cpp/telemetry/script_executor/src/LuaEngine.h

/*
 * Copyright (c) 2021, The Android Open Source Project
 *
 * 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.
 */

#ifndef CPP_TELEMETRY_SCRIPT_EXECUTOR_SRC_LUAENGINE_H_
#define CPP_TELEMETRY_SCRIPT_EXECUTOR_SRC_LUAENGINE_H_

#include "ScriptExecutorListener.h"

#include <memory>

extern "C" {
#include "lua.h"
}

namespace android {
namespace automotive {
namespace telemetry {
namespace script_executor {

// Encapsulates Lua script execution environment.
class LuaEngine {
public:
    LuaEngine();

    virtual ~LuaEngine();

    // Returns pointer to Lua state object.
    lua_State* GetLuaState();

    // Loads Lua script provided as scriptBody string.
    // Returns 0 if successful. Otherwise returns non-zero Lua error code.
    int LoadScript(const char* scriptBody);

    // Pushes a Lua function under provided name into the stack.
    // Returns true if successful.
    bool PushFunction(const char* functionName);

    // Invokes function with the inputs provided in the stack.
    // Assumes that the script body has been already loaded and successully
    // compiled and run, and all input arguments, and the function have been
    // pushed to the stack.
    // Returns 0 if successful. Otherwise returns non-zero Lua error code.
    int Run();

    // Updates stored listener and destroys the previous one.
    void ResetListener(ScriptExecutorListener* listener);

private:
    lua_State* mLuaState;  // owned

    std::unique_ptr<ScriptExecutorListener> mListener;
};

}  // namespace script_executor
}  // namespace telemetry
}  // namespace automotive
}  // namespace android

#endif  // CPP_TELEMETRY_SCRIPT_EXECUTOR_SRC_LUAENGINE_H_