用LUA扩展cpp程序的几个测试

Lua提供的很多特性（垃圾收集，高效的字符串处理，便捷的开发）都是很吸引人的，能够把C中复杂的业务逻辑剥离到LUA脚本中处理的话会方便不少。下面做的几组测试示例分别展示了C语言如何调用Lua脚本，调用Lua函数以及Lua脚本如何调用C中自定义函数。

测试一：最经典的Hello World

main.cpp

extern "C" { 
	#include "lua.h"
	#include "lualib.h"
	#include "luaconf.h"
	#include "lauxlib.h"
}

int main(void)
{
	//create a new lua state
	lua_State *L = luaL_newstate();
	//open all standard lua libraries into given state
	luaL_openlibs(L);
	//load and run the given file
	luaL_dofile(L, "test.lua");
	//destroy all objects in the given lua state
	lua_close(L);

	return 0;
}

test.lua

print("Hello world")

测试二：从Lua脚本获取width和height的值

main.cpp

extern "C" { 
	#include "lua.h"
	#include "lualib.h"
	#include "luaconf.h"
	#include "lauxlib.h"
}

int main(void)
{
	int width,height;

	lua_State *L = luaL_newstate();

	//to have access to certain libraries
	luaopen_base(L);
	luaopen_io(L);
	luaopen_string(L);

	//load the given file and run it as a function
	if (luaL_loadfile(L, "test.lua") || lua_pcall(L, 0, 0, 0))
	{
		luaL_error(L, "cannot run configuration file: %s",lua_tostring(L, -1));
	}

	//pushes onto the stack the value of the global variables
	lua_getglobal(L, "width");
	lua_getglobal(L, "height");

	if(!lua_isnumber(L, -2))
		luaL_error(L, "'width' should be a number\n");

	if(!lua_isnumber(L, -1))
		luaL_error(L, "'height' should be a number\n");
	width = (int)lua_tonumber(L, -2);
	height = (int)lua_tonumber(L, -1);

	printf("width is %d , height is %d\n", width, height);

	lua_close(L);

	return 0;
}

test.lua

width = 200
height = 300

测试三：调用Lua函数实现两个数相加

main.cpp

extern "C" { 
	#include "lua.h"
	#include "lualib.h"
	#include "luaconf.h"
	#include "lauxlib.h"
}

int main(void)
{
	int x = 3, y = 4, z;

	lua_State *L = luaL_newstate();

	luaopen_base(L);
	luaopen_io(L);
	luaopen_string(L);

	if (luaL_loadfile(L, "test.lua") || lua_pcall(L, 0, 0, 0))
	{
		luaL_error(L, "cannot load lua file: %s",lua_tostring(L, -1));
	}

	//push function and arguments
	lua_getglobal(L, "add");
	lua_pushnumber(L, x);
	lua_pushnumber(L, y);

	//call function
	if (lua_pcall(L, 2, 1, 0) != 0)
		luaL_error(L, "error running function add\n");

	//get result
	if(!lua_isnumber(L, -1))
		luaL_error(L, "function should return a number\n");
	z = lua_tonumber(L, -1);

	printf("x + y = %d\n", z);

	lua_close(L);

	return 0;
}

test.lua

function add(x, y)
	return x + y
end

测试四：调用Lua函数实现字符串截取前六位

main.cpp

extern "C" { 
	#include "lua.h"
	#include "lualib.h"
	#include "luaconf.h"
	#include "lauxlib.h"
}

int main(void)
{
	char *str = "Hello World";
	char *substr;

	lua_State *L = luaL_newstate();

	luaL_openlibs(L);

	if (luaL_loadfile(L, "test.lua") || lua_pcall(L, 0, 0, 0))
	{
		luaL_error(L, "cannot load lua file: %s",lua_tostring(L, -1));
	}

	//push function and arguments
	lua_getglobal(L, "substr5");
	lua_pushstring(L, str);

	//call function
	if (lua_pcall(L, 1, 1, 0) != 0)
		luaL_error(L, "error running function substr5. %s\n", lua_tostring(L, -1));

	substr = (char *)lua_tostring(L, -1);

	printf("substring of '%s' is %s\n", str, substr);

	lua_close(L);

	return 0;
}

test.lua

function substr5(str)
	return string.sub(str,0,5)
end

测试五：Lua中调用自定义C函数实现计算sin值

main.cpp

extern "C" { 
	#include "lua.h"
	#include "lualib.h"
	#include "luaconf.h"
	#include "lauxlib.h"
}

#include<math.h>

static int l_sin (lua_State *L){
	//get arguments
	double d = lua_tonumber(L, 1);
	//push results
	lua_pushnumber(L, sin(d));
	//number of results
	return 1;
}

int main(void)
{
	char *str = "Hello World";
	char *substr;

	lua_State *L = luaL_newstate();

	luaL_openlibs(L);

	//push function and set it to global varaible
	lua_pushcfunction(L, l_sin);
	lua_setglobal(L, "mysin");

	if (luaL_loadfile(L, "test.lua") || lua_pcall(L, 0, 0, 0))
	{
		luaL_error(L, "cannot load lua file: %s",lua_tostring(L, -1));
	}

	lua_close(L);

	return 0;
}

test.lua

print(mysin(1))

Lua和C两者互相的调用是通过相同类型的栈来传递函数名，参数，返回值的，简单易用。

项目的环境和示例程序可在http://dl.dbank.com/c0djezo1b6这里下载得到