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Initial work to support serialization of adjacently tagged enums.

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This commit is contained in:
Elliott Slaughter
2017-02-17 21:44:15 -08:00
parent c590df13b9
commit 4538143d00
4 changed files with 317 additions and 11 deletions
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serde_codegen_internals/src/attr.rs
+50 -5
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@@ -112,6 +112,13 @@ pub enum EnumTag {
/// ```
Internal(String),
/// `#[serde(tag = "type", content = "name")]`
///
/// ```json
/// {"type": "variant1", "name": {"key1": "value1", "key2": "value2"}}
/// ```
Adjacent(String, String),
/// `#[serde(untagged)]`
///
/// ```json
@@ -130,6 +137,7 @@ impl Item {
let mut de_bound = Attr::none(cx, "bound");
let mut untagged = BoolAttr::none(cx, "untagged");
let mut internal_tag = Attr::none(cx, "tag");
let mut internal_content = Attr::none(cx, "content");
for meta_items in item.attrs.iter().filter_map(get_serde_meta_items) {
for meta_item in meta_items {
@@ -198,6 +206,20 @@ impl Item {
}
}
// Parse `#[serde(content = "name")]`
MetaItem(NameValue(ref name, ref lit)) if name == "content" => {
if let Ok(s) = get_string_from_lit(cx, name.as_ref(), name.as_ref(), lit) {
match item.body {
syn::Body::Enum(_) => {
internal_content.set(s);
}
syn::Body::Struct(_) => {
cx.error("#[serde(tag = \"...\")] can only be used on enums")
}
}
}
}
MetaItem(ref meta_item) => {
cx.error(format!("unknown serde container attribute `{}`",
meta_item.name()));
@@ -210,10 +232,10 @@ impl Item {
}
}
let tag = match (untagged.get(), internal_tag.get()) {
(false, None) => EnumTag::External,
(true, None) => EnumTag::None,
(false, Some(tag)) => {
let tag = match (untagged.get(), internal_tag.get(), internal_content.get()) {
(false, None, None) => EnumTag::External,
(true, None, None) => EnumTag::None,
(false, Some(tag), None) => {
// Check that there are no tuple variants.
if let syn::Body::Enum(ref variants) = item.body {
for variant in variants {
@@ -232,10 +254,33 @@ impl Item {
}
EnumTag::Internal(tag)
}
(true, Some(_)) => {
(false, Some(tag), Some(content)) => {
// Check that there are no struct variants.
if let syn::Body::Enum(ref variants) = item.body {
for variant in variants {
match variant.data {
syn::VariantData::Tuple(_) |
syn::VariantData::Unit => {}
syn::VariantData::Struct(ref fields) => {
if fields.len() != 1 {
cx.error("#[serde(tag = \"...\", content = \"...\")] cannot \
be used with struct variants");
break;
}
}
}
}
}
EnumTag::Adjacent(tag, content)
}
(true, Some(_), _) => {
cx.error("enum cannot be both untagged and internally tagged");
EnumTag::External // doesn't matter, will error
}
(_, None, Some(_)) => {
cx.error("#[serde(content = \"...\")] cannot be used without #[serde(tag = \"...\")]");
EnumTag::External // doesn't matter, will error
}
};
Item {