Don't require dropping validation layer to handle validation errors

crates/fj-core/src/layers/validation.rs

@@ -8,15 +8,9 @@ use crate::{
 use super::{objects::InsertObject, Command, Event, Layer};
 
 impl Layer<Validation> {
-    /// Consume the validation layer, returning any validation errors
-    pub fn into_result(self) -> Result<(), ValidationErrors> {
-        let errors = self.into_state().into_errors();
-
-        if errors.0.is_empty() {
-            Ok(())
-        } else {
-            Err(errors)
-        }
+    /// Take all errors stored in the validation layer
+    pub fn take_errors(&mut self) -> Result<(), ValidationErrors> {
+        self.process(TakeErrors, &mut Vec::new())
     }
 }
 
@@ -39,6 +33,38 @@ impl Command<Validation> for InsertObject {
     }
 }
 
+/// Take all errors stored in the validation layer
+///
+/// Serves both as a command for and event produced by `Layer<Validation>`.
+pub struct TakeErrors;
+
+impl Command<Validation> for TakeErrors {
+    type Result = Result<(), ValidationErrors>;
+    type Event = Self;
+
+    fn decide(
+        self,
+        state: &Validation,
+        events: &mut Vec<Self::Event>,
+    ) -> Self::Result {
+        let errors = ValidationErrors(state.errors.values().cloned().collect());
+
+        events.push(self);
+
+        if errors.0.is_empty() {
+            Ok(())
+        } else {
+            Err(errors)
+        }
+    }
+}
+
+impl Event<Validation> for TakeErrors {
+    fn evolve(&self, state: &mut Validation) {
+        state.errors.clear();
+    }
+}
+
 /// Validation of an object failed
 ///
 /// Event produced by `Layer<Validation>`.

crates/fj-core/src/validate/mod.rs

@@ -119,11 +119,6 @@ impl Validation {
         let errors = HashMap::new();
         Self { errors, config }
     }
-
-    /// Drop this instance, returning the errors it contained
-    pub fn into_errors(mut self) -> ValidationErrors {
-        ValidationErrors(self.errors.drain().map(|(_, error)| error).collect())
-    }
 }
 
 impl Drop for Validation {

crates/fj-core/src/validate/solid.rs

@@ -236,7 +236,7 @@ mod tests {
         valid_solid.validate_and_return_first_error()?;
 
         // Ignore remaining validation errors.
-        let _ = core.layers.validation.into_result();
+        let _ = core.layers.validation.take_errors();
 
         Ok(())
     }
@@ -289,7 +289,7 @@ mod tests {
         valid_solid.validate_and_return_first_error()?;
 
         // Ignore remaining validation errors.
-        let _ = core.layers.validation.into_result();
+        let _ = core.layers.validation.take_errors();
 
         Ok(())
     }
@@ -339,7 +339,7 @@ mod tests {
         valid_solid.validate_and_return_first_error()?;
 
         // Ignore remaining validation errors.
-        let _ = core.layers.validation.into_result();
+        let _ = core.layers.validation.take_errors();
 
         Ok(())
     }
@@ -379,7 +379,7 @@ mod tests {
         valid_solid.validate_and_return_first_error()?;
 
         // Ignore remaining validation errors.
-        let _ = core.layers.validation.into_result();
+        let _ = core.layers.validation.take_errors();
 
         Ok(())
     }

crates/fj/src/handle_model.rs

@@ -23,7 +23,7 @@ use crate::Args;
 ///
 /// This function is used by Fornjot's own testing infrastructure, but is useful
 /// beyond that, when using Fornjot directly to define a model.
-pub fn handle_model<M>(model: &M, core: Instance) -> Result
+pub fn handle_model<M>(model: &M, mut core: Instance) -> Result
 where
     for<'r> (&'r M, Tolerance): Triangulate,
     M: BoundingVolume<3>,
@@ -36,7 +36,7 @@ where
     let args = Args::parse();
 
     if !args.ignore_validation {
-        core.layers.validation.into_result()?;
+        core.layers.validation.take_errors()?;
     }
 
     let aabb = model.aabb().unwrap_or(Aabb {