1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155

//! Experimental macros for Actix Web.

use quote::{format_ident, quote};
use syn::{parse_macro_input, punctuated::Punctuated, token::Comma, DeriveInput, Ident};

/// Derive a `FromRequest` implementation for an aggregate struct extractor.
///
/// All fields of the struct need to implement `FromRequest` unless they are marked with annotations
/// that declare different handling is required.
///
/// # Examples
/// ```
/// use actix_web::{get, http, web, Responder};
/// use actix_web_lab::FromRequest;
///
/// #[derive(Debug, FromRequest)]
/// struct RequestParts {
///     // the FromRequest impl is used for these fields
///     method: http::Method,
///     pool: web::Data<u32>,
///     req_body: String,
///
///     // equivalent to `req.app_data::<u64>().copied()`
///     #[from_request(copy_from_app_data)]
///     int: u64,
/// }
///
/// #[get("/")]
/// async fn handler(parts: RequestParts) -> impl Responder {
///     // ...
///     # ""
/// }
/// ```
#[proc_macro_derive(FromRequest, attributes(from_request))]
pub fn derive_from_request(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let input = parse_macro_input!(input as DeriveInput);

    let name = input.ident;

    let data = match input.data {
        syn::Data::Struct(data) => data,
        syn::Data::Enum(_) | syn::Data::Union(_) => {
            return quote! {
                compile_error!("Deriving FromRequest is only supported on structs for now.");
            }
            .into();
        }
    };

    let fields = match data.fields {
        syn::Fields::Named(fields) => fields.named,
        syn::Fields::Unnamed(_) | syn::Fields::Unit => {
            return quote! {
                compile_error!("Deriving FromRequest is only supported on structs with named fields for now.");
            }
            .into();
        }
    };

    let field_names_joined = fields
        .iter()
        .map(|f| f.ident.clone().unwrap())
        .collect::<Punctuated<_, Comma>>();

    // i.e., field has no special handling, it's just extracted using its FromRequest impl
    let fut_fields = fields.iter().filter(|field| {
        field.attrs.is_empty()
            || field
                .attrs
                .iter()
                .any(|attr| attr.parse_args::<Ident>().is_err())
    });

    let field_fut_names_joined = fut_fields
        .clone()
        .map(|f| format_ident!("{}_fut", f.ident.clone().unwrap()))
        .collect::<Punctuated<_, Comma>>();

    let field_post_fut_names_joined = fut_fields
        .clone()
        .map(|f| f.ident.clone().unwrap())
        .collect::<Punctuated<_, Comma>>();

    let field_futs = fut_fields.clone().map(|field| {
        let syn::Field { ident, ty, .. } = field;

        let varname = format_ident!("{}_fut", ident.clone().unwrap());

        quote! {
            let #varname = <#ty>::from_request(&req, pl).map_err(Into::into);
        }
    });

    let fields_copied_from_app_data = fields
        .iter()
        .filter(|field| {
            field.attrs.iter().any(|attr| {
                attr.parse_args::<Ident>()
                    .map_or(false, |ident| ident == "copy_from_app_data")
            })
        })
        .map(|field| {
            let syn::Field { ident, ty, .. } = field;

            let varname = ident.clone().unwrap();

            quote! {
                let #varname = if let Some(st) = req.app_data::<#ty>().copied() {
                    st
                } else {
                    ::actix_web_lab::__reexports::tracing::debug!(
                        "Failed to extract `{}` for `{}` handler. For this extractor to work \
                        correctly, pass the data to `App::app_data()`. Ensure that types align in \
                        both the set and retrieve calls.",
                        ::std::any::type_name::<#ty>(),
                        req.match_name().unwrap_or_else(|| req.path())
                    );

                    return ::std::boxed::Box::pin(async move {
                        ::std::result::Result::Err(
                            ::actix_web_lab::__reexports::actix_web::error::ErrorInternalServerError(
                            "Requested application data is not configured correctly. \
                            View/enable debug logs for more details.",
                        ))
                    })
                };
            }
        });

    let output = quote! {
        impl ::actix_web::FromRequest for #name {
            type Error = ::actix_web::Error;
            type Future = ::std::pin::Pin<::std::boxed::Box<
                dyn ::std::future::Future<Output = ::std::result::Result<Self, Self::Error>>
            >>;

            fn from_request(req: &::actix_web::HttpRequest, pl: &mut ::actix_web::dev::Payload) -> Self::Future {
                use ::actix_web_lab::__reexports::actix_web::FromRequest as _;
                use ::actix_web_lab::__reexports::futures_util::{FutureExt as _, TryFutureExt as _};
                use ::actix_web_lab::__reexports::tokio::try_join;

                #(#fields_copied_from_app_data)*

                #(#field_futs)*

                ::std::boxed::Box::pin(
                    async move { try_join!( #field_fut_names_joined ) }
                        .map_ok(move |( #field_post_fut_names_joined )| Self { #field_names_joined })
                )
           }
        }
    };

    proc_macro::TokenStream::from(output)
}