7 files changed, 589 insertions, 0 deletions

diff --git a/crates/ra_ide_api_light/src/assists/add_derive.rs b/crates/ra_ide_api_light/src/assists/add_derive.rs
new file mode 100644
index 000000000..6e964d011
--- /dev/null
+++ b/crates/ra_ide_api_light/src/assists/add_derive.rs
@@ -0,0 +1,84 @@
+use ra_syntax::{
+    ast::{self, AstNode, AttrsOwner},
+    SyntaxKind::{WHITESPACE, COMMENT},
+    TextUnit,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn add_derive(ctx: AssistCtx) -> Option<Assist> {
+    let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
+    let node_start = derive_insertion_offset(nominal)?;
+    ctx.build("add `#[derive]`", |edit| {
+        let derive_attr = nominal
+            .attrs()
+            .filter_map(|x| x.as_call())
+            .filter(|(name, _arg)| name == "derive")
+            .map(|(_name, arg)| arg)
+            .next();
+        let offset = match derive_attr {
+            None => {
+                edit.insert(node_start, "#[derive()]\n");
+                node_start + TextUnit::of_str("#[derive(")
+            }
+            Some(tt) => tt.syntax().range().end() - TextUnit::of_char(')'),
+        };
+        edit.set_cursor(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::assists::check_assist;
+
+    #[test]
+    fn add_derive_new() {
+        check_assist(
+            add_derive,
+            "struct Foo { a: i32, <|>}",
+            "#[derive(<|>)]\nstruct Foo { a: i32, }",
+        );
+        check_assist(
+            add_derive,
+            "struct Foo { <|> a: i32, }",
+            "#[derive(<|>)]\nstruct Foo {  a: i32, }",
+        );
+    }
+
+    #[test]
+    fn add_derive_existing() {
+        check_assist(
+            add_derive,
+            "#[derive(Clone)]\nstruct Foo { a: i32<|>, }",
+            "#[derive(Clone<|>)]\nstruct Foo { a: i32, }",
+        );
+    }
+
+    #[test]
+    fn add_derive_new_with_doc_comment() {
+        check_assist(
+            add_derive,
+            "
+/// `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, }
+            ",
+        );
+    }
+}
diff --git a/crates/ra_ide_api_light/src/assists/add_impl.rs b/crates/ra_ide_api_light/src/assists/add_impl.rs
new file mode 100644
index 000000000..2eda7cae2
--- /dev/null
+++ b/crates/ra_ide_api_light/src/assists/add_impl.rs
@@ -0,0 +1,66 @@
+use join_to_string::join;
+use ra_syntax::{
+    ast::{self, AstNode, AstToken, NameOwner, TypeParamsOwner},
+    TextUnit,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn add_impl(ctx: AssistCtx) -> Option<Assist> {
+    let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
+    let name = nominal.name()?;
+    ctx.build("add impl", |edit| {
+        let type_params = nominal.type_param_list();
+        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");
+        edit.set_cursor(start_offset + TextUnit::of_str(&buf));
+        buf.push_str("\n}");
+        edit.insert(start_offset, buf);
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn test_add_impl() {
+        check_assist(
+            add_impl,
+            "struct Foo {<|>}\n",
+            "struct Foo {}\n\nimpl Foo {\n<|>\n}\n",
+        );
+        check_assist(
+            add_impl,
+            "struct Foo<T: Clone> {<|>}",
+            "struct Foo<T: Clone> {}\n\nimpl<T: Clone> Foo<T> {\n<|>\n}",
+        );
+        check_assist(
+            add_impl,
+            "struct Foo<'a, T: Foo<'a>> {<|>}",
+            "struct Foo<'a, T: Foo<'a>> {}\n\nimpl<'a, T: Foo<'a>> Foo<'a, T> {\n<|>\n}",
+        );
+    }
+
+}
diff --git a/crates/ra_ide_api_light/src/assists/change_visibility.rs b/crates/ra_ide_api_light/src/assists/change_visibility.rs
new file mode 100644
index 000000000..89729e2c2
--- /dev/null
