oblivion_codegen/
lib.rs

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
156
157
158
159
//! # Oblivion Macros
//!
//! Oblivion use Rust macros to implement the business function processing and routing system,
//! which allows you to use synchronous or asynchronous functions.

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, ItemFn};

enum ReturnType {
    ServerResponse,
    String,
    Json,
    Result(Box<Self>),
}

fn extract_result_return_type(segment: &syn::PathSegment) -> Option<ReturnType> {
    assert!(segment.ident == "Result");
    match &segment.arguments {
        syn::PathArguments::AngleBracketed(args) => {
            let ok_type = args.args[0].clone();

            if let syn::GenericArgument::Type(syn::Type::Path(type_path)) = ok_type {
                assert!(type_path.path.segments.len() == 1);
                match type_path.path.segments[0].ident.to_string().as_str() {
                    "ServerResponse" => {
                        Some(ReturnType::Result(Box::new(ReturnType::ServerResponse)))
                    }
                    "String" => Some(ReturnType::Result(Box::new(ReturnType::String))),
                    "Value" => Some(ReturnType::Result(Box::new(ReturnType::Json))),
                    _ => None,
                }
            } else {
                None
            }
        }
        _ => None,
    }
}

/// ## Oblivion Macro for Route Handler
#[proc_macro_attribute]
pub fn async_route(_: TokenStream, item: TokenStream) -> TokenStream {
    let input = parse_macro_input!(item as ItemFn);

    let func_name = &input.sig.ident;
    let func_args = &input.sig.inputs;
    let func_return = match &input.sig.output {
        syn::ReturnType::Default => {
            return TokenStream::from(
                quote! { compile_error!("Handler function must have a return type"); },
            )
        }
        syn::ReturnType::Type(_, ty) => ty,
    };

    let return_type = match &input.sig.output {
        syn::ReturnType::Default => {
            return TokenStream::from(
                quote! { compile_error!("Handler function must have a return type"); },
            )
        }
        syn::ReturnType::Type(_, ty) => match ty.as_ref() {
            syn::Type::Path(type_path) => {
                if type_path.path.segments.len() == 1 {
                    match type_path.path.segments[0].ident.to_string().as_str() {
                        "ServerResponse" => ReturnType::ServerResponse,
                        "String" => ReturnType::String,
                        "Value" => ReturnType::Json,
                        "Result" => {
                            let extracted_type =
                                extract_result_return_type(&type_path.path.segments[0]);
                            if extracted_type.is_none() {
                                return TokenStream::from(
                                    quote! { compile_error!("Unsupported [Result] return type")},
                                );
                            }
                            extracted_type.unwrap()
                        }
                        _ => {
                            return TokenStream::from(
                                quote! { compile_error!("Unsupported path like return type"); },
                            )
                        }
                    }
                } else {
                    return TokenStream::from(
                        quote! { compile_error!("Unsupported complex path like return type"); },
                    );
                }
            }
            _ => return TokenStream::from(quote! { compile_error!("Unsupported return type"); }),
        },
    };
    let input_block = &input.block;
    let func_block = match return_type {
        ReturnType::ServerResponse => quote! {
            Box::pin(async move {
                #input_block
            })
        },
        ReturnType::String | ReturnType::Json => quote! {
            Box::pin(async move {
                let result = async move {
                    #input_block
                }.await;
                Ok(result.into())
            })
        },
        ReturnType::Result(return_type) => match *return_type {
            ReturnType::String | ReturnType::Json => quote! {
                Box::pin(async move {
                    let result: #func_return = async move {
                        #input_block
                    }.await;
                    Ok(result?.into())
                })
            },
            ReturnType::ServerResponse => {
                return TokenStream::from(
                    quote! { compile_error!("Unsupported [ServerResponse] in [Result] return type")},
                )
            }
            ReturnType::Result(_) => {
                return TokenStream::from(
                    quote! { compile_error!("Unsupported complex [Result] return type")},
                )
            }
        },
    };

    let expanded = quote! {
        use oblivion::prelude::*;

        pub fn #func_name(#func_args) -> ServerResponse {
            #func_block
        }
    };

    TokenStream::from(expanded)
}

#[proc_macro_attribute]
pub fn internal_handler(_input: TokenStream, item: TokenStream) -> TokenStream {
    let input = parse_macro_input!(item as ItemFn);

    let func_name = &input.sig.ident;
    let func_args = &input.sig.inputs;
    let func_block = &input.block;
    let func_return = &input.sig.output;

    let expanded = quote! {
        pub fn #func_name(#func_args) #func_return {
            Box::pin(async move { #func_block })
        }
    };

    TokenStream::from(expanded)
}