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#![feature(proc_macro_span)]
extern crate proc_macro;
use std::collections::HashMap;
use std::fs;
use proc_macro::TokenStream;
use quote::quote;
#[proc_macro_derive(Model, attributes(model))]
pub fn model_derive(input: TokenStream) -> TokenStream {
// Construct a representation of Rust code as a syntax tree
// that we can manipulate
let ast = syn::parse(input).unwrap();
// Build the trait implementation
impl_model(&ast)
}
fn to_field_spec(field: &syn::Field) -> impl quote::ToTokens {
fn parse_type(ty: &str) -> syn::Type {
syn::parse_str(ty).unwrap()
}
let field_name = &field.ident;
let field_type = &field.ty;
let model_options: HashMap<syn::Path, syn::Lit> = field.attrs.iter()
.filter_map(|attr| attr.parse_meta().ok())
.filter_map(|meta| if let syn::Meta::List(meta) = meta { Some(meta) } else { None })
.filter(|meta| meta.path.get_ident().map_or(false, |path| path == "model"))
.flat_map(|model| {
model.nested.into_iter().filter_map(|item| {
if let syn::NestedMeta::Meta(syn::Meta::NameValue(data)) = item {
Some((data.path, data.lit))
} else {
None
}
})
})
.collect();
if field_type == &parse_type("Option<Id>") {
quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } }
} else if field_type == &parse_type("Id") {
// TODO foreign key constraint
quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } }
} else if field_type == &parse_type("usize") {
// TODO default
quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } }
} else if field_type == &parse_type("String") {
let max_length = model_options.iter()
.find(|(name, _value)| name.get_ident().map_or(false, |path| path == "max_length"))
.map(|(_name, value)| value);
if let Some(max_length) = max_length {
quote! { ::tosin::db::models::Field::CharField { name: stringify!(#field_name), max_length: Some(#max_length) } }
} else {
quote! { ::tosin::db::models::Field::CharField { name: stringify!(#field_name), max_length: None } }
}
} else if field_type == &parse_type("time::PrimitiveDateTime") {
quote! { ::tosin::db::models::Field::DateTimeField { name: stringify!(#field_name) } }
} else {
use quote::ToTokens;
panic!("can't handle {}", field.to_token_stream())
}
}
fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
let name = &ast.ident;
let fields = if let syn::Data::Struct(ast) = &ast.data {
ast.fields.iter()
.map(to_field_spec)
} else {
panic!("not on a struct");
};
let gen = quote! {
impl #name {
pub const META: ::tosin::db::models::ModelMeta = ::tosin::db::models::ModelMeta {
name: stringify!(#name),
fields: &[ #(#fields),* ],
};
}
};
gen.into()
}
#[proc_macro]
pub fn gather_migrations(_input: TokenStream) -> TokenStream {
let call_site = proc_macro::Span::call_site();
let call_site_file = call_site.source_file();
let call_site_path = call_site_file.path();
if !call_site_file.is_real() {
panic!("call site does not have a real path");
}
let migrations_dir = call_site_path.parent().unwrap();
let migrations: Vec<syn::Ident> = migrations_dir.read_dir()
.unwrap()
.map(Result::unwrap)
.map(|x| x.path().file_stem().unwrap().to_string_lossy().into_owned())
.filter(|x| x != "mod")
.map(|x| syn::parse_str(&x).unwrap())
.collect();
let gen = quote! {
#( mod #migrations; )*
pub const ALL: &[Migration] = &[
#(#migrations::MIGRATION),*
];
};
gen.into()
}
#[proc_macro]
pub fn gather_models(_input: TokenStream) -> TokenStream {
let call_site = proc_macro::Span::call_site();
let call_site_file = call_site.source_file();
let call_site_path = call_site_file.path();
if !call_site_file.is_real() {
panic!("call site does not have a real path");
}
let call_site_ast = syn::parse_file(&fs::read_to_string(call_site_path).unwrap()).unwrap();
let models = call_site_ast.items.iter()
.filter_map(|item| if let syn::Item::Struct(item) = item { Some(item) } else { None })
.filter(|item| item.attrs.iter().any(|attr| {
let attr = if let Ok(syn::Meta::List(attr)) = attr.parse_meta() { attr } else { return false; };
if attr.path.get_ident().map_or(false, |hopefully_derive| hopefully_derive == "derive") {
let mut derived = attr.nested.iter()
.filter_map(|derived| if let syn::NestedMeta::Meta(derived) = derived { Some(derived) } else { None });
derived.any(|derived| derived.path().get_ident().map_or(false, |hopefully_model| hopefully_model == "Model"))
} else {
false
}
}))
.map(|item| &item.ident);
let gen = quote! {
pub const ALL: &[tosin::db::models::ModelMeta] = &[
#(#models::META),*
];
};
gen.into()
}
|
