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use proc_macro2::TokenStream;
use quote::{quote, ToTokens};
use syn::Field;
use super::*;
/// Generate the implementation of [struct_merge::StructMerge] for given structs.
pub(crate) fn impl_owned(params: &Parameters, fields: Vec<(Field, Field)>) -> TokenStream {
let mut functions_tokens = TokenStream::new();
let stream = merge(params, fields.clone());
functions_tokens.extend(vec![stream]);
let stream = merge_soft(params, fields);
functions_tokens.extend(vec![stream]);
let src_ident = ¶ms.src_struct.ident;
let target_path = ¶ms.target_path;
quote! {
impl struct_merge::StructMergeInto<#target_path> for #src_ident {
#functions_tokens
}
}
}
/// Generate the [struct_merge::StructMerge::merge] function for the given structs.
fn merge(params: &Parameters, fields: Vec<(Field, Field)>) -> TokenStream {
let mut merge_code = TokenStream::new();
for (src_field, dest_field) in fields {
let src_ident = src_field.ident;
let dest_ident = dest_field.ident;
// Find out, whether the fields are optional or not.
let src_field_type = determine_field_type(src_field.ty);
let dest_field_type = determine_field_type(dest_field.ty);
let snippet = match (src_field_type, dest_field_type) {
// Both fields have the same type
(FieldType::Normal(src_type), FieldType::Normal(dest_type)) => {
equal_type_or_continue!(
src_type,
dest_type,
"",
quote! {
dest.#dest_ident = self.#src_ident;
}
)
}
// The src is optional and needs to be `Some(T)` to be merged.
(
FieldType::Optional {
inner: src_type, ..
},
FieldType::Normal(dest_type),
) => {
equal_type_or_continue!(
src_type,
dest_type,
"Inner",
quote! {
if let Some(value) = self.#src_ident {
dest.#dest_ident = value;
}
}
)
}
// The dest is optional and needs to be wrapped in `Some(T)` to be merged.
(
FieldType::Normal(src_type),
FieldType::Optional {
inner: dest_type, ..
},
) => {
equal_type_or_continue!(
src_type,
dest_type,
"",
quote! {
dest.#dest_ident = Some(self.#src_ident);
}
)
}
// Both fields are optional. It can now be either of these:
// - (Option<T>, Option<T>)
// - (Option<Option<T>>, Option<T>)
// - (Option<T>, Option<Option<T>>)
(
FieldType::Optional {
inner: inner_src_type,
outer: outer_src_type,
},
FieldType::Optional {
inner: inner_dest_type,
outer: outer_dest_type,
},
) => {
// Handling the (Option<T>, Option<T>) case
if is_equal_type(&inner_src_type, &inner_dest_type) {
quote! {
dest.#dest_ident = self.#src_ident;
}
// Handling the (Option<Option<<T>>, Option<T>) case
} else if is_equal_type(&inner_src_type, &outer_dest_type) {
quote! {
if let Some(value) = self.#src_ident {
dest.#dest_ident = value;
}
}
// Handling the (Option<<T>, Option<Option<T>)> case
} else {
equal_type_or_continue!(
outer_src_type,
inner_dest_type,
"",
quote! {
dest.#dest_ident = Some(self.#src_ident);
}
)
}
}
// Skip anything where either of the fields are invalid
(FieldType::Invalid, _) | (_, FieldType::Invalid) => continue,
};
merge_code.extend(vec![snippet]);
}
let merge_code = merge_code.to_token_stream();
let target_path = ¶ms.target_path;
quote! {
fn merge_into(self, dest: &mut #target_path) {
#merge_code
}
}
}
/// Generate the [struct_merge::StructMerge::merge_soft] function for the given structs.
fn merge_soft(params: &Parameters, fields: Vec<(Field, Field)>) -> TokenStream {
let mut merge_code = TokenStream::new();
for (src_field, dest_field) in fields {
let src_ident = src_field.ident;
let dest_ident = dest_field.ident;
// Find out, whether the fields are optional or not.
let src_field_type = determine_field_type(src_field.ty);
let dest_field_type = determine_field_type(dest_field.ty);
let snippet = match (src_field_type, dest_field_type) {
// Soft merge only applies if the dest field is `Optional`.
(FieldType::Normal(_), FieldType::Normal(_))
| (FieldType::Optional { .. }, FieldType::Normal(_)) => continue,
// The dest is optional and needs to be wrapped in `Some(T)` to be merged.
(
FieldType::Normal(src_type),
FieldType::Optional {
inner: dest_type, ..
},
) => {
equal_type_or_continue!(
src_type,
dest_type,
"",
quote! {
if dest.#dest_ident.is_none() {
dest.#dest_ident = Some(self.#src_ident);
}
}
)
}
// Both fields are optional. It can now be either of these:
// - (Option<T>, Option<T>)
// - (Option<Option<T>>, Option<T>)
// - (Option<T>, Option<Option<T>>)
(
FieldType::Optional {
inner: inner_src_type,
outer: outer_src_type,
},
FieldType::Optional {
inner: inner_dest_type,
outer: outer_dest_type,
},
) => {
// Handling the (Option<T>, Option<T>) case
if is_equal_type(&inner_src_type, &inner_dest_type) {
quote! {
if dest.#dest_ident.is_none() {
dest.#dest_ident = self.#src_ident;
}
}
// Handling the (Option<Option<<T>>, Option<T>) case
} else if is_equal_type(&inner_src_type, &outer_dest_type) {
quote! {
if let Some(value) = self.#src_ident {
if dest.#dest_ident.is_none() {
dest.#dest_ident = value;
}
}
}
// Handling the (Option<<T>, Option<Option<T>)> case
} else {
equal_type_or_continue!(
outer_src_type,
inner_dest_type,
"",
quote! {
if dest.#dest_ident.is_none() {
dest.#dest_ident = Some(self.#src_ident);
}
}
)
}
}
// Skip anything where either of the fields are invalid
(FieldType::Invalid, _) | (_, FieldType::Invalid) => continue,
};
merge_code.extend(vec![snippet]);
}
let merge_code = merge_code.to_token_stream();
let target_path = ¶ms.target_path;
quote! {
fn merge_into_soft(self, dest: &mut #target_path) {
#merge_code
}
}
}