Vendor dependencies for 0.3.0 release

vendor/bevy_reflect_derive/src/result_sifter.rs

@@ -0,0 +1,46 @@
+/// Helper struct used to process an iterator of `Result<Vec<T>, syn::Error>`,
+/// combining errors into one along the way.
+pub(crate) struct ResultSifter<T> {
+    items: Vec<T>,
+    errors: Option<syn::Error>,
+}
+
+impl<T> Default for ResultSifter<T> {
+    fn default() -> Self {
+        Self {
+            items: Vec::new(),
+            errors: None,
+        }
+    }
+}
+
+impl<T> ResultSifter<T> {
+    /// Sift the given result, combining errors if necessary.
+    pub fn sift(&mut self, result: Result<T, syn::Error>) {
+        match result {
+            Ok(data) => self.items.push(data),
+            Err(err) => {
+                if let Some(ref mut errors) = self.errors {
+                    errors.combine(err);
+                } else {
+                    self.errors = Some(err);
+                }
+            }
+        }
+    }
+
+    /// Associated method that provides a convenient implementation for [`Iterator::fold`].
+    pub fn fold(mut sifter: Self, result: Result<T, syn::Error>) -> Self {
+        sifter.sift(result);
+        sifter
+    }
+
+    /// Complete the sifting process and return the final result.
+    pub fn finish(self) -> Result<Vec<T>, syn::Error> {
+        if let Some(errors) = self.errors {
+            Err(errors)
+        } else {
+            Ok(self.items)
+        }
+    }
+}