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//! Provides the plugin derive macro
#![recursion_limit="128"]
extern crate proc_macro;
extern crate syn;
#[macro_use]
extern crate quote;
extern crate failure;
use proc_macro::TokenStream;
#[proc_macro_derive(PluginName)]
pub fn derive_plugin(data: TokenStream) -> TokenStream {
let ast = syn::parse(data).unwrap();
let gen = expand_plugin(&ast);
gen.into()
}
fn expand_plugin(ast: &syn::DeriveInput) -> quote::Tokens {
let name = &ast.ident;
let generics = &ast.generics;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
quote! {
impl #impl_generics PluginName for #name #ty_generics #where_clause {
fn name(&self) -> &str {
stringify!(#name)
}
}
}
}
#[proc_macro_derive(Error, attributes(error))]
pub fn derive_error(data: TokenStream) -> TokenStream {
let ast = syn::parse(data).unwrap();
let tokens = expand_error(&ast);
tokens.into()
}
fn expand_error(ast: &syn::DeriveInput) -> quote::Tokens {
if let syn::Data::Enum(_) = ast.data {
} else {
panic!("Error should only be derived on ErrorKind enums");
};
let mut name = None;
for attr in &ast.attrs {
if let Some(syn::Meta::NameValue(name_value)) = attr.interpret_meta() {
if "error" == name_value.ident.to_string() {
if let syn::Lit::Str(lit) = name_value.lit {
name = Some(lit.value());
}
}
}
};
let struct_name = if let Some(name) = name {
syn::Ident::from(name)
} else {
panic!("Define the error attribute for all Error derives");
};
let enum_name = &ast.ident;
quote! {
#[derive(Debug)]
pub struct #struct_name {
inner: ::failure::Context<#enum_name>,
}
impl #struct_name {
pub fn kind(&self) -> #enum_name {
*self.inner.get_context()
}
}
impl From<#enum_name> for #struct_name {
fn from(kind: #enum_name) -> #struct_name {
#struct_name {
inner: ::failure::Context::new(kind),
}
}
}
impl From<::failure::Context<#enum_name>> for #struct_name {
fn from(inner: ::failure::Context<#enum_name>) -> #struct_name {
#struct_name { inner: inner }
}
}
impl ::failure::Fail for #struct_name {
fn cause(&self) -> Option<&::failure::Fail> {
self.inner.cause()
}
fn backtrace(&self) -> Option<&::failure::Backtrace> {
self.inner.backtrace()
}
}
impl ::std::fmt::Display for #struct_name {
fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
use std::fmt;
fmt::Display::fmt(&self.inner, f)
}
}
}
}
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