19 files changed, 167 insertions, 38 deletions

diff --git a/crates/ra_assists/src/assists/add_derive.rs b/crates/ra_assists/src/assists/add_derive.rs
index 9c88644df..77ecc33c9 100644
--- a/crates/ra_assists/src/assists/add_derive.rs
+++ b/crates/ra_assists/src/assists/add_derive.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::{
     ast::{self, AstNode, AttrsOwner},
@@ -13,7 +15,7 @@ pub(crate) fn add_derive(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist>
     ctx.add_action(AssistId("add_derive"), "add `#[derive]`", |edit| {
         let derive_attr = nominal
             .attrs()
-            .filter_map(|x| x.as_call())
+            .filter_map(|x| x.as_simple_call())
             .filter(|(name, _arg)| name == "derive")
             .map(|(_name, arg)| arg)
             .next();
diff --git a/crates/ra_assists/src/assists/add_explicit_type.rs b/crates/ra_assists/src/assists/add_explicit_type.rs
index 78f0f7f28..8c83dc987 100644
--- a/crates/ra_assists/src/assists/add_explicit_type.rs
+++ b/crates/ra_assists/src/assists/add_explicit_type.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::{db::HirDatabase, HirDisplay, Ty};
 use ra_syntax::{
     ast::{self, AstNode, LetStmt, NameOwner},
diff --git a/crates/ra_assists/src/assists/add_impl.rs b/crates/ra_assists/src/assists/add_impl.rs
index 4b61f4031..94801fbc9 100644
--- a/crates/ra_assists/src/assists/add_impl.rs
+++ b/crates/ra_assists/src/assists/add_impl.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use format_buf::format;
 use hir::db::HirDatabase;
 use join_to_string::join;
diff --git a/crates/ra_assists/src/assists/add_missing_impl_members.rs b/crates/ra_assists/src/assists/add_missing_impl_members.rs
index 23da1e65f..565b96fb5 100644
--- a/crates/ra_assists/src/assists/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/assists/add_missing_impl_members.rs
@@ -1,10 +1,12 @@
+//! FIXME: write short doc here
+
 use hir::{db::HirDatabase, HasSource};
 use ra_syntax::{
-    ast::{self, make, AstNode, NameOwner},
+    ast::{self, edit, make, AstNode, NameOwner},
     SmolStr,
 };
 
-use crate::{ast_editor::AstEditor, Assist, AssistCtx, AssistId};
+use crate::{Assist, AssistCtx, AssistId};
 
 #[derive(PartialEq)]
 enum AddMissingImplMembersMode {
@@ -75,37 +77,32 @@ fn add_missing_impl_members_inner(
 
     ctx.add_action(AssistId(assist_id), label, |edit| {
         let n_existing_items = impl_item_list.impl_items().count();
-        let items = missing_items.into_iter().map(|it| match it {
-            ast::ImplItem::FnDef(def) => strip_docstring(add_body(def).into()),
-            _ => strip_docstring(it),
-        });
-        let mut ast_editor = AstEditor::new(impl_item_list);
-
-        ast_editor.append_items(items);
-
-        let first_new_item = ast_editor.ast().impl_items().nth(n_existing_items).unwrap();
-        let cursor_position = first_new_item.syntax().text_range().start();
-        ast_editor.into_text_edit(edit.text_edit_builder());
-
+        let items = missing_items
+            .into_iter()
+            .map(|it| match it {
+                ast::ImplItem::FnDef(def) => ast::ImplItem::FnDef(add_body(def)),
+                _ => it,
+            })
+            .map(|it| edit::strip_attrs_and_docs(&it));
+        let new_impl_item_list = impl_item_list.append_items(items);
+        let cursor_position = {
+            let first_new_item = new_impl_item_list.impl_items().nth(n_existing_items).unwrap();
+            first_new_item.syntax().text_range().start()
+        };
+
+        edit.replace_ast(impl_item_list, new_impl_item_list);
         edit.set_cursor(cursor_position);
     });
 
     ctx.build()
 }
 
-fn strip_docstring(item: ast::ImplItem) -> ast::ImplItem {
-    let mut ast_editor = AstEditor::new(item);
-    ast_editor.strip_attrs_and_docs();
-    ast_editor.ast().to_owned()
-}
-
 fn add_body(fn_def: ast::FnDef) -> ast::FnDef {
-    let mut ast_editor = AstEditor::new(fn_def.clone());
     if fn_def.body().is_none() {
-        let body = make::block_from_expr(make::expr_unimplemented());
-        ast_editor.set_body(&body);
+        fn_def.with_body(make::block_from_expr(make::expr_unimplemented()))
+    } else {
+        fn_def
     }
-    ast_editor.ast().to_owned()
 }
 
