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#![recursion_limit = "196"]
extern crate proc_macro;
use quote::quote;
use proc_macro::TokenStream;
use syn::{ItemStruct, Field, Fields};
use syn::punctuated::Punctuated;
use syn::token::Comma;
use fnv::FnvHasher;
use std::hash::Hasher;
type UnitFields = Punctuated<Field, Comma>;
#[proc_macro_derive(Content, attributes(md))]
pub fn content_derive(input: TokenStream) -> TokenStream {
let item: ItemStruct = syn::parse(input).expect("#[derive(Content)] can be only applied to structs");
let name = &item.ident;
let generics = &item.generics;
let unit_fields = UnitFields::new();
let fields = match &item.fields {
Fields::Named(fields) => fields.named.iter(),
Fields::Unnamed(fields) => fields.unnamed.iter(),
_ => unit_fields.iter(),
};
let mut fields = fields
.enumerate()
.map(|(index, field)| {
let iter = field.attrs
.iter()
.filter_map(|attr| attr.path.segments.first())
.map(|pair| &pair.ident);
let mut method = None;
for attr in iter {
if attr == "md" {
method = Some(quote!(render_cmark));
}
}
let (name, token) = field.ident
.as_ref()
.map(|ident| (ident.to_string(), quote!(#ident)))
.unwrap_or_else(|| {
use syn::{LitInt};
use proc_macro2::Span;
let index = index.to_string();
let lit = LitInt::new(&index, Span::call_site());
(index, quote!(#lit))
});
let mut hasher = FnvHasher::default();
hasher.write(name.as_bytes());
let hash = hasher.finish();
(name, token, hash, method)
})
.collect::<Vec<_>>();
fields.sort_unstable_by(|a, b| (a.2).cmp(&b.2));
let render_escaped = quote!(render_escaped);
let render_field_escaped = fields.iter().map(|(_, field, hash, method)| {
let method = method.as_ref().unwrap_or(&render_escaped);
quote! {
#hash => self.#field.#method(encoder).map(|_| true),
}
});
let render_unescaped = quote!(render_unescaped);
let render_field_unescaped = fields.iter().map(|(_, field, hash, method)| {
let method = method.as_ref().unwrap_or(&render_unescaped);
quote! {
#hash => self.#field.#method(encoder).map(|_| true),
}
});
let render_field_section = fields.iter().map(|(_, field, hash, _)| {
quote! {
#hash => self.#field.render_section(section, encoder).map(|_| true),
}
});
let render_field_inverse = fields.iter().map(|(_, field, hash, _)| {
quote! {
#hash => self.#field.render_inverse(section, encoder).map(|_| true),
}
});
let fields = fields.iter().map(|(_, field, _, _)| field);
let tokens = quote! {
impl#generics ramhorns::Content for #name#generics {
#[inline]
fn capacity_hint(&self, tpl: &ramhorns::Template) -> usize {
tpl.capacity_hint() #( + self.#fields.capacity_hint(tpl) )*
}
#[inline]
fn render_field_escaped<E>(&self, hash: u64, _: &str, encoder: &mut E) -> Result<bool, E::Error>
where
E: ramhorns::encoding::Encoder,
{
match hash {
#( #render_field_escaped )*
_ => Ok(false)
}
}
#[inline]
fn render_field_unescaped<E>(&self, hash: u64, _: &str, encoder: &mut E) -> Result<bool, E::Error>
where
E: ramhorns::encoding::Encoder,
{
match hash {
#( #render_field_unescaped )*
_ => Ok(false)
}
}
fn render_field_section<P, E>(&self, hash: u64, _: &str, section: ramhorns::Section<P>, encoder: &mut E) -> Result<bool, E::Error>
where
P: ramhorns::traits::ContentSequence,
E: ramhorns::encoding::Encoder,
{
match hash {
#( #render_field_section )*
_ => Ok(false)
}
}
fn render_field_inverse<P, E>(&self, hash: u64, _: &str, section: ramhorns::Section<P>, encoder: &mut E) -> Result<bool, E::Error>
where
P: ramhorns::traits::ContentSequence,
E: ramhorns::encoding::Encoder,
{
match hash {
#( #render_field_inverse )*
_ => Ok(false)
}
}
}
};
TokenStream::from(tokens)
}