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lib.rs
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lib.rs
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#![macro_use]
#![deny(unused)]
use std::collections::{HashMap, HashSet};
use proc_macro2::{Ident, TokenStream};
use quote::{format_ident, quote};
use syn::{
parse_quote, spanned::Spanned, ConstParam, GenericParam, Generics, Item, LifetimeParam, Result,
Type, TypeArray, TypeParam, TypeParen, TypePath, TypeReference, TypeSlice, TypeTuple,
WhereClause,
};
use crate::{deps::Dependencies, utils::format_generics};
#[macro_use]
mod utils;
mod attr;
mod deps;
mod types;
struct DerivedTS {
ts_name: String,
docs: String,
inline: TokenStream,
inline_flattened: Option<TokenStream>,
dependencies: Dependencies,
concrete: HashMap<Ident, Type>,
export: bool,
export_to: Option<String>,
}
impl DerivedTS {
fn into_impl(mut self, rust_ty: Ident, generics: Generics) -> TokenStream {
let export = self
.export
.then(|| self.generate_export_test(&rust_ty, &generics));
let output_path_fn = {
let path = match self.export_to.as_deref() {
Some(dirname) if dirname.ends_with('/') => {
format!("{}{}.ts", dirname, self.ts_name)
}
Some(filename) => filename.to_owned(),
None => format!("{}.ts", self.ts_name),
};
quote! {
fn output_path() -> Option<&'static std::path::Path> {
Some(std::path::Path::new(#path))
}
}
};
let docs = match &*self.docs {
"" => None,
docs => Some(quote!(const DOCS: Option<&'static str> = Some(#docs);)),
};
let ident = self.ts_name.clone();
let impl_start = generate_impl_block_header(&rust_ty, &generics, &self.dependencies);
let assoc_type = generate_assoc_type(&rust_ty, &generics, &self.concrete);
let name = self.generate_name_fn(&generics);
let inline = self.generate_inline_fn();
let decl = self.generate_decl_fn(&rust_ty, &generics);
let dependencies = &self.dependencies;
let generics_fn = self.generate_generics_fn(&generics);
quote! {
#impl_start {
#assoc_type
fn ident() -> String {
#ident.to_owned()
}
#docs
#name
#decl
#inline
#generics_fn
#output_path_fn
#[allow(clippy::unused_unit)]
fn dependency_types() -> impl ::ts_rs::typelist::TypeList
where
Self: 'static,
{
#dependencies
}
}
#export
}
}
/// Returns an expression which evaluates to the TypeScript name of the type, including generic
/// parameters.
fn name_with_generics(&self, generics: &Generics) -> TokenStream {
let name = &self.ts_name;
let mut generics_ts_names = generics
.type_params()
.filter(|ty| !self.concrete.contains_key(&ty.ident))
.map(|ty| &ty.ident)
.map(|generic| quote!(<#generic as ::ts_rs::TS>::name()))
.peekable();
if generics_ts_names.peek().is_some() {
quote! {
format!("{}<{}>", #name, vec![#(#generics_ts_names),*].join(", "))
}
} else {
quote!(#name.to_owned())
}
}
/// Generate a dummy unit struct for every generic type parameter of this type.
