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use std::os::raw::c_int;
use std::ptr;
use crate::error::{Error, Result};
use crate::ffi;
use crate::types::LuaRef;
use crate::util::{
assert_stack, check_stack, error_traceback, pop_error, protect_lua_closure, StackGuard,
};
use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
/// Handle to an internal Lua function.
#[derive(Clone, Debug)]
pub struct Function<'lua>(pub(crate) LuaRef<'lua>);
impl<'lua> Function<'lua> {
/// Calls the function, passing `args` as function arguments.
///
/// The function's return values are converted to the generic type `R`.
///
/// # Examples
///
/// Call Lua's built-in `tostring` function:
///
/// ```
/// # use rlua::{Lua, Function, Result};
/// # fn main() -> Result<()> {
/// let lua = Lua::new();
/// let globals = lua.globals();
///
/// let tostring: Function = globals.get("tostring")?;
///
/// assert_eq!(tostring.call::<_, String>(123)?, "123");
///
/// # Ok(())
/// # }
/// ```
///
/// Call a function with multiple arguments:
///
/// ```
/// # use rlua::{Lua, Function, Result};
/// # fn main() -> Result<()> {
/// let lua = Lua::new();
///
/// let sum: Function = lua.load(
/// r#"
/// function(a, b)
/// return a + b
/// end
/// "#).eval()?;
///
/// assert_eq!(sum.call::<_, u32>((3, 4))?, 3 + 4);
///
/// # Ok(())
/// # }
/// ```
pub fn call<A: ToLuaMulti<'lua>, R: FromLuaMulti<'lua>>(&self, args: A) -> Result<R> {
let lua = self.0.lua;
let args = args.to_lua_multi(lua)?;
let nargs = args.len() as c_int;
let results = unsafe {
let _sg = StackGuard::new(lua.state);
check_stack(lua.state, nargs + 3)?;
ffi::lua_pushcfunction(lua.state, error_traceback);
let stack_start = ffi::lua_gettop(lua.state);
lua.push_ref(&self.0);
for arg in args {
lua.push_value(arg)?;
}
let ret = ffi::lua_pcall(lua.state, nargs, ffi::LUA_MULTRET, stack_start);
if ret != ffi::LUA_OK {
return Err(pop_error(lua.state, ret));
}
let nresults = ffi::lua_gettop(lua.state) - stack_start;
let mut results = MultiValue::new();
assert_stack(lua.state, 2);
for _ in 0..nresults {
results.push_front(lua.pop_value());
}
ffi::lua_pop(lua.state, 1);
results
};
R::from_lua_multi(results, lua)
}
/// Returns a function that, when called, calls `self`, passing `args` as the first set of
/// arguments.
///
/// If any arguments are passed to the returned function, they will be passed after `args`.
///
/// # Examples
///
/// ```
/// # use rlua::{Lua, Function, Result};
/// # fn main() -> Result<()> {
/// let lua = Lua::new();
///
/// let sum: Function = lua_context.load(r#"
/// function(a, b)
/// return a + b
/// end
/// "#).eval()?;
///
/// let bound_a = sum.bind(1)?;
/// assert_eq!(bound_a.call::<_, u32>(2)?, 1 + 2);
///
/// let bound_a_and_b = sum.bind(13)?.bind(57)?;
/// assert_eq!(bound_a_and_b.call::<_, u32>(())?, 13 + 57);
///
/// # Ok(())
/// # }
/// ```
pub fn bind<A: ToLuaMulti<'lua>>(&self, args: A) -> Result<Function<'lua>> {
unsafe extern "C" fn bind_call_impl(state: *mut ffi::lua_State) -> c_int {
let nargs = ffi::lua_gettop(state);
let nbinds = ffi::lua_tointeger(state, ffi::lua_upvalueindex(2)) as c_int;
ffi::luaL_checkstack(state, nbinds + 2, ptr::null());
ffi::lua_settop(state, nargs + nbinds + 1);
ffi::lua_rotate(state, -(nargs + nbinds + 1), nbinds + 1);
ffi::lua_pushvalue(state, ffi::lua_upvalueindex(1));
ffi::lua_replace(state, 1);
for i in 0..nbinds {
ffi::lua_pushvalue(state, ffi::lua_upvalueindex(i + 3));
ffi::lua_replace(state, i + 2);
}
ffi::lua_call(state, nargs + nbinds, ffi::LUA_MULTRET);
ffi::lua_gettop(state)
}
let lua = self.0.lua;
let args = args.to_lua_multi(lua)?;
let nargs = args.len() as c_int;
if nargs + 2 > ffi::LUA_MAX_UPVALUES {
return Err(Error::BindError);
}
unsafe {
let _sg = StackGuard::new(lua.state);
check_stack(lua.state, nargs + 5)?;
lua.push_ref(&self.0);
ffi::lua_pushinteger(lua.state, nargs as ffi::lua_Integer);
for arg in args {
lua.push_value(arg)?;
}
protect_lua_closure(lua.state, nargs + 2, 1, |state| {
ffi::lua_pushcclosure(state, bind_call_impl, nargs + 2);
})?;
Ok(Function(lua.pop_ref()))
}
}
}
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