 /// Given an `ast::ImplBlock`, resolves the target trait (the one being
@@ -332,5 +329,4 @@ impl Foo for S {
 }",
         )
     }
-
 }
diff --git a/crates/ra_assists/src/assists/apply_demorgan.rs b/crates/ra_assists/src/assists/apply_demorgan.rs
new file mode 100644
index 000000000..5f2b0dd18
--- /dev/null
+++ b/crates/ra_assists/src/assists/apply_demorgan.rs
@@ -0,0 +1,102 @@
+//! This contains the functions associated with the demorgan assist.
+//! This assist transforms boolean expressions of the form `!a || !b` into
+//! `!(a && b)`.
+use hir::db::HirDatabase;
+use ra_syntax::ast::{self, AstNode};
+use ra_syntax::SyntaxNode;
+
+use crate::{Assist, AssistCtx, AssistId};
+
+/// Assist for applying demorgan's law
+///
+/// This transforms expressions of the form `!l || !r` into `!(l && r)`.
+/// This also works with `&&`. This assist can only be applied with the cursor
+/// on either `||` or `&&`, with both operands being a negation of some kind.
+/// This means something of the form `!x` or `x != y`.
+pub(crate) fn apply_demorgan(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let expr = ctx.node_at_offset::<ast::BinExpr>()?;
+    let op = expr.op_kind()?;
+    let op_range = expr.op_token()?.text_range();
+    let opposite_op = opposite_logic_op(op)?;
+    let cursor_in_range = ctx.frange.range.is_subrange(&op_range);
+    if !cursor_in_range {
+        return None;
+    }
+    let lhs = expr.lhs()?.syntax().clone();
+    let lhs_range = lhs.text_range();
+    let rhs = expr.rhs()?.syntax().clone();
+    let rhs_range = rhs.text_range();
+    let not_lhs = undo_negation(lhs)?;
+    let not_rhs = undo_negation(rhs)?;
+
+    ctx.add_action(AssistId("apply_demorgan"), "apply demorgan's law", |edit| {
+        edit.target(op_range);
+        edit.replace(op_range, opposite_op);
+        edit.replace(lhs_range, format!("!({}", not_lhs));
+        edit.replace(rhs_range, format!("{})", not_rhs));
+    });
+    ctx.build()
+}
+
+// Return the opposite text for a given logical operator, if it makes sense
+fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
+    match kind {
+        ast::BinOp::BooleanOr => Some("&&"),
+        ast::BinOp::BooleanAnd => Some("||"),
+        _ => None,
+    }
+}
+
+// This function tries to undo unary negation, or inequality
+fn undo_negation(node: SyntaxNode) -> Option<String> {
+    match ast::Expr::cast(node)? {
+        ast::Expr::BinExpr(bin) => match bin.op_kind()? {
+            ast::BinOp::NegatedEqualityTest => {
+                let lhs = bin.lhs()?.syntax().text();
+                let rhs = bin.rhs()?.syntax().text();
+                Some(format!("{} == {}", lhs, rhs))
+            }
+            _ => None,
+        },
+        ast::Expr::PrefixExpr(pe) => match pe.op_kind()? {
+            ast::PrefixOp::Not => {
+                let child = pe.expr()?.syntax().text();
+                Some(String::from(child))
+            }
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate::helpers::{check_assist, check_assist_not_applicable};
+
+    #[test]
+    fn demorgan_turns_and_into_or() {
+        check_assist(apply_demorgan, "fn f() { !x &&<|> !x }", "fn f() { !(x ||<|> x) }")
+    }
+
+    #[test]
+    fn demorgan_turns_or_into_and() {
+        check_assist(apply_demorgan, "fn f() { !x ||<|> !x }", "fn f() { !(x &&<|> x) }")
+    }
+
+    #[test]
+    fn demorgan_removes_inequality() {
+        check_assist(apply_demorgan, "fn f() { x != x ||<|> !x }", "fn f() { !(x == x &&<|> x) }")
+    }
+
+    #[test]
+    fn demorgan_doesnt_apply_with_cursor_not_on_op() {
+        check_assist_not_applicable(apply_demorgan, "fn f() { <|> !x || !x }")
+    }
+
+    #[test]
+    fn demorgan_doesnt_apply_when_operands_arent_negated_already() {
+        check_assist_not_applicable(apply_demorgan, "fn f() { x ||<|> x }")
+    }
+}
diff --git a/crates/ra_assists/src/assists/auto_import.rs b/crates/ra_assists/src/assists/auto_import.rs
index 5aae98546..02c58e7c6 100644
--- a/crates/ra_assists/src/assists/auto_import.rs
+++ b/crates/ra_assists/src/assists/auto_import.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::{self, db::HirDatabase};
 use ra_text_edit::TextEditBuilder;
 