/// # Example:
/// ```compile_fail
/// struct Generic<A, B, const C: usize> { /* ... */ }
/// ```
/// has two generic type parameters, `A` and `B`. This function will therefore generate
/// ```compile_fail
/// struct A;
/// impl ts_rs::TS for A { /* .. */ }
///
/// struct B;
/// impl ts_rs::TS for B { /* .. */ }
/// ```
fn generate_generic_types(&self, generics: &Generics) -> TokenStream {
let generics = generics
.type_params()
.filter(|ty| !self.concrete.contains_key(&ty.ident))
.map(|ty| ty.ident.clone());
quote! {
#(
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, Ord, PartialOrd)]
struct #generics;
impl std::fmt::Display for #generics {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{:?}", self)
}
}
impl TS for #generics {
type WithoutGenerics = #generics;
fn name() -> String { stringify!(#generics).to_owned() }
fn inline() -> String { panic!("{} cannot be inlined", Self::name()) }
fn inline_flattened() -> String { panic!("{} cannot be flattened", Self::name()) }
fn decl() -> String { panic!("{} cannot be declared", Self::name()) }
fn decl_concrete() -> String { panic!("{} cannot be declared", Self::name()) }
}
)*
}
}
fn generate_export_test(&self, rust_ty: &Ident, generics: &Generics) -> TokenStream {
let test_fn = format_ident!(
"export_bindings_{}",
rust_ty.to_string().to_lowercase().replace("r#", "")
);
let generic_params = generics
.type_params()
.map(|ty| match self.concrete.get(&ty.ident) {
None => quote! { ::ts_rs::Dummy },
Some(ty) => quote! { #ty },
});
let ty = quote!(<#rust_ty<#(#generic_params),*> as ::ts_rs::TS>);
quote! {
#[cfg(test)]
#[test]
fn #test_fn() {
#ty::export_all().expect("could not export type");
}
}
}
fn generate_generics_fn(&self, generics: &Generics) -> TokenStream {
let generics = generics
.type_params()
.filter(|ty| !self.concrete.contains_key(&ty.ident))
.map(|TypeParam { ident, .. }| quote![.push::<#ident>().extend(<#ident as ::ts_rs::TS>::generics())]);
quote! {
#[allow(clippy::unused_unit)]
fn generics() -> impl ::ts_rs::typelist::TypeList
where
Self: 'static,
{
use ::ts_rs::typelist::TypeList;
()#(#generics)*
}
}
}
fn generate_name_fn(&self, generics: &Generics) -> TokenStream {
let name = self.name_with_generics(generics);
quote! {
fn name() -> String {
#name
}
}
}
fn generate_inline_fn(&self) -> TokenStream {
let inline = &self.inline;
let inline_flattened = self.inline_flattened.as_ref().map_or_else(
|| {
quote! {
fn inline_flattened() -> String {
panic!("{} cannot be flattened", Self::name())
}
}
},
|inline_flattened| {
quote! {
fn inline_flattened() -> String {
#inline_flattened
}
}
},
);
let inline = quote! {
fn inline() -> String {
#inline
}
};
quote! {
#inline
#inline_flattened
}
}
/// Generates the `decl()` and `decl_concrete()` methods.
/// `decl_concrete()` is simple, and simply defers to `inline()`.
/// For `decl()`, however, we need to change out the generic parameters of the type, replacing
/// them with the dummy types generated by `generate_generic_types()`.
fn generate_decl_fn(&mut self, rust_ty: &Ident, generics: &Generics) -> TokenStream {
let name = &self.ts_name;
let generic_types = self.generate_generic_types(generics);
let ts_generics = format_generics(&mut self.dependencies, generics, &self.concrete);
use GenericParam as G;
// These are the generic parameters we'll be using.
let generic_idents = generics.params.iter().filter_map(|p| match p {
G::Lifetime(_) => None,
G::Type(TypeParam { ident, .. }) => match self.concrete.get(ident) {
// Since we named our dummy types the same as the generic parameters, we can just keep
// the identifier of the generic parameter - its name is shadowed by the dummy struct.
None => Some(quote!(#ident)),
// If the type parameter is concrete, we use the type the user provided using
// `#[ts(concrete)]`
Some(concrete) => Some(quote!(#concrete)),
},
// We keep const parameters as they are, since there's no sensible default value we can
// use instead. This might be something to change in the future.
G::Const(ConstParam { ident, .. }) => Some(quote!(#ident)),
});
quote! {
fn decl_concrete() -> String {
format!("type {} = {};", #name, Self::inline())
}
fn decl() -> String {
#generic_types
let inline = <#rust_ty<#(#generic_idents,)*> as ::ts_rs::TS>::inline();
let generics = #ts_generics;
format!("type {}{generics} = {inline};", #name)
}
}
}
}
fn generate_assoc_type(
rust_ty: &Ident,
generics: &Generics,
concrete: &HashMap<Ident, Type>,
) -> TokenStream {
use GenericParam as G;
let generics_params = generics.params.iter().map(|x| match x {
G::Type(ty) => match concrete.get(&ty.ident) {
None => quote! { ::ts_rs::Dummy },
Some(ty) => quote! { #ty },
},
G::Const(ConstParam { ident, .. }) => quote! { #ident },
G::Lifetime(LifetimeParam { lifetime, .. }) => quote! { #lifetime },
});
quote! { type WithoutGenerics = #rust_ty<#(#generics_params),*>; }
}
// generate start of the `impl TS for #ty` block, up to (excluding) the open brace
fn generate_impl_block_header(
ty: &Ident,
generics: &Generics,
dependencies: &Dependencies,
) -> TokenStream {
use GenericParam as G;
let bounds = generics.params.iter().map(|param| match param {
G::Type(TypeParam {
ident,
colon_token,
bounds,
..