+++ b/crates/ra_ide_api_light/src/assists/change_visibility.rs
@@ -0,0 +1,116 @@
+use ra_syntax::{
+    AstNode,
+    ast::{self, VisibilityOwner, NameOwner},
+    SyntaxKind::{VISIBILITY, FN_KW, MOD_KW, STRUCT_KW, ENUM_KW, TRAIT_KW, FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF, IDENT},
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn change_visibility(ctx: AssistCtx) -> Option<Assist> {
+    if let Some(vis) = ctx.node_at_offset::<ast::Visibility>() {
+        return change_vis(ctx, vis);
+    }
+    add_vis(ctx)
+}
+
+fn add_vis(ctx: AssistCtx) -> Option<Assist> {
+    let item_keyword = ctx.leaf_at_offset().find(|leaf| match leaf.kind() {
+        FN_KW | MOD_KW | STRUCT_KW | ENUM_KW | TRAIT_KW => true,
+        _ => false,
+    });
+
+    let offset = if let Some(keyword) = item_keyword {
+        let parent = keyword.parent()?;
+        let def_kws = vec![FN_DEF, MODULE, STRUCT_DEF, ENUM_DEF, TRAIT_DEF];
+        // Parent is not a definition, can't add visibility
+        if !def_kws.iter().any(|&def_kw| def_kw == parent.kind()) {
+            return None;
+        }
+        // Already have visibility, do nothing
+        if parent.children().any(|child| child.kind() == VISIBILITY) {
+            return None;
+        }
+        parent.range().start()
+    } else {
+        let ident = ctx.leaf_at_offset().find(|leaf| leaf.kind() == IDENT)?;
+        let field = ident.ancestors().find_map(ast::NamedFieldDef::cast)?;
+        if field.name()?.syntax().range() != ident.range() && field.visibility().is_some() {
+            return None;
+        }
+        field.syntax().range().start()
+    };
+
+    ctx.build("make pub(crate)", |edit| {
+        edit.insert(offset, "pub(crate) ");
+        edit.set_cursor(offset);
+    })
+}
+
+fn change_vis(ctx: AssistCtx, vis: &ast::Visibility) -> Option<Assist> {
+    if vis.syntax().text() != "pub" {
+        return None;
+    }
+    ctx.build("chage to pub(crate)", |edit| {
+        edit.replace(vis.syntax().range(), "pub(crate)");
+        edit.set_cursor(vis.syntax().range().start());
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn change_visibility_adds_pub_crate_to_items() {
+        check_assist(
+            change_visibility,
+            "<|>fn foo() {}",
+            "<|>pub(crate) fn foo() {}",
+        );
+        check_assist(
+            change_visibility,
+            "f<|>n foo() {}",
+            "<|>pub(crate) fn foo() {}",
+        );
+        check_assist(
+            change_visibility,
+            "<|>struct Foo {}",
+            "<|>pub(crate) struct Foo {}",
+        );
+        check_assist(
+            change_visibility,
+            "<|>mod foo {}",
+            "<|>pub(crate) mod foo {}",
+        );
+        check_assist(
+            change_visibility,
+            "<|>trait Foo {}",
+            "<|>pub(crate) trait Foo {}",
+        );
+        check_assist(change_visibility, "m<|>od {}", "<|>pub(crate) mod {}");
+        check_assist(
+            change_visibility,
+            "unsafe f<|>n foo() {}",
+            "<|>pub(crate) unsafe fn foo() {}",
+        );
+    }
+
+    #[test]
+    fn change_visibility_works_with_struct_fields() {
+        check_assist(
+            change_visibility,
+            "struct S { <|>field: u32 }",
+            "struct S { <|>pub(crate) field: u32 }",
+        )
+    }
+
+    #[test]
+    fn change_visibility_pub_to_pub_crate() {
+        check_assist(
+            change_visibility,
+            "<|>pub fn foo() {}",
+            "<|>pub(crate) fn foo() {}",
+        )
+    }
+}
diff --git a/crates/ra_ide_api_light/src/assists/flip_comma.rs b/crates/ra_ide_api_light/src/assists/flip_comma.rs
new file mode 100644
index 000000000..a343413cc
--- /dev/null
