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use swc_macros_common::prelude::*;
use syn::{
parse::{Parse, ParseStream},
*,
};
struct VariantAttr {
tags: Punctuated<Lit, Token![,]>,
}
impl Parse for VariantAttr {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
Ok(VariantAttr {
tags: input.call(Punctuated::parse_terminated)?,
})
}
}
pub fn expand(
DeriveInput {
generics,
ident,
data,
..
}: DeriveInput,
) -> ItemImpl {
let data = match data {
Data::Enum(data) => data,
_ => unreachable!("expand_enum is called with none-enum item"),
};
let mut has_wildcard = false;
let deserialize = {
let mut all_tags: Punctuated<_, token::Comma> = Default::default();
let tag_match_arms = data
.variants
.iter()
.filter(|v| !crate::encoding::is_unknown(&v.attrs))
.map(|variant| {
let field_type = match variant.fields {
Fields::Unnamed(ref fields) => {
assert_eq!(
fields.unnamed.len(),
1,
"#[ast_node] enum cannot contain variant with multiple fields"
);
fields.unnamed.last().unwrap().ty.clone()
}
_ => {
unreachable!("#[ast_node] enum cannot contain named fields or unit variant")
}
};
let tags = variant
.attrs
.iter()
.filter_map(|attr| -> Option<VariantAttr> {
if !is_attr_name(attr, "tag") {
return None;
}
let tokens = match &attr.meta {
Meta::List(meta) => meta.tokens.clone(),
_ => {
panic!("#[tag] attribute must be in form of #[tag(..)]")
}
};
let tags = parse2(tokens).expect("failed to parse #[tag] attribute");
Some(tags)
})
.flat_map(|v| v.tags)
.collect::<Punctuated<_, token::Comma>>();
assert!(
!tags.is_empty(),
"All #[ast_node] enum variants have one or more tag"
);
// TODO: Clean up this code
if tags.len() == 1
&& match tags.first() {
Some(Lit::Str(s)) => &*s.value() == "*",
_ => false,
}
{
has_wildcard = true;
} else {
for tag in tags.iter() {
all_tags.push(tag.clone());
}
}
let vi = &variant.ident;
Arm {
attrs: Default::default(),
pat: Pat::Path(parse_quote!(__TypeVariant::#vi)),
guard: Default::default(),
fat_arrow_token: Token),
body: parse_quote!(
swc_common::private::serde::Result::map(
<#field_type as serde::Deserialize>::deserialize(
swc_common::private::serde::de::ContentDeserializer::<
__D::Error,
>::new(__content),
),
Self::#vi,
)
),
comma: Some(Token)),
}
})
.collect::<Vec<Arm>>();
let tag_expr: Expr = {
let mut visit_str_arms = Vec::new();
let mut visit_bytes_arms = Vec::new();
for variant in &data.variants {
if crate::encoding::is_unknown(&variant.attrs) {
continue;
}
let tags = variant
.attrs
.iter()
.filter_map(|attr| -> Option<VariantAttr> {
if !is_attr_name(attr, "tag") {
return None;
}
let tokens = match &attr.meta {
Meta::List(meta) => meta.tokens.clone(),
_ => {
panic!("#[tag] attribute must be in form of #[tag(..)]")
}
};
let tags = parse2(tokens).expect("failed to parse #[tag] attribute");
Some(tags)
})
.flat_map(|v| v.tags)
.collect::<Punctuated<_, token::Comma>>();
assert!(
!tags.is_empty(),
"All #[ast_node] enum variants have one or more tag"
);
let (str_pat, bytes_pat) = {
if tags.len() == 1
&& match tags.first() {
Some(Lit::Str(s)) => &*s.value() == "*",
_ => false,
}
{
(
Pat::Wild(PatWild {
attrs: Default::default(),
underscore_token: Token),
}),
Pat::Wild(PatWild {
attrs: Default::default(),
underscore_token: Token),
}),
)
} else {
fn make_pat(lit: Lit) -> (Pat, Pat) {
let s = match lit.clone() {
Lit::Str(s) => s.value(),
_ => {
unreachable!()
}
};
(
Pat::Lit(PatLit {
attrs: Default::default(),
lit,
}),
Pat::Lit(PatLit {
attrs: Default::default(),
lit: Lit::ByteStr(LitByteStr::new(s.as_bytes(), call_site())),
}),
)
}
if tags.len() == 1 {
make_pat(tags.into_iter().next().unwrap())
} else {
let mut str_cases = Punctuated::new();
let mut bytes_cases = Punctuated::new();
for tag in tags {
let (str_pat, bytes_pat) = make_pat(tag);
str_cases.push(str_pat);
bytes_cases.push(bytes_pat);
}
(
Pat::Or(PatOr {
attrs: Default::default(),
leading_vert: Default::default(),
cases: str_cases,
