src/libsyntax/ext/deriving/clone.rs

   1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use ast::{MetaItem, Item, Expr};
  12 use codemap::Span;
  13 use ext::base::ExtCtxt;
  14 use ext::build::AstBuilder;
  15 use ext::deriving::generic::*;
  16 use ext::deriving::generic::ty::*;
  17 use parse::token::InternedString;
  18 use ptr::P;
  19
  20 pub fn expand_deriving_clone<F>(cx: &mut ExtCtxt,
  21                                 span: Span,
  22                                 mitem: &MetaItem,
  23                                 item: &Item,
  24                                 push: F) where
  25     F: FnOnce(P<Item>),
  26 {
  27     let inline = cx.meta_word(span, InternedString::new("inline"));
  28     let attrs = vec!(cx.attribute(span, inline));
  29     let trait_def = TraitDef {
  30         span: span,
  31         attributes: Vec::new(),
  32         path: Path::new(vec!("std", "clone", "Clone")),
  33         additional_bounds: Vec::new(),
  34         generics: LifetimeBounds::empty(),
  35         methods: vec!(
  36             MethodDef {
  37                 name: "clone",
  38                 generics: LifetimeBounds::empty(),
  39                 explicit_self: borrowed_explicit_self(),
  40                 args: Vec::new(),
  41                 ret_ty: Self,
  42                 attributes: attrs,
  43                 combine_substructure: combine_substructure(box |c, s, sub| {
  44                     cs_clone("Clone", c, s, sub)
  45                 }),
  46             }
  47         ),
  48         associated_types: Vec::new(),
  49     };
  50
  51     trait_def.expand(cx, mitem, item, push)
  52 }
  53
  54 fn cs_clone(
  55     name: &str,
  56     cx: &mut ExtCtxt, trait_span: Span,
  57     substr: &Substructure) -> P<Expr> {
  58     let ctor_path;
  59     let all_fields;
  60     let fn_path = vec![
  61         cx.ident_of("std"),
  62         cx.ident_of("clone"),
  63         cx.ident_of("Clone"),
  64         cx.ident_of("clone"),
  65     ];
  66     let subcall = |field: &FieldInfo| {
  67         let args = vec![cx.expr_addr_of(field.span, field.self_.clone())];
  68
  69         cx.expr_call_global(field.span, fn_path.clone(), args)
  70     };
  71
  72     match *substr.fields {
  73         Struct(ref af) => {
  74             ctor_path = cx.path(trait_span, vec![substr.type_ident]);
  75             all_fields = af;
  76         }
  77         EnumMatching(_, variant, ref af) => {
  78             ctor_path = cx.path(trait_span, vec![substr.type_ident, variant.node.name]);
  79             all_fields = af;
  80         },
  81         EnumNonMatchingCollapsed (..) => {
  82             cx.span_bug(trait_span,
  83                         &format!("non-matching enum variants in \
  84                                  `derive({})`", name)[])
  85         }
  86         StaticEnum(..) | StaticStruct(..) => {
  87             cx.span_bug(trait_span,
  88                         &format!("static method in `derive({})`", name)[])
  89         }
  90     }
  91
  92     if all_fields.len() >= 1 && all_fields[0].name.is_none() {
  93         // enum-like
  94         let subcalls = all_fields.iter().map(subcall).collect();
  95         let path = cx.expr_path(ctor_path);
  96         cx.expr_call(trait_span, path, subcalls)
  97     } else {
  98         // struct-like
  99         let fields = all_fields.iter().map(|field| {
 100             let ident = match field.name {
 101                 Some(i) => i,
 102                 None => {
 103                     cx.span_bug(trait_span,
 104                                 &format!("unnamed field in normal struct in \
 105                                          `derive({})`", name)[])
 106                 }
 107             };
 108             cx.field_imm(field.span, ident, subcall(field))
 109         }).collect::<Vec<_>>();
 110
 111         if fields.is_empty() {
 112             // no fields, so construct like `None`
 113             cx.expr_path(ctor_path)
 114         } else {
 115             cx.expr_struct(trait_span, ctor_path, fields)
 116         }
 117     }
 118 }