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README.md

@@ -72,3 +72,102 @@ fn mobilenetv2_mnist() -> Result<()> {
     test_mnist(&FlatBufferModel::build_from_buffer(buf)?)
 }
 ```
+
+### Using the FlatBuffers model APIs
+
+This crate also provides a limited set of FlatBuffers model APIs.
+
+```rust
+use tflite::model::stl::vector::{VectorInsert, VectorErase, VectorSlice};
+use tflite::model::{BuiltinOperator, BuiltinOptions, Model, SoftmaxOptionsT};
+
+#[test]
+fn flatbuffer_model_apis_inspect() {
+    let model = Model::from_file("data/MNISTnet_uint8_quant.tflite").unwrap();
+    assert_eq!(model.version, 3);
+    assert_eq!(model.operator_codes.size(), 5);
+    assert_eq!(model.subgraphs.size(), 1);
+    assert_eq!(model.buffers.size(), 24);
+    assert_eq!(
+        model.description.c_str().to_string_lossy(),
+        "TOCO Converted."
+    );
+
+    assert_eq!(
+        model.operator_codes[0].builtin_code,
+        BuiltinOperator::BuiltinOperator_AVERAGE_POOL_2D
+    );
+
+    assert_eq!(
+        model
+            .operator_codes
+            .iter()
+            .map(|oc| oc.builtin_code)
+            .collect::<Vec<_>>(),
+        vec![
+            BuiltinOperator::BuiltinOperator_AVERAGE_POOL_2D,
+            BuiltinOperator::BuiltinOperator_CONV_2D,
+            BuiltinOperator::BuiltinOperator_DEPTHWISE_CONV_2D,
+            BuiltinOperator::BuiltinOperator_SOFTMAX,
+            BuiltinOperator::BuiltinOperator_RESHAPE
+        ]
+    );
+
+    let subgraph = &model.subgraphs[0];
+    assert_eq!(subgraph.tensors.size(), 23);
+    assert_eq!(subgraph.operators.size(), 9);
+    assert_eq!(subgraph.inputs.as_slice(), &[22]);
+    assert_eq!(subgraph.outputs.as_slice(), &[21]);
+
+    let softmax = subgraph
+        .operators
+        .iter()
+        .position(|op| {
+            model.operator_codes[op.opcode_index as usize].builtin_code
+                == BuiltinOperator::BuiltinOperator_SOFTMAX
+        })
+        .unwrap();
+
+    assert_eq!(subgraph.operators[softmax].inputs.as_slice(), &[4]);
+    assert_eq!(subgraph.operators[softmax].outputs.as_slice(), &[21]);
+    assert_eq!(
+        subgraph.operators[softmax].builtin_options.type_,
+        BuiltinOptions::BuiltinOptions_SoftmaxOptions
+    );
+
+    let softmax_options: &SoftmaxOptionsT = subgraph.operators[softmax].builtin_options.as_ref();
+    assert_eq!(softmax_options.beta, 1.);
+}
+
+#[test]
+fn flatbuffer_model_apis_mutate() {
+    let mut model = Model::from_file("data/MNISTnet_uint8_quant.tflite").unwrap();
+    model.version = 2;
+    model.operator_codes.erase(4);
+    model.buffers.erase(22);
+    model.buffers.erase(23);
+    model
+        .description
+        .assign(CString::new("flatbuffer").unwrap());
+
+    {
+        let subgraph = &mut model.subgraphs[0];
+        subgraph.inputs.erase(0);
+        subgraph.outputs.assign(vec![1, 2, 3, 4]);
+    }
+
+    let model_buffer = model.to_buffer();
+    let model = Model::from_buffer(&model_buffer);
+    assert_eq!(model.version, 2);
+    assert_eq!(model.operator_codes.size(), 4);
+    assert_eq!(model.subgraphs.size(), 1);
+    assert_eq!(model.buffers.size(), 22);
+    assert_eq!(model.description.c_str().to_string_lossy(), "flatbuffer");
+
+    let subgraph = &model.subgraphs[0];
+    assert_eq!(subgraph.tensors.size(), 23);
+    assert_eq!(subgraph.operators.size(), 9);
+    assert!(subgraph.inputs.as_slice().is_empty());
+    assert_eq!(subgraph.outputs.as_slice(), &[1, 2, 3, 4]);
+}
+```