4 files changed, 152 insertions, 5 deletions

diff --git a/crates/syntax/src/ast/edit_in_place.rs b/crates/syntax/src/ast/edit_in_place.rs
new file mode 100644
index 000000000..449b058fb
--- /dev/null
+++ b/crates/syntax/src/ast/edit_in_place.rs
@@ -0,0 +1,129 @@
+//! Structural editing for ast.
+
+use std::iter::empty;
+
+use ast::{edit::AstNodeEdit, make, GenericParamsOwner, WhereClause};
+use parser::T;
+
+use crate::{
+    ast,
+    ted::{self, Position},
+    AstNode, Direction, SyntaxElement,
+};
+
+use super::NameOwner;
+
+pub trait GenericParamsOwnerEdit: ast::GenericParamsOwner + AstNodeEdit {
+    fn get_or_create_where_clause(&self) -> ast::WhereClause;
+}
+
+impl GenericParamsOwnerEdit for ast::Fn {
+    fn get_or_create_where_clause(&self) -> WhereClause {
+        if self.where_clause().is_none() {
+            let position = if let Some(ty) = self.ret_type() {
+                Position::after(ty.syntax().clone())
+            } else if let Some(param_list) = self.param_list() {
+                Position::after(param_list.syntax().clone())
+            } else {
+                Position::last_child_of(self.syntax().clone())
+            };
+            create_where_clause(position)
+        }
+        self.where_clause().unwrap()
+    }
+}
+
+impl GenericParamsOwnerEdit for ast::Impl {
+    fn get_or_create_where_clause(&self) -> WhereClause {
+        if self.where_clause().is_none() {
+            let position = if let Some(items) = self.assoc_item_list() {
+                Position::before(items.syntax().clone())
+            } else {
+                Position::last_child_of(self.syntax().clone())
+            };
+            create_where_clause(position)
+        }
+        self.where_clause().unwrap()
+    }
+}
+
+impl GenericParamsOwnerEdit for ast::Trait {
+    fn get_or_create_where_clause(&self) -> WhereClause {
+        if self.where_clause().is_none() {
+            let position = if let Some(items) = self.assoc_item_list() {
+                Position::before(items.syntax().clone())
+            } else {
+                Position::last_child_of(self.syntax().clone())
+            };
+            create_where_clause(position)
+        }
+        self.where_clause().unwrap()
+    }
+}
+
+impl GenericParamsOwnerEdit for ast::Struct {
+    fn get_or_create_where_clause(&self) -> WhereClause {
+        if self.where_clause().is_none() {
+            let tfl = self.field_list().and_then(|fl| match fl {
+                ast::FieldList::RecordFieldList(_) => None,
+                ast::FieldList::TupleFieldList(it) => Some(it),
+            });
+            let position = if let Some(tfl) = tfl {
+                Position::after(tfl.syntax().clone())
+            } else if let Some(gpl) = self.generic_param_list() {
+                Position::after(gpl.syntax().clone())
+            } else if let Some(name) = self.name() {
+                Position::after(name.syntax().clone())
+            } else {
+                Position::last_child_of(self.syntax().clone())
+            };
+            create_where_clause(position)
+        }
+        self.where_clause().unwrap()
+    }
+}
+
+impl GenericParamsOwnerEdit for ast::Enum {
+    fn get_or_create_where_clause(&self) -> WhereClause {
+        if self.where_clause().is_none() {
+            let position = if let Some(gpl) = self.generic_param_list() {
+                Position::after(gpl.syntax().clone())
+            } else if let Some(name) = self.name() {
+                Position::after(name.syntax().clone())
+            } else {
+                Position::last_child_of(self.syntax().clone())
+            };
+            create_where_clause(position)
+        }
+        self.where_clause().unwrap()
+    }
+}
+
+fn create_where_clause(position: Position) {
+    let where_clause: SyntaxElement =
+        make::where_clause(empty()).clone_for_update().syntax().clone().into();
+    ted::insert(position, where_clause);
+}
+
+impl ast::WhereClause {
+    pub fn add_predicate(&self, predicate: ast::WherePred) {
+        if let Some(pred) = self.predicates().last() {
+            if !pred.syntax().siblings_with_tokens(Direction::Next).any(|it| it.kind() == T![,]) {
+                ted::append_child_raw(self.syntax().clone(), make::token(T![,]));
+            }
+        }
+        ted::append_child(self.syntax().clone(), predicate.syntax().clone())
+    }
+}
+
+impl ast::TypeBoundList {
+    pub fn remove(&self) {
+        if let Some(colon) =
+            self.syntax().siblings_with_tokens(Direction::Prev).find(|it| it.kind() == T![:])
+        {
+            ted::remove_all(colon..=self.syntax().clone().into())
