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// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::panic;
use errors::FatalError;
use proc_macro::{TokenStream, __internal};
use syntax::ast::{self, ItemKind, Attribute, Mac};
use syntax::attr::{mark_used, mark_known};
use syntax::codemap::Span;
use syntax::ext::base::*;
use syntax::visit::Visitor;
struct MarkAttrs<'a>(&'a [ast::Name]);
impl<'a> Visitor<'a> for MarkAttrs<'a> {
fn visit_attribute(&mut self, attr: &Attribute) {
if self.0.contains(&attr.name()) {
mark_used(attr);
mark_known(attr);
}
}
fn visit_mac(&mut self, _mac: &Mac) {}
}
pub struct ProcMacroDerive {
inner: fn(TokenStream) -> TokenStream,
attrs: Vec<ast::Name>,
}
impl ProcMacroDerive {
pub fn new(inner: fn(TokenStream) -> TokenStream, attrs: Vec<ast::Name>) -> ProcMacroDerive {
ProcMacroDerive { inner: inner, attrs: attrs }
}
}
impl MultiItemModifier for ProcMacroDerive {
fn expand(&self,
ecx: &mut ExtCtxt,
span: Span,
_meta_item: &ast::MetaItem,
item: Annotatable)
-> Vec<Annotatable> {
let item = match item {
Annotatable::Item(item) => item,
Annotatable::ImplItem(_) |
Annotatable::TraitItem(_) |
Annotatable::ForeignItem(_) |
Annotatable::Stmt(_) |
Annotatable::Expr(_) => {
ecx.span_err(span, "proc-macro derives may only be \
applied to struct/enum items");
return Vec::new()
}
};
match item.node {
ItemKind::Struct(..) |
ItemKind::Enum(..) => {},
_ => {
ecx.span_err(span, "proc-macro derives may only be \
applied to struct/enum items");
return Vec::new()
}
}
// Mark attributes as known, and used.
MarkAttrs(&self.attrs).visit_item(&item);
let input = __internal::new_token_stream(ecx.resolver.eliminate_crate_var(item.clone()));
let res = __internal::set_sess(ecx, || {
let inner = self.inner;
panic::catch_unwind(panic::AssertUnwindSafe(|| inner(input)))
});
let stream = match res {
Ok(stream) => stream,
Err(e) => {
let msg = "proc-macro derive panicked";
let mut err = ecx.struct_span_fatal(span, msg);
if let Some(s) = e.downcast_ref::<String>() {
err.help(&format!("message: {}", s));
}
if let Some(s) = e.downcast_ref::<&'static str>() {
err.help(&format!("message: {}", s));
}
err.emit();
FatalError.raise();
}
};
let error_count_before = ecx.parse_sess.span_diagnostic.err_count();
__internal::set_sess(ecx, || {
let msg = "proc-macro derive produced unparseable tokens";
match __internal::token_stream_parse_items(stream) {
// fail if there have been errors emitted
Ok(_) if ecx.parse_sess.span_diagnostic.err_count() > error_count_before => {
ecx.struct_span_fatal(span, msg).emit();
FatalError.raise();
}
Ok(new_items) => new_items.into_iter().map(Annotatable::Item).collect(),
Err(_) => {
// FIXME: handle this better
ecx.struct_span_fatal(span, msg).emit();
FatalError.raise();
}
}
})
}
}
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