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// Copyright 2014 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 ast;
use ast::{MetaItem, Expr,};
use codemap::Span;
use ext::base::{ExtCtxt, Annotatable};
use ext::build::AstBuilder;
use ext::deriving::generic::*;
use ext::deriving::generic::ty::*;
use parse::token;
use ptr::P;
pub fn expand_deriving_show(cx: &mut ExtCtxt,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut FnMut(Annotatable))
{
// &mut ::std::fmt::Formatter
let fmtr = Ptr(Box::new(Literal(path_std!(cx, core::fmt::Formatter))),
Borrowed(None, ast::MutMutable));
let trait_def = TraitDef {
span: span,
attributes: Vec::new(),
path: path_std!(cx, core::fmt::Debug),
additional_bounds: Vec::new(),
generics: LifetimeBounds::empty(),
is_unsafe: false,
methods: vec![
MethodDef {
name: "fmt",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: vec!(fmtr),
ret_ty: Literal(path_std!(cx, core::fmt::Result)),
attributes: Vec::new(),
is_unsafe: false,
combine_substructure: combine_substructure(Box::new(|a, b, c| {
show_substructure(a, b, c)
}))
}
],
associated_types: Vec::new(),
};
trait_def.expand(cx, mitem, item, push)
}
/// We use the debug builders to do the heavy lifting here
fn show_substructure(cx: &mut ExtCtxt, span: Span,
substr: &Substructure) -> P<Expr> {
// build fmt.debug_struct(<name>).field(<fieldname>, &<fieldval>)....build()
// or fmt.debug_tuple(<name>).field(&<fieldval>)....build()
// based on the "shape".
let ident = match *substr.fields {
Struct(_) => substr.type_ident,
EnumMatching(_, v, _) => v.node.name,
EnumNonMatchingCollapsed(..) | StaticStruct(..) | StaticEnum(..) => {
cx.span_bug(span, "nonsensical .fields in `#[derive(Debug)]`")
}
};
// We want to make sure we have the expn_id set so that we can use unstable methods
let span = Span { expn_id: cx.backtrace(), .. span };
let name = cx.expr_lit(span, ast::Lit_::LitStr(ident.name.as_str(),
ast::StrStyle::CookedStr));
let mut expr = substr.nonself_args[0].clone();
match *substr.fields {
Struct(ref fields) | EnumMatching(_, _, ref fields) => {
if fields.is_empty() || fields[0].name.is_none() {
// tuple struct/"normal" variant
expr = cx.expr_method_call(span,
expr,
token::str_to_ident("debug_tuple"),
vec![name]);
for field in fields {
// Use double indirection to make sure this works for unsized types
let field = cx.expr_addr_of(field.span, field.self_.clone());
let field = cx.expr_addr_of(field.span, field);
expr = cx.expr_method_call(span,
expr,
token::str_to_ident("field"),
vec![field]);
}
} else {
// normal struct/struct variant
expr = cx.expr_method_call(span,
expr,
token::str_to_ident("debug_struct"),
vec![name]);
for field in fields {
let name = cx.expr_lit(field.span, ast::Lit_::LitStr(
field.name.unwrap().name.as_str(),
ast::StrStyle::CookedStr));
// Use double indirection to make sure this works for unsized types
let field = cx.expr_addr_of(field.span, field.self_.clone());
let field = cx.expr_addr_of(field.span, field);
expr = cx.expr_method_call(span,
expr,
token::str_to_ident("field"),
vec![name, field]);
}
}
}
_ => unreachable!()
}
cx.expr_method_call(span,
expr,
token::str_to_ident("finish"),
vec![])
}
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