More fluent indent API

crates/ra_assists/src/handlers/add_function.rs

@@ -1,7 +1,11 @@
 use hir::HirDisplay;
 use ra_db::FileId;
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, ArgListOwner, AstNode, ModuleItemOwner},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        ArgListOwner, AstNode, ModuleItemOwner,
+    },
     SyntaxKind, SyntaxNode, TextSize,
 };
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -116,17 +120,16 @@ impl FunctionBuilder {
         let (fn_def, insert_offset) = match self.target {
             GeneratedFunctionTarget::BehindItem(it) => {
                 let with_leading_blank_line = ast::make::add_leading_newlines(2, fn_def);
-                let indented = IndentLevel::from_node(&it).increase_indent(with_leading_blank_line);
+                let indented = with_leading_blank_line.indent(IndentLevel::from_node(&it));
                 (indented, it.text_range().end())
             }
             GeneratedFunctionTarget::InEmptyItemList(it) => {
                 let indent_once = IndentLevel(1);
                 let indent = IndentLevel::from_node(it.syntax());
-
                 let fn_def = ast::make::add_leading_newlines(1, fn_def);
-                let fn_def = indent_once.increase_indent(fn_def);
+                let fn_def = fn_def.indent(indent_once);
                 let fn_def = ast::make::add_trailing_newlines(1, fn_def);
-                let fn_def = indent.increase_indent(fn_def);
+                let fn_def = fn_def.indent(indent);
                 (fn_def, it.syntax().text_range().start() + TextSize::of('{'))
             }
         };

crates/ra_assists/src/handlers/add_missing_impl_members.rs

@@ -2,7 +2,7 @@ use hir::HasSource;
 use ra_syntax::{
     ast::{
         self,
-        edit::{self, IndentLevel},
+        edit::{self, AstNodeEdit, IndentLevel},
         make, AstNode, NameOwner,
     },
     SmolStr,
@@ -176,8 +176,7 @@ fn add_body(fn_def: ast::FnDef) -> ast::FnDef {
     if fn_def.body().is_some() {
         return fn_def;
     }
-    let body = make::block_expr(None, Some(make::expr_todo()));
+    let body = make::block_expr(None, Some(make::expr_todo())).indent(IndentLevel(1));
-    let body = IndentLevel(1).increase_indent(body);
     fn_def.with_body(body)
 }
 

crates/ra_assists/src/handlers/early_return.rs

@@ -2,7 +2,11 @@ use std::{iter::once, ops::RangeInclusive};
 
 use ra_syntax::{
     algo::replace_children,
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
     SyntaxKind::{FN_DEF, LOOP_EXPR, L_CURLY, R_CURLY, WHILE_EXPR, WHITESPACE},
     SyntaxNode,
@@ -105,8 +109,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
                     let then_branch =
                         make::block_expr(once(make::expr_stmt(early_expression).into()), None);
                     let cond = invert_boolean_expression(cond_expr);
-                    let e = make::expr_if(make::condition(cond, None), then_branch);
+                    make::expr_if(make::condition(cond, None), then_branch).indent(if_indent_level)
-                    if_indent_level.increase_indent(e)
                 };
                 replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
             }
@@ -140,7 +143,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
                     make::bind_pat(make::name(&bound_ident.syntax().to_string())).into(),
                     Some(match_expr),
                 );
-                let let_stmt = if_indent_level.increase_indent(let_stmt);
+                let let_stmt = let_stmt.indent(if_indent_level);
                 replace(let_stmt.syntax(), &then_block, &parent_block, &if_expr)
             }
         };
@@ -153,7 +156,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
             parent_block: &ast::BlockExpr,
             if_expr: &ast::IfExpr,
         ) -> SyntaxNode {
-            let then_block_items = IndentLevel::from(1).decrease_indent(then_block.clone());
+            let then_block_items = then_block.unindent(IndentLevel::from(1));
             let end_of_then = then_block_items.syntax().last_child_or_token().unwrap();
             let end_of_then =
                 if end_of_then.prev_sibling_or_token().map(|n| n.kind()) == Some(WHITESPACE) {

crates/ra_assists/src/handlers/replace_if_let_with_match.rs

@@ -1,6 +1,10 @@
 use ra_fmt::unwrap_trivial_block;
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
 };
 
@@ -61,10 +65,9 @@ pub(crate) fn replace_if_let_with_match(acc: &mut Assists, ctx: &AssistContext)
                 make::match_arm(vec![pattern], else_expr)
             };
             make::expr_match(expr, make::match_arm_list(vec![then_arm, else_arm]))
+                .indent(IndentLevel::from_node(if_expr.syntax()))
         };
 
