5 files changed, 466 insertions, 0 deletions

diff --git a/crates/ra_editor/src/assists/add_derive.rs b/crates/ra_editor/src/assists/add_derive.rs
new file mode 100644
index 000000000..33d9d2c31
--- /dev/null
+++ b/crates/ra_editor/src/assists/add_derive.rs
@@ -0,0 +1,97 @@
+use ra_text_edit::TextEditBuilder;
+use ra_syntax::{
+    ast::{self, AstNode, AttrsOwner},
+    SourceFileNode,
+    SyntaxKind::{WHITESPACE, COMMENT},
+    TextUnit,
+};
+
+use crate::{
+    find_node_at_offset,
+    assists::LocalEdit,
+};
+
+pub fn add_derive<'a>(
+    file: &'a SourceFileNode,
+    offset: TextUnit,
+) -> Option<impl FnOnce() -> LocalEdit + 'a> {
+    let nominal = find_node_at_offset::<ast::NominalDef>(file.syntax(), offset)?;
+    let node_start = derive_insertion_offset(nominal)?;
+    return Some(move || {
+        let derive_attr = nominal
+            .attrs()
+            .filter_map(|x| x.as_call())
+            .filter(|(name, _arg)| name == "derive")
+            .map(|(_name, arg)| arg)
+            .next();
+        let mut edit = TextEditBuilder::new();
+        let offset = match derive_attr {
+            None => {
+                edit.insert(node_start, "#[derive()]\n".to_string());
+                node_start + TextUnit::of_str("#[derive(")
+            }
+            Some(tt) => tt.syntax().range().end() - TextUnit::of_char(')'),
+        };
+        LocalEdit {
+            label: "add `#[derive]`".to_string(),
+            edit: edit.finish(),
+            cursor_position: Some(offset),
+        }
+    });
+
+    // Insert `derive` after doc comments.
+    fn derive_insertion_offset(nominal: ast::NominalDef) -> Option<TextUnit> {
+        let non_ws_child = nominal
+            .syntax()
+            .children()
+            .find(|it| it.kind() != COMMENT && it.kind() != WHITESPACE)?;
+        Some(non_ws_child.range().start())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_utils::check_action;
+
+    #[test]
+    fn add_derive_new() {
+        check_action(
+            "struct Foo { a: i32, <|>}",
+            "#[derive(<|>)]\nstruct Foo { a: i32, }",
+            |file, off| add_derive(file, off).map(|f| f()),
+        );
+        check_action(
+            "struct Foo { <|> a: i32, }",
+            "#[derive(<|>)]\nstruct Foo {  a: i32, }",
+            |file, off| add_derive(file, off).map(|f| f()),
+        );
+    }
+
+    #[test]
+    fn add_derive_existing() {
+        check_action(
+            "#[derive(Clone)]\nstruct Foo { a: i32<|>, }",
+            "#[derive(Clone<|>)]\nstruct Foo { a: i32, }",
+            |file, off| add_derive(file, off).map(|f| f()),
+        );
+    }
+
+    #[test]
+    fn add_derive_new_with_doc_comment() {
+        check_action(
+            "
+/// `Foo` is a pretty important struct.
+/// It does stuff.
+struct Foo { a: i32<|>, }
+            ",
+            "
+/// `Foo` is a pretty important struct.
+/// It does stuff.
