#[macro_use]
extern crate quote;
#[macro_use]
extern crate syn;
extern crate proc_macro;
mod attr;
mod metadata;
use metadata::*;
use proc_macro2::TokenStream;
use quote::ToTokens;
use serde_derive_internals::ast::{Container, Data, Field, Style, Variant};
use serde_derive_internals::attr::{self as serde_attr, Default as SerdeDefault, TagType};
use serde_derive_internals::{Ctxt, Derive};
use syn::spanned::Spanned;
#[proc_macro_derive(JsonSchema, attributes(schemars, serde))]
pub fn derive_json_schema(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let mut input = parse_macro_input!(input as syn::DeriveInput);
add_trait_bounds(&mut input.generics);
if let Err(e) = attr::process_serde_attrs(&mut input) {
return compile_error(&e).into();
}
let ctxt = Ctxt::new();
let cont = Container::from_ast(&ctxt, &input, Derive::Deserialize);
if let Err(e) = ctxt.check() {
return compile_error(&e).into();
}
let cont = cont.expect("from_ast set no errors on Ctxt, so should have returned Some");
let schema_expr = match cont.data {
Data::Struct(Style::Unit, _) => schema_for_unit_struct(),
Data::Struct(Style::Newtype, ref fields) => schema_for_newtype_struct(&fields[0]),
Data::Struct(Style::Tuple, ref fields) => schema_for_tuple_struct(fields),
Data::Struct(Style::Struct, ref fields) => schema_for_struct(fields, Some(&cont.attrs)),
Data::Enum(ref variants) => schema_for_enum(variants, &cont.attrs),
};
let doc_metadata = SchemaMetadata::from_doc_attrs(&cont.original.attrs);
let schema_expr = doc_metadata.apply_to_schema(schema_expr);
let type_name = cont.ident;
let type_params: Vec<_> = cont.generics.type_params().map(|ty| &ty.ident).collect();
let mut schema_base_name = cont.attrs.name().deserialize_name();
let schema_is_renamed = type_name != schema_base_name;
if !schema_is_renamed {
if let Some(path) = cont.attrs.remote() {
if let Some(segment) = path.segments.last() {
schema_base_name = segment.ident.to_string();
}
}
}
let schema_name = if type_params.is_empty() {
quote! {
#schema_base_name.to_owned()
}
} else if schema_is_renamed {
let mut schema_name_fmt = schema_base_name;
for tp in &type_params {
schema_name_fmt.push_str(&format!("{{{}:.0}}", tp));
}
quote! {
format!(#schema_name_fmt #(,#type_params=#type_params::schema_name())*)
}
} else {
let mut schema_name_fmt = schema_base_name;
schema_name_fmt.push_str("_for_{}");
schema_name_fmt.push_str(&"_and_{}".repeat(type_params.len() - 1));
quote! {
format!(#schema_name_fmt #(,#type_params::schema_name())*)
}
};
let (impl_generics, ty_generics, where_clause) = cont.generics.split_for_impl();
let impl_block = quote! {
#[automatically_derived]
impl #impl_generics schemars::JsonSchema for #type_name #ty_generics #where_clause {
fn schema_name() -> std::string::String {
#schema_name
}
fn json_schema(gen: &mut schemars::gen::SchemaGenerator) -> schemars::schema::Schema {
#schema_expr
}
};
};
proc_macro::TokenStream::from(impl_block)
}
fn add_trait_bounds(generics: &mut syn::Generics) {
for param in &mut generics.params {
if let syn::GenericParam::Type(ref mut type_param) = *param {
type_param.bounds.push(parse_quote!(schemars::JsonSchema));
}
}
}
fn wrap_schema_fields(schema_contents: TokenStream) -> TokenStream {
quote! {
schemars::schema::Schema::Object(
schemars::schema::SchemaObject {
#schema_contents
..Default::default()
})
}
}
fn compile_error<'a>(errors: impl IntoIterator<Item = &'a syn::Error>) -> TokenStream {
let compile_errors = errors.into_iter().map(syn::Error::to_compile_error);
quote! {
#(#compile_errors)*
}
}
fn is_unit_variant(v: &Variant) -> bool {
match v.style {
Style::Unit => true,
_ => false,
}
}
fn schema_for_enum(variants: &[Variant], cattrs: &serde_attr::Container) -> TokenStream {
let variants = variants.iter().filter(|v| !v.attrs.skip_deserializing());
