feat: implement copy

oras/copy/__init__.py

@@ -0,0 +1,87 @@
+"""
+ORAS Copy Engine.
+
+Provides a complete OCI content copy implementation that copies content
+DAGs between OCI targets (registries, OCI layouts, in-memory stores, etc.).
+
+This is a Python port of the copy engine from oras-go
+(https://github.com/oras-project/oras-go).
+
+Public API:
+    copy()              - Copy content between targets by reference
+    CopyOptions         - Options for the copy function
+    CopyGraphOptions    - Options for graph traversal behavior
+    SkipNode            - Sentinel to skip a node in pre_copy callbacks
+    CopyError           - Structured error with operation and origin info
+    CopyErrorOrigin     - Source or destination origin enum
+
+Content Protocols:
+    Target              - Full read/write target with tag/resolve
+    ReadOnlyTarget      - Read-only target with resolve
+    Storage             - Content-addressable read/write storage
+    ReadOnlyStorage     - Content-addressable read-only storage
+    ReferencePusher     - Atomic push with reference tag
+    ReferenceFetcher    - Fetch by reference (resolve + fetch in one call)
+    Mounter             - Cross-repo blob mounting
+
+Adapters:
+    RegistryTarget      - Adapts Registry + container to Target/ReferencePusher/Mounter
+    LayoutTarget        - Adapts Layout directory to Target (full read/write)
+"""
+
+__author__ = "The ORAS Authors"
+__copyright__ = "Copyright The ORAS Authors."
+__license__ = "Apache-2.0"
+
+from oras.copy.content import (
+    Fetcher,
+    Mounter,
+    Pusher,
+    ReadOnlyStorage,
+    ReadOnlyTarget,
+    ReferenceFetcher,
+    ReferencePusher,
+    Resolver,
+    Storage,
+    Tagger,
+    TagResolver,
+    Target,
+)
+from oras.copy.adapters import LayoutTarget, RegistryTarget
+from oras.copy.copy import copy
+from oras.copy.errors import CopyError, CopyErrorOrigin
+from oras.copy.graph import SkipNode
+from oras.copy.options import CopyGraphOptions, CopyOptions
+from oras.types import Descriptor
+
+__all__ = [
+    # Core function
+    "copy",
+    # Options
+    "CopyOptions",
+    "CopyGraphOptions",
+    # Sentinel
+    "SkipNode",
+    # Errors
+    "CopyError",
+    "CopyErrorOrigin",
+    # Types
+    "Descriptor",
+    # Content Protocols
+    "Fetcher",
+    "Pusher",
+    "Storage",
+    "ReadOnlyStorage",
+    "Resolver",
+    "Tagger",
+    "TagResolver",
+    "Target",
+    "ReadOnlyTarget",
+    # Registry Protocols
+    "ReferencePusher",
+    "ReferenceFetcher",
+    "Mounter",
+    # Adapters
+    "RegistryTarget",
+    "LayoutTarget",
+]