juniper_codegen/graphql_scalar/mod.rs
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//! Code generation for [GraphQL scalar][1].
//!
//! [1]: https://spec.graphql.org/October2021#sec-Scalars
use proc_macro2::{Literal, TokenStream};
use quote::{format_ident, quote, ToTokens, TokenStreamExt};
use syn::{
ext::IdentExt as _,
parse::{Parse, ParseStream},
parse_quote,
spanned::Spanned as _,
token,
visit_mut::VisitMut,
};
use url::Url;
use crate::common::{
filter_attrs,
parse::{
attr::{err, OptionExt as _},
ParseBufferExt as _,
},
scalar, AttrNames, Description, SpanContainer,
};
pub mod attr;
pub mod derive;
/// Available arguments behind `#[graphql]`/`#[graphql_scalar]` attributes when
/// generating code for [GraphQL scalar][1].
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
#[derive(Debug, Default)]
struct Attr {
/// Name of this [GraphQL scalar][1] in GraphQL schema.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
name: Option<SpanContainer<String>>,
/// Description of this [GraphQL scalar][1] to put into GraphQL schema.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
description: Option<SpanContainer<Description>>,
/// Spec [`Url`] of this [GraphQL scalar][1] to put into GraphQL schema.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
specified_by_url: Option<SpanContainer<Url>>,
/// Explicitly specified type (or type parameter with its bounds) of
/// [`ScalarValue`] to use for resolving this [GraphQL scalar][1] type with.
///
/// If [`None`], then generated code will be generic over any
/// [`ScalarValue`] type, which, in turn, requires all [scalar][1] fields to
/// be generic over any [`ScalarValue`] type too. That's why this type
/// should be specified only if one of the variants implements
/// [`GraphQLType`] in a non-generic way over [`ScalarValue`] type.
///
/// [`GraphQLType`]: juniper::GraphQLType
/// [`ScalarValue`]: juniper::ScalarValue
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
scalar: Option<SpanContainer<scalar::AttrValue>>,
/// Explicitly specified function to be used as
/// [`ToInputValue::to_input_value`] implementation.
///
/// [`ToInputValue::to_input_value`]: juniper::ToInputValue::to_input_value
to_output: Option<SpanContainer<syn::ExprPath>>,
/// Explicitly specified function to be used as
/// [`FromInputValue::from_input_value`] implementation.
///
/// [`FromInputValue::from_input_value`]: juniper::FromInputValue::from_input_value
from_input: Option<SpanContainer<syn::ExprPath>>,
/// Explicitly specified resolver to be used as
/// [`ParseScalarValue::from_str`] implementation.
///
/// [`ParseScalarValue::from_str`]: juniper::ParseScalarValue::from_str
parse_token: Option<SpanContainer<ParseToken>>,
/// Explicitly specified module with all custom resolvers for
/// [`Self::to_output`], [`Self::from_input`] and [`Self::parse_token`].
with: Option<SpanContainer<syn::ExprPath>>,
/// Explicit where clause added to [`syn::WhereClause`].
where_clause: Option<SpanContainer<Vec<syn::WherePredicate>>>,
/// Indicator for single-field structs allowing to delegate implmemntations
/// of non-provided resolvers to that field.
transparent: bool,
}
impl Parse for Attr {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let mut out = Self::default();
while !input.is_empty() {
let ident = input.parse_any_ident()?;
match ident.to_string().as_str() {
"name" => {
input.parse::<token::Eq>()?;
let name = input.parse::<syn::LitStr>()?;
out.name
.replace(SpanContainer::new(
ident.span(),
Some(name.span()),
name.value(),
))
.none_or_else(|_| err::dup_arg(&ident))?
}
"desc" | "description" => {
input.parse::<token::Eq>()?;
let desc = input.parse::<Description>()?;
out.description
.replace(SpanContainer::new(ident.span(), Some(desc.span()), desc))
.none_or_else(|_| err::dup_arg(&ident))?
}
"specified_by_url" => {
input.parse::<token::Eq>()?;
let lit = input.parse::<syn::LitStr>()?;
let url = lit.value().parse::<Url>().map_err(|err| {
syn::Error::new(lit.span(), format!("Invalid URL: {err}"))
})?;
out.specified_by_url
.replace(SpanContainer::new(ident.span(), Some(lit.span()), url))
.none_or_else(|_| err::dup_arg(&ident))?