match cattrs.tag() {
TagType::External => schema_for_external_tagged_enum(variants),
TagType::None => schema_for_untagged_enum(variants),
TagType::Internal { tag } => schema_for_internal_tagged_enum(variants, tag),
TagType::Adjacent { .. } => unimplemented!("Adjacent tagged enums not yet supported."),
}
}
fn schema_for_external_tagged_enum<'a>(
variants: impl Iterator<Item = &'a Variant<'a>>,
) -> TokenStream {
let (unit_variants, complex_variants): (Vec<_>, Vec<_>) =
variants.partition(|v| is_unit_variant(v));
let unit_count = unit_variants.len();
let unit_names = unit_variants
.into_iter()
.map(|v| v.attrs.name().deserialize_name());
let unit_schema = wrap_schema_fields(quote! {
enum_values: Some(vec![#(#unit_names.into()),*]),
});
if complex_variants.is_empty() {
return unit_schema;
}
let mut schemas = Vec::new();
if unit_count > 0 {
schemas.push(unit_schema);
}
schemas.extend(complex_variants.into_iter().map(|variant| {
let name = variant.attrs.name().deserialize_name();
let sub_schema = schema_for_untagged_enum_variant(variant);
let schema_expr = wrap_schema_fields(quote! {
instance_type: Some(schemars::schema::InstanceType::Object.into()),
object: Some(Box::new(schemars::schema::ObjectValidation {
properties: {
let mut props = schemars::Map::new();
props.insert(#name.to_owned(), #sub_schema);
props
},
required: {
let mut required = schemars::Set::new();
required.insert(#name.to_owned());
required
},
..Default::default()
})),
});
let doc_metadata = SchemaMetadata::from_doc_attrs(&variant.original.attrs);
doc_metadata.apply_to_schema(schema_expr)
}));
wrap_schema_fields(quote! {
subschemas: Some(Box::new(schemars::schema::SubschemaValidation {
any_of: Some(vec![#(#schemas),*]),
..Default::default()
})),
})
}
fn schema_for_internal_tagged_enum<'a>(
variants: impl Iterator<Item = &'a Variant<'a>>,
tag_name: &str,
) -> TokenStream {
let schemas = variants.map(|variant| {
let name = variant.attrs.name().deserialize_name();
let type_schema = wrap_schema_fields(quote! {
instance_type: Some(schemars::schema::InstanceType::String.into()),
enum_values: Some(vec![#name.into()]),
});
let tag_schema = wrap_schema_fields(quote! {
instance_type: Some(schemars::schema::InstanceType::Object.into()),
object: Some(Box::new(schemars::schema::ObjectValidation {
properties: {
let mut props = schemars::Map::new();
props.insert(#tag_name.to_owned(), #type_schema);
props
},
required: {
let mut required = schemars::Set::new();
required.insert(#tag_name.to_owned());
required
},
..Default::default()
})),
});
let doc_metadata = SchemaMetadata::from_doc_attrs(&variant.original.attrs);
let tag_schema = doc_metadata.apply_to_schema(tag_schema);
let variant_schema = match variant.style {
Style::Unit => return tag_schema,
Style::Newtype => {
let field = &variant.fields[0];
let ty = get_json_schema_type(field);
quote_spanned! {field.original.span()=>
<#ty>::json_schema(gen)
}
}
Style::Struct => schema_for_struct(&variant.fields, None),
Style::Tuple => unreachable!("Internal tagged enum tuple variants will have caused serde_derive_internals to output a compile error already."),
};
quote! {
#tag_schema.flatten(#variant_schema)
}
});
wrap_schema_fields(quote! {
subschemas: Some(Box::new(schemars::schema::SubschemaValidation {
any_of: Some(vec![#(#schemas),*]),
..Default::default()
})),
})
}
fn schema_for_untagged_enum<'a>(variants: impl Iterator<Item = &'a Variant<'a>>) -> TokenStream {
let schemas = variants.map(|variant| {
let schema_expr = schema_for_untagged_enum_variant(variant);
let doc_metadata = SchemaMetadata::from_doc_attrs(&variant.original.attrs);
doc_metadata.apply_to_schema(schema_expr)
});
wrap_schema_fields(quote! {
subschemas: Some(Box::new(schemars::schema::SubschemaValidation {
any_of: Some(vec![#(#schemas),*]),
..Default::default()
