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/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#include "property.hpp"
#include <memory>
#include <string>
#include "lua.h"
#include "lua.hpp"
#include "lvgl.h"
#include "service_locator.hpp"
namespace lua {
static const char kMetatableName[] = "property";
static const char kBindingsTable[] = "bindings";
static auto check_property(lua_State* state) -> Property* {
void* data = luaL_checkudata(state, 1, kMetatableName);
luaL_argcheck(state, data != NULL, 1, "`property` expected");
return *reinterpret_cast<Property**>(data);
}
static auto property_get(lua_State* state) -> int {
Property* p = check_property(state);
p->PushValue(*state);
return 1;
}
static auto property_set(lua_State* state) -> int {
Property* p = check_property(state);
luaL_argcheck(state, p->IsTwoWay(), 1, "property is read-only");
bool valid = p->PopValue(*state);
lua_pushboolean(state, valid);
return 1;
}
static auto property_bind(lua_State* state) -> int {
Property* p = check_property(state);
luaL_checktype(state, 2, LUA_TFUNCTION);
// Copy the function, as we need to invoke it then store our reference.
lua_pushvalue(state, 2);
// ...and another copy, since we return the original closure.
lua_pushvalue(state, 2);
// FIXME: This should ideally be lua_pcall, for safety.
p->PushValue(*state);
lua_call(state, 1, 0); // Invoke the initial binding.
lua_pushstring(state, kBindingsTable);
lua_gettable(state, LUA_REGISTRYINDEX); // REGISTRY[kBindingsTable]
lua_insert(state, -2); // Move bindings to the bottom, with fn above.
int ref = luaL_ref(state, -2); // bindings[ref] = fn
p->AddLuaBinding(state, ref);
// Pop the bindings table, leaving one of the copiesw of the callback fn at
// the top of the stack.
lua_pop(state, 1);
return 1;
}
static const struct luaL_Reg kPropertyBindingFuncs[] = {{"get", property_get},
{"set", property_set},
{"bind", property_bind},
{NULL, NULL}};
PropertyBindings::PropertyBindings(lua_State& s) {
// Create the metatable responsible for the Property API.
luaL_newmetatable(&s, kMetatableName);
lua_pushliteral(&s, "__index");
lua_pushvalue(&s, -2);
lua_settable(&s, -3); // metatable.__index = metatable
// Add our binding funcs (get, set, bind) to the metatable.
luaL_setfuncs(&s, kPropertyBindingFuncs, 0);
// Create a weak table in the registry to hold live bindings.
lua_pushstring(&s, kBindingsTable);
lua_newtable(&s); // bindings = {}
// Metatable for the weak table. Values are weak.
lua_newtable(&s); // meta = {}
lua_pushliteral(&s, "__mode");
lua_pushliteral(&s, "v");
lua_settable(&s, -3); // meta.__mode='v'
lua_setmetatable(&s, -2); // setmetatable(bindings, meta)
lua_settable(&s, LUA_REGISTRYINDEX); // REGISTRY[kBindingsTable] = bindings
}
auto PropertyBindings::Register(lua_State* s, Property* prop) -> void {
Property** data =
reinterpret_cast<Property**>(lua_newuserdata(s, sizeof(Property*)));
*data = prop;
luaL_setmetatable(s, kMetatableName);
}
template <class... Ts>
inline constexpr bool always_false_v = false;
Property::Property(const LuaValue& val) : value_(val), cb_() {}
Property::Property(const LuaValue& val,
std::function<bool(const LuaValue& val)> cb)
: value_(val), cb_(cb) {}
auto Property::PushValue(lua_State& s) -> int {
std::visit(
[&](auto&& arg) {
using T = std::decay_t<decltype(arg)>;
if constexpr (std::is_same_v<T, std::monostate>) {
lua_pushnil(&s);
} else if constexpr (std::is_same_v<T, int>) {
lua_pushinteger(&s, arg);
} else if constexpr (std::is_same_v<T, float>) {
lua_pushnumber(&s, arg);
} else if constexpr (std::is_same_v<T, bool>) {
lua_pushboolean(&s, arg);
} else if constexpr (std::is_same_v<T, std::string>) {
lua_pushstring(&s, arg.c_str());
} else {
static_assert(always_false_v<T>, "PushValue missing type");
}
},
value_);
return 1;
}
auto Property::PopValue(lua_State& s) -> bool {
LuaValue new_val;
switch (lua_type(&s, 2)) {
case LUA_TNIL:
new_val = std::monostate{};
break;
case LUA_TNUMBER:
if (lua_isinteger(&s, 2)) {
new_val = lua_tointeger(&s, 2);
} else {
new_val = lua_tonumber(&s, 2);
}
break;
case LUA_TBOOLEAN:
new_val = lua_toboolean(&s, 2);
break;
case LUA_TSTRING:
new_val = lua_tostring(&s, 2);
break;
default:
return false;
}
if (cb_ && std::invoke(*cb_, new_val)) {
Update(new_val);
return true;
}
return false;
}
auto Property::Update(const LuaValue& v) -> void {
value_ = v;
for (int i = bindings_.size() - 1; i >= 0; i--) {
auto& b = bindings_[i];
lua_pushstring(b.first, kBindingsTable);
lua_gettable(b.first, LUA_REGISTRYINDEX); // REGISTRY[kBindingsTable]
int type = lua_rawgeti(b.first, -1, b.second); // push bindings[i]
// Has closure has been GCed?
if (type == LUA_TNIL) {
// Clean up after ourselves.
lua_pop(b.first, 1);
// Remove the binding.
bindings_.erase(bindings_.begin() + i);
continue;
}
PushValue(*b.first); // push the argument
lua_call(b.first, 1, 0); // invoke the closure
}
}
auto Property::AddLuaBinding(lua_State* state, int ref) -> void {
bindings_.push_back({state, ref});
}
} // namespace lua
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