use crate::struct_builder::{BuilderContext, GenericsContext};
use proc_macro2::TokenStream;
use quote::{format_ident, ToTokens};
use syn::{parse_quote, Fields, ImplItemFn, Index, ItemImpl, ItemStruct};
pub struct ImplBuilderFns {
ctx: BuilderContext,
fields: Fields
}
impl From<&ItemStruct> for ImplBuilderFns {
fn from(value: &ItemStruct) -> Self {
let ctx: BuilderContext = value.into();
let fields = value.fields.clone();
Self { ctx, fields }
}
}
impl ToTokens for ImplBuilderFns {
fn to_tokens(&self, tokens: &mut TokenStream) {
let BuilderContext {
subject,
builder,
builder_subject_field,
generics,
..
} = &self.ctx;
let optional_functions: Option<Vec<ImplItemFn>> = match &self.fields {
Fields::Named(named_fields) => {
let fns = named_fields.named
.iter()
.map(|field| {
let field_ident = field.ident.as_ref().expect("named field missing ident");
let field_type = &field.ty;
let fn_ident = format_ident!("with_{}", &field_ident);
parse_quote! {
pub fn #fn_ident(mut self, value: #field_type) -> Self {
self.#builder_subject_field.#field_ident = value;
self
}
}
})
.collect::<Vec<ImplItemFn>>();
Some(fns)
},
Fields::Unnamed(unnamed_fields) => {
let fns = unnamed_fields.unnamed
.iter()
.enumerate()
.map(|(i, field)| {
let field_index = Index::from(i);
let field_type = &field.ty;
let fn_ident = format_ident!("with_{}", &field_index);
parse_quote! {
pub fn #fn_ident(mut self, value: #field_type) -> Self {
self.#builder_subject_field.#field_index = value;
self
}
}
})
.collect::<Vec<ImplItemFn>>();
Some(fns)
},
Fields::Unit => None
};
if let Some(functions) = optional_functions {
let GenericsContext {
generics_def,
generics_expr,
where_clause
} = &generics;
let item_impl: ItemImpl = parse_quote! {
impl #generics_def #builder #generics_expr #where_clause {
#(#functions)*
pub fn build(self) -> #subject #generics_expr {
self.#builder_subject_field
}
}
};
item_impl.to_tokens(tokens);
}
}
}
#[cfg(test)]
mod tests {
use crate::components::ImplBuilderFns;
use crate::test_util::{sample_named_item_struct, sample_unit_item_struct, sample_unnamed_item_struct};
use proc_macro::TokenStream;
use quote::ToTokens;
use syn::{parse_quote, ItemImpl};
#[test]
fn test_with_named_fields() {
let item_struct = sample_named_item_struct();
let expected: ItemImpl = parse_quote! {
impl<T, I: Send, W> MyStructBuilder<T, I, W>
where
W: Sync
{
pub fn with_public_field(mut self, value: String) -> Self {
self.inner.public_field = value;
self
}
pub fn with_private_field(mut self, value: String) -> Self {
self.inner.private_field = value;
self
}
pub fn with_optional(mut self, value: Option<usize>) -> Self {
self.inner.optional = value;
self
}
pub fn with_test(mut self, value: std::option::Option<String>) -> Self {
self.inner.test = value;
self
}
pub fn with_test2(mut self, value: option::Option<T>) -> Self {
self.inner.test2 = value;
self
}
pub fn with_dynamic(mut self, value: Box<dyn Send>) -> Self {
self.inner.dynamic = value;
self
}
pub fn with_dynamic2(mut self, value: Box<Option<dyn Send>>) -> Self {
self.inner.dynamic2 = value;
self
}
pub fn with_generic(mut self, value: T) -> Self {
self.inner.generic = value;
self
}
pub fn with_generic_inline(mut self, value: I) -> Self {
self.inner.generic_inline = value;
self
}
pub fn with_generic_where(mut self, value: W) -> Self {
self.inner.generic_where = value;
self
}
pub fn build(self) -> MyStruct<T, I, W> {
self.inner
}
}
};
let impl_subject_fn_builder = ImplBuilderFns::from(&item_struct);
assert_eq!(
impl_subject_fn_builder.to_token_stream().to_string(),
expected.to_token_stream().to_string()
);
}
#[test]
fn test_with_unnamed_fields() {
let item_struct = sample_unnamed_item_struct();
let expected: ItemImpl = parse_quote! {
impl<T, I: Send, W> MyStructBuilder<T, I, W>
where
W: Sync
{
pub fn with_0(mut self, value: String) -> Self {
self.inner.0 = value;
self
}
pub fn with_1(mut self, value: String) -> Self {
self.inner.1 = value;
self
}
pub fn with_2(mut self, value: Option<usize>) -> Self {
self.inner.2 = value;
self
}
pub fn with_3(mut self, value: std::option::Option<String>) -> Self {
self.inner.3 = value;
self
}
pub fn with_4(mut self, value: option::Option<T>) -> Self {
self.inner.4 = value;
self
}
pub fn with_5(mut self, value: Box<dyn Send>) -> Self {
self.inner.5 = value;
self
}
pub fn with_6(mut self, value: Box<Option<dyn Send>>) -> Self {
self.inner.6 = value;
self
}
pub fn with_7(mut self, value: T) -> Self {
self.inner.7 = value;
self
}
pub fn with_8(mut self, value: I) -> Self {
self.inner.8 = value;
self
}
pub fn with_9(mut self, value: W) -> Self {
self.inner.9 = value;
self
}
pub fn build(self) -> MyStruct<T, I, W> {
self.inner
}
}
};
let subject_impl = ImplBuilderFns::from(&item_struct);
assert_eq!(
subject_impl.to_token_stream().to_string(),
expected.to_token_stream().to_string()
);
}
#[test]
fn test_with_unit_struct() {
let item_struct = sample_unit_item_struct();
let impl_builder_fns = ImplBuilderFns::from(&item_struct);
assert_eq!(
impl_builder_fns.to_token_stream().to_string(),
TokenStream::new().to_string()
);
}
}