-        let match_expr = IndentLevel::from_node(if_expr.syntax()).increase_indent(match_expr);
-
         edit.set_cursor(if_expr.syntax().text_range().start());
         edit.replace_ast::<ast::Expr>(if_expr.into(), match_expr);
     })

crates/ra_assists/src/handlers/replace_let_with_if_let.rs

@@ -53,8 +53,7 @@ pub(crate) fn replace_let_with_if_let(acc: &mut Assists, ctx: &AssistContext) ->
             )
             .into(),
         };
-        let block =
+        let block = make::block_expr(None, None).indent(IndentLevel::from_node(let_stmt.syntax()));
-            IndentLevel::from_node(let_stmt.syntax()).increase_indent(make::block_expr(None, None));
         let if_ = make::expr_if(make::condition(init, Some(with_placeholder)), block);
         let stmt = make::expr_stmt(if_);
 

crates/ra_assists/src/handlers/replace_unwrap_with_match.rs

@@ -1,7 +1,11 @@
 use std::iter;
 
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
 };
 
@@ -51,8 +55,8 @@ pub(crate) fn replace_unwrap_with_match(acc: &mut Assists, ctx: &AssistContext)
         let err_arm = make::match_arm(iter::once(make::placeholder_pat().into()), unreachable_call);
 
         let match_arm_list = make::match_arm_list(vec![ok_arm, err_arm]);
-        let match_expr = make::expr_match(caller.clone(), match_arm_list);
+        let match_expr = make::expr_match(caller.clone(), match_arm_list)
-        let match_expr = IndentLevel::from_node(method_call.syntax()).increase_indent(match_expr);
+            .indent(IndentLevel::from_node(method_call.syntax()));
 
         edit.set_cursor(caller.syntax().text_range().start());
         edit.replace_ast::<ast::Expr>(method_call.into(), match_expr);

crates/ra_syntax/src/ast/edit.rs

@@ -453,11 +453,7 @@ impl IndentLevel {
         IndentLevel(0)
     }
 
-    pub fn increase_indent<N: AstNode>(self, node: N) -> N {
+    fn increase_indent(self, node: SyntaxNode) -> SyntaxNode {
-        N::cast(self._increase_indent(node.syntax().clone())).unwrap()
-    }
-
-    fn _increase_indent(self, node: SyntaxNode) -> SyntaxNode {
         let mut rewriter = SyntaxRewriter::default();
         node.descendants_with_tokens()
             .filter_map(|el| el.into_token())
@@ -478,11 +474,7 @@ impl IndentLevel {
         rewriter.rewrite(&node)
     }
 
-    pub fn decrease_indent<N: AstNode>(self, node: N) -> N {
+    fn decrease_indent(self, node: SyntaxNode) -> SyntaxNode {
-        N::cast(self._decrease_indent(node.syntax().clone())).unwrap()
-    }
-
-    fn _decrease_indent(self, node: SyntaxNode) -> SyntaxNode {
         let mut rewriter = SyntaxRewriter::default();
         node.descendants_with_tokens()
             .filter_map(|el| el.into_token())
@@ -521,7 +513,7 @@ fn prev_tokens(token: SyntaxToken) -> impl Iterator<Item = SyntaxToken> {
     iter::successors(Some(token), |token| token.prev_token())
 }
 
-pub trait AstNodeEdit: AstNode + Sized {
+pub trait AstNodeEdit: AstNode + Clone + Sized {
     #[must_use]
     fn insert_children(
         &self,
@@ -558,9 +550,17 @@ pub trait AstNodeEdit: AstNode + Sized {
         }
         rewriter.rewrite_ast(self)
     }
+    #[must_use]
+    fn indent(&self, indent: IndentLevel) -> Self {
+        Self::cast(indent.increase_indent(self.syntax().clone())).unwrap()
+    }
+    #[must_use]
+    fn unindent(&self, indent: IndentLevel) -> Self {
+        Self::cast(indent.decrease_indent(self.syntax().clone())).unwrap()
+    }
 }
 
-impl<N: AstNode> AstNodeEdit for N {}
+impl<N: AstNode + Clone> AstNodeEdit for N {}
 
 fn single_node(element: impl Into<SyntaxElement>) -> RangeInclusive<SyntaxElement> {
     let element = element.into();
@@ -580,7 +580,7 @@ fn test_increase_indent() {
     _ => (),
 }"
     );
-    let indented = IndentLevel(2).increase_indent(arm_list);
+    let indented = arm_list.indent(IndentLevel(2));
     assert_eq!(
         indented.syntax().to_string(),
         "{