'_>> for Fold {
     type Output = lsp_types::FoldingRange;
 
-    fn conv_with(self, line_index: &LineIndex) -> lsp_types::FoldingRange {
-        let range = self.range.conv_with(&line_index);
-        lsp_types::FoldingRange {
-            start_line: range.start.line,
-            start_character: Some(range.start.character),
-            end_line: range.end.line,
-            end_character: Some(range.end.character),
-            kind: match self.kind {
-                FoldKind::Comment => Some(lsp_types::FoldingRangeKind::Comment),
-                FoldKind::Imports => Some(lsp_types::FoldingRangeKind::Imports),
-                FoldKind::Mods => None,
-                FoldKind::Block => None,
-            },
+    fn conv_with(self, ctx: &FoldConvCtx) -> lsp_types::FoldingRange {
+        let kind = match self.kind {
+            FoldKind::Comment => Some(lsp_types::FoldingRangeKind::Comment),
+            FoldKind::Imports => Some(lsp_types::FoldingRangeKind::Imports),
+            FoldKind::Mods => None,
+            FoldKind::Block => None,
+        };
+
+        let range = self.range.conv_with(&ctx.line_index);
+
+        if ctx.line_folding_only {
+            // Clients with line_folding_only == true (such as VSCode) will fold the whole end line
+            // even if it contains text not in the folding range. To prevent that we exclude
+            // range.end.line from the folding region if there is more text after range.end
+            // on the same line.
+            let has_more_text_on_end_line = ctx.text
+                [TextRange::from_to(self.range.end(), TextUnit::of_str(ctx.text))]
+            .chars()
+            .take_while(|it| *it != '\n')
+            .any(|it| !it.is_whitespace());
+
+            let end_line = if has_more_text_on_end_line {
+                range.end.line.saturating_sub(1)
+            } else {
+                range.end.line
+            };
+
+            lsp_types::FoldingRange {
+                start_line: range.start.line,
+                start_character: None,
+                end_line,
+                end_character: None,
+                kind,
+            }
+        } else {
+            lsp_types::FoldingRange {
+                start_line: range.start.line,
+                start_character: Some(range.start.character),
+                end_line: range.end.line,
+                end_character: Some(range.end.character),
+                kind,
+            }
         }
     }
 }