Lua之实现一个bool数组

参考《Lua程序设计》第28章 用户自定义类型

#include <stdlib.h>#include <limits.h>#include "lua.h"#include "lauxlib.h"#define BITS_PER_WORD (CHAR_BIT*sizeof(unsigned int))#define I_WORD(n) ((n-1+BITS_PER_WORD)/BITS_PER_WORD)#define I_MASK(n) (1<<((n-1)%BITS_PER_WORD))typedef struct BoolArray {    int size;    unsigned int value[0];} BoolArray;static int newArray(lua_State *L){    int n = luaL_checkint(L, 1);    luaL_argcheck(L, n>0, 1, "invalid size");    int nbytes = sizeof(int) + sizeof(unsigned int)*I_WORD(n);    BoolArray *b = (BoolArray*)lua_newuserdata(L, nbytes);    b->size = n;    int i=0;    for(; i<I_WORD(n); ++i)        b->value[i] = 0;    luaL_getmetatable(L, "ba.meta");    lua_setmetatable(L, -2);//将创建的userdata的metatable设为栈顶的ba.meta    return 1;}static int setArray(lua_State *L){    BoolArray *b = (BoolArray*)luaL_checkudata(L, 1, "ba.meta");    int index = luaL_checkint(L, 2);    luaL_argcheck(L, index>0 && index<=b->size, 1, "index out of range");    if(lua_toboolean(L, 3))        b->value[I_WORD(index)] |= I_MASK(index);    else        b->value[I_WORD(index)] &= ~I_MASK(index);    return 0;}static int getArray(lua_State *L){    BoolArray *b = (BoolArray*)luaL_checkudata(L, 1, "ba.meta");    int index = luaL_checkint(L, 2);    luaL_argcheck(L, index>0 && index<=b->size, 1, "index out of range");    lua_pushboolean(L, b->value[I_WORD(index)] & I_MASK(index));    return 1;}static int getSize(lua_State *L){    BoolArray *b = (BoolArray*)luaL_checkudata(L, 1, "ba.meta");    lua_pushinteger(L, b->size);    return 1;}static const luaL_Reg lib[] = {    {"new", newArray},    {NULL, NULL}};static const luaL_Reg lib_m[] = {    {"size", getSize},    {"set", setArray},    {"get", getArray},    {NULL, NULL}};LUA_API int luaopen_boolarray (lua_State *L) {    luaL_newmetatable(L, "ba.meta");//创建一个metatable    lua_pushvalue(L, -1);//复制它    lua_setfield(L, -2, "__index");//将它的__index指向它自己    luaL_register(L, NULL, lib_m);//为栈顶的table添加一些成员    luaL_register(L, "boolarray", lib);//创建名为boolarray的table,并为其添加一个new成员    return 1;}

编译
gcc -fpic -shared boolarray.c -o boolarray.so

测试

require "boolarray"m=boolarray.new(4)print(m:size())m:set(3,true)m:set(2,false)print(m:get(1))print(m:get(2))print(m:get(3))print(m:get(4))