4 files changed, 42 insertions, 20 deletions

diff --git a/crates/ra_ide/src/ssr.rs b/crates/ra_ide/src/ssr.rs
index 7b93ff2d2..e213da606 100644
--- a/crates/ra_ide/src/ssr.rs
+++ b/crates/ra_ide/src/ssr.rs
@@ -401,16 +401,22 @@ fn render_replace(
     ignored_comments: &Vec<Comment>,
     template: &SsrTemplate,
 ) -> String {
-    let mut builder = TextEditBuilder::default();
-    for element in template.template.descendants() {
-        if let Some(var) = template.placeholders.get(&element) {
-            builder.replace(element.text_range(), binding[var].to_string())
+    let edit = {
+        let mut builder = TextEditBuilder::default();
+        for element in template.template.descendants() {
+            if let Some(var) = template.placeholders.get(&element) {
+                builder.replace(element.text_range(), binding[var].to_string())
+            }
         }
-    }
-    for comment in ignored_comments {
-        builder.insert(template.template.text_range().end(), comment.syntax().to_string())
-    }
-    builder.finish().apply(&template.template.text().to_string())
+        for comment in ignored_comments {
+            builder.insert(template.template.text_range().end(), comment.syntax().to_string())
+        }
+        builder.finish()
+    };
+
+    let mut text = template.template.text().to_string();
+    edit.apply(&mut text);
+    text
 }
 
 #[cfg(test)]
diff --git a/crates/ra_syntax/src/lib.rs b/crates/ra_syntax/src/lib.rs
index 1a7348dac..61e686da5 100644
--- a/crates/ra_syntax/src/lib.rs
+++ b/crates/ra_syntax/src/lib.rs
@@ -142,7 +142,8 @@ impl Parse<SourceFile> {
     }
 
     fn full_reparse(&self, indel: &Indel) -> Parse<SourceFile> {
-        let text = indel.apply(self.tree().syntax().text().to_string());
+        let mut text = self.tree().syntax().text().to_string();
+        indel.apply(&mut text);
         SourceFile::parse(&text)
     }
 }
diff --git a/crates/ra_syntax/src/parsing/reparsing.rs b/crates/ra_syntax/src/parsing/reparsing.rs
index 6257e3f33..edbc190f8 100644
--- a/crates/ra_syntax/src/parsing/reparsing.rs
+++ b/crates/ra_syntax/src/parsing/reparsing.rs
@@ -109,14 +109,14 @@ fn reparse_block<'node>(
 }
 
 fn get_text_after_edit(element: SyntaxElement, edit: &Indel) -> String {
-    let edit =
-        Indel::replace(edit.delete - element.text_range().start(), edit.insert.clone());
+    let edit = Indel::replace(edit.delete - element.text_range().start(), edit.insert.clone());
 
-    let text = match element {
+    let mut text = match element {
         NodeOrToken::Token(token) => token.text().to_string(),
         NodeOrToken::Node(node) => node.text().to_string(),
     };
-    edit.apply(text)
+    edit.apply(&mut text);
+    text
 }
 
 fn is_contextual_kw(text: &str) -> bool {
@@ -199,7 +199,11 @@ mod tests {
     fn do_check(before: &str, replace_with: &str, reparsed_len: u32) {
         let (range, before) = extract_range(before);
         let edit = Indel::replace(range, replace_with.to_owned());
-        let after = edit.apply(before.clone());
+        let after = {
+            let mut after = before.clone();
+            edit.apply(&mut after);
+            after
+        };
 
         let fully_reparsed = SourceFile::parse(&after);
         let incrementally_reparsed: Parse<SourceFile> = {
diff --git a/crates/ra_text_edit/src/lib.rs b/crates/ra_text_edit/src/lib.rs
index c41bf324b..7138bbc65 100644
--- a/crates/ra_text_edit/src/lib.rs
+++ b/crates/ra_text_edit/src/lib.rs
@@ -37,11 +37,10 @@ impl Indel {
         Indel { delete: range, insert: replace_with }
     }
 
-    pub fn apply(&self, mut text: String) -> String {
+    pub fn apply(&self, text: &mut String) {
         let start: usize = self.delete.start().into();
         let end: usize = self.delete.end().into();
         text.replace_range(start..end, &self.insert);
-        text
     }
 }
 
@@ -76,8 +75,17 @@ impl TextEdit {
         &self.indels
     }
 
-    pub fn apply(&self, text: &str) -> String {
-        let mut total_len = TextSize::of(text);
+    pub fn apply(&self, text: &mut String) {
+        match self.indels.len() {
+            0 => return,
+            1 => {
+                self.indels[0].apply(text);
+                return;
+            }
+            _ => (),
+        }
+
+        let mut total_len = TextSize::of(&*text);
         for indel in self.indels.iter() {
             total_len += TextSize::of(&indel.insert);
             total_len -= indel.delete.end() - indel.delete.start();
@@ -95,7 +103,10 @@ impl TextEdit {
         }
         buf.push_str(&text[prev..text.len()]);
         assert_eq!(TextSize::of(&buf), total_len);
-        buf
+
+        // FIXME: figure out a way to mutate the text in-place or reuse the
+        // memory in some other way
+        *text = buf
     }
 
     pub fn apply_to_offset(&self, offset: TextSize) -> Option<TextSize> {