}
"scalar" | "Scalar" | "ScalarValue" => {
input.parse::<token::Eq>()?;
let scl = input.parse::<scalar::AttrValue>()?;
out.scalar
.replace(SpanContainer::new(ident.span(), Some(scl.span()), scl))
.none_or_else(|_| err::dup_arg(&ident))?
}
"to_output_with" => {
input.parse::<token::Eq>()?;
let scl = input.parse::<syn::ExprPath>()?;
out.to_output
.replace(SpanContainer::new(ident.span(), Some(scl.span()), scl))
.none_or_else(|_| err::dup_arg(&ident))?
}
"from_input_with" => {
input.parse::<token::Eq>()?;
let scl = input.parse::<syn::ExprPath>()?;
out.from_input
.replace(SpanContainer::new(ident.span(), Some(scl.span()), scl))
.none_or_else(|_| err::dup_arg(&ident))?
}
"parse_token_with" => {
input.parse::<token::Eq>()?;
let scl = input.parse::<syn::ExprPath>()?;
out.parse_token
.replace(SpanContainer::new(
ident.span(),
Some(scl.span()),
ParseToken::Custom(scl),
))
.none_or_else(|_| err::dup_arg(&ident))?
}
"parse_token" => {
let types;
let _ = syn::parenthesized!(types in input);
let parsed_types = types.parse_terminated(syn::Type::parse, token::Comma)?;
if parsed_types.is_empty() {
return Err(syn::Error::new(ident.span(), "expected at least 1 type."));
}
out.parse_token
.replace(SpanContainer::new(
ident.span(),
Some(parsed_types.span()),
ParseToken::Delegated(parsed_types.into_iter().collect()),
))
.none_or_else(|_| err::dup_arg(&ident))?
}
"with" => {
input.parse::<token::Eq>()?;
let scl = input.parse::<syn::ExprPath>()?;
out.with
.replace(SpanContainer::new(ident.span(), Some(scl.span()), scl))
.none_or_else(|_| err::dup_arg(&ident))?
}
"where" => {
let (span, parsed_predicates) = {
let predicates;
let _ = syn::parenthesized!(predicates in input);
let parsed_predicates = predicates
.parse_terminated(syn::WherePredicate::parse, token::Comma)?;
if parsed_predicates.is_empty() {
return Err(syn::Error::new(
ident.span(),
"expected at least 1 where predicate",
));
}
(
parsed_predicates.span(),
parsed_predicates.into_iter().collect(),
)
};
out.where_clause
.replace(SpanContainer::new(
ident.span(),
Some(span),
parsed_predicates,
))
.none_or_else(|_| err::dup_arg(&ident))?
}
"transparent" => {
out.transparent = true;
}
name => {
return Err(err::unknown_arg(&ident, name));
}
}
input.try_parse::<token::Comma>()?;
}
Ok(out)
}
}
impl Attr {
/// Tries to merge two [`Attr`]s into a single one, reporting about
/// duplicates, if any.
fn try_merge(self, mut another: Self) -> syn::Result<Self> {
Ok(Self {
name: try_merge_opt!(name: self, another),
description: try_merge_opt!(description: self, another),
specified_by_url: try_merge_opt!(specified_by_url: self, another),
scalar: try_merge_opt!(scalar: self, another),
to_output: try_merge_opt!(to_output: self, another),
from_input: try_merge_opt!(from_input: self, another),
parse_token: try_merge_opt!(parse_token: self, another),
with: try_merge_opt!(with: self, another),
where_clause: try_merge_opt!(where_clause: self, another),
transparent: self.transparent || another.transparent,
})
}
/// Parses an [`Attr`] from the provided multiple [`syn::Attribute`]s with
/// the specified `names`, placed on a type definition.
fn from_attrs(names: impl AttrNames, attrs: &[syn::Attribute]) -> syn::Result<Self> {
let mut attr = filter_attrs(names, attrs)
.map(|attr| attr.parse_args())
.try_fold(Self::default(), |prev, curr| prev.try_merge(curr?))?;
if attr.description.is_none() {
attr.description = Description::parse_from_doc_attrs(attrs)?;
}
Ok(attr)
}
}
/// [`syn::Type`] in case of `#[graphql_scalar]` or [`syn::Ident`] in case of
/// `#[derive(GraphQLScalar)]`.
