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#![cfg_attr(feature = "strict", deny(warnings))]
#![recursion_limit="128"]
extern crate proc_macro;
extern crate syn;
#[macro_use] extern crate quote;
extern crate itertools;
#[macro_use] extern crate bitflags;
use proc_macro::TokenStream;
use quote::{Tokens, ToTokens};
mod ast;
mod visibility;
#[proc_macro_derive(Shrinkwrap, attributes(shrinkwrap))]
pub fn shrinkwrap(tokens: TokenStream) -> TokenStream {
use ast::{ShrinkwrapFlags, validate_derive_input};
use visibility::field_visibility;
use visibility::FieldVisibility::*;
let input: syn::DeriveInput = syn::parse(tokens)
.unwrap();
let (details, input) = validate_derive_input(input);
let mut tokens = Tokens::new();
impl_immut_borrows(&details, &input)
.to_tokens(&mut tokens);
impl_map(&details, &input)
.to_tokens(&mut tokens);
if details.flags.contains(ShrinkwrapFlags::SW_MUT) {
if !details.flags.contains(ast::ShrinkwrapFlags::SW_IGNORE_VIS) {
match field_visibility(&details.visibility, &input.inner_visibility) {
Restricted =>
panic!("shrinkwraprs: cowardly refusing to implement mutable
conversion traits because inner field is less visible
than shrinkwrapped struct. Implementing mutable traits
could allow violation of struct invariants. If you'd
like to override this, use
#[shrinkwrap(unsafe_ignore_visibility)] on your struct."),
CantDetermine =>
panic!("shrinkwraprs: cowardly refusing to implement mutable
conversion traits because I can't figure out whether
the inner field is as visible as the shrinkwrapped
struct or not. This is usually because there is a mix
of visibilities starting at the crate root and
visiblities starting at self/super. If you'd like to
override this, use #[shrinkwrap(unsafe_ignore_visibility)] on
your struct."),
_ => ()
}
}
impl_mut_borrows(&details, &input)
.to_tokens(&mut tokens);
}
tokens.into()
}
fn impl_immut_borrows(details: &ast::StructDetails, input: &ast::Struct) -> Tokens {
let &ast::StructDetails { ref ident, ref generics, .. } = details;
let &ast::Struct { ref inner_field, ref inner_type, .. } = input;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let rust = syn::Ident::from(RUST);
quote! {
impl #impl_generics ::#rust::ops::Deref for #ident #ty_generics #where_clause {
type Target = #inner_type;
fn deref(&self) -> &Self::Target {
&self.#inner_field
}
}
impl #impl_generics ::#rust::borrow::Borrow<#inner_type> for #ident #ty_generics #where_clause {
fn borrow(&self) -> &#inner_type {
&self.#inner_field
}
}
impl #impl_generics ::#rust::convert::AsRef<#inner_type> for #ident #ty_generics #where_clause {
fn as_ref(&self) -> &#inner_type {
&self.#inner_field
}
}
}
}
fn impl_mut_borrows(details: &ast::StructDetails, input: &ast::Struct) -> Tokens {
let &ast::StructDetails { ref ident, ref generics, .. } = details;
let &ast::Struct { ref inner_field, ref inner_type, .. } = input;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let rust = syn::Ident::from(RUST);
quote! {
impl #impl_generics ::#rust::ops::DerefMut for #ident #ty_generics #where_clause {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.#inner_field
}
}
impl #impl_generics ::#rust::borrow::BorrowMut<#inner_type> for #ident #ty_generics #where_clause {
fn borrow_mut(&mut self) -> &mut #inner_type {
&mut self.#inner_field
}
}
impl #impl_generics ::#rust::convert::AsMut<#inner_type> for #ident #ty_generics #where_clause {
fn as_mut(&mut self) -> &mut #inner_type {
&mut self.#inner_field
}
}
}
}
fn impl_map(details: &ast::StructDetails, input: &ast::Struct) -> Tokens {
let &ast::StructDetails { ref ident, ref generics, .. } = details;
let &ast::Struct { ref inner_field, ref inner_type, ref inner_visibility } = input;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let f = quote!( __SHRINKWRAP_F );
let t = quote!( __SHRINKWRAP_T );
quote! {
#[allow(dead_code, non_camel_case_types)]
impl #impl_generics #ident #ty_generics #where_clause {
pub fn map<#t, #f: FnMut(#inner_type) -> #t>(self, mut f: #f) -> #t {
f(self.#inner_field)
}
pub fn map_ref<#t, #f: FnMut(&#inner_type) -> #t>(&self, mut f: #f) -> #t {
f(&self.#inner_field)
}
#inner_visibility fn map_mut<#t, #f>(&mut self, mut f: #f) -> #t
where #f: FnMut(&mut #inner_type) -> #t
{
f(&mut self.#inner_field)
}
}
}
}
#[cfg(feature = "std")]
const RUST: &str = "std";
#[cfg(not(feature = "std"))]
const RUST: &str = "core";