+#[derive(<|>)]
+struct Foo { a: i32, }
+            ",
+            |file, off| add_derive(file, off).map(|f| f()),
+        );
+    }
+}
diff --git a/crates/ra_editor/src/assists/add_impl.rs b/crates/ra_editor/src/assists/add_impl.rs
new file mode 100644
index 000000000..50e00688e
--- /dev/null
+++ b/crates/ra_editor/src/assists/add_impl.rs
@@ -0,0 +1,78 @@
+use join_to_string::join;
+use ra_text_edit::TextEditBuilder;
+use ra_syntax::{
+    ast::{self, AstNode, NameOwner, TypeParamsOwner},
+    SourceFileNode,
+    TextUnit,
+};
+
+use crate::{find_node_at_offset, assists::LocalEdit};
+
+pub fn add_impl<'a>(
+    file: &'a SourceFileNode,
+    offset: TextUnit,
+) -> Option<impl FnOnce() -> LocalEdit + 'a> {
+    let nominal = find_node_at_offset::<ast::NominalDef>(file.syntax(), offset)?;
+    let name = nominal.name()?;
+
+    Some(move || {
+        let type_params = nominal.type_param_list();
+        let mut edit = TextEditBuilder::new();
+        let start_offset = nominal.syntax().range().end();
+        let mut buf = String::new();
+        buf.push_str("\n\nimpl");
+        if let Some(type_params) = type_params {
+            type_params.syntax().text().push_to(&mut buf);
+        }
+        buf.push_str(" ");
+        buf.push_str(name.text().as_str());
+        if let Some(type_params) = type_params {
+            let lifetime_params = type_params
+                .lifetime_params()
+                .filter_map(|it| it.lifetime())
+                .map(|it| it.text());
+            let type_params = type_params
+                .type_params()
+                .filter_map(|it| it.name())
+                .map(|it| it.text());
+            join(lifetime_params.chain(type_params))
+                .surround_with("<", ">")
+                .to_buf(&mut buf);
+        }
+        buf.push_str(" {\n");
+        let offset = start_offset + TextUnit::of_str(&buf);
+        buf.push_str("\n}");
+        edit.insert(start_offset, buf);
+        LocalEdit {
+            label: "add impl".to_string(),
+            edit: edit.finish(),
+            cursor_position: Some(offset),
+        }
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_utils::check_action;
+
+    #[test]
+    fn test_add_impl() {
+        check_action(
+            "struct Foo {<|>}\n",
+            "struct Foo {}\n\nimpl Foo {\n<|>\n}\n",
+            |file, off| add_impl(file, off).map(|f| f()),
+        );
+        check_action(
+            "struct Foo<T: Clone> {<|>}",
+            "struct Foo<T: Clone> {}\n\nimpl<T: Clone> Foo<T> {\n<|>\n}",
+            |file, off| add_impl(file, off).map(|f| f()),
+        );
+        check_action(
+            "struct Foo<'a, T: Foo<'a>> {<|>}",
+            "struct Foo<'a, T: Foo<'a>> {}\n\nimpl<'a, T: Foo<'a>> Foo<'a, T> {\n<|>\n}",
+            |file, off| add_impl(file, off).map(|f| f()),
+        );
+    }
+
+}
diff --git a/crates/ra_editor/src/assists/change_visibility.rs b/crates/ra_editor/src/assists/change_visibility.rs
new file mode 100644
index 000000000..98c218f32
--- /dev/null
+++ b/crates/ra_editor/src/assists/change_visibility.rs
@@ -0,0 +1,90 @@
+use ra_text_edit::TextEditBuilder;
+use ra_syntax::{
+    SourceFileNode,
+    algo::find_leaf_at_offset,
+    SyntaxKind::{VISIBILITY, FN_KW, MOD_KW, STRUCT_KW, ENUM_KW, TRAIT_KW, FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF},
+    TextUnit,
+};
+
+use crate::assists::LocalEdit;
+
+pub fn change_visibility<'a>(
+    file: &'a SourceFileNode,
+    offset: TextUnit,
+) -> Option<impl FnOnce() -> LocalEdit + 'a> {
+    let syntax = file.syntax();
+
+    let keyword = find_leaf_at_offset(syntax, offset).find(|leaf| match leaf.kind() {
+        FN_KW | MOD_KW | STRUCT_KW | ENUM_KW | TRAIT_KW => true,
+        _ => false,
+    })?;
+    let parent = keyword.parent()?;
+    let def_kws = vec![FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF];
