use syn::{self, aster, Ident};
use quote::Tokens;
use bound;
use internals::ast::{Body, Field, Item, Style, Variant};
use internals::{self, attr};
pub fn expand_derive_serialize(item: &syn::DeriveInput) -> Result<Tokens, String> {
let ctxt = internals::Ctxt::new();
let item = Item::from_ast(&ctxt, item);
try!(ctxt.check());
let impl_generics = build_impl_generics(&item);
let ty = aster::ty().path()
.segment(item.ident.clone()).with_generics(impl_generics.clone()).build()
.build();
let body = serialize_body(&item,
&impl_generics,
ty.clone());
let where_clause = &impl_generics.where_clause;
let dummy_const = Ident::new(format!("_IMPL_SERIALIZE_FOR_{}", item.ident));
Ok(quote! {
#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
const #dummy_const: () = {
extern crate serde as _serde;
#[automatically_derived]
impl #impl_generics _serde::Serialize for #ty #where_clause {
fn serialize<__S>(&self, _serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
where __S: _serde::Serializer
{
#body
}
}
};
})
}
fn build_impl_generics(item: &Item) -> syn::Generics {
let generics = bound::without_defaults(item.generics);
let generics = bound::with_where_predicates_from_fields(
item, &generics,
|attrs| attrs.ser_bound());
match item.attrs.ser_bound() {
Some(predicates) => {
bound::with_where_predicates(&generics, predicates)
}
None => {
bound::with_bound(item, &generics,
needs_serialize_bound,
&aster::path().ids(&["_serde", "Serialize"]).build())
}
}
}
fn needs_serialize_bound(attrs: &attr::Field) -> bool {
!attrs.skip_serializing()
&& attrs.serialize_with().is_none()
&& attrs.ser_bound().is_none()
}
fn serialize_body(
item: &Item,
impl_generics: &syn::Generics,
ty: syn::Ty,
) -> Tokens {
match item.body {
Body::Enum(ref variants) => {
serialize_item_enum(
&item.ident,
impl_generics,
ty,
variants,
&item.attrs)
}
Body::Struct(Style::Struct, ref fields) => {
if fields.iter().any(|field| field.ident.is_none()) {
panic!("struct has unnamed fields");
}
serialize_struct(
impl_generics,
ty,
fields,
&item.attrs)
}
Body::Struct(Style::Tuple, ref fields) => {
if fields.iter().any(|field| field.ident.is_some()) {
panic!("tuple struct has named fields");
}
serialize_tuple_struct(
impl_generics,
ty,
fields,
&item.attrs)
}
Body::Struct(Style::Newtype, ref fields) => {
serialize_newtype_struct(
impl_generics,
ty,
&fields[0],
&item.attrs)
}
Body::Struct(Style::Unit, _) => {
serialize_unit_struct(
&item.attrs)
}
}
}
fn serialize_unit_struct(item_attrs: &attr::Item) -> Tokens {
let type_name = item_attrs.name().serialize_name();
quote! {
_serializer.serialize_unit_struct(#type_name)
}
}
fn serialize_newtype_struct(
impl_generics: &syn::Generics,
item_ty: syn::Ty,
field: &Field,
item_attrs: &attr::Item,
) -> Tokens {
let type_name = item_attrs.name().serialize_name();
let mut field_expr = quote!(&self.0);
if let Some(path) = field.attrs.serialize_with() {
field_expr = wrap_serialize_with(
&item_ty, impl_generics, field.ty, path, field_expr);
}
quote! {
_serializer.serialize_newtype_struct(#type_name, #field_expr)
}
}
fn serialize_tuple_struct(
impl_generics: &syn::Generics,
ty: syn::Ty,
fields: &[Field],
item_attrs: &attr::Item,
) -> Tokens {
let serialize_stmts = serialize_tuple_struct_visitor(
ty.clone(),
fields,
impl_generics,
false,
quote!(_serde::ser::SerializeTupleStruct::serialize_field),
);
let type_name = item_attrs.name().serialize_name();
let len = serialize_stmts.len();
let let_mut = mut_if(len > 0);
quote! {
let #let_mut __serde_state = try!(_serializer.serialize_tuple_struct(#type_name, #len));
#(#serialize_stmts)*
_serde::ser::SerializeTupleStruct::end(__serde_state)
}
}
fn serialize_struct(
impl_generics: &syn::Generics,
ty: syn::Ty,
fields: &[Field],
item_attrs: &attr::Item,
) -> Tokens {
let serialize_fields = serialize_struct_visitor(
