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use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::quote;
use std::collections::HashMap;
use syn::{parse_macro_input, DeriveInput};
fn get_types(data: &syn::Data) -> Vec<(proc_macro2::Ident, syn::Type)> {
let mut map = vec![];
if let syn::Data::Struct(syn::DataStruct {
fields: syn::Fields::Named(syn::FieldsNamed { named, .. }),
..
}) = data.to_owned()
{
let mut iter = named.into_iter();
while let Some(syn::Field {
ident: Some(ident),
ty,
..
}) = iter.next()
{
map.push((ident, ty));
}
}
map
}
fn is_vec(ty: &syn::Type) -> bool {
match ty.to_owned() {
syn::Type::Path(syn::TypePath {
path: syn::Path { segments, .. },
..
}) => match segments.iter().next() {
Some(syn::PathSegment { ident, arguments })
if ident == &syn::Ident::new("Option", proc_macro2::Span::call_site()) =>
{
match arguments {
syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
args,
..
}) => match args.iter().next() {
Some(syn::GenericArgument::Type(ty2)) => is_vec(ty2),
_ => false,
},
_ => unreachable!(),
}
}
Some(syn::PathSegment { ident, .. })
if ident == &syn::Ident::new("Vec", proc_macro2::Span::call_site()) =>
{
true
}
_ => false,
},
_ => false,
}
}
fn attr_ident(attr: &syn::Attribute) -> Option<&syn::Ident> {
let syn::Path { segments, .. } = &attr.path;
if let Some(syn::PathSegment { ident, .. }) = segments.iter().next() {
Some(ident)
} else {
None
}
}
fn attr_lit(attr: &syn::Attribute) -> Option<proc_macro2::Literal> {
match attr.tokens.clone().into_iter().nth(1) {
Some(proc_macro2::TokenTree::Literal(lit)) => Some(lit),
_ => None,
}
}
fn literal_to_ident(lit: proc_macro2::Literal) -> syn::Ident {
syn::Ident::new(&literal_to_string(lit), proc_macro2::Span::call_site())
}
fn literal_to_string(lit: proc_macro2::Literal) -> String {
let mut s = format!("{}", lit);
s.pop();
s.remove(0);
s
}
fn str_to_segments<S: ToString>(
s: S,
) -> syn::punctuated::Punctuated<syn::PathSegment, syn::Token![::]> {
let s = s.to_string();
s.split("::")
.fold(syn::punctuated::Punctuated::new(), |mut segs, cur| {
segs.push(str_to_seg(cur));
segs
})
}
fn str_to_seg<S: ToString>(s: S) -> syn::PathSegment {
syn::PathSegment {
ident: syn::Ident::new(&s.to_string(), proc_macro2::Span::call_site()),
arguments: syn::PathArguments::None,
}
}
fn table_name(item: &syn::DeriveInput) -> Option<syn::Ident> {
attrs(item)
.get(&syn::Ident::new(
"table_name",
proc_macro2::Span::call_site(),
))
.map(|lit| literal_to_ident(lit.clone()))
}
fn schema_prefix(item: &syn::DeriveInput) -> Option<String> {
attrs(item)
.get(&syn::Ident::new(
"schema_prefix",
proc_macro2::Span::call_site(),
))
.map(|lit| literal_to_string(lit.clone()))
}
fn attrs(item: &syn::DeriveInput) -> HashMap<syn::Ident, proc_macro2::Literal> {
item.attrs
.iter()
.filter(|attr| attr_lit(attr).is_some() && attr_ident(attr).is_some())
.map(|attr| (attr_ident(attr).unwrap(), attr_lit(attr).unwrap()))
.fold(HashMap::new(), |mut map, (label, ident)| {
map.insert(label.clone(), ident);
map
})
}
#[cfg(any(feature = "mysql", feature = "postgres", feature = "sqlite"))]
#[proc_macro_derive(IntoQuery, attributes(table_name, schema_prefix))]
pub fn derive_into_query(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let types = get_types(&input.data);
let struct_ident = &input.ident;
let table = table_name(&input).expect("table_name not specified");
let schema_prefix = match schema_prefix(&input) {
Some(prefix) => str_to_segments(format!("{}::schema", prefix.to_string())),
None => str_to_segments("crate::schema"),
};
let body = types
.iter()
.map(|(ident, ty)| {
if is_vec(ty) {
quote! {
if let Some(container) = self.#ident {
let mut iter = container.into_iter();
if let Some(first) = iter.next() {
query = query.filter(#ident.eq(first));
for item in iter {
query = query.or_filter(#ident.eq(item));
}
}
}
}
} else {
quote! {
if let Some(item) = self.#ident {
query = query.filter(#ident.eq(item));
}
}
}
})
.fold(TokenStream2::new(), |mut acc, cur| {
acc.extend(cur.into_iter());
acc
});
#[cfg(feature = "mysql")]
let db = quote! { diesel::mysql::Mysql };
#[cfg(feature = "postgres")]
let db = quote! { diesel::pg::Pg };
#[cfg(feature = "sqlite")]
let db = quote! { diesel::sqlite::Sqlite };
let gen = quote! {
impl ::into_query::IntoQuery<#schema_prefix::#table::dsl::#table, #db> for #struct_ident {
fn into_query(
self,
) -> diesel::helper_types::IntoBoxed<
'static,
#schema_prefix::#table::dsl::#table,
#db,
> {
use #schema_prefix::#table::dsl::*;
use diesel::prelude::*;
let mut query = #table.into_boxed();
#body
query
}
}
};
gen.into()
}