+    let node_start = parent.range().start();
+    Some(move || {
+        let mut edit = TextEditBuilder::new();
+
+        if !def_kws.iter().any(|&def_kw| def_kw == parent.kind())
+            || parent.children().any(|child| child.kind() == VISIBILITY)
+        {
+            return LocalEdit {
+                label: "make pub crate".to_string(),
+                edit: edit.finish(),
+                cursor_position: Some(offset),
+            };
+        }
+
+        edit.insert(node_start, "pub(crate) ".to_string());
+        LocalEdit {
+            label: "make pub crate".to_string(),
+            edit: edit.finish(),
+            cursor_position: Some(node_start),
+        }
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_utils::check_action;
+
+    #[test]
+    fn test_change_visibility() {
+        check_action(
+            "<|>fn foo() {}",
+            "<|>pub(crate) fn foo() {}",
+            |file, off| change_visibility(file, off).map(|f| f()),
+        );
+        check_action(
+            "f<|>n foo() {}",
+            "<|>pub(crate) fn foo() {}",
+            |file, off| change_visibility(file, off).map(|f| f()),
+        );
+        check_action(
+            "<|>struct Foo {}",
+            "<|>pub(crate) struct Foo {}",
+            |file, off| change_visibility(file, off).map(|f| f()),
+        );
+        check_action("<|>mod foo {}", "<|>pub(crate) mod foo {}", |file, off| {
+            change_visibility(file, off).map(|f| f())
+        });
+        check_action(
+            "<|>trait Foo {}",
+            "<|>pub(crate) trait Foo {}",
+            |file, off| change_visibility(file, off).map(|f| f()),
+        );
+        check_action("m<|>od {}", "<|>pub(crate) mod {}", |file, off| {
+            change_visibility(file, off).map(|f| f())
+        });
+        check_action(
+            "pub(crate) f<|>n foo() {}",
+            "pub(crate) f<|>n foo() {}",
+            |file, off| change_visibility(file, off).map(|f| f()),
+        );
+        check_action(
+            "unsafe f<|>n foo() {}",
+            "<|>pub(crate) unsafe fn foo() {}",
+            |file, off| change_visibility(file, off).map(|f| f()),
+        );
+    }
+}
diff --git a/crates/ra_editor/src/assists/flip_comma.rs b/crates/ra_editor/src/assists/flip_comma.rs
new file mode 100644
index 000000000..d8727db0d
--- /dev/null
+++ b/crates/ra_editor/src/assists/flip_comma.rs
@@ -0,0 +1,45 @@
+use ra_text_edit::TextEditBuilder;
+use ra_syntax::{
+    algo::find_leaf_at_offset,
+    Direction, SourceFileNode,
+    SyntaxKind::COMMA,
+    TextUnit,
+};
+
+use crate::assists::{LocalEdit, non_trivia_sibling};
+
+pub fn flip_comma<'a>(
+    file: &'a SourceFileNode,
+    offset: TextUnit,
+) -> Option<impl FnOnce() -> LocalEdit + 'a> {
+    let syntax = file.syntax();
+
+    let comma = find_leaf_at_offset(syntax, offset).find(|leaf| leaf.kind() == COMMA)?;
+    let prev = non_trivia_sibling(comma, Direction::Prev)?;
+    let next = non_trivia_sibling(comma, Direction::Next)?;
+    Some(move || {
+        let mut edit = TextEditBuilder::new();
+        edit.replace(prev.range(), next.text().to_string());
+        edit.replace(next.range(), prev.text().to_string());
+        LocalEdit {
+            label: "flip comma".to_string(),
+            edit: edit.finish(),
+            cursor_position: None,
+        }
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_utils::check_action;
+
+    #[test]
+    fn test_swap_comma() {
+        check_action(
+            "fn foo(x: i32,<|> y: Result<(), ()>) {}",
+            "fn foo(y: Result<(), ()>,<|> x: i32) {}",
+            |file, off| flip_comma(file, off).map(|f| f()),
+        )
+    }
+}
diff --git a/crates/ra_editor/src/assists/introduce_variable.rs b/crates/ra_editor/src/assists/introduce_variable.rs
new file mode 100644
index 000000000..17ab521fa
--- /dev/null
+++ b/crates/ra_editor/src/assists/introduce_variable.rs
