Merge pull request #18483 from tareknaser/syntax_factory_introduce_named_generic

Migrate `introduce_named_generic` Assist to Use `SyntaxFactory`

crates/syntax/src/ast/syntax_factory/constructors.rs

@@ -2,7 +2,7 @@
 use itertools::Itertools;
 
 use crate::{
-    ast::{self, make, HasName},
+    ast::{self, make, HasName, HasTypeBounds},
     syntax_editor::SyntaxMappingBuilder,
     AstNode,
 };
@@ -14,6 +14,32 @@ impl SyntaxFactory {
         make::name(name).clone_for_update()
     }
 
+    pub fn ty(&self, text: &str) -> ast::Type {
+        make::ty(text).clone_for_update()
+    }
+
+    pub fn type_param(
+        &self,
+        name: ast::Name,
+        bounds: Option<ast::TypeBoundList>,
+    ) -> ast::TypeParam {
+        let ast = make::type_param(name.clone(), bounds.clone()).clone_for_update();
+
+        if let Some(mut mapping) = self.mappings() {
+            let mut builder = SyntaxMappingBuilder::new(ast.syntax().clone());
+            builder.map_node(name.syntax().clone(), ast.name().unwrap().syntax().clone());
+            if let Some(input) = bounds {
+                builder.map_node(
+                    input.syntax().clone(),
+                    ast.type_bound_list().unwrap().syntax().clone(),
+                );
+            }
+            builder.finish(&mut mapping);
+        }
+
+        ast
+    }
+
     pub fn ident_pat(&self, ref_: bool, mut_: bool, name: ast::Name) -> ast::IdentPat {
         let ast = make::ident_pat(ref_, mut_, name.clone()).clone_for_update();
 

crates/syntax/src/syntax_editor.rs

@@ -16,6 +16,7 @@ use rustc_hash::FxHashMap;
 use crate::{SyntaxElement, SyntaxNode, SyntaxToken};
 
 mod edit_algo;
+mod edits;
 mod mapping;
 
 pub use mapping::{SyntaxMapping, SyntaxMappingBuilder};

crates/syntax/src/syntax_editor/edits.rs

@@ -0,0 +1,72 @@
+//! Structural editing for ast using `SyntaxEditor`
+
+use crate::{
+    ast::make, ast::AstNode, ast::Fn, ast::GenericParam, ast::HasGenericParams, ast::HasName,
+    syntax_editor::Position, syntax_editor::SyntaxEditor, SyntaxKind,
+};
+
+impl SyntaxEditor {
+    /// Adds a new generic param to the function using `SyntaxEditor`
+    pub fn add_generic_param(&mut self, function: &Fn, new_param: GenericParam) {
+        match function.generic_param_list() {
+            Some(generic_param_list) => match generic_param_list.generic_params().last() {
+                Some(last_param) => {
+                    // There exists a generic param list and it's not empty
+                    let position = generic_param_list.r_angle_token().map_or_else(
+                        || Position::last_child_of(function.syntax()),
+                        Position::before,
+                    );
+
+                    if last_param
+                        .syntax()
+                        .next_sibling_or_token()
+                        .map_or(false, |it| it.kind() == SyntaxKind::COMMA)
+                    {
+                        self.insert(
+                            Position::after(last_param.syntax()),
+                            new_param.syntax().clone(),
+                        );
+                        self.insert(
+                            Position::after(last_param.syntax()),
+                            make::token(SyntaxKind::WHITESPACE),
+                        );
+                        self.insert(
+                            Position::after(last_param.syntax()),
+                            make::token(SyntaxKind::COMMA),
+                        );
+                    } else {
+                        let elements = vec![
+                            make::token(SyntaxKind::COMMA).into(),
+                            make::token(SyntaxKind::WHITESPACE).into(),
+                            new_param.syntax().clone().into(),
+                        ];
+                        self.insert_all(position, elements);
+                    }
+                }
+                None => {
+                    // There exists a generic param list but it's empty
+                    let position = Position::after(generic_param_list.l_angle_token().unwrap());
+                    self.insert(position, new_param.syntax());
+                }
+            },
+            None => {
+                // There was no generic param list
+                let position = if let Some(name) = function.name() {
+                    Position::after(name.syntax)
+                } else if let Some(fn_token) = function.fn_token() {
+                    Position::after(fn_token)
+                } else if let Some(param_list) = function.param_list() {
+                    Position::before(param_list.syntax)
+                } else {
+                    Position::last_child_of(function.syntax())
+                };
+                let elements = vec![
+                    make::token(SyntaxKind::L_ANGLE).into(),
+                    new_param.syntax().clone().into(),
+                    make::token(SyntaxKind::R_ANGLE).into(),
+                ];
+                self.insert_all(position, elements);
+            }
+        }
+    }
+}