ty.clone(),
fields,
impl_generics,
false,
quote!(_serde::ser::SerializeStruct::serialize_field),
);
let type_name = item_attrs.name().serialize_name();
let mut serialized_fields = fields.iter()
.filter(|&field| !field.attrs.skip_serializing())
.peekable();
let let_mut = mut_if(serialized_fields.peek().is_some());
let len = serialized_fields
.map(|field| {
let ident = field.ident.clone().expect("struct has unnamed fields");
let field_expr = quote!(&self.#ident);
match field.attrs.skip_serializing_if() {
Some(path) => quote!(if #path(#field_expr) { 0 } else { 1 }),
None => quote!(1),
}
})
.fold(quote!(0), |sum, expr| quote!(#sum + #expr));
quote! {
let #let_mut __serde_state = try!(_serializer.serialize_struct(#type_name, #len));
#(#serialize_fields)*
_serde::ser::SerializeStruct::end(__serde_state)
}
}
fn serialize_item_enum(
type_ident: &syn::Ident,
impl_generics: &syn::Generics,
ty: syn::Ty,
variants: &[Variant],
item_attrs: &attr::Item,
) -> Tokens {
let arms: Vec<_> =
variants.iter()
.enumerate()
.map(|(variant_index, variant)| {
serialize_variant(
type_ident,
impl_generics,
ty.clone(),
variant,
variant_index,
item_attrs,
)
})
.collect();
quote! {
match *self {
#(#arms)*
}
}
}
fn serialize_variant(
type_ident: &syn::Ident,
generics: &syn::Generics,
ty: syn::Ty,
variant: &Variant,
variant_index: usize,
item_attrs: &attr::Item,
) -> Tokens {
let type_name = item_attrs.name().serialize_name();
let variant_ident = variant.ident.clone();
let variant_name = variant.attrs.name().serialize_name();
if variant.attrs.skip_serializing() {
let skipped_msg = format!("the enum variant {}::{} cannot be serialized",
type_ident, variant_ident);
let skipped_err = quote! {
Err(_serde::ser::Error::custom(#skipped_msg))
};
let fields_pat = match variant.style {
Style::Unit => quote!(),
Style::Newtype | Style::Tuple => quote!( (..) ),
Style::Struct => quote!( {..} ),
};
quote! {
#type_ident::#variant_ident #fields_pat => #skipped_err,
}
} else { match variant.style {
Style::Unit => {
quote! {
#type_ident::#variant_ident =>
_serde::Serializer::serialize_unit_variant(
_serializer,
#type_name,
#variant_index,
#variant_name,
),
}
},
Style::Newtype => {
let block = serialize_newtype_variant(
type_name,
variant_index,
variant_name,
ty,
generics,
&variant.fields[0],
);
quote! {
#type_ident::#variant_ident(ref __simple_value) => #block,
}
},
Style::Tuple => {
let field_names = (0 .. variant.fields.len())
.map(|i| Ident::new(format!("__field{}", i)));
let block = serialize_tuple_variant(
type_name,
variant_index,
variant_name,
generics,
ty,
&variant.fields,
);
quote! {
#type_ident::#variant_ident(#(ref #field_names),*) => { #block }
}
}
Style::Struct => {
let fields = variant.fields.iter()
.map(|f| f.ident.clone().expect("struct variant has unnamed fields"));
let block = serialize_struct_variant(
variant_index,
variant_name,
generics,
ty,
&variant.fields,
item_attrs,
);
quote! {
#type_ident::#variant_ident { #(ref #fields),* } => { #block }
}
}
}
}
}
fn serialize_newtype_variant(
type_name: String,
variant_index: usize,
variant_name: String,
item_ty: syn::Ty,
generics: &syn::Generics,
field: &Field,
) -> Tokens {
let mut field_expr = quote!(__simple_value);
if let Some(path) = field.attrs.serialize_with() {
field_expr = wrap_serialize_with(
&item_ty, generics, field.ty, path, field_expr);
}
quote! {
_serde::Serializer::serialize_newtype_variant(
_serializer,
#type_name,
#variant_index,
#variant_name,
#field_expr,
)
}
}
fn serialize_tuple_variant(
type_name: String,
variant_index: usize,
variant_name: String,
generics: &syn::Generics,
structure_ty: syn::Ty,
fields: &[Field],
) -> Tokens {
let serialize_stmts = serialize_tuple_struct_visitor(
structure_ty,
fields,
generics,
true,
quote!(_serde::ser::SerializeTupleVariant::serialize_field),
);
