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use {
crate::{
attr::MethodOrFunction,
builder::{builder_for_fields, builder_for_functions},
shared::remove_ty_from_generics,
},
proc_macro2::{Span, TokenStream as TokenStream2},
quote::{ToTokens, quote},
std::iter::repeat_with,
syn::{DataEnum, Generics, Ident, Variant},
};
/// Function that impl the `mlua_gen::LuaBuilder` trait for an enum
pub fn builder(
name: &Ident,
de: &DataEnum,
functions: Vec<&MethodOrFunction>,
generics: &Generics,
) -> TokenStream2 {
let (names, builders): (Vec<_>, Vec<_>) = de
.variants
.iter()
.map(|v| {
let var_name = &v.ident;
(
var_name,
builder_for_fields("e! {Self::#var_name}, &v.fields),
)
})
.unzip();
let no_ty_generics = remove_ty_from_generics(generics);
let builder_fn_code = builder_for_functions("e! {Self}, functions);
quote! {
impl #generics ::mlua_gen::LuaBuilder<
::mlua::Table,
::mlua::Lua,
::mlua::Error,
::mlua::Table,
> for #name #no_ty_generics {
fn lua_builder(lua: &::mlua::Lua) -> ::mlua::Result<::mlua::Table> {
let enum_variants_table = lua.create_table()?;
#( enum_variants_table.set(stringify!(#names), #builders?)?; )*
Ok(enum_variants_table)
}
fn lua_fn_builder(lua: &::mlua::Lua) -> ::mlua::Result<Option<::mlua::Table>> {
#builder_fn_code
}
fn to_globals(lua: &::mlua::Lua) -> ::mlua::Result<()> {
Self::to_globals_as(lua, stringify!(#name))
}
fn to_globals_as<S: AsRef<str>>(lua: &::mlua::Lua, s: S) -> ::mlua::Result<()> {
let table = Self::lua_builder(&lua)?;
if let Some(table_to_extend_with) = Self::lua_fn_builder(&lua)? {
// Equivalent to extend, tho, doesn't seems to exists
for pairs in table_to_extend_with.pairs() {
let (k,v): (String, ::mlua::Function) = pairs?;
table.set(k, v)?;
}
}
lua.globals()
.set(s.as_ref(), Self::lua_builder(&lua)?)?;
Ok(())
}
}
}
}
pub(crate) fn user_data<'l, I: Iterator<Item = &'l Variant>>(
name: &Ident,
generics: &Generics,
variants: I,
custom_field: Option<syn::Ident>,
custom_method_or_fn: Option<syn::Ident>,
) -> proc_macro2::TokenStream {
let non_typed_generics = remove_ty_from_generics(generics);
// Create the fields to access a value.
let (impl_from_lua_match, fields): (Vec<_>, Vec<_>) = variants
.map(|variant| {
let original_variant_string = variant.ident.to_string();
let variant_ident = syn::Ident::new(&original_variant_string, Span::call_site());
let variant_accessor_name = &original_variant_string.to_lowercase();
let (match_stmt_get, field_set, from_lua_impl) = match &variant.fields {
// For enum fields that are named
//
// ```
// enum A {
// Named {
// name: String,
// }
// }
// ```
syn::Fields::Named(field_named) => {
let (set, (fields, field_constructors)): (Vec<_>, (Vec<_>, Vec<_>)) =
field_named
.named
.iter()
.map(|named| named.ident.as_ref().expect("Is named"))
.map(|ident| {
let stringified_ident = ident.to_token_stream().to_string();
(
quote!(
let _ = table.set(#stringified_ident, #ident.to_owned());
),
(
quote!(#ident),
quote!(
#ident: table.get(#stringified_ident)?,
),
),
)
})
.unzip();
(
quote!(
match this {
Self::#variant_ident { #(#fields),* } => Some({
let mut table = lua.create_table().unwrap();
#(#set)*
table
}),
_ => None
}
),
quote!(
reserved_fields.add_field_method_set(
#variant_accessor_name,
|lua, this, table: ::mlua::Table| {
*this = Self::#variant_ident {
#(#field_constructors)*
};
Ok(())
}
);
),
quote!(
::mlua::Value::Table(table) => {
Some(Self::#variant_ident {
#(#field_constructors)*
})
},
),
)
},
// For enum fields that don't have a name / tuple
//
// ```
// enum A {
// Unnamed(String),
// }
// ```
syn::Fields::Unnamed(field_unnamed) => {
// For field access
let (set, field_idents): (Vec<_>, Vec<_>) = (0..field_unnamed.unnamed.len())
.map(|idx| {
// We name fields `v` + idx only for deconstruction
let ident = syn::Ident::new(&format!("v{idx}"), Span::call_site());
(
quote!(let _ = table.push(#ident.to_owned());),
quote!(#ident),
)
})
.unzip();
let indexed = (1..=field_unnamed.unnamed.len()).map(|i| quote!(value.get(#i)?));
// For impl from lua
let impl_from_lua = repeat_with(|| {
quote!(::mlua::FromLua::from_lua(
sequence_value.next().ok_or_else(|| {
::mlua::Error::runtime("Not enough values in sequence table.")
