diff options
| -rw-r--r-- | indra/llcommon/lua_function.cpp | 87 |
1 files changed, 54 insertions, 33 deletions
diff --git a/indra/llcommon/lua_function.cpp b/indra/llcommon/lua_function.cpp index e4758d25a4..da88f57a5b 100644 --- a/indra/llcommon/lua_function.cpp +++ b/indra/llcommon/lua_function.cpp @@ -568,46 +568,67 @@ void replace_entry(lua_State* L, int index, int lua_metapairs(lua_State* L) { // pairs(obj): object is at index 1 - // discard any erroneous surplus parameters - lua_settop(L, 1); - // stack: obj + // How many args were we passed? + int args = lua_gettop(L); + // stack: obj, ... if (luaL_getmetafield(L, 1, "__iter")) { - // stack: obj, getmetatable(obj).__iter - lua_insert(L, 1); - // stack: __iter, obj - // We don't use the even nicer shorthand luaL_callmeta() because - // luaL_callmeta() only permits the metamethod to return a single - // value, and __iter() returns up to 3. Use lua_call() instead. - lua_call(L, 1, LUA_MULTRET); - // return as many values as __iter(obj) returned - return lua_gettop(L); + // stack: obj, ..., getmetatable(obj).__iter + } + else + { + // Push the original pairs() function, captured as our upvalue. + lua_pushvalue(L, lua_upvalueindex(1)); + // stack: obj, ..., original pairs() } - // otherwise, just return (next, obj) - lluau_checkstack(L, 1); - // stack: obj - lua_getglobal(L, "next"); - // stack: obj, next lua_insert(L, 1); - // stack: next, obj - return 2; + // stack: (__iter() or pairs()), obj, ... + // call whichever function(obj, ...) (args args, up to 3 return values) + lua_call(L, args, LUA_MULTRET); + // return as many values as the selected function returned + return lua_gettop(L); } int lua_metaipairs(lua_State* L) { - lua_checkdelta(L, 2); // ipairs(obj): object is at index 1 - // discard any erroneous surplus parameters - lua_settop(L, 1); - // stack: obj - lua_pushcfunction(L, lua_metaipair, "lua_metaipair"); - // stack: obj, lua_metaipair - lua_insert(L, 1); - // stack: lua_metaipair, obj - // push explicit 0 so lua_metaipair need not special-case nil - lua_pushinteger(L, 0); - // stack: lua_metaipair, obj, 0 - return 3; + // How many args were we passed? + int args = lua_gettop(L); + // stack: obj, ... + if (luaL_getmetafield(L, 1, "__index")) + { + // stack: obj, ..., getmetatable(obj).__index + // discard __index and everything but obj: + // we don't want to call __index(), just check its presence + lua_settop(L, 1); + // stack: obj + lua_pushcfunction(L, lua_metaipair, "lua_metaipair"); + // stack: obj, lua_metaipair + lua_insert(L, 1); + // stack: lua_metaipair, obj + // push explicit 0 so lua_metaipair need not special-case nil + lua_pushinteger(L, 0); + // stack: lua_metaipair, obj, 0 + return 3; + } + else // no __index() metamethod + { + // Although our lua_metaipair() function demonstrably works whether or + // not our object has an __index() metamethod, the code below assumes + // that the Lua engine may have a more efficient implementation for + // built-in ipairs() than our lua_metaipair(). + // Push the original ipairs() function, captured as our upvalue. + lua_pushvalue(L, lua_upvalueindex(1)); + // stack: obj, ..., original ipairs() + // Shift the stack so the original function is first. + lua_insert(L, 1); + // stack: original ipairs(), obj, ... + // Call original ipairs() with all original args, no error checking. + // Don't truncate however many values that function returns. + lua_call(L, args, LUA_MULTRET); + // Return as many values as the original function returned. + return lua_gettop(L); + } } int lua_metaipair(lua_State* L) @@ -624,7 +645,7 @@ int lua_metaipair(lua_State* L) lua_insert(L, 1); // stack: i, obj, i lua_gettable(L, -2); - // stack: i, obj, obj[i] + // stack: i, obj, obj[i] (honoring __index()) lua_remove(L, -2); // stack: i, obj[i] if (! lua_isnil(L, -1)) @@ -1388,7 +1409,7 @@ int setdtor_refs::meta__index(lua_State* L) return 1; } -// replacement for global next(), pairs(), ipairs(): +// replacement for global next(): // its lua_upvalueindex(1) is the original function it's replacing int lua_proxydrill(lua_State* L) { |