99 lines
3.0 KiB
C++
99 lines
3.0 KiB
C++
#define SOL_ALL_SAFETIES_ON 1
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#include <sol/sol.hpp>
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#include <iostream>
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// Simple sol2 version of the below
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void simple(sol::this_state ts, sol::this_environment te) {
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sol::state_view lua = ts;
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if (te) {
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sol::environment& env = te;
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sol::environment freshenv = lua["freshenv"];
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bool is_same_env = freshenv == env;
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std::cout << "this_environment -- env == freshenv : "
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<< is_same_env << std::endl;
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}
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std::cout << "this_environment -- no environment present"
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<< std::endl;
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}
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// NOTE:
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// THIS IS A LOW-LEVEL EXAMPLE, using pieces of sol2
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// to facilitate better usage
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// It is recommended you just do the simple version, as it is
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// basically this code but it is sometimes useful to show the
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// hoops you need to jump through to use the Lua C API
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void complicated(sol::this_state ts) {
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lua_State* L = ts;
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lua_Debug info;
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// Level 0 means current function (this C function, which is
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// useless for our purposes) Level 1 means next call frame
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// up the stack. This is probably the environment we're
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// looking for?
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int level = 1;
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int pre_stack_size = lua_gettop(L);
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if (lua_getstack(L, level, &info) != 1) {
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// failure: call it quits
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std::cout << "error: unable to traverse the stack"
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<< std::endl;
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lua_settop(L, pre_stack_size);
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return;
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}
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// the "f" identifier is the most important here
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// it pushes the function running at `level` onto the stack:
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// we can get the environment from this
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// the rest is for printing / debugging purposes
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if (lua_getinfo(L, "fnluS", &info) == 0) {
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// failure?
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std::cout << "manually -- error: unable to get stack "
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"information"
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<< std::endl;
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lua_settop(L, pre_stack_size);
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return;
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}
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// Okay, so all the calls worked.
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// Print out some information about this "level"
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std::cout << "manually -- [" << level << "] "
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<< info.short_src << ":" << info.currentline
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<< " -- " << (info.name ? info.name : "<unknown>")
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<< "[" << info.what << "]" << std::endl;
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// Grab the function off the top of the stack
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// remember: -1 means top, -2 means 1 below the top, and so
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// on... 1 means the very bottom of the stack, 2 means 1
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// more up, and so on to the top value...
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sol::function f(L, -1);
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// The environment can now be ripped out of the function
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sol::environment env(sol::env_key, f);
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if (!env.valid()) {
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std::cout << "manually -- error: no environment to get"
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<< std::endl;
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lua_settop(L, pre_stack_size);
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return;
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}
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sol::state_view lua(L);
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sol::environment freshenv = lua["freshenv"];
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bool is_same_env = freshenv == env;
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std::cout << "manually -- env == freshenv : " << is_same_env
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<< std::endl;
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}
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int main() {
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std::cout << "=== environment snooping ===" << std::endl;
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sol::state lua;
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sol::environment freshenv(lua, sol::create, lua.globals());
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lua["freshenv"] = freshenv;
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lua.set_function("f", simple);
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lua.set_function("g", complicated);
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lua.script("f()", freshenv);
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lua.script("g()", freshenv);
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std::cout << std::endl;
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return 0;
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}
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