})??,
lua,
)?)
})
.take(field_unnamed.unnamed.len());
(
quote!(
match this {
Self::#variant_ident ( #(#field_idents),* ) => Some({
let mut table = lua.create_table().unwrap();
#(#set)*
table
}),
_ => None
}
),
quote!(
reserved_fields.add_field_method_set(
#variant_accessor_name,
|lua, this, value: ::mlua::Table| {
*this = Self::#variant_ident(
#(#indexed),*
);
Ok(())
}
);
),
quote!(
::mlua::Value::Table(table) => {
let mut sequence_value: ::mlua::TableSequence<::mlua::Value> =
table.sequence_values();
Some(Self::#variant_ident(
#(#impl_from_lua),*
))
},
),
)
},
// For enum fields that don't have a value associated to them
//
// ```
// enum A {
// Unit,
// }
// ```
syn::Fields::Unit => {
(
quote!(
match this { Self::#variant_ident => Some(true), _ => None}
),
quote!(),
quote!(::mlua::Value::Boolean(_) => Some(Self::#variant_ident),),
)
},
};
(
quote!(
if let Ok(table_value) = table.get(#variant_accessor_name) {
if let Some(value) = match table_value {
#from_lua_impl
::mlua::Value::Nil => None,
_ => return Err(::mlua::Error::runtime("Invalid data format.")),
} {
return Ok(value);
}
}
),
quote!(
reserved_fields.add_field_method_get(
#variant_accessor_name,
|lua, this| Ok(#match_stmt_get)
);
#field_set
),
)
})
.unzip();
let extra_fields = if let Some(field) = custom_field {
quote! {#field(reserved_fields)}
} else {
quote!()
};
let extra_impls = if let Some(method_or_fn) = custom_method_or_fn {
quote!(#method_or_fn(methods))
} else {
quote!()
};
quote! {
impl #generics ::mlua::FromLua for #name #non_typed_generics{
fn from_lua(value: ::mlua::Value, lua: &::mlua::Lua) -> ::mlua::Result<#name #non_typed_generics> {
match value {
::mlua::Value::Table(table) => {
#(#impl_from_lua_match)*
Err(::mlua::Error::runtime("No valid variant found."))
},
::mlua::Value::UserData(user_data) => {
user_data.take()
},
val => Err(::mlua::Error::runtime(format!("Expected a table or a UserData. Got: {val:?}"))),
}
}
}
impl #generics ::mlua::UserData for #name #non_typed_generics {
fn add_fields<MluaUserDataFields: ::mlua::UserDataFields<Self>>(reserved_fields: &mut MluaUserDataFields) {
#(#fields)*
;
#extra_fields
}
fn add_methods<MluaUserDataMethods: ::mlua::UserDataMethods<Self>>(methods: &mut MluaUserDataMethods) {
#extra_impls
}
}
}
}