@@ -448,7 +450,6 @@ fn make_assist_add_in_tree_list(
         fmt_segments_raw(target, &mut buf);
         edit.insert(offset, buf);
     } else {
-
     }
 }
 
@@ -512,7 +513,7 @@ pub fn collect_hir_path_segments(path: &hir::Path) -> Option<Vec<SmolStr>> {
         hir::PathKind::Plain => {}
         hir::PathKind::Self_ => ps.push("self".into()),
         hir::PathKind::Super => ps.push("super".into()),
-        hir::PathKind::Type(_) => return None,
+        hir::PathKind::Type(_) | hir::PathKind::DollarCrate(_) => return None,
     }
     for s in path.segments.iter() {
         ps.push(s.name.to_string().into());
diff --git a/crates/ra_assists/src/assists/change_visibility.rs b/crates/ra_assists/src/assists/change_visibility.rs
index 60c74debc..df92c6b67 100644
--- a/crates/ra_assists/src/assists/change_visibility.rs
+++ b/crates/ra_assists/src/assists/change_visibility.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::{
     ast::{self, NameOwner, VisibilityOwner},
diff --git a/crates/ra_assists/src/assists/fill_match_arms.rs b/crates/ra_assists/src/assists/fill_match_arms.rs
index db82db89a..7335cce09 100644
--- a/crates/ra_assists/src/assists/fill_match_arms.rs
+++ b/crates/ra_assists/src/assists/fill_match_arms.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use std::iter;
 
 use hir::{db::HirDatabase, Adt, HasSource};
diff --git a/crates/ra_assists/src/assists/flip_binexpr.rs b/crates/ra_assists/src/assists/flip_binexpr.rs
index b55b36a8e..c51035282 100644
--- a/crates/ra_assists/src/assists/flip_binexpr.rs
+++ b/crates/ra_assists/src/assists/flip_binexpr.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::ast::{AstNode, BinExpr, BinOp};
 
diff --git a/crates/ra_assists/src/assists/flip_comma.rs b/crates/ra_assists/src/assists/flip_comma.rs
index 5ee7561bc..e31cc5e7d 100644
--- a/crates/ra_assists/src/assists/flip_comma.rs
+++ b/crates/ra_assists/src/assists/flip_comma.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::{algo::non_trivia_sibling, Direction, T};
 
diff --git a/crates/ra_assists/src/assists/inline_local_variable.rs b/crates/ra_assists/src/assists/inline_local_variable.rs
index eedb29199..9bd64decc 100644
--- a/crates/ra_assists/src/assists/inline_local_variable.rs
+++ b/crates/ra_assists/src/assists/inline_local_variable.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::{
     ast::{self, AstNode, AstToken},
diff --git a/crates/ra_assists/src/assists/introduce_variable.rs b/crates/ra_assists/src/assists/introduce_variable.rs
index 470ffe120..43378c4b0 100644
--- a/crates/ra_assists/src/assists/introduce_variable.rs
+++ b/crates/ra_assists/src/assists/introduce_variable.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use format_buf::format;
 use hir::db::HirDatabase;
 use ra_syntax::{
diff --git a/crates/ra_assists/src/assists/merge_match_arms.rs b/crates/ra_assists/src/assists/merge_match_arms.rs
index 3b6a99895..17baa98f9 100644
--- a/crates/ra_assists/src/assists/merge_match_arms.rs
+++ b/crates/ra_assists/src/assists/merge_match_arms.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use crate::{Assist, AssistCtx, AssistId, TextRange, TextUnit};
 use hir::db::HirDatabase;
 use ra_syntax::ast::{AstNode, MatchArm};
diff --git a/crates/ra_assists/src/assists/move_bounds.rs b/crates/ra_assists/src/assists/move_bounds.rs
index fd4bdc55c..f791d22b0 100644
--- a/crates/ra_assists/src/assists/move_bounds.rs
+++ b/crates/ra_assists/src/assists/move_bounds.rs
@@ -1,11 +1,13 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::{
-    ast::{self, make, AstNode, NameOwner, TypeBoundsOwner},
+    ast::{self, edit, make, AstNode, NameOwner, TypeBoundsOwner},
     SyntaxElement,
     SyntaxKind::*,
 };
 
