/*!
-The compiler code necessary to implement the #[deriving(Encodable)]
-(and Decodable, in decodable.rs) extension. The idea here is that
-type-defining items may be tagged with #[deriving(Encodable,
-Decodable)].
+The compiler code necessary to implement the `#[deriving(Encodable)]`
+(and `Decodable`, in decodable.rs) extension. The idea here is that
+type-defining items may be tagged with `#[deriving(Encodable, Decodable)]`.
For example, a type like:
- #[deriving(Encodable, Decodable)]
- struct Node {id: uint}
+```ignore
+#[deriving(Encodable, Decodable)]
+struct Node { id: uint }
+```
would generate two implementations like:
+```ignore
impl<S:serialize::Encoder> Encodable<S> for Node {
fn encode(&self, s: &S) {
s.emit_struct("Node", 1, || {
fn decode(d: &D) -> Node {
d.read_struct("Node", 1, || {
Node {
- id: d.read_field(~"x", 0, || decode(d))
+ id: d.read_field("x".to_owned(), 0, || decode(d))
}
})
}
}
+```
Other interesting scenarios are whe the item has type parameters or
references other non-built-in types. A type definition like:
- #[deriving(Encodable, Decodable)]
- struct spanned<T> {node: T, span: Span}
+```ignore
+#[deriving(Encodable, Decodable)]
+struct spanned<T> { node: T, span: Span }
+```
would yield functions like:
+```ignore
impl<
S: Encoder,
T: Encodable<S>
fn decode(d: &D) -> spanned<T> {
d.read_rec(|| {
{
- node: d.read_field(~"node", 0, || decode(d)),
- span: d.read_field(~"span", 1, || decode(d)),
+ node: d.read_field("node".to_owned(), 0, || decode(d)),
+ span: d.read_field("span".to_owned(), 1, || decode(d)),
}
})
}
}
+```
*/
-use ast::{MetaItem, Item, Expr, MutMutable};
+use ast::{MetaItem, Item, Expr, ExprRet, MutMutable, LitNil};
use codemap::Span;
use ext::base::ExtCtxt;
use ext::build::AstBuilder;
pub fn expand_deriving_encodable(cx: &mut ExtCtxt,
span: Span,
mitem: @MetaItem,
- in_items: ~[@Item]) -> ~[@Item] {
+ item: @Item,
+ push: |@Item|) {
let trait_def = TraitDef {
- cx: cx, span: span,
-
- path: Path::new_(~["serialize", "Encodable"], None,
- ~[~Literal(Path::new_local("__E"))], true),
- additional_bounds: ~[],
+ span: span,
+ attributes: Vec::new(),
+ path: Path::new_(vec!("serialize", "Encodable"), None,
+ vec!(~Literal(Path::new_local("__S")),
+ ~Literal(Path::new_local("__E"))), true),
+ additional_bounds: Vec::new(),
generics: LifetimeBounds {
- lifetimes: ~[],
- bounds: ~[("__E", ~[Path::new(~["serialize", "Encoder"])])],
+ lifetimes: Vec::new(),
+ bounds: vec!(("__S", vec!(Path::new_(
+ vec!("serialize", "Encoder"), None,
+ vec!(~Literal(Path::new_local("__E"))), true))),
+ ("__E", vec!()))
},
- methods: ~[
+ methods: vec!(
MethodDef {
name: "encode",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
- args: ~[Ptr(~Literal(Path::new_local("__E")),
- Borrowed(None, MutMutable))],
- ret_ty: nil_ty(),
+ args: vec!(Ptr(~Literal(Path::new_local("__S")),
+ Borrowed(None, MutMutable))),
+ ret_ty: Literal(Path::new_(vec!("std", "result", "Result"),
+ None,
+ vec!(~Tuple(Vec::new()),
+ ~Literal(Path::new_local("__E"))),
+ true)),
inline: false,
const_nonmatching: true,
combine_substructure: encodable_substructure,
- },
- ]
+ })
};
- trait_def.expand(mitem, in_items)
+ trait_def.expand(cx, mitem, item, push)
}
fn encodable_substructure(cx: &mut ExtCtxt, trait_span: Span,
return match *substr.fields {
Struct(ref fields) => {
let emit_struct_field = cx.ident_of("emit_struct_field");
- let mut stmts = ~[];
+ let mut stmts = Vec::new();
+ let last = fields.len() - 1;
for (i, &FieldInfo {
name,
self_,
..
