| // Copyright 2012-2013 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 deriving::path_std; |
| use deriving::generic::*; |
| use deriving::generic::ty::*; |
| |
| use syntax::ast::{Expr, MetaItem}; |
| use syntax::ext::base::{Annotatable, ExtCtxt}; |
| use syntax::ext::build::AstBuilder; |
| use syntax::ptr::P; |
| use syntax::symbol::Symbol; |
| use syntax_pos::Span; |
| |
| pub fn expand_deriving_default(cx: &mut ExtCtxt, |
| span: Span, |
| mitem: &MetaItem, |
| item: &Annotatable, |
| push: &mut dyn FnMut(Annotatable)) { |
| let inline = cx.meta_word(span, Symbol::intern("inline")); |
| let attrs = vec![cx.attribute(span, inline)]; |
| let trait_def = TraitDef { |
| span, |
| attributes: Vec::new(), |
| path: path_std!(cx, default::Default), |
| additional_bounds: Vec::new(), |
| generics: LifetimeBounds::empty(), |
| is_unsafe: false, |
| supports_unions: false, |
| methods: vec![MethodDef { |
| name: "default", |
| generics: LifetimeBounds::empty(), |
| explicit_self: None, |
| args: Vec::new(), |
| ret_ty: Self_, |
| attributes: attrs, |
| is_unsafe: false, |
| unify_fieldless_variants: false, |
| combine_substructure: combine_substructure(Box::new(|a, b, c| { |
| default_substructure(a, b, c) |
| })), |
| }], |
| associated_types: Vec::new(), |
| }; |
| trait_def.expand(cx, mitem, item, push) |
| } |
| |
| fn default_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> { |
| let default_ident = cx.std_path(&["default", "Default", "default"]); |
| let default_call = |span| cx.expr_call_global(span, default_ident.clone(), Vec::new()); |
| |
| return match *substr.fields { |
| StaticStruct(_, ref summary) => { |
| match *summary { |
| Unnamed(ref fields, is_tuple) => { |
| if !is_tuple { |
| cx.expr_ident(trait_span, substr.type_ident) |
| } else { |
| let exprs = fields.iter().map(|sp| default_call(*sp)).collect(); |
| cx.expr_call_ident(trait_span, substr.type_ident, exprs) |
| } |
| } |
| Named(ref fields) => { |
| let default_fields = fields.iter() |
| .map(|&(ident, span)| cx.field_imm(span, ident, default_call(span))) |
| .collect(); |
| cx.expr_struct_ident(trait_span, substr.type_ident, default_fields) |
| } |
| } |
| } |
| StaticEnum(..) => { |
| span_err!(cx, trait_span, E0665, |
| "`Default` cannot be derived for enums, only structs"); |
| // let compilation continue |
| cx.expr_usize(trait_span, 0) |
| } |
| _ => cx.span_bug(trait_span, "Non-static method in `derive(Default)`"), |
| }; |
| } |