@@ -0,0 +1,156 @@
+use ra_text_edit::TextEditBuilder;
+use ra_syntax::{
+    algo::{find_covering_node},
+    ast::{self, AstNode},
+    SourceFileNode,
+    SyntaxKind::{WHITESPACE},
+    SyntaxNodeRef, TextRange, TextUnit,
+};
+
+use crate::assists::LocalEdit;
+
+pub fn introduce_variable<'a>(
+    file: &'a SourceFileNode,
+    range: TextRange,
+) -> Option<impl FnOnce() -> LocalEdit + 'a> {
+    let node = find_covering_node(file.syntax(), range);
+    let expr = node.ancestors().filter_map(ast::Expr::cast).next()?;
+
+    let anchor_stmt = anchor_stmt(expr)?;
+    let indent = anchor_stmt.prev_sibling()?;
+    if indent.kind() != WHITESPACE {
+        return None;
+    }
+    return Some(move || {
+        let mut buf = String::new();
+        let mut edit = TextEditBuilder::new();
+
+        buf.push_str("let var_name = ");
+        expr.syntax().text().push_to(&mut buf);
+        let is_full_stmt = if let Some(expr_stmt) = ast::ExprStmt::cast(anchor_stmt) {
+            Some(expr.syntax()) == expr_stmt.expr().map(|e| e.syntax())
+        } else {
+            false
+        };
+        if is_full_stmt {
+            edit.replace(expr.syntax().range(), buf);
+        } else {
+            buf.push_str(";");
+            indent.text().push_to(&mut buf);
+            edit.replace(expr.syntax().range(), "var_name".to_string());
+            edit.insert(anchor_stmt.range().start(), buf);
+        }
+        let cursor_position = anchor_stmt.range().start() + TextUnit::of_str("let ");
+        LocalEdit {
+            label: "introduce variable".to_string(),
+            edit: edit.finish(),
+            cursor_position: Some(cursor_position),
+        }
+    });
+
+    /// Statement or last in the block expression, which will follow
+    /// the freshly introduced var.
+    fn anchor_stmt(expr: ast::Expr) -> Option<SyntaxNodeRef> {
+        expr.syntax().ancestors().find(|&node| {
+            if ast::Stmt::cast(node).is_some() {
+                return true;
+            }
+            if let Some(expr) = node
+                .parent()
+                .and_then(ast::Block::cast)
+                .and_then(|it| it.expr())
+            {
+                if expr.syntax() == node {
+                    return true;
+                }
+            }
+            false
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_utils::check_action_range;
+
+    #[test]
+    fn test_introduce_var_simple() {
+        check_action_range(
+            "
+fn foo() {
+    foo(<|>1 + 1<|>);
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+    foo(var_name);
+}",
+            |file, range| introduce_variable(file, range).map(|f| f()),
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_expr_stmt() {
+        check_action_range(
+            "
+fn foo() {
+    <|>1 + 1<|>;
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+}",
+            |file, range| introduce_variable(file, range).map(|f| f()),
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_part_of_expr_stmt() {
+        check_action_range(
+            "
+fn foo() {
+    <|>1<|> + 1;
+}",
+            "
+fn foo() {
+    let <|>var_name = 1;
+    var_name + 1;
+}",
+            |file, range| introduce_variable(file, range).map(|f| f()),
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_last_expr() {
+        check_action_range(
+            "
+fn foo() {
+    bar(<|>1 + 1<|>)
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+    bar(var_name)
+}",
+            |file, range| introduce_variable(file, range).map(|f| f()),
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_last_full_expr() {
+        check_action_range(
+            "
+fn foo() {
+    <|>bar(1 + 1)<|>
+}",
+            "
+fn foo() {
+    let <|>var_name = bar(1 + 1);
+    var_name
+}",
+            |file, range| introduce_variable(file, range).map(|f| f()),
+        );
+    }
+
+}