#[derive(Clone)]
enum TypeOrIdent {
/// [`syn::Type`].
Type(Box<syn::Type>),
/// [`syn::Ident`].
Ident(syn::Ident),
}
/// Definition of [GraphQL scalar][1] for code generation.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
struct Definition {
/// Name of this [GraphQL scalar][1] in GraphQL schema.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
name: String,
/// [`TypeOrIdent`] of this [GraphQL scalar][1] in GraphQL schema.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
ty: TypeOrIdent,
/// Additional [`Self::generics`] [`syn::WhereClause`] predicates.
where_clause: Vec<syn::WherePredicate>,
/// Generics of the Rust type that this [GraphQL scalar][1] is implemented
/// for.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
generics: syn::Generics,
/// [`GraphQLScalarMethods`] representing [GraphQL scalar][1].
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
methods: Methods,
/// Description of this [GraphQL scalar][1] to put into GraphQL schema.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
description: Option<Description>,
/// Spec [`Url`] of this [GraphQL scalar][1] to put into GraphQL schema.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
specified_by_url: Option<Url>,
/// [`ScalarValue`] parametrization to generate [`GraphQLType`]
/// implementation with for this [GraphQL scalar][1].
///
/// [`GraphQLType`]: juniper::GraphQLType
/// [`ScalarValue`]: juniper::ScalarValue
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
scalar: scalar::Type,
}
impl ToTokens for Definition {
fn to_tokens(&self, into: &mut TokenStream) {
self.impl_output_and_input_type_tokens().to_tokens(into);
self.impl_type_tokens().to_tokens(into);
self.impl_value_tokens().to_tokens(into);
self.impl_value_async_tokens().to_tokens(into);
self.impl_to_input_value_tokens().to_tokens(into);
self.impl_from_input_value_tokens().to_tokens(into);
self.impl_parse_scalar_value_tokens().to_tokens(into);
self.impl_reflection_traits_tokens().to_tokens(into);
}
}
impl Definition {
/// Returns generated code implementing [`marker::IsInputType`] and
/// [`marker::IsOutputType`] trait for this [GraphQL scalar][1].
///
/// [`marker::IsInputType`]: juniper::marker::IsInputType
/// [`marker::IsOutputType`]: juniper::marker::IsOutputType
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
#[must_use]
fn impl_output_and_input_type_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let (ty, generics) = self.impl_self_and_generics(false);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::marker::IsInputType<#scalar> for #ty
#where_clause { }
#[automatically_derived]
impl #impl_gens ::juniper::marker::IsOutputType<#scalar> for #ty
#where_clause { }
}
}
/// Returns generated code implementing [`GraphQLType`] trait for this
/// [GraphQL scalar][1].
///
/// [`GraphQLType`]: juniper::GraphQLType
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn impl_type_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let name = &self.name;
let description = &self.description;
let specified_by_url = self.specified_by_url.as_ref().map(|url| {
let url_lit = url.as_str();
quote! { .specified_by_url(#url_lit) }
});
let (ty, generics) = self.impl_self_and_generics(false);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::GraphQLType<#scalar> for #ty
#where_clause
{
fn name(
_: &Self::TypeInfo,
) -> ::core::option::Option<&'static ::core::primitive::str> {
::core::option::Option::Some(#name)
}
fn meta<'r>(
info: &Self::TypeInfo,
registry: &mut ::juniper::Registry<'r, #scalar>,
) -> ::juniper::meta::MetaType<'r, #scalar>
where
#scalar: 'r,
{
registry.build_scalar_type::<Self>(info)
#description
#specified_by_url
.into_meta()
}
}
}
}
/// Returns generated code implementing [`GraphQLValue`] trait for this
/// [GraphQL scalar][1].
///
/// [`GraphQLValue`]: juniper::GraphQLValue
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn impl_value_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let resolve = self.methods.expand_resolve(scalar);
let (ty, generics) = self.impl_self_and_generics(false);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::GraphQLValue<#scalar> for #ty
#where_clause
{
type Context = ();
type TypeInfo = ();
fn type_name<'i>(
&self,
info: &'i Self::TypeInfo,
) -> ::core::option::Option<&'i ::core::primitive::str> {
<Self as ::juniper::GraphQLType<#scalar>>::name(info)
}
fn resolve(
&self,
info: &(),
selection: ::core::option::Option<&[::juniper::Selection<'_, #scalar>]>,
executor: &::juniper::Executor<'_, '_, Self::Context, #scalar>,
) -> ::juniper::ExecutionResult<#scalar> {
#resolve
}
}
}
}
/// Returns generated code implementing [`GraphQLValueAsync`] trait for this
/// [GraphQL scalar][1].