}) in fields.iter().enumerate() {
let name = match name {
- Some(id) => token::get_ident(id.name),
+ Some(id) => token::get_ident(id),
None => {
token::intern_and_get_ident(format!("_field{}", i))
}
};
- let enc = cx.expr_method_call(span, self_, encode, ~[blkencoder]);
+ let enc = cx.expr_method_call(span, self_, encode, vec!(blkencoder));
let lambda = cx.lambda_expr_1(span, enc, blkarg);
let call = cx.expr_method_call(span, blkencoder,
emit_struct_field,
- ~[cx.expr_str(span, name),
+ vec!(cx.expr_str(span, name),
cx.expr_uint(span, i),
- lambda]);
+ lambda));
+
+ // last call doesn't need a try!
+ let call = if i != last {
+ cx.expr_try(span, call)
+ } else {
+ cx.expr(span, ExprRet(Some(call)))
+ };
stmts.push(cx.stmt_expr(call));
}
cx.expr_method_call(trait_span,
encoder,
cx.ident_of("emit_struct"),
- ~[
- cx.expr_str(trait_span,
- token::get_ident(substr.type_ident.name)),
+ vec!(
+ cx.expr_str(trait_span, token::get_ident(substr.type_ident)),
cx.expr_uint(trait_span, fields.len()),
blk
- ])
+ ))
}
EnumMatching(idx, variant, ref fields) => {
let me = cx.stmt_let(trait_span, false, blkarg, encoder);
let encoder = cx.expr_ident(trait_span, blkarg);
let emit_variant_arg = cx.ident_of("emit_enum_variant_arg");
- let mut stmts = ~[];
+ let mut stmts = Vec::new();
+ let last = fields.len() - 1;
for (i, &FieldInfo { self_, span, .. }) in fields.iter().enumerate() {
- let enc = cx.expr_method_call(span, self_, encode, ~[blkencoder]);
+ let enc = cx.expr_method_call(span, self_, encode, vec!(blkencoder));
let lambda = cx.lambda_expr_1(span, enc, blkarg);
let call = cx.expr_method_call(span, blkencoder,
emit_variant_arg,
- ~[cx.expr_uint(span, i),
- lambda]);
+ vec!(cx.expr_uint(span, i),
+ lambda));
+ let call = if i != last {
+ cx.expr_try(span, call)
+ } else {
+ cx.expr(span, ExprRet(Some(call)))
+ };
stmts.push(cx.stmt_expr(call));
}
+ // enums with no fields need to return Ok()
+ if stmts.len() == 0 {
+ let ret_ok = cx.expr(trait_span,
+ ExprRet(Some(cx.expr_ok(trait_span,
+ cx.expr_lit(trait_span, LitNil)))));
+ stmts.push(cx.stmt_expr(ret_ok));
+ }
+
let blk = cx.lambda_stmts_1(trait_span, stmts, blkarg);
- let name = cx.expr_str(trait_span,
- token::get_ident(variant.node.name.name));
+ let name = cx.expr_str(trait_span, token::get_ident(variant.node.name));
let call = cx.expr_method_call(trait_span, blkencoder,
cx.ident_of("emit_enum_variant"),
- ~[name,
+ vec!(name,
cx.expr_uint(trait_span, idx),
cx.expr_uint(trait_span, fields.len()),
- blk]);
+ blk));
let blk = cx.lambda_expr_1(trait_span, call, blkarg);
let ret = cx.expr_method_call(trait_span,
encoder,
cx.ident_of("emit_enum"),
- ~[
- cx.expr_str(trait_span,
- token::get_ident(substr.type_ident.name)),
+ vec!(
+ cx.expr_str(trait_span, token::get_ident(substr.type_ident)),
blk
- ]);
- cx.expr_block(cx.block(trait_span, ~[me], Some(ret)))
+ ));
+ cx.expr_block(cx.block(trait_span, vec!(me), Some(ret)))
}
_ => cx.bug("expected Struct or EnumMatching in deriving(Encodable)")
projects / rust.git / blobdiff