diesel_derives/
util.rs

1use proc_macro2::TokenStream;
2use quote::quote;
3use syn::parse::Result;
4use syn::{Data, DeriveInput, GenericArgument, Type, parse_quote};
5
6use crate::model::Model;
7
8pub fn wrap_in_dummy_mod(item: TokenStream) -> TokenStream {
9    {
    let mut _s = ::quote::__private::TokenStream::new();
    ::quote::__private::push_ident(&mut _s, "const");
    ::quote::__private::push_underscore(&mut _s);
    ::quote::__private::push_colon(&mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Parenthesis,
        ::quote::__private::TokenStream::new());
    ::quote::__private::push_eq(&mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Brace,
        {
            let mut _s = ::quote::__private::TokenStream::new();
            ::quote::__private::push_ident(&mut _s, "use");
            ::quote::__private::push_ident(&mut _s, "diesel");
            ::quote::__private::push_semi(&mut _s);
            ::quote::ToTokens::to_tokens(&item, &mut _s);
            _s
        });
    ::quote::__private::push_semi(&mut _s);
    _s
}quote! {
10        const _: () = {
11            // This import is not actually redundant. When using diesel_derives
12            // inside of diesel, `diesel` doesn't exist as an extern crate, and
13            // to work around that it contains a private
14            // `mod diesel { pub use super::*; }` that this import will then
15            // refer to. In all other cases, this imports refers to the extern
16            // crate diesel.
17            use diesel;
18
19            #item
20        };
21    }
22}
23
24pub fn inner_of_option_ty(ty: &Type) -> &Type {
25    option_ty_arg(ty).unwrap_or(ty)
26}
27
28pub fn is_option_ty(ty: &Type) -> bool {
29    option_ty_arg(ty).is_some()
30}
31
32fn option_ty_arg(mut ty: &Type) -> Option<&Type> {
33    use syn::PathArguments::AngleBracketed;
34
35    // Check the inner equivalent type
36    loop {
37        match ty {
38            Type::Group(group) => ty = &group.elem,
39            Type::Paren(paren) => ty = &paren.elem,
40            _ => break,
41        }
42    }
43
44    match *ty {
45        Type::Path(ref ty) => {
46            let last_segment = ty.path.segments.iter().next_back().unwrap();
47            match last_segment.arguments {
48                AngleBracketed(ref args) if last_segment.ident == "Option" => {
49                    match args.args.iter().next_back() {
50                        Some(GenericArgument::Type(ty)) => Some(ty),
51                        _ => None,
52                    }
53                }
54                _ => None,
55            }
56        }
57        _ => None,
58    }
59}
60
61pub fn ty_for_foreign_derive(item: &DeriveInput, model: &Model) -> Result<Type> {
62    if model.foreign_derive {
63        match item.data {
64            Data::Struct(ref body) => match body.fields.iter().next() {
65                Some(field) => Ok(field.ty.clone()),
66                None => Err(syn::Error::new(
67                    proc_macro2::Span::mixed_site(),
68                    "foreign_derive requires at least one field",
69                )),
70            },
71            _ => Err(syn::Error::new(
72                proc_macro2::Span::mixed_site(),
73                "foreign_derive can only be used with structs",
74            )),
75        }
76    } else {
77        let ident = &item.ident;
78        let (_, ty_generics, ..) = item.generics.split_for_impl();
79        Ok(::syn::__private::parse_quote({
        let mut _s = ::quote::__private::TokenStream::new();
        ::quote::ToTokens::to_tokens(&ident, &mut _s);
        ::quote::ToTokens::to_tokens(&ty_generics, &mut _s);
        _s
    })parse_quote!(#ident #ty_generics))
80    }
81}
82
83pub fn camel_to_snake(name: &str) -> String {
84    let mut result = String::with_capacity(name.len());
85    result.push_str(&name[..1].to_lowercase());
86    for character in name[1..].chars() {
87        if character.is_uppercase() {
88            result.push('_');
89            for lowercase in character.to_lowercase() {
90                result.push(lowercase);
91            }
92        } else {
93            result.push(character);
94        }
95    }
96    result
97}
diesel_derives/util.rs

diesel_derives/
util.rs
