rewrite merge use trees assist to use muatable syntax trees

changelog internal

crates/syntax/src/ast/edit.rs

@@ -9,7 +9,7 @@ use std::{
 use arrayvec::ArrayVec;
 
 use crate::{
-    algo::{self, neighbor, SyntaxRewriter},
+    algo::{self, SyntaxRewriter},
     ast::{
         self,
         make::{self, tokens},
@@ -322,27 +322,6 @@ impl ast::Use {
         }
         self.clone()
     }
-
-    pub fn remove(&self) -> SyntaxRewriter<'static> {
-        let mut res = SyntaxRewriter::default();
-        res.delete(self.syntax());
-        let next_ws = self
-            .syntax()
-            .next_sibling_or_token()
-            .and_then(|it| it.into_token())
-            .and_then(ast::Whitespace::cast);
-        if let Some(next_ws) = next_ws {
-            let ws_text = next_ws.syntax().text();
-            if let Some(rest) = ws_text.strip_prefix('\n') {
-                if rest.is_empty() {
-                    res.delete(next_ws.syntax())
-                } else {
-                    res.replace(next_ws.syntax(), &make::tokens::whitespace(rest));
-                }
-            }
-        }
-        res
-    }
 }
 
 impl ast::UseTree {
@@ -396,22 +375,6 @@ impl ast::UseTree {
             Some(res)
         }
     }
-
-    pub fn remove(&self) -> SyntaxRewriter<'static> {
-        let mut res = SyntaxRewriter::default();
-        res.delete(self.syntax());
-        for &dir in [Direction::Next, Direction::Prev].iter() {
-            if let Some(nb) = neighbor(self, dir) {
-                self.syntax()
-                    .siblings_with_tokens(dir)
-                    .skip(1)
-                    .take_while(|it| it.as_node() != Some(nb.syntax()))
-                    .for_each(|el| res.delete(&el));
-                return res;
-            }
-        }
-        res
-    }
 }
 
 impl ast::MatchArmList {
@@ -592,6 +555,13 @@ impl ops::Add<u8> for IndentLevel {
 }
 
 impl IndentLevel {
+    pub fn from_element(element: &SyntaxElement) -> IndentLevel {
+        match element {
+            rowan::NodeOrToken::Node(it) => IndentLevel::from_node(it),
+            rowan::NodeOrToken::Token(it) => IndentLevel::from_token(it),
+        }
+    }
+
     pub fn from_node(node: &SyntaxNode) -> IndentLevel {
         match node.first_token() {
             Some(it) => Self::from_token(&it),

crates/syntax/src/ast/edit_in_place.rs

@@ -2,13 +2,13 @@
 
 use std::iter::empty;
 
-use ast::{edit::AstNodeEdit, make, GenericParamsOwner, WhereClause};
 use parser::T;
 
 use crate::{
-    ast,
+    algo::neighbor,
+    ast::{self, edit::AstNodeEdit, make, GenericParamsOwner, WhereClause},
     ted::{self, Position},
-    AstNode, Direction,
+    AstNode, AstToken, Direction,
 };
 
 use super::NameOwner;
@@ -126,3 +126,41 @@ impl ast::TypeBoundList {
         }
     }
 }
+
+impl ast::UseTree {
+    pub fn remove(&self) {
+        for &dir in [Direction::Next, Direction::Prev].iter() {
+            if let Some(next_use_tree) = neighbor(self, dir) {
+                let separators = self
+                    .syntax()
+                    .siblings_with_tokens(dir)
+                    .skip(1)
+                    .take_while(|it| it.as_node() != Some(next_use_tree.syntax()));
+                ted::remove_all_iter(separators);
+                break;
+            }
+        }
+        ted::remove(self.syntax())
+    }
+}
+
+impl ast::Use {
+    pub fn remove(&self) {
+        let next_ws = self
+            .syntax()
+            .next_sibling_or_token()
+            .and_then(|it| it.into_token())
+            .and_then(ast::Whitespace::cast);
+        if let Some(next_ws) = next_ws {
+            let ws_text = next_ws.syntax().text();
+            if let Some(rest) = ws_text.strip_prefix('\n') {
+                if rest.is_empty() {
+                    ted::remove(next_ws.syntax())
+                } else {
+                    ted::replace(next_ws.syntax(), make::tokens::whitespace(rest))
+                }
+            }
+        }
+        ted::remove(self.syntax())
+    }
+}

crates/syntax/src/ast/make.rs

@@ -560,7 +560,7 @@ pub mod tokens {
     pub fn whitespace(text: &str) -> SyntaxToken {
         assert!(text.trim().is_empty());
         let sf = SourceFile::parse(text).ok().unwrap();
-        sf.syntax().first_child_or_token().unwrap().into_token().unwrap()
+        sf.syntax().clone_for_update().first_child_or_token().unwrap().into_token().unwrap()
     }
 
     pub fn doc_comment(text: &str) -> SyntaxToken {

crates/syntax/src/ted.rs

@@ -2,11 +2,14 @@
 //!
 //! The `_raw`-suffixed functions insert elements as is, unsuffixed versions fix
 //! up elements around the edges.
-use std::ops::RangeInclusive;
+use std::{mem, ops::RangeInclusive};
 
 use parser::T;
 
-use crate::{ast::make, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken};
+use crate::{
+    ast::{edit::IndentLevel, make},
+    SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken,
+};
 
 /// Utility trait to allow calling `ted` functions with references or owned
 /// nodes. Do not use outside of this module.
@@ -101,12 +104,25 @@ pub fn insert_all_raw(position: Position, elements: Vec<SyntaxElement>) {
 }
 
 pub fn remove(elem: impl Element) {
-    let elem = elem.syntax_element();
-    remove_all(elem.clone()..=elem)
+    elem.syntax_element().detach()
 }
 pub fn remove_all(range: RangeInclusive<SyntaxElement>) {
     replace_all(range, Vec::new())
 }
+pub fn remove_all_iter(range: impl IntoIterator<Item = SyntaxElement>) {
+    let mut it = range.into_iter();
+    if let Some(mut first) = it.next() {
+        match it.last() {
+            Some(mut last) => {
+                if first.index() > last.index() {
+                    mem::swap(&mut first, &mut last)
+                }
+                remove_all(first..=last)
+            }
+            None => remove(first),
+        }
+    }
+}
 
 pub fn replace(old: impl Element, new: impl Element) {
     let old = old.syntax_element();
@@ -149,5 +165,9 @@ fn ws_between(left: &SyntaxElement, right: &SyntaxElement) -> Option<SyntaxToken
     if right.kind() == T![;] || right.kind() == T![,] {
         return None;
     }
+    if right.kind() == SyntaxKind::USE {
+        let indent = IndentLevel::from_element(left);
+        return Some(make::tokens::whitespace(&format!("\n{}", indent)));
+    }
     Some(make::tokens::single_space())
 }