///
/// [`GraphQLValueAsync`]: juniper::GraphQLValueAsync
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn impl_value_async_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let (ty, generics) = self.impl_self_and_generics(true);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::GraphQLValueAsync<#scalar> for #ty
#where_clause
{
fn resolve_async<'b>(
&'b self,
info: &'b Self::TypeInfo,
selection_set: ::core::option::Option<&'b [::juniper::Selection<'_, #scalar>]>,
executor: &'b ::juniper::Executor<'_, '_, Self::Context, #scalar>,
) -> ::juniper::BoxFuture<'b, ::juniper::ExecutionResult<#scalar>> {
let v = ::juniper::GraphQLValue::resolve(self, info, selection_set, executor);
::std::boxed::Box::pin(::juniper::futures::future::ready(v))
}
}
}
}
/// Returns generated code implementing [`InputValue`] trait for this
/// [GraphQL scalar][1].
///
/// [`InputValue`]: juniper::InputValue
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn impl_to_input_value_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let to_input_value = self.methods.expand_to_input_value(scalar);
let (ty, generics) = self.impl_self_and_generics(false);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::ToInputValue<#scalar> for #ty
#where_clause
{
fn to_input_value(&self) -> ::juniper::InputValue<#scalar> {
#to_input_value
}
}
}
}
/// Returns generated code implementing [`FromInputValue`] trait for this
/// [GraphQL scalar][1].
///
/// [`FromInputValue`]: juniper::FromInputValue
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn impl_from_input_value_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let from_input_value = self.methods.expand_from_input_value(scalar);
let (ty, generics) = self.impl_self_and_generics(false);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::FromInputValue<#scalar> for #ty
#where_clause
{
type Error = ::juniper::executor::FieldError<#scalar>;
fn from_input_value(
input: &::juniper::InputValue<#scalar>,
) -> ::core::result::Result<Self, Self::Error> {
#from_input_value
.map_err(::juniper::executor::IntoFieldError::<#scalar>::into_field_error)
}
}
}
}
/// Returns generated code implementing [`ParseScalarValue`] trait for this
/// [GraphQL scalar][1].
///
/// [`ParseScalarValue`]: juniper::ParseScalarValue
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn impl_parse_scalar_value_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let from_str = self.methods.expand_parse_scalar_value(scalar);
let (ty, generics) = self.impl_self_and_generics(false);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::ParseScalarValue<#scalar> for #ty
#where_clause
{
fn from_str(
token: ::juniper::parser::ScalarToken<'_>,
) -> ::juniper::ParseScalarResult<#scalar> {
#from_str
}
}
}
}
/// Returns generated code implementing [`BaseType`], [`BaseSubTypes`] and
/// [`WrappedType`] traits for this [GraphQL scalar][1].
///
/// [`BaseSubTypes`]: juniper::macros::reflection::BaseSubTypes
/// [`BaseType`]: juniper::macros::reflection::BaseType
/// [`WrappedType`]: juniper::macros::reflection::WrappedType
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn impl_reflection_traits_tokens(&self) -> TokenStream {
let scalar = &self.scalar;
let name = &self.name;
let (ty, generics) = self.impl_self_and_generics(false);
let (impl_gens, _, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_gens ::juniper::macros::reflect::BaseType<#scalar> for #ty
#where_clause
{
const NAME: ::juniper::macros::reflect::Type = #name;
}
#[automatically_derived]
impl #impl_gens ::juniper::macros::reflect::BaseSubTypes<#scalar> for #ty
#where_clause
{
const NAMES: ::juniper::macros::reflect::Types =
&[<Self as ::juniper::macros::reflect::BaseType<#scalar>>::NAME];
}
#[automatically_derived]
impl #impl_gens ::juniper::macros::reflect::WrappedType<#scalar> for #ty
#where_clause
{
const VALUE: ::juniper::macros::reflect::WrappedValue = 1;
}
}
}
/// Returns prepared self type and [`syn::Generics`] for [`GraphQLType`]
/// trait (and similar) implementation.
