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#![feature(plugin_registrar, rustc_private)]
#![doc(html_logo_url = "https://rust-num.github.io/num/rust-logo-128x128-blk-v2.png",
html_favicon_url = "https://rust-num.github.io/num/favicon.ico",
html_root_url = "https://rust-num.github.io/num/",
html_playground_url = "http://play.integer32.com/")]
extern crate syntax;
extern crate syntax_ext;
extern crate rustc_plugin;
use syntax::ast::{MetaItem, Expr, BinOpKind};
use syntax::ast;
use syntax::codemap::Span;
use syntax::ext::base::{ExtCtxt, Annotatable};
use syntax::ext::build::AstBuilder;
use syntax_ext::deriving::generic::*;
use syntax_ext::deriving::generic::ty::*;
use syntax::symbol::Symbol;
use syntax::ptr::P;
use syntax::ext::base::MultiDecorator;
use rustc_plugin::Registry;
macro_rules! pathvec {
($($x:ident)::+) => (
vec![ $( stringify!($x) ),+ ]
)
}
macro_rules! path {
($($x:tt)*) => (
::syntax_ext::deriving::generic::ty::Path::new( pathvec!( $($x)* ) )
)
}
macro_rules! path_local {
($x:ident) => (
::syntax_ext::deriving::generic::ty::Path::new_local(stringify!($x))
)
}
macro_rules! pathvec_std {
($cx:expr, $first:ident :: $($rest:ident)::+) => ({
let mut v = pathvec!($($rest)::+);
if let Some(s) = $cx.crate_root {
v.insert(0, s);
}
v
})
}
pub fn expand_deriving_from_primitive(cx: &mut ExtCtxt,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut FnMut(Annotatable))
{
let inline = cx.meta_word(span, Symbol::intern("inline"));
let attrs = vec!(cx.attribute(span, inline));
let trait_def = TraitDef {
is_unsafe: false,
span: span,
attributes: Vec::new(),
path: path!(num::FromPrimitive),
additional_bounds: Vec::new(),
generics: LifetimeBounds::empty(),
methods: vec!(
MethodDef {
name: "from_i64",
is_unsafe: false,
unify_fieldless_variants: false,
generics: LifetimeBounds::empty(),
explicit_self: None,
args: vec!(Literal(path_local!(i64))),
ret_ty: Literal(Path::new_(pathvec_std!(cx, core::option::Option),
None,
vec!(Box::new(Self_)),
true)),
attributes: attrs.clone(),
combine_substructure: combine_substructure(Box::new(|c, s, sub| {
cs_from("i64", c, s, sub)
})),
},
MethodDef {
name: "from_u64",
is_unsafe: false,
unify_fieldless_variants: false,
generics: LifetimeBounds::empty(),
explicit_self: None,
args: vec!(Literal(path_local!(u64))),
ret_ty: Literal(Path::new_(pathvec_std!(cx, core::option::Option),
None,
vec!(Box::new(Self_)),
true)),
attributes: attrs,
combine_substructure: combine_substructure(Box::new(|c, s, sub| {
cs_from("u64", c, s, sub)
})),
}
),
associated_types: Vec::new(),
supports_unions: false,
};
trait_def.expand(cx, mitem, &item, push)
}
fn cs_from(name: &str, cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
if substr.nonself_args.len() != 1 {
cx.span_bug(trait_span, "incorrect number of arguments in `derive(FromPrimitive)`")
}
let n = &substr.nonself_args[0];
match *substr.fields {
StaticStruct(..) => {
cx.span_err(trait_span, "`FromPrimitive` cannot be derived for structs");
return cx.expr_fail(trait_span, Symbol::intern(""));
}
StaticEnum(enum_def, _) => {
if enum_def.variants.is_empty() {
cx.span_err(trait_span,
"`FromPrimitive` cannot be derived for enums with no variants");
return cx.expr_fail(trait_span, Symbol::intern(""));
}
let mut arms = Vec::new();
for variant in &enum_def.variants {
match variant.node.data {
ast::VariantData::Unit(..) => {
let span = variant.span;
let path = cx.path(span, vec![substr.type_ident, variant.node.name]);
let variant = cx.expr_path(path);
let ty = cx.ty_ident(span, cx.ident_of(name));
let cast = cx.expr_cast(span, variant.clone(), ty);
let guard = cx.expr_binary(span, BinOpKind::Eq, n.clone(), cast);
let body = cx.expr_some(span, variant);
let arm = ast::Arm {
attrs: vec!(),
pats: vec!(cx.pat_wild(span)),
guard: Some(guard),
body: body,
beginning_vert: None,
};
arms.push(arm);
}
ast::VariantData::Tuple(..) => {
cx.span_err(trait_span,
"`FromPrimitive` cannot be derived for \
enum variants with arguments");
return cx.expr_fail(trait_span,
Symbol::intern(""));
}
ast::VariantData::Struct(..) => {
cx.span_err(trait_span,
"`FromPrimitive` cannot be derived for enums \
with struct variants");
return cx.expr_fail(trait_span,
Symbol::intern(""));
}
}
}
let arm = ast::Arm {
attrs: vec!(),
pats: vec!(cx.pat_wild(trait_span)),
guard: None,
body: cx.expr_none(trait_span),
beginning_vert: None,
};
arms.push(arm);
cx.expr_match(trait_span, n.clone(), arms)
}
_ => cx.span_bug(trait_span, "expected StaticEnum in derive(FromPrimitive)")
}
}
#[plugin_registrar]
#[doc(hidden)]
pub fn plugin_registrar(reg: &mut Registry) {
reg.register_syntax_extension(
Symbol::intern("derive_NumFromPrimitive"),
MultiDecorator(Box::new(expand_deriving_from_primitive)));
}