-use crate::{ast_editor::AstEditor, Assist, AssistCtx, AssistId};
+use crate::{Assist, AssistCtx, AssistId};
 
 pub(crate) fn move_bounds_to_where_clause(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     let type_param_list = ctx.node_at_offset::<ast::TypeParamList>()?;
@@ -39,14 +41,12 @@ pub(crate) fn move_bounds_to_where_clause(mut ctx: AssistCtx<impl HirDatabase>)
                 .type_params()
                 .filter(|it| it.type_bound_list().is_some())
                 .map(|type_param| {
-                    let without_bounds =
-                        AstEditor::new(type_param.clone()).remove_bounds().ast().clone();
+                    let without_bounds = type_param.remove_bounds();
                     (type_param, without_bounds)
                 });
 
-            let mut ast_editor = AstEditor::new(type_param_list.clone());
-            ast_editor.replace_descendants(new_params);
-            ast_editor.into_text_edit(edit.text_edit_builder());
+            let new_type_param_list = edit::replace_descendants(&type_param_list, new_params);
+            edit.replace_ast(type_param_list.clone(), new_type_param_list);
 
             let where_clause = {
                 let predicates = type_param_list.type_params().filter_map(build_predicate);
diff --git a/crates/ra_assists/src/assists/move_guard.rs b/crates/ra_assists/src/assists/move_guard.rs
index 699221e33..51aea6334 100644
--- a/crates/ra_assists/src/assists/move_guard.rs
+++ b/crates/ra_assists/src/assists/move_guard.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::{
     ast,
diff --git a/crates/ra_assists/src/assists/raw_string.rs b/crates/ra_assists/src/assists/raw_string.rs
index 200aaa59a..2d2e31e51 100644
--- a/crates/ra_assists/src/assists/raw_string.rs
+++ b/crates/ra_assists/src/assists/raw_string.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use hir::db::HirDatabase;
 use ra_syntax::{ast::AstNode, ast::Literal, TextRange, TextUnit};
 use rustc_lexer;
diff --git a/crates/ra_assists/src/assists/remove_dbg.rs b/crates/ra_assists/src/assists/remove_dbg.rs
index 870133fda..1a7e2b305 100644
--- a/crates/ra_assists/src/assists/remove_dbg.rs
+++ b/crates/ra_assists/src/assists/remove_dbg.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use crate::{Assist, AssistCtx, AssistId};
 use hir::db::HirDatabase;
 use ra_syntax::{
diff --git a/crates/ra_assists/src/assists/replace_if_let_with_match.rs b/crates/ra_assists/src/assists/replace_if_let_with_match.rs
index 401835c57..749ff338a 100644
--- a/crates/ra_assists/src/assists/replace_if_let_with_match.rs
+++ b/crates/ra_assists/src/assists/replace_if_let_with_match.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use format_buf::format;
 use hir::db::HirDatabase;
 use ra_fmt::extract_trivial_expression;
diff --git a/crates/ra_assists/src/assists/split_import.rs b/crates/ra_assists/src/assists/split_import.rs
index 2c1edddb9..fe3e64af5 100644
--- a/crates/ra_assists/src/assists/split_import.rs
+++ b/crates/ra_assists/src/assists/split_import.rs
@@ -1,3 +1,5 @@
+//! FIXME: write short doc here
+
 use std::iter::successors;
 
 use hir::db::HirDatabase;
@@ -49,13 +51,13 @@ mod tests {
     fn split_import_works_with_trees() {
         check_assist(
             split_import,
-            "use algo:<|>:visitor::{Visitor, visit}",
-            "use algo::{<|>visitor::{Visitor, visit}}",
+            "use crate:<|>:db::{RootDatabase, FileSymbol}",
+            "use crate::{<|>db::{RootDatabase, FileSymbol}}",
         )
     }
 
     #[test]
     fn split_import_target() {
-        check_assist_target(split_import, "use algo::<|>visitor::{Visitor, visit}", "::");
+        check_assist_target(split_import, "use crate::<|>db::{RootDatabase, FileSymbol}", "::");
     }
 }