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use deriving::generic::*;
use deriving::generic::ty::*;
use syntax::ast::{self, Ident};
use syntax::ast::{Expr, MetaItem};
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ext::build::AstBuilder;
use syntax::ptr::P;
use syntax_pos::{DUMMY_SP, Span};
pub fn expand_deriving_debug(cx: &mut ExtCtxt,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut FnMut(Annotatable)) {
let fmtr = Ptr(Box::new(Literal(path_std!(cx, core::fmt::Formatter))),
Borrowed(None, ast::Mutability::Mutable));
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,
supports_unions: 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,
unify_fieldless_variants: 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)
}
fn show_substructure(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
let (ident, is_struct) = match *substr.fields {
Struct(vdata, _) => (substr.type_ident, vdata.is_struct()),
EnumMatching(_, v, _) => (v.node.name, v.node.data.is_struct()),
EnumNonMatchingCollapsed(..) |
StaticStruct(..) |
StaticEnum(..) => cx.span_bug(span, "nonsensical .fields in `#[derive(Debug)]`"),
};
let span = Span { expn_id: cx.backtrace(), ..span };
let name = cx.expr_lit(span, ast::LitKind::Str(ident.name, ast::StrStyle::Cooked));
let builder = Ident::from_str("builder");
let builder_expr = cx.expr_ident(span, builder.clone());
let fmt = substr.nonself_args[0].clone();
let mut stmts = match *substr.fields {
Struct(_, ref fields) |
EnumMatching(.., ref fields) => {
let mut stmts = vec![];
if !is_struct {
let expr =
cx.expr_method_call(span, fmt, Ident::from_str("debug_tuple"), vec![name]);
stmts.push(cx.stmt_let(DUMMY_SP, true, builder, expr));
for field in fields {
let field = cx.expr_addr_of(field.span, field.self_.clone());
let field = cx.expr_addr_of(field.span, field);
let expr = cx.expr_method_call(span,
builder_expr.clone(),
Ident::from_str("field"),
vec![field]);
stmts.push(stmt_let_undescore(cx, span, expr));
}
} else {
let expr =
cx.expr_method_call(span, fmt, Ident::from_str("debug_struct"), vec![name]);
stmts.push(cx.stmt_let(DUMMY_SP, true, builder, expr));
for field in fields {
let name = cx.expr_lit(field.span,
ast::LitKind::Str(field.name.unwrap().name,
ast::StrStyle::Cooked));
let field = cx.expr_addr_of(field.span, field.self_.clone());
let field = cx.expr_addr_of(field.span, field);
let expr = cx.expr_method_call(span,
builder_expr.clone(),
Ident::from_str("field"),
vec![name, field]);
stmts.push(stmt_let_undescore(cx, span, expr));
}
}
stmts
}
_ => unreachable!(),
};
let expr = cx.expr_method_call(span, builder_expr, Ident::from_str("finish"), vec![]);
stmts.push(cx.stmt_expr(expr));
let block = cx.block(span, stmts);
cx.expr_block(block)
}
fn stmt_let_undescore(cx: &mut ExtCtxt, sp: Span, expr: P<ast::Expr>) -> ast::Stmt {
let local = P(ast::Local {
pat: cx.pat_wild(sp),
ty: None,
init: Some(expr),
id: ast::DUMMY_NODE_ID,
span: sp,
attrs: ast::ThinVec::new(),
});
ast::Stmt {
id: ast::DUMMY_NODE_ID,
node: ast::StmtKind::Local(local),
span: sp,
}
}