jslt_macro/
lib.rs

1use std::sync::LazyLock;
2
3use derive_syn_parse::Parse;
4use quote::{format_ident, quote};
5use syn::parse_macro_input;
6
7static CRATE_NAME: LazyLock<&str> = LazyLock::new(|| {
8  if "jslt" == std::env::var("CARGO_PKG_NAME").unwrap_or_default() {
9    "crate"
10  } else {
11    "jslt"
12  }
13});
14
15#[proc_macro_attribute]
16pub fn static_function(
17  _attr: proc_macro::TokenStream,
18  item: proc_macro::TokenStream,
19) -> proc_macro::TokenStream {
20  let mut item = parse_macro_input!(item as syn::ItemFn);
21
22  let mut vis = syn::Visibility::Inherited;
23  std::mem::swap(&mut item.vis, &mut vis);
24
25  // replace original ident with `_wrapped_implementation` and store the original in ident
26  let mut ident = format_ident!("_wrapped_implementation");
27  std::mem::swap(&mut item.sig.ident, &mut ident);
28
29  let arguments_ident = format_ident!("arguments");
30
31  let arguments = item.sig.inputs.iter().enumerate().map(|(index, item)| {
32    let required = !matches!(item, syn::FnArg::Typed(syn::PatType { ty, .. }) if matches!(**ty, syn::Type::Path(_)));
33    let required = required.then(|| quote! { .unwrap_or(&serde_json::Value::Null) });
34
35    quote! {
36      #arguments_ident .get(#index) #required
37    }
38  });
39
40  let jslt = format_ident!("{}", *CRATE_NAME);
41
42  quote! {
43    #vis fn #ident(#arguments_ident: &[serde_json::Value]) -> Result<serde_json::Value, #jslt::error::JsltError> {
44      #item
45
46      _wrapped_implementation( #(#arguments,)* )
47    }
48  }.into()
49}
50
51#[derive(Parse, Debug)]
52struct ExpectInnerArgs {
53  pairs: syn::Ident,
54  _period_token: syn::Token![,],
55  rule: syn::Type,
56}
57
58#[proc_macro]
59pub fn expect_inner(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
60  let ExpectInnerArgs { pairs, rule, .. } = parse_macro_input!(item as ExpectInnerArgs);
61
62  let jslt = format_ident!("{}", *CRATE_NAME);
63
64  quote! {
65    {
66      let Some(pair) = #pairs.next() else {
67        return Err(#jslt::error::JsltError::UnexpectedEnd);
68      };
69
70      let rule = pair.as_rule();
71
72      if !matches!(rule, #rule) {
73        return Err(#jslt::error::JsltError::UnexpectedInput(
74          #rule,
75          rule,
76          pair.as_str().to_owned(),
77        ));
78      }
79
80      Ok::<Pairs<_>, #jslt::error::JsltError>(pair.into_inner())
81    }
82  }
83  .into()
84}
jslt_macro/lib.rs

jslt_macro/
lib.rs
