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use ahash::AHashMap;
#[cfg(debug_assertions)]
use ahash::AHashSet;
use quote::quote;
use syn::{spanned::Spanned, Error, Expr, ExprArray, ExprTuple, Lit};
pub(super) fn alphabet_match_inner(input: ExprArray) -> syn::Result<proc_macro2::TokenStream> {
let mut value_to_keys = AHashMap::new();
let mut keys_all = Vec::new();
// Parse the input array of tuples
for tuple in input.elems {
match tuple {
Expr::Tuple(ExprTuple { elems, .. }) => {
// We assume the key can be any expression, so we just clone it
let key = &elems[0];
keys_all.push(key.clone());
// Handle the array of values associated with the key
match &elems[1] {
Expr::Array(ExprArray { elems: values, .. }) => {
#[cfg(debug_assertions)]
let mut values_set: AHashSet<char> = AHashSet::new();
for val in values {
let value = match val {
Expr::Lit(expr_lit) => match &expr_lit.lit {
Lit::Char(lit_char) => lit_char.value(),
v => {
return Err(Error::new(
v.span(),
"Expected char literal for value",
))
}
},
v => {
return Err(Error::new(
v.span(),
"Expected char literal for value",
))
}
};
#[cfg(debug_assertions)]
if let Expr::Path(ep) = key {
let ki = &ep.path.segments[1].ident;
if !values_set.insert(value) {
return Err(Error::new(
val.span(),
format!(
"Char literal: {} was already added for key: {}",
value, ki
),
));
}
}
value_to_keys
.entry(value)
.or_insert_with(Vec::new)
.push(key.clone()); // Clone the key to store it in the map
}
}
v => {
return Err(Error::new(v.span(), "Expected an array of values"));
}
}
}
v => {
return Err(Error::new(v.span(), "Expected a tuple"));
}
}
}
// Generate match arms
let arms = value_to_keys
.iter()
.filter(|(_, k)| k.len() < keys_all.len())
.map(|(value, keys)| {
quote! {
#value => &[#(#keys),*],
}
});
let chars = value_to_keys.keys().map(|c| quote! { #c });
// Generate the entire match block
let expanded = quote! {{
#[cfg(all(debug_assertions, feature = "test_chars"))]
{
let chars = [#(#chars),*];
test_chars(script, &chars);
}
match ch {
#(#arms)*
_ => &[#(#keys_all),*],
}
}};
Ok(expanded)
}