Derive ComputeSquaredDistance

This commit is contained in:
Anthony Ramine 2017-08-13 00:50:36 +02:00
parent 51b740033b
commit 277351da35
22 changed files with 162 additions and 391 deletions

View file

@ -0,0 +1,117 @@
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use quote;
use std::borrow::Cow;
use syn;
use synstructure;
pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
let name = &input.ident;
let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
let mut where_clause = where_clause.clone();
for param in &input.generics.ty_params {
where_clause.predicates.push(where_predicate(syn::Ty::Path(None, param.ident.clone().into())))
}
let variants = variants(&input);
let mut match_body = quote!();
match_body.append_all(variants.iter().map(|variant| {
let name = match input.body {
syn::Body::Struct(_) => Cow::Borrowed(&input.ident),
syn::Body::Enum(_) => {
Cow::Owned(syn::Ident::from(format!("{}::{}", input.ident, variant.ident)))
},
};
let (this_pattern, this_info) = synstructure::match_pattern(
&name,
&variant.data,
&synstructure::BindOpts::with_prefix(
synstructure::BindStyle::Ref,
"this".to_owned(),
),
);
let (other_pattern, other_info) = synstructure::match_pattern(
&name,
&variant.data,
&synstructure::BindOpts::with_prefix(
synstructure::BindStyle::Ref,
"other".to_owned(),
),
);
let sum = if this_info.is_empty() {
quote! { ::values::distance::SquaredDistance::Value(0.) }
} else {
let mut sum = quote!();
sum.append_separated(this_info.iter().zip(&other_info).map(|(this, other)| {
where_clause.predicates.push(where_predicate(this.field.ty.clone()));
quote! {
::values::distance::ComputeSquaredDistance::compute_squared_distance(#this, #other)?
}
}), "+");
sum
};
quote! {
(&#this_pattern, &#other_pattern) => {
Ok(#sum)
}
}
}));
if variants.len() > 1 {
match_body = quote! { #match_body, _ => Err(()), };
}
quote! {
impl #impl_generics ::values::distance::ComputeSquaredDistance for #name #ty_generics #where_clause {
#[allow(unused_variables, unused_imports)]
#[inline]
fn compute_squared_distance(
&self,
other: &Self,
) -> Result<::values::distance::SquaredDistance, ()> {
match (self, other) {
#match_body
}
}
}
}
}
fn variants(input: &syn::DeriveInput) -> Cow<[syn::Variant]> {
match input.body {
syn::Body::Enum(ref variants) => (&**variants).into(),
syn::Body::Struct(ref data) => {
vec![syn::Variant {
ident: input.ident.clone(),
attrs: input.attrs.clone(),
data: data.clone(),
discriminant: None,
}].into()
},
}
}
fn where_predicate(ty: syn::Ty) -> syn::WherePredicate {
syn::WherePredicate::BoundPredicate(
syn::WhereBoundPredicate {
bound_lifetimes: vec![],
bounded_ty: ty,
bounds: vec![syn::TyParamBound::Trait(
syn::PolyTraitRef {
bound_lifetimes: vec![],
trait_ref: syn::Path {
global: true,
segments: vec![
"values".into(),
"distance".into(),
"ComputeSquaredDistance".into(),
],
},
},
syn::TraitBoundModifier::None,
)],
},
)
}