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#![allow(unused_imports)]
extern crate proc_macro;
use quote::{format_ident, quote, ToTokens};
use std::any::Any;
use syn::parse::{Parse, ParseStream, Result};
use syn::token::Token;
use syn::{
bracketed,
fold::{fold_ident, Fold},
visit_mut::{self, VisitMut},
ExprLit, Lit,
};
use syn::{parse_macro_input, Expr, Ident, Local, Pat, Stmt, Token};
const CLONE_NAME: &str = "_clone__fate__";
const VALUE_NAME: &str = "_value__fate__";
struct CloneFold<'a> {
pub(crate) exclusions: &'a Vec<Ident>,
pub(crate) clones: String,
pub(crate) values: String,
pub(crate) dependencies: String,
}
impl Fold for CloneFold<'_> {
fn fold_ident(&mut self, i: Ident) -> Ident {
if self.exclusions.contains(&i) {
return i;
}
let clone_ident = format_ident!("{}{}", i, CLONE_NAME);
let value_ident = format_ident!("{}{}", i, VALUE_NAME);
self.clones += &format!("let {} = {}.clone(); ", clone_ident, i);
self.dependencies += &format!("{}.clone(), ", i);
let value_expr_str = &format!("let {} = {}.get();", value_ident, clone_ident);
if !self.values.contains(value_expr_str) {
self.values += value_expr_str;
}
value_ident
}
}
impl<'a> CloneFold<'a> {
pub(crate) fn new(exclusions: &'a Vec<Ident>) -> Self {
CloneFold {
exclusions,
clones: "".to_string(),
values: "".to_string(),
dependencies: "".to_string(),
}
}
}
struct Fate {
quotes: Vec<proc_macro2::TokenStream>,
}
impl Parse for Fate {
fn parse(input: ParseStream) -> Result<Self> {
let mut quotes: Vec<proc_macro2::TokenStream> = Vec::new();
let mut exclusions: Vec<Ident> = Vec::new();
let content;
if input.peek(syn::token::Bracket) {
bracketed!(content in input);
while !content.is_empty() {
let exclusion = content.parse::<Ident>()?;
exclusions.push(exclusion);
if content.peek(Token![,]) {
content.parse::<Token![,]>()?;
}
}
}
while !input.is_empty() {
let is_new = if input.peek(Token![let]) {
input.parse::<Token![let]>()?;
true
} else {
false
};
let fate_ident: Ident = input.parse()?;
input.parse::<Token![=]>()?;
let expr = input.parse::<Expr>()?;
input.parse::<Token![;]>()?;
let mut clone_fold = CloneFold::new(&exclusions);
let fixed_expr = clone_fold.fold_expr(expr);
let clones: proc_macro2::TokenStream = clone_fold.clones.parse().unwrap();
let dependencies: proc_macro2::TokenStream =
clone_fold.dependencies.parse().unwrap();
let value_expr: proc_macro2::TokenStream =
clone_fold.values.parse().unwrap();
let binding_quote = if is_new {
quote! {
let #fate_ident = Fate::from_expression
}
} else {
quote! {
#fate_ident.bind_expression
}
};
let quote = quote! {
#clones;
#binding_quote(
Box::new(move || {#value_expr #fixed_expr}), vec![#dependencies]);
};
quotes.push(quote);
}
Ok(Fate { quotes })
}
}
#[proc_macro]
pub fn fate(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let Fate { quotes } = parse_macro_input!(input as Fate);
let expanded = quote! {
#(#quotes)*
};
proc_macro::TokenStream::from(expanded)
}