4 files changed, 35 insertions, 17 deletions

diff --git a/crates/ra_assists/src/handlers/raw_string.rs b/crates/ra_assists/src/handlers/raw_string.rs
index 96679e160..6d77dff13 100644
--- a/crates/ra_assists/src/handlers/raw_string.rs
+++ b/crates/ra_assists/src/handlers/raw_string.rs
@@ -1,5 +1,7 @@
+use std::borrow::Cow;
+
 use ra_syntax::{
-    ast::{self, HasStringValue},
+    ast::{self, HasQuotes, HasStringValue},
     AstToken,
     SyntaxKind::{RAW_STRING, STRING},
     TextSize,
@@ -32,14 +34,17 @@ pub(crate) fn make_raw_string(acc: &mut Assists, ctx: &AssistContext) -> Option<
         target,
         |edit| {
             let max_hash_streak = count_hashes(&value);
-            let mut hashes = String::with_capacity(max_hash_streak + 1);
-            for _ in 0..hashes.capacity() {
-                hashes.push('#');
-            }
-            edit.replace(
-                token.syntax().text_range(),
-                format!("r{}\"{}\"{}", hashes, value, hashes),
-            );
+            let hashes = "#".repeat(max_hash_streak + 1);
+            if matches!(value, Cow::Borrowed(_)) {
+                // Avoid replacing the whole string to better position the cursor.
+                edit.insert(token.syntax().text_range().start(), format!("r{}", hashes));
+                edit.insert(token.syntax().text_range().end(), format!("{}", hashes));
+            } else {
+                edit.replace(
+                    token.syntax().text_range(),
+                    format!("r{}\"{}\"{}", hashes, value, hashes),
+                );
+            }
         },
     )
 }
@@ -70,6 +75,14 @@ pub(crate) fn make_usual_string(acc: &mut Assists, ctx: &AssistContext) -> Optio
         |edit| {
             // parse inside string to escape `"`
             let escaped = value.escape_default().to_string();
+            if let Some(offsets) = token.quote_offsets() {
+                if token.text()[offsets.contents - token.syntax().text_range().start()] == escaped {
+                    edit.replace(offsets.quotes.0, "\"");
+                    edit.replace(offsets.quotes.1, "\"");
+                    return;
+                }
+            }
+
             edit.replace(token.syntax().text_range(), format!("\"{}\"", escaped));
         },
     )
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index 626f9efd0..9f50569dc 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -272,7 +272,7 @@ fn format_args_expand(
 fn unquote_str(lit: &tt::Literal) -> Option<String> {
     let lit = ast::make::tokens::literal(&lit.to_string());
     let token = ast::String::cast(lit)?;
-    token.value()
+    token.value().map(|it| it.into_owned())
 }
 
 fn concat_expand(
diff --git a/crates/ra_ide/src/syntax_highlighting/injection.rs b/crates/ra_ide/src/syntax_highlighting/injection.rs
index 181c21256..8665b480f 100644
--- a/crates/ra_ide/src/syntax_highlighting/injection.rs
+++ b/crates/ra_ide/src/syntax_highlighting/injection.rs
@@ -25,7 +25,7 @@ pub(super) fn highlight_injection(
         return None;
     }
     let value = literal.value()?;
-    let (analysis, tmp_file_id) = Analysis::from_single_file(value);
+    let (analysis, tmp_file_id) = Analysis::from_single_file(value.into_owned());
 
     if let Some(range) = literal.open_quote_text_range() {
         acc.add(HighlightedRange {
diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
index 2e72d4927..045f69133 100644
--- a/crates/ra_syntax/src/ast/tokens.rs
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -1,6 +1,9 @@
 //! There are many AstNodes, but only a few tokens, so we hand-write them here.
 
-use std::convert::{TryFrom, TryInto};
+use std::{
+    borrow::Cow,
+    convert::{TryFrom, TryInto},
+};
 
 use crate::{
     ast::{AstToken, Comment, RawString, String, Whitespace},
@@ -138,11 +141,11 @@ impl HasQuotes for String {}
 impl HasQuotes for RawString {}
 
 pub trait HasStringValue: HasQuotes {
-    fn value(&self) -> Option<std::string::String>;
+    fn value(&self) -> Option<Cow<'_, str>>;
 }
 
 impl HasStringValue for String {
-    fn value(&self) -> Option<std::string::String> {
+    fn value(&self) -> Option<Cow<'_, str>> {
         let text = self.text().as_str();
         let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
 
@@ -156,15 +159,17 @@ impl HasStringValue for String {
         if has_error {
             return None;
         }
-        Some(buf)
+        // FIXME: don't actually allocate for borrowed case
+        let res = if buf == text { Cow::Borrowed(text) } else { Cow::Owned(buf) };
+        Some(res)
     }
 }
 
 impl HasStringValue for RawString {
-    fn value(&self) -> Option<std::string::String> {
+    fn value(&self) -> Option<Cow<'_, str>> {
         let text = self.text().as_str();
         let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
-        Some(text.to_string())
+        Some(Cow::Borrowed(text))
     }
 }