}) => quote!(#ident #colon_token #bounds),
G::Lifetime(LifetimeParam {
lifetime,
colon_token,
bounds,
..
}) => quote!(#lifetime #colon_token #bounds),
G::Const(ConstParam {
const_token,
ident,
colon_token,
ty,
..
}) => quote!(#const_token #ident #colon_token #ty),
});
let type_args = generics.params.iter().map(|param| match param {
G::Type(TypeParam { ident, .. }) | G::Const(ConstParam { ident, .. }) => quote!(#ident),
G::Lifetime(LifetimeParam { lifetime, .. }) => quote!(#lifetime),
});
let where_bound = generate_where_clause(generics, dependencies);
quote!(impl <#(#bounds),*> ::ts_rs::TS for #ty <#(#type_args),*> #where_bound)
}
fn generate_where_clause(generics: &Generics, dependencies: &Dependencies) -> WhereClause {
let used_types = {
let is_type_param = |id: &Ident| generics.type_params().any(|p| &p.ident == id);
let mut used_types = HashSet::new();
for ty in &dependencies.types {
used_type_params(&mut used_types, ty, is_type_param);
}
used_types.into_iter()
};
let existing = generics.where_clause.iter().flat_map(|w| &w.predicates);
parse_quote! {
where #(#existing,)* #(#used_types: ::ts_rs::TS),*
}
}
// Extracts all type parameters which are used within the given type.
// Associated types of a type parameter are extracted as well.
// Note: This will not extract `I` from `I::Item`, but just `I::Item`!
fn used_type_params<'ty, 'out>(
out: &'out mut HashSet<&'ty Type>,
ty: &'ty Type,
is_type_param: impl Fn(&'ty Ident) -> bool + Copy + 'out,
) {
use syn::{
AngleBracketedGenericArguments as GenericArgs, GenericArgument as G, PathArguments as P,
};
match ty {
Type::Array(TypeArray { elem, .. })
| Type::Paren(TypeParen { elem, .. })
| Type::Reference(TypeReference { elem, .. })
| Type::Slice(TypeSlice { elem, .. }) => used_type_params(out, elem, is_type_param),
Type::Tuple(TypeTuple { elems, .. }) => elems
.iter()
.for_each(|elem| used_type_params(out, elem, is_type_param)),
Type::Path(TypePath { qself: None, path }) => {
let first = path.segments.first().unwrap();
if is_type_param(&first.ident) {
// The type is either a generic parameter (e.g `T`), or an associated type of that
// generic parameter (e.g `I::Item`). Either way, we return it.
out.insert(ty);
return;
}
let last = path.segments.last().unwrap();
if let P::AngleBracketed(GenericArgs { ref args, .. }) = last.arguments {
for generic in args {
if let G::Type(ty) = generic {
used_type_params(out, ty, is_type_param);
}
}
}
}
_ => (),
}
}
/// Derives [TS](./trait.TS.html) for a struct or enum.
/// Please take a look at [TS](./trait.TS.html) for documentation.
#[proc_macro_derive(TS, attributes(ts))]
pub fn typescript(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
match entry(input) {
Err(err) => err.to_compile_error(),
Ok(result) => result,
}
.into()
}
fn entry(input: proc_macro::TokenStream) -> Result<TokenStream> {
let input = syn::parse::<Item>(input)?;
let (ts, ident, generics) = match input {
Item::Struct(s) => (types::struct_def(&s)?, s.ident, s.generics),
Item::Enum(e) => (types::enum_def(&e)?, e.ident, e.generics),
_ => syn_err!(input.span(); "unsupported item"),
};
Ok(ts.into_impl(ident, generics))
}