})),
})
}
fn schema_for_untagged_enum_variant(variant: &Variant) -> TokenStream {
match variant.style {
Style::Unit => schema_for_unit_struct(),
Style::Newtype => schema_for_newtype_struct(&variant.fields[0]),
Style::Tuple => schema_for_tuple_struct(&variant.fields),
Style::Struct => schema_for_struct(&variant.fields, None),
}
}
fn schema_for_unit_struct() -> TokenStream {
quote! {
gen.subschema_for::<()>()
}
}
fn schema_for_newtype_struct(field: &Field) -> TokenStream {
let ty = get_json_schema_type(field);
quote_spanned! {field.original.span()=>
gen.subschema_for::<#ty>()
}
}
fn schema_for_tuple_struct(fields: &[Field]) -> TokenStream {
let types = fields
.iter()
.filter(|f| !f.attrs.skip_deserializing())
.map(get_json_schema_type);
quote! {
gen.subschema_for::<(#(#types),*)>()
}
}
fn schema_for_struct(fields: &[Field], cattrs: Option<&serde_attr::Container>) -> TokenStream {
let (flattened_fields, property_fields): (Vec<_>, Vec<_>) = fields
.iter()
.filter(|f| !f.attrs.skip_deserializing() || !f.attrs.skip_serializing())
.partition(|f| f.attrs.flatten());
let set_container_default = match cattrs.map_or(&SerdeDefault::None, |c| c.default()) {
SerdeDefault::None => None,
SerdeDefault::Default => Some(quote!(let container_default = Self::default();)),
SerdeDefault::Path(path) => Some(quote!(let container_default = #path();)),
};
let properties = property_fields.iter().map(|field| {
let name = field.attrs.name().deserialize_name();
let default = field_default_expr(field, set_container_default.is_some());
let required = match default {
Some(_) => quote!(false),
None => quote!(true),
};
let metadata = &SchemaMetadata {
read_only: field.attrs.skip_deserializing(),
write_only: field.attrs.skip_serializing(),
default,
..SchemaMetadata::from_doc_attrs(&field.original.attrs)
};
let ty = get_json_schema_type(field);
let span = field.original.span();
quote_spanned! {span=>
<#ty>::add_schema_as_property(gen, &mut schema_object, #name.to_owned(), #metadata, #required);
}
});
let flattens = flattened_fields.iter().map(|field| {
let ty = get_json_schema_type(field);
let span = field.original.span();
quote_spanned! {span=>
.flatten(<#ty>::json_schema_for_flatten(gen))
}
});
quote! {
{
#set_container_default
let mut schema_object = schemars::schema::SchemaObject {
instance_type: Some(schemars::schema::InstanceType::Object.into()),
..Default::default()
};
#(#properties)*
schemars::schema::Schema::Object(schema_object)
#(#flattens)*
}
}
}
fn field_default_expr(field: &Field, container_has_default: bool) -> Option<TokenStream> {
let field_default = field.attrs.default();
if field.attrs.skip_serializing() || (field_default.is_none() && !container_has_default) {
return None;
}
let ty = field.ty;
let default_expr = match field_default {
SerdeDefault::None => {
let member = &field.member;
quote!(container_default.#member)
}
SerdeDefault::Default => quote!(<#ty>::default()),
SerdeDefault::Path(path) => quote!(#path()),
};
let default_expr = match field.attrs.skip_serializing_if() {
Some(skip_if) => {
quote! {
{
let default = #default_expr;
if #skip_if(&default) {
None
} else {
Some(default)
}
}
}
}
None => quote!(Some(#default_expr)),
};
Some(if let Some(ser_with) = field.attrs.serialize_with() {
quote! {
{
struct _SchemarsDefaultSerialize<T>(T);
impl serde::Serialize for _SchemarsDefaultSerialize<#ty>
{
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: serde::Serializer
{
#ser_with(&self.0, serializer)
}
}
#default_expr.map(|d| _SchemarsDefaultSerialize(d))
}
}
} else {
default_expr
})
}
fn get_json_schema_type(field: &Field) -> Box<dyn ToTokens> {
match attr::get_with_from_attrs(&field.original) {
None => Box::new(field.ty.clone()),
Some(Ok(expr_path)) => Box::new(expr_path),
Some(Err(e)) => Box::new(compile_error(&[e])),
}
}