[executorch][core] NamedDataMap interface

Add NamedDataMap interface to runtime.

Differential Revision: [D66834552](https://our.internmc.facebook.com/intern/diff/D66834552/)

[ghstack-poisoned]

Author: lucylq

runtime/core/named_data_map.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <executorch/runtime/core/exec_aten/exec_aten.h>
+#include <executorch/runtime/core/freeable_buffer.h>
+#include <executorch/runtime/core/result.h>
+#include <executorch/runtime/core/span.h>
+#include <executorch/runtime/core/tensor_layout.h>
+#include <executorch/runtime/platform/compiler.h>
+
+namespace executorch {
+namespace runtime {
+
+/**
+ * Interface to access and retrieve data via name from a loaded data file.
+ * See executorch/extension/flat_tensor/ for an example.
+ */
+class NamedDataMap {
+ public:
+  virtual ~NamedDataMap() = default;
+  /**
+   * Get tensor metadata by fully qualified name (FQN).
+   *
+   * @param fqn Fully qualified name of the tensor.
+   * @return Result containing a pointer to the metadata.
+   */
+  ET_NODISCARD virtual Result<const executorch::runtime::TensorLayout>
+  get_metadata(const char* fqn) const = 0;
+  /**
+   * Get tensor data by fully qualified name (FQN).
+   *
+   * @param fqn Fully qualified name of the tensor.
+   * @return Result containing a span of uint8_t representing the tensor data.
+   */
+  ET_NODISCARD virtual Result<Span<const uint8_t>> get_data(
+      const char* fqn) const = 0;
+};
+
+} // namespace runtime
+} // namespace executorch

runtime/core/targets.bzl

@@ -32,6 +32,7 @@ def define_common_targets():
             "data_loader.h",
             "error.h",
             "freeable_buffer.h",
+            "named_data_map.h",
             "result.h",
             "span.h",
             "tensor_layout.h",