+++ b/crates/ra_ide_api_light/src/assists/flip_comma.rs
@@ -0,0 +1,31 @@
+use ra_syntax::{
+    Direction,
+    SyntaxKind::COMMA,
+};
+
+use crate::assists::{non_trivia_sibling, AssistCtx, Assist};
+
+pub fn flip_comma(ctx: AssistCtx) -> Option<Assist> {
+    let comma = ctx.leaf_at_offset().find(|leaf| leaf.kind() == COMMA)?;
+    let prev = non_trivia_sibling(comma, Direction::Prev)?;
+    let next = non_trivia_sibling(comma, Direction::Next)?;
+    ctx.build("flip comma", |edit| {
+        edit.replace(prev.range(), next.text());
+        edit.replace(next.range(), prev.text());
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn flip_comma_works_for_function_parameters() {
+        check_assist(
+            flip_comma,
+            "fn foo(x: i32,<|> y: Result<(), ()>) {}",
+            "fn foo(y: Result<(), ()>,<|> x: i32) {}",
+        )
+    }
+}
diff --git a/crates/ra_ide_api_light/src/assists/introduce_variable.rs b/crates/ra_ide_api_light/src/assists/introduce_variable.rs
new file mode 100644
index 000000000..523ec7034
--- /dev/null
+++ b/crates/ra_ide_api_light/src/assists/introduce_variable.rs
@@ -0,0 +1,144 @@
+use ra_syntax::{
+    ast::{self, AstNode},
+    SyntaxKind::WHITESPACE,
+    SyntaxNode, TextUnit,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn introduce_variable<'a>(ctx: AssistCtx) -> Option<Assist> {
+    let node = ctx.covering_node();
+    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;
+    }
+    ctx.build("introduce variable", move |edit| {
+        let mut buf = String::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);
+        }
+        edit.set_cursor(anchor_stmt.range().start() + TextUnit::of_str("let "));
+    })
+}
+
+/// Statement or last in the block expression, which will follow
+/// the freshly introduced var.
+fn anchor_stmt(expr: &ast::Expr) -> Option<&SyntaxNode> {
+    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::assists::check_assist_range;
+
+    #[test]
+    fn test_introduce_var_simple() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    foo(<|>1 + 1<|>);
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+    foo(var_name);
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_expr_stmt() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    <|>1 + 1<|>;
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_part_of_expr_stmt() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    <|>1<|> + 1;
+}",
+            "
+fn foo() {
+    let <|>var_name = 1;
+    var_name + 1;
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_last_expr() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    bar(<|>1 + 1<|>)
+}",
+            "
+fn foo() {
+    let <|>var_name = 1 + 1;
+    bar(var_name)
+}",
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_last_full_expr() {
+        check_assist_range(
+            introduce_variable,
+            "
+fn foo() {
+    <|>bar(1 + 1)<|>
+}",
+            "
+fn foo() {
+    let <|>var_name = bar(1 + 1);
+    var_name
+}",
+        );
+    }
+
+}
diff --git a/crates/ra_ide_api_light/src/assists/replace_if_let_with_match.rs b/crates/ra_ide_api_light/src/assists/replace_if_let_with_match.rs
new file mode 100644
index 000000000..30c371480
--- /dev/null
+++ b/crates/ra_ide_api_light/src/assists/replace_if_let_with_match.rs
@@ -0,0 +1,92 @@
+use ra_syntax::{
+    AstNode, SyntaxKind::{L_CURLY, R_CURLY, WHITESPACE},
+    ast,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn replace_if_let_with_match(ctx: AssistCtx) -> Option<Assist> {
+    let if_expr: &ast::IfExpr = ctx.node_at_offset()?;
+    let cond = if_expr.condition()?;
+    let pat = cond.pat()?;
+    let expr = cond.expr()?;
+    let then_block = if_expr.then_branch()?;
+    let else_block = if_expr.else_branch()?;
