Implement Python language binding (#1192) (#1195)

Implement the first version of Python language binding

Co-authored-by: liang.he <liang.he@intel.com>

language-bindings/python/samples/hello_procedural.py

@@ -0,0 +1,93 @@
+# -*- coding: utf-8 -*-
+#!/usr/bin/env python3
+#
+# Copyright (C) 2019 Intel Corporation.  All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+import ctypes
+import wamr.ffi as ffi
+
+WAMS_BINARY_CONTENT = (
+    b"\x00asm\x01\x00\x00\x00\x01\x84\x80\x80\x80\x00\x01`\x00\x00\x02\x8a\x80"
+    b"\x80\x80\x00\x01\x00\x05hello\x00\x00\x03\x82\x80\x80\x80\x00\x01\x00"
+    b"\x07\x87\x80\x80\x80\x00\x01\x03run\x00\x01\n\x8a\x80\x80\x80\x00\x01"
+    b"\x84\x80\x80\x80\x00\x00\x10\x00\x0b"
+)
+
+
+@ffi.wasm_func_cb_decl
+def hello_callback(args, results):
+    print("Calling back...")
+    print("> Hello World!")
+
+
+def main():
+    print("Initializing...")
+    engine = ffi.wasm_engine_new()
+    store = ffi.wasm_store_new(engine)
+
+    print("Loading binary...")
+
+    # for convenience, use binary content instead of open file
+    # with open("./hello.wasm", "rb") as f:
+    #     wasm = f.read()
+    wasm = WAMS_BINARY_CONTENT
+    binary = ffi.wasm_byte_vec_t()
+    ffi.wasm_byte_vec_new_uninitialized(binary, len(wasm))
+    # underlying buffer is not writable
+    binary.data = (ctypes.c_ubyte * len(wasm)).from_buffer_copy(wasm)
+
+    print("Compiling module...")
+    module = ffi.wasm_module_new(store, binary)
+    if not module:
+        raise RuntimeError("Compiling module failed")
+
+    binary.data = None
+    ffi.wasm_byte_vec_delete(binary)
+
+    print("Creating callback...")
+    hello_type = ffi.wasm_functype_new_0_0()
+    hello_func = ffi.wasm_func_new(
+        store,
+        hello_type,
+        hello_callback,
+    )
+
+    ffi.wasm_functype_delete(hello_type)
+
+    print("Instantiating module...")
+
+    imports = ffi.wasm_extern_vec_t()
+    ffi.wasm_extern_vec_new((imports), 1, ffi.wasm_func_as_extern(hello_func))
+    instance = ffi.wasm_instance_new(store, module, imports, None)
+
+    ffi.wasm_func_delete(hello_func)
+
+    print("Extracting export...")
+    exports = ffi.wasm_extern_vec_t()
+    ffi.wasm_instance_exports(instance, exports)
+
+    run_func = ffi.wasm_extern_as_func(exports.data[0])
+    if not run_func:
+        raise RuntimeError("can not extract exported function")
+
+    ffi.wasm_instance_delete(instance)
+    ffi.wasm_module_delete(module)
+
+    print("Calling export...")
+    args = ffi.wasm_val_vec_t()
+    results = ffi.wasm_val_vec_t()
+
+    ffi.wasm_val_vec_new_empty(args)
+    ffi.wasm_val_vec_new_empty(results)
+    ffi.wasm_func_call(run_func, args, results)
+
+    print("Shutting down...")
+    ffi.wasm_store_delete(store)
+    ffi.wasm_engine_delete(engine)
+
+    print("Done.")
+
+
+if __name__ == "__main__":
+    main()