Add transform to deduplicate entities in CDI spec

Signed-off-by: Evan Lezar <elezar@nvidia.com>

pkg/nvcdi/transform/simplify.go

@@ -0,0 +1,74 @@
+/**
+# Copyright (c) NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package transform
+
+import (
+	"fmt"
+
+	"github.com/container-orchestrated-devices/container-device-interface/specs-go"
+)
+
+type simplify struct{}
+
+var _ Transformer = (*simplify)(nil)
+
+// NewSimplifier creates a simplifier transformer.
+// This transoformer ensures that entities in the spec are deduplicated and that common edits are removed from device-specific edits.
+func NewSimplifier() (Transformer, error) {
+	return &simplify{}, nil
+}
+
+// Transform simplifies the supplied spec.
+// Edits that are present in the common edits are removed from device-specific edits.
+func (s simplify) Transform(spec *specs.Spec) error {
+	if spec == nil {
+		return nil
+	}
+
+	dedupe := dedupe{}
+	if err := dedupe.Transform(spec); err != nil {
+		return err
+	}
+
+	commonEntityIDs, err := (*containerEdits)(&spec.ContainerEdits).getEntityIds()
+	if err != nil {
+		return err
+	}
+
+	toRemove := newRemover(commonEntityIDs...)
+	var updatedDevices []specs.Device
+	for _, device := range spec.Devices {
+		deviceAsSpec := specs.Spec{
+			ContainerEdits: device.ContainerEdits,
+		}
+		err := toRemove.Transform(&deviceAsSpec)
+		if err != nil {
+			return fmt.Errorf("failed to transform device edits: %w", err)
+		}
+
+		if !(containerEdits)(deviceAsSpec.ContainerEdits).IsEmpty() {
+			// Devices with empty edits are invalid.
+			// We only update the container edits for the device if this would
+			// result in a valid device.
+			device.ContainerEdits = deviceAsSpec.ContainerEdits
+		}
+		updatedDevices = append(updatedDevices, device)
+	}
+	spec.Devices = updatedDevices
+
+	return nil
+}