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|
use std::collections::HashMap;
use proc_macro2::Span;
use quote::quote;
use syn::{
spanned::Spanned, GenericArgument, Generics, Ident, PathArguments, TraitBound, Type,
TypeParamBound, TypePath, TypeReference, TypeTraitObject, WherePredicate,
};
use crate::{
filter_map_assoc_paths, match_assoc_type,
parse_assoc_type::DestType,
parse_trait_sig::{MethodParseError, TypeTransform},
syn_utils::{iter_path, iter_type},
};
#[derive(Default)]
pub struct AssocTypeConversions<'a>(pub HashMap<Ident, DestType<'a>>);
pub enum TransformError {
UnconvertibleAssocType(Span),
AssocTypeInUnsupportedType(Span),
}
impl AssocTypeConversions<'_> {
pub fn parse_type_path(&self, type_: &mut Type) -> Result<TypeTransform, TransformError> {
let assoc_span = match iter_type(type_).filter_map(filter_map_assoc_paths).next() {
Some(path) => path.span(),
None => return Ok(TypeTransform::NoOp),
};
if let Type::Reference(TypeReference {
lifetime: None,
mutability: Some(_),
elem,
..
}) = type_
{
if let Type::TraitObject(TypeTraitObject {
dyn_token: Some(_),
bounds,
}) = elem.as_mut()
{
if bounds.len() == 1 {
if let TypeParamBound::Trait(bound) = bounds.first_mut().unwrap() {
if bound.path.segments.len() == 1 {
let first = bound.path.segments.first_mut().unwrap();
if first.ident == "Iterator" {
if let PathArguments::AngleBracketed(args) = &mut first.arguments {
if args.args.len() == 1 {
if let GenericArgument::Binding(binding) =
args.args.first_mut().unwrap()
{
if binding.ident == "Item"
&& iter_type(&binding.ty).any(match_assoc_type)
{
let inner =
self.parse_type_path(&mut binding.ty)?;
*type_ = Type::Verbatim(quote! {Box<#elem + '_>});
return Ok(TypeTransform::Iterator(inner.into()));
}
}
}
}
}
}
}
}
}
}
if let Type::Path(TypePath { path, qself: None }) = type_ {
let ident = &path.segments.first().unwrap().ident;
if ident == "Self" && path.segments.len() == 2 {
let ident = &path.segments.last().unwrap().ident;
let dest_type = self
.0
.get(ident)
.ok_or_else(|| TransformError::UnconvertibleAssocType(ident.span()))?;
*type_ = dest_type.get_dest();
return Ok(dest_type.type_transformation());
} else if ident == "Option" && path.segments.len() == 1 {
let first_seg = path.segments.first_mut().unwrap();
if let PathArguments::AngleBracketed(args) = &mut first_seg.arguments {
if args.args.len() == 1 {
if let GenericArgument::Type(generic_type) = args.args.first_mut().unwrap()
{
if iter_type(generic_type).any(match_assoc_type) {
return Ok(TypeTransform::Map(
self.parse_type_path(generic_type)?.into(),
));
}
}
}
}
} else if ident == "Result" && path.segments.len() == 1 {
let first_seg = path.segments.first_mut().unwrap();
if let PathArguments::AngleBracketed(args) = &mut first_seg.arguments {
if args.args.len() == 2 {
let mut args_iter = args.args.iter_mut();
if let (GenericArgument::Type(ok_type), GenericArgument::Type(err_type)) =
(args_iter.next().unwrap(), args_iter.next().unwrap())
{
if iter_type(ok_type).any(match_assoc_type)
|| iter_type(err_type).any(match_assoc_type)
{
return Ok(TypeTransform::Result(
self.parse_type_path(ok_type)?.into(),
self.parse_type_path(err_type)?.into(),
));
}
}
}
}
} else {
let last_seg = &path.segments.last().unwrap();
if last_seg.ident == "Result" {