///
/// If `for_async` is `true`, then additional predicates are added to suit
/// the [`GraphQLAsyncValue`] trait (and similar) requirements.
///
/// [`GraphQLAsyncValue`]: juniper::GraphQLAsyncValue
/// [`GraphQLType`]: juniper::GraphQLType
#[must_use]
fn impl_self_and_generics(&self, for_async: bool) -> (TokenStream, syn::Generics) {
let mut generics = self.generics.clone();
let ty = match &self.ty {
TypeOrIdent::Type(ty) => ty.into_token_stream(),
TypeOrIdent::Ident(ident) => {
let (_, ty_gen, _) = self.generics.split_for_impl();
quote! { #ident #ty_gen }
}
};
if !self.where_clause.is_empty() {
generics
.make_where_clause()
.predicates
.extend(self.where_clause.clone())
}
let scalar = &self.scalar;
if scalar.is_implicit_generic() {
generics.params.push(parse_quote! { #scalar });
}
if scalar.is_generic() {
generics
.make_where_clause()
.predicates
.push(parse_quote! { #scalar: ::juniper::ScalarValue });
}
if let Some(bound) = scalar.bounds() {
generics.make_where_clause().predicates.push(bound);
}
if for_async {
let self_ty = if self.generics.lifetimes().next().is_some() {
let mut generics = self.generics.clone();
ModifyLifetimes.visit_generics_mut(&mut generics);
let lifetimes = generics.lifetimes().map(|lt| <.lifetime);
let ty = match self.ty.clone() {
TypeOrIdent::Type(mut ty) => {
ModifyLifetimes.visit_type_mut(&mut ty);
ty.into_token_stream()
}
TypeOrIdent::Ident(ident) => {
let (_, ty_gens, _) = generics.split_for_impl();
quote! { #ident #ty_gens }
}
};
quote! { for<#( #lifetimes ),*> #ty }
} else {
quote! { Self }
};
generics
.make_where_clause()
.predicates
.push(parse_quote! { #self_ty: ::core::marker::Sync });
if scalar.is_generic() {
generics
.make_where_clause()
.predicates
.push(parse_quote! { #scalar: ::core::marker::Send + ::core::marker::Sync });
}
}
(ty, generics)
}
}
/// Adds `__fa__` prefix to all lifetimes to avoid "lifetime name `'a` shadows a
/// lifetime name that is already in scope" error.
struct ModifyLifetimes;
impl VisitMut for ModifyLifetimes {
fn visit_lifetime_mut(&mut self, lf: &mut syn::Lifetime) {
lf.ident = format_ident!("__fa__{}", lf.ident.unraw());
}
}
/// Methods representing [GraphQL scalar][1].
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
enum Methods {
/// [GraphQL scalar][1] represented with only custom resolvers.
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
Custom {
/// Function provided with `#[graphql(to_output_with = ...)]`.
to_output: syn::ExprPath,
/// Function provided with `#[graphql(from_input_with = ...)]`.
from_input: syn::ExprPath,
/// [`ParseToken`] provided with `#[graphql(parse_token_with = ...)]`
/// or `#[graphql(parse_token(...))]`.
parse_token: ParseToken,
},
/// [GraphQL scalar][1] maybe partially represented with custom resolver.
/// Other methods are used from [`Field`].
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
Delegated {
/// Function provided with `#[graphql(to_output_with = ...)]`.
to_output: Option<syn::ExprPath>,
/// Function provided with `#[graphql(from_input_with = ...)]`.
from_input: Option<syn::ExprPath>,
/// [`ParseToken`] provided with `#[graphql(parse_token_with = ...)]`
/// or `#[graphql(parse_token(...))]`.
parse_token: Option<ParseToken>,
/// [`Field`] to resolve not provided methods.
field: Box<Field>,
},
}
impl Methods {
/// Expands [`GraphQLValue::resolve`] method.
///
/// [`GraphQLValue::resolve`]: juniper::GraphQLValue::resolve
fn expand_resolve(&self, scalar: &scalar::Type) -> TokenStream {
match self {
Self::Custom { to_output, .. }
| Self::Delegated {
to_output: Some(to_output),
..