+        } else {
+            ted::remove(self.syntax().clone())
+        }
+    }
+}
diff --git a/crates/syntax/src/ast/generated/nodes.rs b/crates/syntax/src/ast/generated/nodes.rs
index 064931aec..6097178b6 100644
--- a/crates/syntax/src/ast/generated/nodes.rs
+++ b/crates/syntax/src/ast/generated/nodes.rs
@@ -1336,6 +1336,7 @@ pub enum Expr {
     Literal(Literal),
     LoopExpr(LoopExpr),
     MacroCall(MacroCall),
+    MacroStmts(MacroStmts),
     MatchExpr(MatchExpr),
     MethodCallExpr(MethodCallExpr),
     ParenExpr(ParenExpr),
@@ -3034,6 +3035,9 @@ impl From<LoopExpr> for Expr {
 impl From<MacroCall> for Expr {
     fn from(node: MacroCall) -> Expr { Expr::MacroCall(node) }
 }
+impl From<MacroStmts> for Expr {
+    fn from(node: MacroStmts) -> Expr { Expr::MacroStmts(node) }
+}
 impl From<MatchExpr> for Expr {
     fn from(node: MatchExpr) -> Expr { Expr::MatchExpr(node) }
 }
@@ -3078,8 +3082,8 @@ impl AstNode for Expr {
         match kind {
             ARRAY_EXPR | AWAIT_EXPR | BIN_EXPR | BLOCK_EXPR | BOX_EXPR | BREAK_EXPR | CALL_EXPR
             | CAST_EXPR | CLOSURE_EXPR | CONTINUE_EXPR | EFFECT_EXPR | FIELD_EXPR | FOR_EXPR
-            | IF_EXPR | INDEX_EXPR | LITERAL | LOOP_EXPR | MACRO_CALL | MATCH_EXPR
-            | METHOD_CALL_EXPR | PAREN_EXPR | PATH_EXPR | PREFIX_EXPR | RANGE_EXPR
+            | IF_EXPR | INDEX_EXPR | LITERAL | LOOP_EXPR | MACRO_CALL | MACRO_STMTS
+            | MATCH_EXPR | METHOD_CALL_EXPR | PAREN_EXPR | PATH_EXPR | PREFIX_EXPR | RANGE_EXPR
             | RECORD_EXPR | REF_EXPR | RETURN_EXPR | TRY_EXPR | TUPLE_EXPR | WHILE_EXPR
             | YIELD_EXPR => true,
             _ => false,
@@ -3105,6 +3109,7 @@ impl AstNode for Expr {
             LITERAL => Expr::Literal(Literal { syntax }),
             LOOP_EXPR => Expr::LoopExpr(LoopExpr { syntax }),
             MACRO_CALL => Expr::MacroCall(MacroCall { syntax }),
+            MACRO_STMTS => Expr::MacroStmts(MacroStmts { syntax }),
             MATCH_EXPR => Expr::MatchExpr(MatchExpr { syntax }),
             METHOD_CALL_EXPR => Expr::MethodCallExpr(MethodCallExpr { syntax }),
             PAREN_EXPR => Expr::ParenExpr(ParenExpr { syntax }),
@@ -3142,6 +3147,7 @@ impl AstNode for Expr {
             Expr::Literal(it) => &it.syntax,
             Expr::LoopExpr(it) => &it.syntax,
             Expr::MacroCall(it) => &it.syntax,
+            Expr::MacroStmts(it) => &it.syntax,
             Expr::MatchExpr(it) => &it.syntax,
             Expr::MethodCallExpr(it) => &it.syntax,
             Expr::ParenExpr(it) => &it.syntax,
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index 05a6b0b25..810c8d4c8 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -174,6 +174,11 @@ pub fn block_expr(
 pub fn expr_unit() -> ast::Expr {
     expr_from_text("()")
 }
+pub fn expr_literal(text: &str) -> ast::Literal {
+    assert_eq!(text.trim(), text);
+    ast_from_text(&format!("fn f() {{ let _ = {}; }}", text))
+}
+
 pub fn expr_empty_block() -> ast::Expr {
     expr_from_text("{}")
 }
@@ -390,6 +395,7 @@ pub fn token(kind: SyntaxKind) -> SyntaxToken {
     tokens::SOURCE_FILE
         .tree()
         .syntax()
+        .clone_for_update()
         .descendants_with_tokens()
         .filter_map(|it| it.into_token())
         .find(|it| it.kind() == kind)
@@ -544,6 +550,7 @@ pub mod tokens {
         SOURCE_FILE
             .tree()
             .syntax()
+            .clone_for_update()
             .descendants_with_tokens()
             .filter_map(|it| it.into_token())
             .find(|it| it.kind() == WHITESPACE && it.text() == " ")
@@ -569,13 +576,16 @@ pub mod tokens {
     }
 
     pub fn single_newline() -> SyntaxToken {
-        SOURCE_FILE
+        let res = SOURCE_FILE
             .tree()
             .syntax()
+            .clone_for_update()
             .descendants_with_tokens()
             .filter_map(|it| it.into_token())
             .find(|it| it.kind() == WHITESPACE && it.text() == "\n")
-            .unwrap()
+            .unwrap();
+        res.detach();
+        res
     }
 
     pub fn blank_line() -> SyntaxToken {
diff --git a/crates/syntax/src/ast/node_ext.rs b/crates/syntax/src/ast/node_ext.rs
index 52ac97c84..0b0d39a75 100644
--- a/crates/syntax/src/ast/node_ext.rs
+++ b/crates/syntax/src/ast/node_ext.rs
@@ -34,7 +34,9 @@ impl ast::NameRef {
 }
 
 fn text_of_first_token(node: &SyntaxNode) -> &str {
-    node.green().children().next().and_then(|it| it.into_token()).unwrap().text()
+    let t =
+        node.green().children().next().and_then(|it| it.into_token()).unwrap().text().to_string();
+    Box::leak(Box::new(t))
 }
 
 pub enum Macro {