let last_seg = path.segments.last_mut().unwrap();
if let PathArguments::AngleBracketed(args) = &mut last_seg.arguments {
if args.args.len() == 1 {
if let GenericArgument::Type(generic_type) =
args.args.first_mut().unwrap()
{
if iter_type(generic_type).any(match_assoc_type) {
return Ok(TypeTransform::Map(
self.parse_type_path(generic_type)?.into(),
));
}
}
}
}
}
}
}
// the type contains an associated type but we
// don't know how to deal with it so we abort
Err(TransformError::AssocTypeInUnsupportedType(assoc_span))
}
}
pub fn dynamize_function_bounds(
generics: &mut Generics,
assoc_type_conversions: &AssocTypeConversions,
) -> Result<HashMap<Ident, Vec<TypeTransform>>, (Span, MethodParseError)> {
let mut type_param_transforms = HashMap::new();
for type_param in generics.type_params_mut() {
for bound in &mut type_param.bounds {
if let TypeParamBound::Trait(bound) = bound {
dynamize_trait_bound(
bound,
assoc_type_conversions,
&type_param.ident,
&mut type_param_transforms,
)?;
}
}
}
if let Some(where_clause) = &mut generics.where_clause {
for predicate in &mut where_clause.predicates {
if let WherePredicate::Type(predicate_type) = predicate {
if let Type::Path(path) = &mut predicate_type.bounded_ty {
if let Some(ident) = path.path.get_ident() {
for bound in &mut predicate_type.bounds {
if let TypeParamBound::Trait(bound) = bound {
dynamize_trait_bound(
bound,
assoc_type_conversions,
ident,
&mut type_param_transforms,
)?;
}
}
continue;
}
}
// just to provide better error messages
if let Some(assoc_type) =
iter_type(&predicate_type.bounded_ty).find_map(filter_map_assoc_paths)
{
return Err((
assoc_type.span(),
MethodParseError::UnconvertibleAssocTypeInWhereClause,
));
}
// just to provide better error messages
for bound in &mut predicate_type.bounds {
if let TypeParamBound::Trait(bound) = bound {
if let Some(assoc_type) =
iter_path(&bound.path).find_map(filter_map_assoc_paths)
{
return Err((
assoc_type.span(),
MethodParseError::UnconvertibleAssocTypeInWhereClause,
));
}
}
}
}
}
}
Ok(type_param_transforms)
}
fn dynamize_trait_bound(
bound: &mut TraitBound,
assoc_type_conversions: &AssocTypeConversions,
type_ident: &Ident,
type_param_transforms: &mut HashMap<Ident, Vec<TypeTransform>>,
) -> Result<(), (Span, MethodParseError)> {
if bound.path.segments.len() == 1 {
let segment = bound.path.segments.first_mut().unwrap();
if let PathArguments::Parenthesized(args) = &mut segment.arguments {
if segment.ident == "Fn" || segment.ident == "FnOnce" || segment.ident == "FnMut" {
let mut transforms = Vec::new();
for input_type in &mut args.inputs {
match assoc_type_conversions.parse_type_path(input_type) {
Ok(ret_type) => {
transforms.push(ret_type);
}
Err(TransformError::UnconvertibleAssocType(span)) => {
return Err((span, MethodParseError::UnconvertibleAssocType));
}
Err(TransformError::AssocTypeInUnsupportedType(span)) => {
return Err((span, MethodParseError::UnconvertibleAssocTypeInFnInput));
}
}
}
if transforms.iter().any(|t| !matches!(t, TypeTransform::NoOp)) {
type_param_transforms.insert(type_ident.clone(), transforms);
}
}
}
}
if let Some(path) = iter_path(&bound.path)
.filter_map(filter_map_assoc_paths)
.next()
{
return Err((
path.span(),
MethodParseError::UnconvertibleAssocTypeInTraitBound,
));
}
Ok(())
}
|