} => {
quote! { ::core::result::Result::Ok(#to_output(self)) }
}
Self::Delegated { field, .. } => {
quote! {
::juniper::GraphQLValue::<#scalar>::resolve(
&self.#field,
info,
selection,
executor,
)
}
}
}
}
/// Expands [`ToInputValue::to_input_value`] method.
///
/// [`ToInputValue::to_input_value`]: juniper::ToInputValue::to_input_value
fn expand_to_input_value(&self, scalar: &scalar::Type) -> TokenStream {
match self {
Self::Custom { to_output, .. }
| Self::Delegated {
to_output: Some(to_output),
..
} => {
quote! {
let v = #to_output(self);
::juniper::ToInputValue::to_input_value(&v)
}
}
Self::Delegated { field, .. } => {
quote! {
::juniper::ToInputValue::<#scalar>::to_input_value(&self.#field)
}
}
}
}
/// Expands [`FromInputValue::from_input_value`][1] method.
///
/// [1]: juniper::FromInputValue::from_input_value
fn expand_from_input_value(&self, scalar: &scalar::Type) -> TokenStream {
match self {
Self::Custom { from_input, .. }
| Self::Delegated {
from_input: Some(from_input),
..
} => {
quote! { #from_input(input) }
}
Self::Delegated { field, .. } => {
let field_ty = field.ty();
let self_constructor = field.closure_constructor();
quote! {
<#field_ty as ::juniper::FromInputValue<#scalar>>::from_input_value(input)
.map(#self_constructor)
}
}
}
}
/// Expands [`ParseScalarValue::from_str`] method.
///
/// [`ParseScalarValue::from_str`]: juniper::ParseScalarValue::from_str
fn expand_parse_scalar_value(&self, scalar: &scalar::Type) -> TokenStream {
match self {
Self::Custom { parse_token, .. }
| Self::Delegated {
parse_token: Some(parse_token),
..
} => {
let parse_token = parse_token.expand_from_str(scalar);
quote! { #parse_token }
}
Self::Delegated { field, .. } => {
let field_ty = field.ty();
quote! {
<#field_ty as ::juniper::ParseScalarValue<#scalar>>::from_str(token)
}
}
}
}
}
/// Representation of [`ParseScalarValue::from_str`] method.
///
/// [`ParseScalarValue::from_str`]: juniper::ParseScalarValue::from_str
#[derive(Clone, Debug)]
enum ParseToken {
/// Custom method.
Custom(syn::ExprPath),
/// Tries to parse using [`syn::Type`]s [`ParseScalarValue`] impls until
/// first success.
///
/// [`ParseScalarValue`]: juniper::ParseScalarValue
Delegated(Vec<syn::Type>),
}
impl ParseToken {
/// Expands [`ParseScalarValue::from_str`] method.
///
/// [`ParseScalarValue::from_str`]: juniper::ParseScalarValue::from_str
fn expand_from_str(&self, scalar: &scalar::Type) -> TokenStream {
match self {
Self::Custom(parse_token) => {
quote! { #parse_token(token) }
}
Self::Delegated(delegated) => delegated
.iter()
.fold(None, |acc, ty| {
acc.map_or_else(
|| Some(quote! { <#ty as ::juniper::ParseScalarValue<#scalar>>::from_str(token) }),
|prev| {
Some(quote! {
#prev.or_else(|_| {
<#ty as ::juniper::ParseScalarValue<#scalar>>::from_str(token)
})
})
}
)
})
.unwrap_or_default(),
}
}
}
/// Struct field to resolve not provided methods.
enum Field {
/// Named [`Field`].
Named(syn::Field),
/// Unnamed [`Field`].
Unnamed(syn::Field),
}
impl ToTokens for Field {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
Self::Named(f) => f.ident.to_tokens(tokens),
Self::Unnamed(_) => tokens.append(Literal::u8_unsuffixed(0)),
}
}
}
impl Field {
/// [`syn::Type`] of this [`Field`].
fn ty(&self) -> &syn::Type {
match self {
Self::Named(f) | Self::Unnamed(f) => &f.ty,
}
}
/// Closure to construct [GraphQL scalar][1] struct from [`Field`].
///
/// [1]: https://spec.graphql.org/October2021#sec-Scalars
fn closure_constructor(&self) -> TokenStream {
match self {
Field::Named(syn::Field { ident, .. }) => {
quote! { |v| Self { #ident: v } }
}
Field::Unnamed(_) => quote! { Self },
}
}
}