Lua与C\C++语言的交互-C调用Lua

最新推荐文章于 2024-10-02 18:09:17 发布

原创

最新推荐文章于 2024-10-02 18:09:17 发布 · 629 阅读

1 ·

CC 4.0 BY-SA版权

文章标签：

#Lua源码编译 #lua交互

本文介绍了如何在C语言中与Lua进行交互，包括获取和设置Lua全局变量、调用Lua函数以及操作Lua Table。通过理解Lua的虚拟堆栈工作原理，确保了C代码能正确地与Lua交互。

前言

首先需要明白的是 C与 Lua 的虚拟堆栈。
引用 Lua 官方的解释：

The Stack

Lua uses a virtual stack to pass values to and from C. Each element in this stack represents a Lua value (nil, number, string, etc.).
Whenever Lua calls C, the called function gets a new stack, which is independent of previous stacks and of stacks of C functions that are still active. This stack initially contains any arguments to the C function and it is where the C function pushes its results to be returned to the caller (see lua_CFunction).
For convenience, most query operations in the API do not follow a strict stack discipline. Instead, they can refer to any element in the stack by using an index: A positive index represents an absolute stack position (starting at 1); a negative index represents an offset relative to the top of the stack. More specifically, if the stack has n elements, then index 1 represents the first element (that is, the element that was pushed onto the stack first) and index n represents the last element; index -1 also represents the last element (that is, the element at the top) and index -n represents the first element.

Stack Size

When you interact with the Lua API, you are responsible for ensuring consistency. In particular, you are responsible for controlling stack overflow. You can use the function lua_checkstack to ensure that the stack has extra slots when pushing new elements.
Whenever Lua calls C, it ensures that the stack has at least LUA_MINSTACK extra slots. LUA_MINSTACK is defined as 20, so that usually you do not have to worry about stack space unless your code has loops pushing elements onto the stack.
When you call a Lua function without a fixed number of results (see lua_call), Lua ensures that the stack has enough size for all results, but it does not ensure any extra space. So, before pushing anything in the stack after such a call you should use lua_checkstack.