let len = serialize_stmts.len();
let let_mut = mut_if(len > 0);
quote! {
let #let_mut __serde_state = try!(_serializer.serialize_tuple_variant(
#type_name,
#variant_index,
#variant_name,
#len));
#(#serialize_stmts)*
_serde::ser::SerializeTupleVariant::end(__serde_state)
}
}
fn serialize_struct_variant(
variant_index: usize,
variant_name: String,
generics: &syn::Generics,
ty: syn::Ty,
fields: &[Field],
item_attrs: &attr::Item,
) -> Tokens {
let serialize_fields = serialize_struct_visitor(
ty.clone(),
fields,
generics,
true,
quote!(_serde::ser::SerializeStructVariant::serialize_field),
);
let item_name = item_attrs.name().serialize_name();
let mut serialized_fields = fields.iter()
.filter(|&field| !field.attrs.skip_serializing())
.peekable();
let let_mut = mut_if(serialized_fields.peek().is_some());
let len = serialized_fields
.map(|field| {
let ident = field.ident.clone().expect("struct has unnamed fields");
match field.attrs.skip_serializing_if() {
Some(path) => quote!(if #path(#ident) { 0 } else { 1 }),
None => quote!(1),
}
})
.fold(quote!(0), |sum, expr| quote!(#sum + #expr));
quote! {
let #let_mut __serde_state = try!(_serializer.serialize_struct_variant(
#item_name,
#variant_index,
#variant_name,
#len,
));
#(#serialize_fields)*
_serde::ser::SerializeStructVariant::end(__serde_state)
}
}
fn serialize_tuple_struct_visitor(
structure_ty: syn::Ty,
fields: &[Field],
generics: &syn::Generics,
is_enum: bool,
func: Tokens,
) -> Vec<Tokens> {
fields.iter()
.enumerate()
.map(|(i, field)| {
let mut field_expr = if is_enum {
let id = Ident::new(format!("__field{}", i));
quote!(#id)
} else {
let i = Ident::new(i);
quote!(&self.#i)
};
let skip = field.attrs.skip_serializing_if()
.map(|path| quote!(#path(#field_expr)));
if let Some(path) = field.attrs.serialize_with() {
field_expr = wrap_serialize_with(
&structure_ty, generics, field.ty, path, field_expr);
}
let ser = quote! {
try!(#func(&mut __serde_state, #field_expr));
};
match skip {
None => ser,
Some(skip) => quote!(if !#skip { #ser }),
}
})
.collect()
}
fn serialize_struct_visitor(
structure_ty: syn::Ty,
fields: &[Field],
generics: &syn::Generics,
is_enum: bool,
func: Tokens,
) -> Vec<Tokens> {
fields.iter()
.filter(|&field| !field.attrs.skip_serializing())
.map(|field| {
let ident = field.ident.clone().expect("struct has unnamed field");
let mut field_expr = if is_enum {
quote!(#ident)
} else {
quote!(&self.#ident)
};
let key_expr = field.attrs.name().serialize_name();
let skip = field.attrs.skip_serializing_if()
.map(|path| quote!(#path(#field_expr)));
if let Some(path) = field.attrs.serialize_with() {
field_expr = wrap_serialize_with(
&structure_ty, generics, field.ty, path, field_expr)
}
let ser = quote! {
try!(#func(&mut __serde_state, #key_expr, #field_expr));
};
match skip {
None => ser,
Some(skip) => quote!(if !#skip { #ser }),
}
})
.collect()
}
fn wrap_serialize_with(
item_ty: &syn::Ty,
generics: &syn::Generics,
field_ty: &syn::Ty,
path: &syn::Path,
value: Tokens,
) -> Tokens {
let where_clause = &generics.where_clause;
let wrapper_generics = aster::from_generics(generics.clone())
.add_lifetime_bound("'__a")
.lifetime_name("'__a")
.build();
let wrapper_ty = aster::path()
.segment("__SerializeWith")
.with_generics(wrapper_generics.clone())
.build()
.build();
quote!({
struct __SerializeWith #wrapper_generics #where_clause {
value: &'__a #field_ty,
phantom: ::std::marker::PhantomData<#item_ty>,
}
impl #wrapper_generics _serde::Serialize for #wrapper_ty #where_clause {
fn serialize<__S>(&self, __s: __S) -> _serde::export::Result<__S::Ok, __S::Error>
where __S: _serde::Serializer
{
#path(self.value, __s)
}
}
&__SerializeWith {
value: #value,
phantom: ::std::marker::PhantomData::<#item_ty>,
}
})
}
fn mut_if(is_mut: bool) -> Option<Tokens> {
if is_mut {
Some(quote!(mut))
} else {
None
}
}