#[macro_use]
extern crate quote;
#[macro_use]
extern crate syn;
extern crate proc_macro;
mod preprocess;
use proc_macro2::{Span, TokenStream};
use serde_derive_internals::ast::{Container, Data, Field, Style, Variant};
use serde_derive_internals::attr::{self, Default as SerdeDefault, EnumTag};
use serde_derive_internals::{Ctxt, Derive};
use syn::spanned::Spanned;
use syn::DeriveInput;
#[proc_macro_derive(MakeSchema, attributes(schemars, serde))]
pub fn derive_make_schema(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let mut input = parse_macro_input!(input as DeriveInput);
preprocess::add_trait_bounds(&mut input.generics);
preprocess::rename_schemars_attrs(&mut input);
let ctxt = Ctxt::new();
let cont = Container::from_ast(&ctxt, &input, Derive::Deserialize);
if let Err(e) = ctxt.check() {
return compile_error(input.span(), e).into();
}
let schema = match cont.data {
Data::Struct(Style::Struct, ref fields) => schema_for_struct(fields, &cont.attrs),
Data::Enum(ref variants) => schema_for_enum(variants, &cont.attrs),
_ => unimplemented!("work in progress!"),
};
let type_name = cont.ident;
let type_params: Vec<_> = cont.generics.type_params().map(|ty| &ty.ident).collect();
let schema_base_name = cont.attrs.name().deserialize_name();
let schema_name = if type_params.is_empty() {
quote! {
#schema_base_name.to_owned()
}
} else if schema_base_name == type_name.to_string() {
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())*)
}
} else {
let mut schema_name_fmt = schema_base_name;
for tp in &type_params {
schema_name_fmt.push_str(&format!("{{{}:.0}}", tp));
}
let fmt_param_names = &type_params;
let type_params = &type_params;
quote! {
format!(#schema_name_fmt #(,#fmt_param_names=#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::MakeSchema for #type_name #ty_generics #where_clause {
fn schema_name() -> String {
#schema_name
}
fn make_schema(gen: &mut schemars::gen::SchemaGenerator) -> schemars::Result {
Ok(#schema)
}
};
};
proc_macro::TokenStream::from(impl_block)
}
fn wrap_schema_fields(schema_contents: TokenStream) -> TokenStream {
quote! {
schemars::schema::Schema::Object(
schemars::schema::SchemaObject {
#schema_contents
..Default::default()
})
}
}
fn compile_error(span: Span, message: String) -> TokenStream {
quote_spanned! {span=>
compile_error!(#message);
}
}
fn is_unit_variant(v: &&Variant) -> bool {
match v.style {
Style::Unit => true,
_ => false,
}
}
fn schema_for_enum(variants: &[Variant], cattrs: &attr::Container) -> TokenStream {
match cattrs.tag() {
EnumTag::External => schema_for_external_tagged_enum(variants, cattrs),
EnumTag::None => schema_for_untagged_enum(variants, cattrs),
EnumTag::Internal { tag } => schema_for_internal_tagged_enum(variants, cattrs, tag),
_ => unimplemented!("Adjacent/internal tagged enums not yet supported."),
}
}
fn schema_for_external_tagged_enum(variants: &[Variant], cattrs: &attr::Container) -> TokenStream {
let (unit_variants, complex_variants): (Vec<_>, Vec<_>) =
variants.into_iter().partition(is_unit_variant);
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, cattrs);
wrap_schema_fields(quote! {
instance_type: Some(schemars::schema::InstanceType::Object.into()),
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
},
})
}));
wrap_schema_fields(quote! {
any_of: Some(vec![#(#schemas),*]),
})
}
fn schema_for_internal_tagged_enum(
variants: &[Variant],
cattrs: &attr::Container,
tag_name: &str,
) -> TokenStream {
let schemas = variants.into_iter().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 schema = wrap_schema_fields(quote! {
instance_type: Some(schemars::schema::InstanceType::Object.into()),
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
},
});
if is_unit_variant(&variant) {
schema
} else {
let sub_schema = schema_for_untagged_enum_variant(variant, cattrs);
quote! {
#schema.flatten(#sub_schema)?
}
}
});
wrap_schema_fields(quote! {
any_of: Some(vec![#(#schemas),*]),
})
}
fn schema_for_untagged_enum(variants: &[Variant], cattrs: &attr::Container) -> TokenStream {
let schemas = variants
.into_iter()
.map(|v| schema_for_untagged_enum_variant(v, cattrs));
wrap_schema_fields(quote! {
any_of: Some(vec![#(#schemas),*]),
})
}
fn schema_for_untagged_enum_variant(variant: &Variant, cattrs: &attr::Container) -> TokenStream {
match variant.style {
Style::Unit => quote! {
gen.subschema_for::<()>()?
},
Style::Newtype => {
let f = &variant.fields[0];
let ty = f.ty;
quote_spanned! {f.original.span()=>
gen.subschema_for::<#ty>()?
}
}
Style::Tuple => {
let types = variant.fields.iter().map(|f| f.ty);
quote! {
gen.subschema_for::<(#(#types),*)>()?
}
}
Style::Struct => schema_for_struct(&variant.fields, cattrs),
}
}
fn schema_for_struct(fields: &[Field], cattrs: &attr::Container) -> TokenStream {
let (nested, flat): (Vec<_>, Vec<_>) = fields.iter().partition(|f| !f.attrs.flatten());
let container_has_default = has_default(cattrs.default());
let mut required = Vec::new();
let recurse = nested.iter().map(|f| {
let name = f.attrs.name().deserialize_name();
if !container_has_default && !has_default(f.attrs.default()) {
required.push(name.clone());
}
let ty = f.ty;
quote_spanned! {f.original.span()=>
props.insert(#name.to_owned(), gen.subschema_for::<#ty>()?);
}
});
let schema = wrap_schema_fields(quote! {
instance_type: Some(schemars::schema::InstanceType::Object.into()),
properties: {
let mut props = schemars::Map::new();
#(#recurse)*
props
},
required: {
let mut required = schemars::Set::new();
#(required.insert(#required.to_owned());)*
required
},
});
let flattens = flat.iter().map(|f| {
let ty = f.ty;
quote_spanned! {f.original.span()=>
.flatten(<#ty>::make_schema(gen)?)?
}
});
quote! {
#schema #(#flattens)*
}
}
fn has_default(d: &SerdeDefault) -> bool {
match d {
SerdeDefault::None => false,
_ => true,
}
}