KCL: Preallocate space for all the paths

rust/kcl-lib/src/execution/exec_ast.rs

@@ -1485,10 +1485,12 @@ pub(crate) async fn execute_pipe_body(
     // should use the previous child expression for %.
     // This means there's no more need for the previous pipe_value from the parent AST node above this one.
     let previous_pipe_value = exec_state.mod_local.pipe_value.replace(output);
+    let previous_pipe_size = exec_state.mod_local.pipe_size.replace(body.len());
     // Evaluate remaining elements.
     let result = inner_execute_pipe_body(exec_state, body, ctx).await;
     // Restore the previous pipe value.
     exec_state.mod_local.pipe_value = previous_pipe_value;
+    exec_state.mod_local.pipe_size = previous_pipe_size;
 
     result
 }

rust/kcl-lib/src/execution/state.rs

@@ -94,6 +94,8 @@ pub(super) struct ModuleState {
     /// The current value of the pipe operator returned from the previous
     /// expression.  If we're not currently in a pipeline, this will be None.
     pub pipe_value: Option<KclValue>,
+    /// How many pipes are in the pipeline.
+    pub pipe_size: Option<usize>,
     /// The closest variable declaration being executed in any parent node in the AST.
     /// This is used to provide better error messages, e.g. noticing when the user is trying
     /// to use the variable `length` inside the RHS of its own definition, like `length = tan(length)`.
@@ -299,6 +301,10 @@ impl ExecState {
         self.mod_local.pipe_value.as_ref()
     }
 
+    pub(crate) fn pipe_size(&self) -> Option<usize> {
+        self.mod_local.pipe_size
+    }
+
     pub(crate) fn error_with_outputs(
         &self,
         error: KclError,
@@ -482,6 +488,7 @@ impl ModuleState {
             id_generator: IdGenerator::new(module_id),
             stack: memory.new_stack(),
             pipe_value: Default::default(),
+            pipe_size: Default::default(),
             being_declared: Default::default(),
             module_exports: Default::default(),
             explicit_length_units: false,

rust/kcl-lib/src/std/sketch.rs

@@ -974,6 +974,7 @@ pub(crate) async fn inner_start_profile(
         _ => {}
     }
 
+    let heuristic_num_paths = exec_state.pipe_size().unwrap_or(1);
     let enable_sketch_id = exec_state.next_uuid();
     let path_id = exec_state.next_uuid();
     let move_pen_id = exec_state.next_uuid();
@@ -1038,7 +1039,7 @@ pub(crate) async fn inner_start_profile(
         original_id: path_id,
         artifact_id: path_id.into(),
         on: sketch_surface.clone(),
-        paths: vec![],
+        paths: Vec::with_capacity(heuristic_num_paths),
         inner_paths: vec![],
         units,
         mirror: Default::default(),