2 files changed, 412 insertions, 3 deletions

diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index a838c30da..c2ef61ae2 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -37,6 +37,7 @@ mod line_index;
 mod folding_ranges;
 mod line_index_utils;
 mod join_lines;
+mod typing;
 
 #[cfg(test)]
 mod marks;
@@ -295,7 +296,7 @@ impl Analysis {
     /// up minor stuff like continuing the comment.
     pub fn on_enter(&self, position: FilePosition) -> Option<SourceChange> {
         let file = self.db.parse(position.file_id);
-        let edit = ra_ide_api_light::on_enter(&file, position.offset)?;
+        let edit = typing::on_enter(&file, position.offset)?;
         Some(SourceChange::from_local_edit(position.file_id, edit))
     }
 
@@ -304,14 +305,14 @@ impl Analysis {
     // FIXME: use a snippet completion instead of this hack here.
     pub fn on_eq_typed(&self, position: FilePosition) -> Option<SourceChange> {
         let file = self.db.parse(position.file_id);
-        let edit = ra_ide_api_light::on_eq_typed(&file, position.offset)?;
+        let edit = typing::on_eq_typed(&file, position.offset)?;
         Some(SourceChange::from_local_edit(position.file_id, edit))
     }
 
     /// Returns an edit which should be applied when a dot ('.') is typed on a blank line, indenting the line appropriately.
     pub fn on_dot_typed(&self, position: FilePosition) -> Option<SourceChange> {
         let file = self.db.parse(position.file_id);
-        let edit = ra_ide_api_light::on_dot_typed(&file, position.offset)?;
+        let edit = typing::on_dot_typed(&file, position.offset)?;
         Some(SourceChange::from_local_edit(position.file_id, edit))
     }
 
