224 lines
6.2 KiB
Rust
224 lines
6.2 KiB
Rust
//! (De)Serialization support using serde.
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use std::os::raw::c_void;
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use std::ptr;
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use serde::{Deserialize, Serialize};
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use crate::error::Result;
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use crate::ffi;
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use crate::lua::Lua;
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use crate::table::Table;
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use crate::types::LightUserData;
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use crate::util::{assert_stack, StackGuard};
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use crate::value::Value;
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pub trait LuaSerdeExt<'lua> {
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/// A special value (lightuserdata) to encode/decode optional (none) values.
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///
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/// Requires `feature = "serialize"`
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///
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/// # Example
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///
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/// ```
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/// use std::collections::HashMap;
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/// use mlua::{Lua, Result, LuaSerdeExt};
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///
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/// fn main() -> Result<()> {
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/// let lua = Lua::new();
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/// lua.globals().set("null", lua.null())?;
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///
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/// let val = lua.load(r#"{a = null}"#).eval()?;
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/// let map: HashMap<String, Option<String>> = lua.from_value(val)?;
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/// assert_eq!(map["a"], None);
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///
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/// Ok(())
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/// }
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/// ```
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fn null(&'lua self) -> Value<'lua>;
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/// A metatable attachable to a Lua table to systematically encode it as Array (instead of Map).
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/// As result, encoded Array will contain only sequence part of the table, with the same length
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/// as the `#` operator on that table.
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///
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/// Requires `feature = "serialize"`
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///
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/// # Example
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///
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/// ```
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/// use mlua::{Lua, Result, LuaSerdeExt};
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/// use serde_json::Value as JsonValue;
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///
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/// fn main() -> Result<()> {
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/// let lua = Lua::new();
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/// lua.globals().set("array_mt", lua.array_metatable())?;
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///
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/// // Encode as an empty array (no sequence part in the lua table)
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/// let val = lua.load("setmetatable({a = 5}, array_mt)").eval()?;
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/// let j: JsonValue = lua.from_value(val)?;
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/// assert_eq!(j.to_string(), "[]");
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///
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/// // Encode as object
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/// let val = lua.load("{a = 5}").eval()?;
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/// let j: JsonValue = lua.from_value(val)?;
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/// assert_eq!(j.to_string(), r#"{"a":5}"#);
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///
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/// Ok(())
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/// }
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/// ```
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fn array_metatable(&'lua self) -> Table<'lua>;
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/// Converts `T` into a `Value` instance.
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///
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/// Requires `feature = "serialize"`
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///
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/// [`Value`]: enum.Value.html
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///
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/// # Example
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///
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/// ```
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/// use mlua::{Lua, Result, LuaSerdeExt};
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/// use serde::Serialize;
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///
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/// #[derive(Serialize)]
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/// struct User {
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/// name: String,
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/// age: u8,
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/// }
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///
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/// fn main() -> Result<()> {
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/// let lua = Lua::new();
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/// let u = User {
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/// name: "John Smith".into(),
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/// age: 20,
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/// };
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/// lua.globals().set("user", lua.to_value(&u)?)?;
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/// lua.load(r#"
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/// assert(user["name"] == "John Smith")
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/// assert(user["age"] == 20)
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/// "#).exec()
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/// }
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/// ```
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fn to_value<T: Serialize + ?Sized>(&'lua self, t: &T) -> Result<Value<'lua>>;
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/// Converts `T` into a `Value` instance with options.
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///
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/// Requires `feature = "serialize"`
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///
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/// [`Value`]: enum.Value.html
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///
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/// # Example
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///
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/// ```
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/// use mlua::{Lua, Result, LuaSerdeExt, SerializeOptions};
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///
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/// fn main() -> Result<()> {
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/// let lua = Lua::new();
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/// let v = vec![1, 2, 3];
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/// lua.globals().set("v", lua.to_value_with(&v, SerializeOptions {
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/// set_array_metatable: false,
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/// ..SerializeOptions::default()
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/// })?)?;
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///
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/// lua.load(r#"
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/// assert(#v == 3 and v[1] == 1 and v[2] == 2 and v[3] == 3)
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/// assert(getmetatable(v) == nil)
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/// "#).exec()
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/// }
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/// ```
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fn to_value_with<T>(&'lua self, t: &T, options: ser::Options) -> Result<Value<'lua>>
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where
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T: Serialize + ?Sized;
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/// Deserializes a `Value` into any serde deserializable object.
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///
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/// Requires `feature = "serialize"`
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///
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/// [`Value`]: enum.Value.html
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///
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/// # Example
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///
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/// ```
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/// use mlua::{Lua, Result, LuaSerdeExt};
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/// use serde::Deserialize;
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///
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/// #[derive(Deserialize, Debug, PartialEq)]
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/// struct User {
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/// name: String,
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/// age: u8,
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/// }
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///
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/// fn main() -> Result<()> {
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/// let lua = Lua::new();
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/// let val = lua.load(r#"{name = "John Smith", age = 20}"#).eval()?;
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/// let u: User = lua.from_value(val)?;
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///
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/// assert_eq!(u, User { name: "John Smith".into(), age: 20 });
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///
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/// Ok(())
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/// }
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/// ```
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fn from_value<T: Deserialize<'lua>>(&'lua self, value: Value<'lua>) -> Result<T>;
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}
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impl<'lua> LuaSerdeExt<'lua> for Lua {
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fn null(&'lua self) -> Value<'lua> {
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Value::LightUserData(LightUserData(ptr::null_mut()))
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}
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fn array_metatable(&'lua self) -> Table<'lua> {
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unsafe {
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let _sg = StackGuard::new(self.state);
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assert_stack(self.state, 1);
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push_array_metatable(self.state);
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Table(self.pop_ref())
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}
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}
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fn to_value<T>(&'lua self, t: &T) -> Result<Value<'lua>>
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where
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T: Serialize + ?Sized,
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{
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t.serialize(ser::Serializer::new(self))
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}
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fn to_value_with<T>(&'lua self, t: &T, options: ser::Options) -> Result<Value<'lua>>
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where
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T: Serialize + ?Sized,
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{
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t.serialize(ser::Serializer::new_with_options(self, options))
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}
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fn from_value<T>(&'lua self, value: Value<'lua>) -> Result<T>
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where
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T: Deserialize<'lua>,
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{
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T::deserialize(de::Deserializer(value))
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}
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}
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pub(crate) unsafe fn init_metatables(state: *mut ffi::lua_State) -> Result<()> {
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ffi::lua_pushlightuserdata(
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state,
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&ARRAY_METATABLE_REGISTRY_KEY as *const u8 as *mut c_void,
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);
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ffi::safe::lua_createtable(state, 0, 1)?;
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ffi::lua_pushboolean(state, 0);
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ffi::safe::lua_rawsetfield(state, -2, "__metatable")?;
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ffi::safe::lua_rawset(state, ffi::LUA_REGISTRYINDEX)
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}
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pub(crate) unsafe fn push_array_metatable(state: *mut ffi::lua_State) {
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let key = &ARRAY_METATABLE_REGISTRY_KEY as *const u8 as *mut c_void;
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ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, key);
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}
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static ARRAY_METATABLE_REGISTRY_KEY: u8 = 0;
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pub mod de;
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pub mod ser;
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