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Make pairs and ipairs call the appropriate metamethods when present

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As is done in Lua 5.2. This makes it possible to use ipairs on the
subtitles object.
This commit is contained in:
Thomas Goyne 2013-05-01 18:26:05 -07:00
parent a6f7375427
commit 995e0d85e9
1 changed files with 48 additions and 0 deletions
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48
aegisub/src/auto4_lua.cpp
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@ -149,6 +149,48 @@ namespace {
set_field(L, "set", clipboard_set);
return 1;
}
struct table_pairs {
static void init(lua_State *L) { lua_pushnil(L); }
static int next(lua_State *L) {
luaL_checktype(L, 1, LUA_TTABLE);
lua_settop(L, 2);
if (lua_next(L, 1))
return 2;
lua_pushnil(L);
return 1;
}
static const char *method() { return "__pairs"; }
};
struct table_ipairs {
static void init(lua_State *L) { push_value(L, 1); }
static int next(lua_State *L) {
luaL_checktype(L, 1, LUA_TTABLE);
int i = luaL_checkint(L, 2) + 1;
lua_pushinteger(L, i);
lua_rawgeti(L, 1, i);
return lua_isnil(L, -1) ? 1 : 2;
}
static const char *method() { return "__ipairs"; }
};
template<typename TableIter>
int pairs(lua_State *L) {
// If the metamethod is defined, call it instead
if (luaL_getmetafield(L, 1, TableIter::method())) {
lua_pushvalue(L, 1);
lua_call(L, 1, 3);
return 3;
}
// No metamethod, so use the table iterators
luaL_checktype(L, 1, LUA_TTABLE);
lua_pushcfunction(L, &TableIter::next);
lua_pushvalue(L, 1);
TableIter::init(L);
return 3;
}
}
namespace Automation4 {
@ -194,6 +236,12 @@ namespace Automation4 {
push_value(L, LuaInclude);
lua_setglobal(L, "include");
// replace pairs and ipairs with lua 5.2-style versions
push_value(L, &pairs<table_pairs>);
lua_setglobal(L, "pairs");
push_value(L, &pairs<table_ipairs>);
lua_setglobal(L, "ipairs");
// add include_path to the module load path
lua_getglobal(L, "package");
push_value(L, "path");