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

//! This crate provides `doodle`'s `Schema` derive macro
#![crate_type = "proc-macro"]

#[macro_use]
extern crate quote;
extern crate proc_macro;
extern crate proc_macro2;
extern crate syn;

use self::proc_macro::TokenStream;
use quote::ToTokens;
use syn::{parse_macro_input, Data, DeriveInput, Fields};

#[proc_macro_derive(Schema)]
pub fn derive_schema(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    implement_derive_schema(input)
}

fn implement_derive_schema(input: DeriveInput) -> TokenStream {
    let name = &input.ident;
    let generics = input.generics;
    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
    let fields = match input.data {
        Data::Struct(data) => data.fields,
        _ => panic!("Only structs are supported!"),
    };
    let fields = match fields {
        Fields::Named(ref fields) => fields.named.iter().cloned().map(|field| {
            let x = field.ident.expect("Unnamed fields are not supported");
            let x = format!("{}", x);
            let y = field.ty;
            let tt = y.into_token_stream();
            let y = format!("{}", tt);
            let y = serialize_type(y.as_str());
            quote! {
                Field {
                    name: #x,
                    json_ty: #y,
                }
            }
        }),
        _ => panic!("Only named fields are supported!"),
    };
    let diplay_name = format!("{}", name);
    let implementation = quote! {
        impl #impl_generics SchemaMeta for #name #ty_generics #where_clause {
            fn get_fields() -> &'static [Field] {
                &[#(#fields),*]
            }

            fn get_name() -> &'static str {
                #diplay_name
            }
        }

        impl #impl_generics Schema for #name #ty_generics #where_clause {}

    };
    TokenStream::from(implementation)
}

fn serialize_type(y: &str) -> proc_macro2::TokenStream {
    if y.starts_with("Vec") {
        serialize_vec(y)
    } else if y.starts_with("Option") {
        let split = split_generics(y);
        assert_eq!(split.len(), 3);
        let ty = split[1].replace(' ', "");
        let ty = serialize_type(ty.as_str());
        quote!( Type::Nullable(& #ty) )
    } else {
        let ty = into_json_type(y);
        match ty {
            Some(ty) => quote! ( Type::Simple(#ty) ),
            None => quote! ( Type::Ref(#y) ),
        }
    }
}

fn serialize_vec(y: &str) -> proc_macro2::TokenStream {
    let split = split_generics(y);
    assert_eq!(
        split.len(),
        3,
        "Vector is of incorrect type, expected: Vec < ... >"
    );
    let inner_type = split[1].replace(' ', "");
    let inner_type = serialize_type(inner_type.as_str());
    quote! ( Type::Array(& #inner_type) )
}

fn split_generics(y: &str) -> Vec<&str> {
    let mut depth = 0;
    y.split(|c| {
        let mut result = false;
        if c == '<' {
            if depth == 0 {
                result = true;
            }
            depth += 1;
        } else if c == '>' {
            depth -= 1;
            if depth == 0 {
                result = true;
            }
        }
        result
    })
    .collect::<Vec<_>>()
}

fn into_json_type(ty: &str) -> Option<String> {
    match ty {
        "usize" | "isize" | "i32" | "u32" | "i8" | "u8" | "i16" | "u16" | "i64" | "u64" | "f32"
        | "f64" => Some("number".into()),
        "String" | "str" => Some("string".into()),
        _ => None,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_vector_serialization() {
        let input = "Vec<Vec<i32>>";
        let result = serialize_vec(input);

        let result = format!("{}", result);

        assert_eq!(
            result,
            "Type :: Array ( & Type :: Array ( & Type :: Simple ( \"number\" ) ) )"
        );
    }
}