Support widgets and placeholders in more complex expressions

CHANGELOG.md

@@ -95,6 +95,9 @@
 - [Improved component browser entry filtering and sorting][5645]. The component
   browser will now provide suggestions matching either the component's label or
   the corresponding code.
+- [Improved argument placeholder resolution in more complex expressions][5656].
+  It is now possible to drop node connections onto missing arguments of chained
+  and nested function calls.
 
 #### EnsoGL (rendering engine)
 
@@ -480,6 +483,7 @@
 [4072]: https://github.com/enso-org/enso/pull/4072
 [5645]: https://github.com/enso-org/enso/pull/5645
 [5646]: https://github.com/enso-org/enso/pull/5646
+[5656]: https://github.com/enso-org/enso/pull/5656
 
 #### Enso Compiler
 

app/gui/language/ast/impl/src/opr.rs

@@ -294,9 +294,19 @@ impl GeneralizedInfix {
             infix_id: self.id,
         };
 
+        let rest_offset = rest.operand.as_ref().map_or_default(|op| op.offset);
+
         let target_subtree_infix = target.clone().and_then(|arg| {
             let offset = arg.offset;
-            GeneralizedInfix::try_new(&arg.arg).map(|arg| ArgWithOffset { arg, offset })
+            GeneralizedInfix::try_new(&arg.arg).map(|arg| ArgWithOffset { arg, offset }).filter(
+                |target_infix| {
+                    // For access operators, do not flatten them if there is a space before the dot.
+                    // For example, `Foo . Bar . Baz` should not be flattened to `Foo.Bar.Baz`, as
+                    // those should be treated as potential separate prefix expressions, allowing
+                    // operator placeholders to be inserted.
+                    rest_offset == 0 || target_infix.arg.name() != predefined::ACCESS
+                },
+            )
         });
         let mut target_subtree_flat = match target_subtree_infix {
             Some(target_infix) if target_infix.arg.name() == self.name() =>

app/gui/language/span-tree/example/src/lib.rs

@@ -26,8 +26,8 @@ pub fn main() {
     let parens_cr1 = ast::crumbs::MatchCrumb::Segs { val: val.clone(), index: 0 };
     let parens_cr = ast::crumbs::MatchCrumb::Segs { val, index: 0 };
     let _input_span_tree = builder::TreeBuilder::<()>::new(36)
-        .add_child(0, 14, node::Kind::Chained, PrefixCrumb::Func)
-        .add_child(0, 9, node::Kind::operation(), PrefixCrumb::Func)
+        .add_child(0, 14, node::Kind::chained(), PrefixCrumb::Func)
+        .add_child(0, 9, node::Kind::Operation, PrefixCrumb::Func)
         .set_ast_id(Uuid::new_v4())
         .done()
         .add_empty_child(10, InsertionPointType::BeforeTarget)
@@ -41,7 +41,7 @@ pub fn main() {
         .set_ast_id(Uuid::new_v4())
         .add_child(1, 19, node::Kind::argument(), parens_cr1)
         .set_ast_id(Uuid::new_v4())
-        .add_child(0, 12, node::Kind::operation(), PrefixCrumb::Func)
+        .add_child(0, 12, node::Kind::Operation, PrefixCrumb::Func)
         .set_ast_id(Uuid::new_v4())
         .done()
         .add_empty_child(13, InsertionPointType::BeforeTarget)
@@ -57,11 +57,11 @@ pub fn main() {
     let input_span_tree2 = Node::<()>::new()
         .new_child(|t| {
             t.new_ast_id()
-                .kind(node::Kind::Chained)
+                .kind(node::Kind::chained())
                 .crumbs(PrefixCrumb::Func)
                 .new_child(|t| {
                     t.size(9.bytes())
-                        .kind(node::Kind::operation())
+                        .kind(node::Kind::Operation)
                         .crumbs(PrefixCrumb::Func)
                         .new_ast_id()
                 })
@@ -85,7 +85,7 @@ pub fn main() {
                         .crumbs(parens_cr)
                         .new_child(|t| {
                             t.size(12.bytes())
-                                .kind(node::Kind::operation())
+                                .kind(node::Kind::Operation)
                                 .crumbs(PrefixCrumb::Func)
                                 .new_ast_id()
                         })

app/gui/language/span-tree/src/action.rs

@@ -390,7 +390,7 @@ mod test {
         // Consider Span Tree for `foo bar` where `foo` is a method known to take 3 parameters.
         // We can try setting each of 3 arguments to `baz`.
         let tree = TreeBuilder::<()>::new(7)
-            .add_leaf(0, 3, node::Kind::operation(), PrefixCrumb::Func)
+            .add_leaf(0, 3, node::Kind::Operation, PrefixCrumb::Func)
             .add_leaf(4, 7, node::Kind::this(), PrefixCrumb::Arg)
             .add_empty_child(7, ExpectedArgument(1))
             .add_empty_child(7, ExpectedArgument(2))
@@ -416,7 +416,7 @@ mod test {
         // parameters. We can try setting each of 2 arguments to `baz`.
         let tree: SpanTree = TreeBuilder::new(10)
             .add_leaf(0, 4, node::Kind::this(), InfixCrumb::LeftOperand)
-            .add_leaf(5, 6, node::Kind::operation(), InfixCrumb::Operator)
+            .add_leaf(5, 6, node::Kind::Operation, InfixCrumb::Operator)
             .add_leaf(7, 10, node::Kind::argument(), InfixCrumb::RightOperand)
             .add_empty_child(10, ExpectedArgument(0))
             .add_empty_child(10, ExpectedArgument(1))