}),
Pat::Or(PatOr {
attrs: Default::default(),
leading_vert: Default::default(),
cases: bytes_cases,
}),
)
}
}
};
visit_str_arms.push(Arm {
attrs: Default::default(),
pat: str_pat,
guard: None,
fat_arrow_token: Token),
body: {
let vi = &variant.ident;
parse_quote!(Ok(__TypeVariant::#vi))
},
comma: Some(Token)),
});
visit_bytes_arms.push(Arm {
attrs: Default::default(),
pat: bytes_pat,
guard: None,
fat_arrow_token: Token),
body: {
let vi = &variant.ident;
parse_quote!(Ok(__TypeVariant::#vi))
},
comma: Some(Token)),
});
}
if !has_wildcard {
visit_str_arms.push(Arm {
attrs: Default::default(),
pat: Pat::Wild(PatWild {
attrs: Default::default(),
underscore_token: Token),
}),
guard: None,
fat_arrow_token: Token),
body: parse_quote!(swc_common::private::serde::Err(
serde::de::Error::unknown_variant(__value, VARIANTS,)
)),
comma: Some(Token)),
});
visit_bytes_arms.push(Arm {
attrs: Default::default(),
pat: Pat::Wild(PatWild {
attrs: Default::default(),
underscore_token: Token!(_)(ident.span()),
}),
guard: None,
fat_arrow_token: Token),
body: parse_quote!({
let __value = &swc_common::private::serde::from_utf8_lossy(__value);
swc_common::private::serde::Err(serde::de::Error::unknown_variant(
__value, VARIANTS,
))
}),
comma: Some(Token)),
});
}
let visit_str_body = Expr::Match(ExprMatch {
attrs: Default::default(),
match_token: Default::default(),
expr: parse_quote!(__value),
brace_token: Default::default(),
arms: visit_str_arms,
});
let visit_bytes_body = Expr::Match(ExprMatch {
attrs: Default::default(),
match_token: Default::default(),
expr: parse_quote!(__value),
brace_token: Default::default(),
arms: visit_bytes_arms,
});
parse_quote!({
static VARIANTS: &[&str] = &[#all_tags];
struct __TypeVariantVisitor;
impl<'de> serde::de::Visitor<'de> for __TypeVariantVisitor {
type Value = __TypeVariant;
fn expecting(
&self,
__formatter: &mut swc_common::private::serde::Formatter,
) -> swc_common::private::serde::fmt::Result {
swc_common::private::serde::Formatter::write_str(
__formatter,
"variant identifier",
)
}
fn visit_str<__E>(
self,
__value: &str,
) -> swc_common::private::serde::Result<Self::Value, __E>
where
__E: serde::de::Error,
{
#visit_str_body
}
fn visit_bytes<__E>(
self,
__value: &[u8],
) -> swc_common::private::serde::Result<Self::Value, __E>
where
__E: serde::de::Error,
{
#visit_bytes_body
}
}
impl<'de> serde::Deserialize<'de> for __TypeVariant {
#[inline]
fn deserialize<__D>(
__deserializer: __D,
) -> swc_common::private::serde::Result<Self, __D::Error>
where
__D: serde::Deserializer<'de>,
{
serde::Deserializer::deserialize_identifier(
__deserializer,
__TypeVariantVisitor,
)
}
}
let ty = swc_common::serializer::Type::deserialize(
swc_common::private::serde::de::ContentRefDeserializer::<__D::Error>::new(
&__content,
),
)?;
let __tagged = __TypeVariant::deserialize(
swc_common::private::serde::de::ContentDeserializer::<__D::Error>::new(
swc_common::private::serde::de::Content::Str(&ty.ty),
),
)?;
__tagged
})
};
let match_type_expr = Expr::Match(ExprMatch {
attrs: Default::default(),
match_token: Default::default(),
expr: parse_quote!(__tagged),
brace_token: Default::default(),
arms: tag_match_arms,
});
let variants: Punctuated<Variant, Token![,]> = {
data.variants
.iter()
.filter(|v| !crate::encoding::is_unknown(&v.attrs))
.cloned()
.map(|variant| Variant {
attrs: Default::default(),
fields: Fields::Unit,
..variant
})
.collect()
};
let item: ItemImpl = parse_quote!(
#[cfg(feature = "serde-impl")]
impl<'de> serde::Deserialize<'de> for #ident {
#[allow(unreachable_code)]
fn deserialize<__D>(__deserializer: __D) -> ::std::result::Result<Self, __D::Error>
where
__D: serde::Deserializer<'de>,
{
enum __TypeVariant {
#variants,
}
let __content = swc_common::private::content::deserialize_content(__deserializer)?;
let __tagged = #tag_expr;
#match_type_expr
}
}
);
item.with_generics(generics)
};
deserialize
}