feat: load model from oci image

vendor/oras.land/oras-go/v2/internal/resolver/memory.go

@@ -0,0 +1,61 @@
+/*
+Copyright The ORAS Authors.
+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 resolver
+
+import (
+	"context"
+	"sync"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"oras.land/oras-go/v2/errdef"
+)
+
+// Memory is a memory based resolver.
+type Memory struct {
+	index sync.Map // map[string]ocispec.Descriptor
+}
+
+// NewMemory creates a new Memory resolver.
+func NewMemory() *Memory {
+	return &Memory{}
+}
+
+// Resolve resolves a reference to a descriptor.
+func (m *Memory) Resolve(_ context.Context, reference string) (ocispec.Descriptor, error) {
+	desc, ok := m.index.Load(reference)
+	if !ok {
+		return ocispec.Descriptor{}, errdef.ErrNotFound
+	}
+	return desc.(ocispec.Descriptor), nil
+}
+
+// Tag tags a descriptor with a reference string.
+func (m *Memory) Tag(_ context.Context, desc ocispec.Descriptor, reference string) error {
+	m.index.Store(reference, desc)
+	return nil
+}
+
+// Map dumps the memory into a built-in map structure.
+// Like other operations, calling Map() is go-routine safe. However, it does not
+// necessarily correspond to any consistent snapshot of the storage contents.
+func (m *Memory) Map() map[string]ocispec.Descriptor {
+	res := make(map[string]ocispec.Descriptor)
+	m.index.Range(func(key, value interface{}) bool {
+		res[key.(string)] = value.(ocispec.Descriptor)
+		return true
+	})
+	return res
+}