+
+    ctx.build("replace with match", |edit| {
+        let match_expr = build_match_expr(expr, pat, then_block, else_block);
+        edit.replace_node_and_indent(if_expr.syntax(), match_expr);
+        edit.set_cursor(if_expr.syntax().range().start())
+    })
+}
+
+fn build_match_expr(
+    expr: &ast::Expr,
+    pat1: &ast::Pat,
+    arm1: &ast::Block,
+    arm2: &ast::Block,
+) -> String {
+    let mut buf = String::new();
+    buf.push_str(&format!("match {} {{\n", expr.syntax().text()));
+    buf.push_str(&format!(
+        "    {} => {}\n",
+        pat1.syntax().text(),
+        format_arm(arm1)
+    ));
+    buf.push_str(&format!("    _ => {}\n", format_arm(arm2)));
+    buf.push_str("}");
+    buf
+}
+
+fn format_arm(block: &ast::Block) -> String {
+    match extract_expression(block) {
+        None => block.syntax().text().to_string(),
+        Some(e) => format!("{},", e.syntax().text()),
+    }
+}
+
+fn extract_expression(block: &ast::Block) -> Option<&ast::Expr> {
+    let expr = block.expr()?;
+    let non_trivial_children = block.syntax().children().filter(|it| {
+        !(it == &expr.syntax()
+            || it.kind() == L_CURLY
+            || it.kind() == R_CURLY
+            || it.kind() == WHITESPACE)
+    });
+    if non_trivial_children.count() > 0 {
+        return None;
+    }
+    Some(expr)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn test_replace_if_let_with_match_unwraps_simple_expressions() {
+        check_assist(
+            replace_if_let_with_match,
+            "
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        if <|>let VariantData::Struct(..) = *self {
+            true
+        } else {
+            false
+        }
+    }
+}           ",
+            "
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        <|>match *self {
+            VariantData::Struct(..) => true,
+            _ => false,
+        }
+    }
+}           ",
+        )
+    }
+}
diff --git a/crates/ra_ide_api_light/src/assists/split_import.rs b/crates/ra_ide_api_light/src/assists/split_import.rs
new file mode 100644
index 000000000..e4015f07d
--- /dev/null
+++ b/crates/ra_ide_api_light/src/assists/split_import.rs
@@ -0,0 +1,56 @@
+use ra_syntax::{
+    TextUnit, AstNode, SyntaxKind::COLONCOLON,
+    ast,
+    algo::generate,
+};
+
+use crate::assists::{AssistCtx, Assist};
+
+pub fn split_import(ctx: AssistCtx) -> Option<Assist> {
+    let colon_colon = ctx
+        .leaf_at_offset()
+        .find(|leaf| leaf.kind() == COLONCOLON)?;
+    let path = colon_colon.parent().and_then(ast::Path::cast)?;
+    let top_path = generate(Some(path), |it| it.parent_path()).last()?;
+
+    let use_tree = top_path.syntax().ancestors().find_map(ast::UseTree::cast);
+    if use_tree.is_none() {
+        return None;
+    }
+
+    let l_curly = colon_colon.range().end();
+    let r_curly = match top_path.syntax().parent().and_then(ast::UseTree::cast) {
+        Some(tree) => tree.syntax().range().end(),
+        None => top_path.syntax().range().end(),
+    };
+
+    ctx.build("split import", |edit| {
+        edit.insert(l_curly, "{");
+        edit.insert(r_curly, "}");
+        edit.set_cursor(l_curly + TextUnit::of_str("{"));
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assists::check_assist;
+
+    #[test]
+    fn test_split_import() {
+        check_assist(
+            split_import,
+            "use crate::<|>db::RootDatabase;",
+            "use crate::{<|>db::RootDatabase};",
+        )
+    }
+
+    #[test]
+    fn split_import_works_with_trees() {
+        check_assist(
+            split_import,
+            "use algo:<|>:visitor::{Visitor, visit}",
+            "use algo::{<|>visitor::{Visitor, visit}}",
+        )
+    }
+}