4 files changed, 78 insertions, 36 deletions

diff --git a/crates/ra_editor/src/typing.rs b/crates/ra_editor/src/typing.rs
index 6c1a91ffb..ae82ff89b 100644
--- a/crates/ra_editor/src/typing.rs
+++ b/crates/ra_editor/src/typing.rs
@@ -58,14 +58,19 @@ pub fn join_lines(file: &File, range: TextRange) -> LocalEdit {
 }
 
 pub fn on_enter(file: &File, offset: TextUnit) -> Option<LocalEdit> {
-    let comment = find_leaf_at_offset(file.syntax(), offset).left_biased().filter(|it| it.kind() == COMMENT)?;
-    let prefix = comment_preffix(comment)?;
-    if offset < comment.range().start() + TextUnit::of_str(prefix) {
+    let comment = find_leaf_at_offset(file.syntax(), offset).left_biased().and_then(|it| ast::Comment::cast(it))?;
+
+    if let ast::CommentFlavor::Multiline = comment.flavor() {
+        return None;
+    }
+
+    let prefix = comment.prefix();
+    if offset < comment.syntax().range().start() + TextUnit::of_str(prefix) + TextUnit::from(1) {
         return None;
     }
 
-    let indent = node_indent(file, comment)?;
-    let inserted = format!("\n{}{}", indent, prefix);
+    let indent = node_indent(file, comment.syntax())?;
+    let inserted = format!("\n{}{} ", indent, prefix);
     let cursor_position = offset + TextUnit::of_str(&inserted);
     let mut edit = EditBuilder::new();
     edit.insert(offset, inserted);
@@ -75,20 +80,6 @@ pub fn on_enter(file: &File, offset: TextUnit) -> Option<LocalEdit> {
     })
 }
 
-fn comment_preffix(comment: SyntaxNodeRef) -> Option<&'static str> {
-    let text = comment.leaf_text().unwrap();
-    let res = if text.starts_with("///") {
-        "/// "
-    } else if text.starts_with("//!") {
-        "//! "
-    } else if text.starts_with("//") {
-        "// "
-    } else {
-        return None;
-    };
-    Some(res)
-}
-
 fn node_indent<'a>(file: &'a File, node: SyntaxNodeRef) -> Option<&'a str> {
     let ws = match find_leaf_at_offset(file.syntax(), node.range().start()) {
         LeafAtOffset::Between(l, r) => {
@@ -166,31 +157,27 @@ fn remove_newline(
                 // Removes: comma, newline (incl. surrounding whitespace)
                 // Adds: a single whitespace
                 edit.replace(range, " ".to_string());
-            } else if prev.kind() == COMMENT && next.kind() == COMMENT {
+            } else if let (Some(_), Some(next)) = (ast::Comment::cast(prev), ast::Comment::cast(next)) {
                 // Removes: newline (incl. surrounding whitespace), start of the next comment
-
-                // FIXME: I guess it is safe to unwrap here? A comment always has text, right?
-                let comment_text = next.leaf_text().unwrap().as_str();
-                let comment_start_length = comment_start_length(comment_text);
-
+                let comment_text = next.text();
                 if let Some(newline_pos) = comment_text.find('\n') {
                     // Special case for multi-line c-like comments: join the comment content but
                     // keep the leading `/*`
 
-                    let newline_offset = next.range().start()
+                    let newline_offset = next.syntax().range().start()
                                         + TextUnit::from(newline_pos as u32)
                                         + TextUnit::of_char('\n');
 
                     edit.insert(newline_offset, "/*".to_string());
                     edit.delete(TextRange::from_to(
                         node.range().start(),
-                        next.range().start() + comment_start_length
+                        next.syntax().range().start() + TextUnit::of_str(next.prefix())
                     ));
                 } else {
                     // Single-line comments
                     edit.delete(TextRange::from_to(
                         node.range().start(),
-                        next.range().start() + comment_start_length
+                        next.syntax().range().start() + TextUnit::of_str(next.prefix())
                     ));
                 }
             } else {
@@ -205,7 +192,7 @@ fn remove_newline(
         }
     }
 
-    // FIXME: do we ever reach this point? What does it mean to be here? I think we should document it
+    // The node is either the first or the last in the file
     let suff = &node_text[TextRange::from_to(
         offset - node.range().start() + TextUnit::of_char('\n'),
         TextUnit::of_str(node_text),
@@ -218,13 +205,6 @@ fn remove_newline(
     );
 }
 
-// Return the start length of the comment (e.g. 2 for `//` and 3 for `//!`)
-fn comment_start_length(_text: &str) -> TextUnit {
-    // TODO: use the parser here instead of reimplementing comment parsing?
-    // Otherwise, reimplement comment parsing :)
-    return TextUnit::from(2);
-}
-
 fn is_trailing_comma(left: SyntaxKind, right: SyntaxKind) -> bool {
     match (left, right) {
        (COMMA, R_PAREN) | (COMMA, R_BRACK) => true,
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index 2db6dff1b..b0b855eb4 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -227,6 +227,24 @@ impl<'a> AstNode<'a> for CastExpr<'a> {
 
 impl<'a> CastExpr<'a> {}
 
+// Comment
+#[derive(Debug, Clone, Copy)]
+pub struct Comment<'a> {
+    syntax: SyntaxNodeRef<'a>,
+}
+
+impl<'a> AstNode<'a> for Comment<'a> {
+    fn cast(syntax: SyntaxNodeRef<'a>) -> Option<Self> {
+        match syntax.kind() {
+            COMMENT => Some(Comment { syntax }),
+            _ => None,
+        }
+    }
+    fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
+}
+
+impl<'a> Comment<'a> {}
+
 // Condition
 #[derive(Debug, Clone, Copy)]
 pub struct Condition<'a> {
diff --git a/crates/ra_syntax/src/ast/mod.rs b/crates/ra_syntax/src/ast/mod.rs
index c1570b868..10dac72e5 100644
--- a/crates/ra_syntax/src/ast/mod.rs
+++ b/crates/ra_syntax/src/ast/mod.rs
@@ -99,6 +99,49 @@ impl<'a> Lifetime<'a> {
     }
 }
 
+impl<'a> Comment<'a> {
+    pub fn text(&self) -> SmolStr {
+        self.syntax().leaf_text().unwrap().clone()
+    }
+
+    pub fn flavor(&self) -> CommentFlavor {
+        let text = self.text();
+        if text.starts_with("///") {
+            CommentFlavor::Doc
+        } else if text.starts_with("//!") {
+            CommentFlavor::ModuleDoc
+        } else if text.starts_with("//") {
+            CommentFlavor::Line
+        } else {
+            CommentFlavor::Multiline
+        }
+    }
+
+    pub fn prefix(&self) -> &'static str {
+        self.flavor().prefix()
+    }
+}
+
+#[derive(Debug)]
+pub enum CommentFlavor {
+    Line,
+    Doc,
+    ModuleDoc,
+    Multiline
+}
+
+impl CommentFlavor {
+    pub fn prefix(&self) -> &'static str {
+        use self::CommentFlavor::*;
+        match *self {
+            Line => "//",
+            Doc => "///",
+            ModuleDoc => "//!",
+            Multiline => "/*"
+        }
+    }
+}
+
 impl<'a> Name<'a> {
     pub fn text(&self) -> SmolStr {
         let ident = self.syntax().first_child()
diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index 4b990fd8d..9da0c2c13 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -537,5 +537,6 @@ Grammar(
         "PathSegment": (
             options: [ "NameRef" ]
         ),
+        "Comment": (),
     },
 )