diff --git a/crates/ra_ide_api/src/typing.rs b/crates/ra_ide_api/src/typing.rs
new file mode 100644
index 000000000..b7e023d60
--- /dev/null
+++ b/crates/ra_ide_api/src/typing.rs
@@ -0,0 +1,408 @@
+use ra_syntax::{
+    AstNode, SourceFile, SyntaxKind::*,
+    SyntaxNode, TextUnit, TextRange,
+    algo::{find_node_at_offset, find_leaf_at_offset, LeafAtOffset},
+    ast::{self, AstToken},
+};
+use ra_fmt::leading_indent;
+use crate::LocalEdit;
+use ra_text_edit::TextEditBuilder;
+
+pub fn on_enter(file: &SourceFile, offset: TextUnit) -> Option<LocalEdit> {
+    let comment =
+        find_leaf_at_offset(file.syntax(), offset).left_biased().and_then(ast::Comment::cast)?;
+
+    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.syntax())?;
+    let inserted = format!("\n{}{} ", indent, prefix);
+    let cursor_position = offset + TextUnit::of_str(&inserted);
+    let mut edit = TextEditBuilder::default();
+    edit.insert(offset, inserted);
+    Some(LocalEdit {
+        label: "on enter".to_string(),
+        edit: edit.finish(),
+        cursor_position: Some(cursor_position),
+    })
+}
+
+fn node_indent<'a>(file: &'a SourceFile, node: &SyntaxNode) -> Option<&'a str> {
+    let ws = match find_leaf_at_offset(file.syntax(), node.range().start()) {
+        LeafAtOffset::Between(l, r) => {
+            assert!(r == node);
+            l
+        }
+        LeafAtOffset::Single(n) => {
+            assert!(n == node);
+            return Some("");
+        }
+        LeafAtOffset::None => unreachable!(),
+    };
+    if ws.kind() != WHITESPACE {
+        return None;
+    }
+    let text = ws.leaf_text().unwrap();
+    let pos = text.as_str().rfind('\n').map(|it| it + 1).unwrap_or(0);
+    Some(&text[pos..])
+}
+
+pub fn on_eq_typed(file: &SourceFile, eq_offset: TextUnit) -> Option<LocalEdit> {
+    assert_eq!(file.syntax().text().char_at(eq_offset), Some('='));
+    let let_stmt: &ast::LetStmt = find_node_at_offset(file.syntax(), eq_offset)?;
+    if let_stmt.has_semi() {
+        return None;
+    }
+    if let Some(expr) = let_stmt.initializer() {
+        let expr_range = expr.syntax().range();
+        if expr_range.contains(eq_offset) && eq_offset != expr_range.start() {
+            return None;
+        }
+        if file.syntax().text().slice(eq_offset..expr_range.start()).contains('\n') {
+            return None;
+        }
+    } else {
+        return None;
+    }
+    let offset = let_stmt.syntax().range().end();
+    let mut edit = TextEditBuilder::default();
+    edit.insert(offset, ";".to_string());
+    Some(LocalEdit {
+        label: "add semicolon".to_string(),
+        edit: edit.finish(),
+        cursor_position: None,
+    })
+}
+
+pub fn on_dot_typed(file: &SourceFile, dot_offset: TextUnit) -> Option<LocalEdit> {
+    assert_eq!(file.syntax().text().char_at(dot_offset), Some('.'));
+
+    let whitespace = find_leaf_at_offset(file.syntax(), dot_offset)
+        .left_biased()
+        .and_then(ast::Whitespace::cast)?;
+
+    let current_indent = {
+        let text = whitespace.text();
+        let newline = text.rfind('\n')?;
+        &text[newline + 1..]
+    };
+    let current_indent_len = TextUnit::of_str(current_indent);
+
+    // Make sure dot is a part of call chain
+    let field_expr = whitespace.syntax().parent().and_then(ast::FieldExpr::cast)?;
+    let prev_indent = leading_indent(field_expr.syntax())?;
+    let target_indent = format!("    {}", prev_indent);
+    let target_indent_len = TextUnit::of_str(&target_indent);
+    if current_indent_len == target_indent_len {
+        return None;
+    }
+    let mut edit = TextEditBuilder::default();
+    edit.replace(
+        TextRange::from_to(dot_offset - current_indent_len, dot_offset),
+        target_indent.into(),
+    );
+    let res = LocalEdit {
+        label: "reindent dot".to_string(),
+        edit: edit.finish(),
+        cursor_position: Some(
+            dot_offset + target_indent_len - current_indent_len + TextUnit::of_char('.'),
+        ),
+    };
+    Some(res)
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::{add_cursor, assert_eq_text, extract_offset};
+
+    use super::*;
+
+    #[test]
+    fn test_on_eq_typed() {
+        fn type_eq(before: &str, after: &str) {
+            let (offset, before) = extract_offset(before);
+            let mut edit = TextEditBuilder::default();
+            edit.insert(offset, "=".to_string());
+            let before = edit.finish().apply(&before);
+            let file = SourceFile::parse(&before);
+            if let Some(result) = on_eq_typed(&file, offset) {
+                let actual = result.edit.apply(&before);
+                assert_eq_text!(after, &actual);
+            } else {
+                assert_eq_text!(&before, after)
+            };
+        }
+
+        //     do_check(r"
+        // fn foo() {
+        //     let foo =<|>
+        // }
+        // ", r"
+        // fn foo() {
+        //     let foo =;
+        // }
+        // ");
+        type_eq(
+            r"
+fn foo() {
+    let foo <|> 1 + 1
+}
+",
+            r"
+fn foo() {
+    let foo = 1 + 1;
+}
+",
+        );
+        //     do_check(r"
+        // fn foo() {
+        //     let foo =<|>
+        //     let bar = 1;
+        // }
+        // ", r"
+        // fn foo() {
+        //     let foo =;
+        //     let bar = 1;
+        // }
+        // ");
+    }
+
+    fn type_dot(before: &str, after: &str) {
+        let (offset, before) = extract_offset(before);
+        let mut edit = TextEditBuilder::default();
+        edit.insert(offset, ".".to_string());
+        let before = edit.finish().apply(&before);
+        let file = SourceFile::parse(&before);
+        if let Some(result) = on_dot_typed(&file, offset) {
+            let actual = result.edit.apply(&before);
+            assert_eq_text!(after, &actual);
+        } else {
+            assert_eq_text!(&before, after)
+        };
+    }
+
+    #[test]
+    fn indents_new_chain_call() {
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                <|>
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .
+            }
+            ",
+        );
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    <|>
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn indents_new_chain_call_with_semi() {
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                <|>;
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .;
+            }
+            ",
+        );
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    <|>;
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .;
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn indents_continued_chain_call() {
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .first()
+                <|>
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .first()
+                    .
+            }
+            ",
+        );
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .first()
+                    <|>
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                self.child_impl(db, name)
+                    .first()
+                    .
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn indents_middle_of_chain_call() {
+        type_dot(
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                <|>
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    .
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+        );
+        type_dot(
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    <|>
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    .
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn dont_indent_freestanding_dot() {
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                <|>
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+                .
+            }
+            ",
+        );
+        type_dot(
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+            <|>
+            }
+            ",
+            r"
+            pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
+            .
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn test_on_enter() {
+        fn apply_on_enter(before: &str) -> Option<String> {
+            let (offset, before) = extract_offset(before);
+            let file = SourceFile::parse(&before);
+            let result = on_enter(&file, offset)?;
+            let actual = result.edit.apply(&before);
+            let actual = add_cursor(&actual, result.cursor_position.unwrap());
+            Some(actual)
+        }
+
+        fn do_check(before: &str, after: &str) {
+            let actual = apply_on_enter(before).unwrap();
+            assert_eq_text!(after, &actual);
+        }
+
+        fn do_check_noop(text: &str) {
+            assert!(apply_on_enter(text).is_none())
+        }
+
+        do_check(
+            r"
+/// Some docs<|>
+fn foo() {
+}
+",
+            r"
+/// Some docs
+/// <|>
+fn foo() {
+}
+",
+        );
+        do_check(
+            r"
+impl S {
+    /// Some<|> docs.
+    fn foo() {}
+}
+",
+            r"
+impl S {
+    /// Some
+    /// <|> docs.
+    fn foo() {}
+}
+",
+        );
+        do_check_noop(r"<|>//! docz");
+    }
+}