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
160
161
162
163
164

mod utils;
use core::panic;

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, Data, DeriveInput, Field, Fields, FieldsNamed, Ident};
use utils::{get_list_attr, has_attribute, validate_attributes};

#[proc_macro_derive(Repository, attributes(index, unique, check))]
pub fn repository(input: TokenStream) -> TokenStream {
    let ast = parse_macro_input!(input as DeriveInput);
    let name = ast.ident;

    let fields = match ast.data {
        Data::Struct(syn::DataStruct {
            fields: Fields::Named(FieldsNamed { ref named, .. }),
            ..
        }) => named,
        _ => panic!("can only derive on a struct"),
    };

    let (index_names, index_members, by_index, index_initializers) =
        match process_fields(&name, fields.iter()) {
            Ok(v) => v,
            Err(e) => return e,
        };

    if let Err(tokens) =
        validate_attributes(&ast.attrs, None, &[("check", true)], &["unique", "index"])
    {
        return tokens.into();
    }

    let checks: Vec<proc_macro2::TokenStream> = match get_list_attr(&ast.attrs, "check") {
        Ok(v) => v,
        Err(err) => return err.into(),
    }
    .iter()
    .map(|check_fn| {
        return quote! {
            _table.constraint(tinybase::Constraint::check(#check_fn))?;
        };
    })
    .collect();

    let vis = ast.vis.clone();
    let wrapper_name = syn::Ident::new(&format!("{}Repository", name.to_string()), name.span());

    let expanded = quote! {
        #[derive(Clone)]
        #vis struct #wrapper_name {
            _table: tinybase::Table<#name>,
            #(#index_members)*
        }

        impl std::ops::Deref for #wrapper_name {
            type Target = tinybase::Table<#name>;

            fn deref(&self) -> &Self::Target {
                &self._table
            }
        }

        impl #wrapper_name {
            #(#by_index)*
        }

        impl #name {
            pub fn init(db: &tinybase::TinyBase, name: &str) -> tinybase::DbResult<#wrapper_name> {
                let _table: tinybase::Table<#name> = db.open_table(name)?;
                #(#index_initializers);*
                #(#checks)*

                Ok(#wrapper_name {
                    _table, #(#index_names),*
                })
            }
        }
    };

    expanded.into()
}

/// Process fields and decide what should be generated for each field.
fn process_fields<'a>(
    struct_name: &proc_macro2::Ident,
    fields: impl Iterator<Item = &'a Field>,
) -> Result<
    (
        Vec<Ident>,
        Vec<proc_macro2::TokenStream>,
        Vec<proc_macro2::TokenStream>,
        Vec<proc_macro2::TokenStream>,
    ),
    TokenStream,
> {
    let mut index_names = vec![];
    let mut index_members = vec![];

    let mut by_index = vec![];
    let mut index_initializers = vec![];

    for field in fields {
        validate_attributes(
            &field.attrs,
            Some("index"),
            &[("unique", false), ("index", false)], // index is here as a hack to prevent allowing list.
            &["check"],
        )?;

        if has_attribute(&field.attrs, "index").is_some() {
            let (field_name, type_name) = (field.ident.as_ref().unwrap(), &field.ty);

            index_names.push(field_name.clone());

            index_members.push(quote! {
                pub #field_name: tinybase::Index<#struct_name, #type_name>,
            });

            let methods = create_methods(field_name, type_name, struct_name);

            by_index.push(methods);

            let field_str = format!("{}", field_name);

            index_initializers.push(quote! {
                let #field_name = _table.create_index(#field_str, |record| record.#field_name.clone())?;
            });

            if has_attribute(&field.attrs, "unique").is_some() {
                index_initializers.push(quote! {
                    _table.constraint(tinybase::Constraint::unique(&#field_name))?;
                })
            }
        }
    }

    Ok((index_names, index_members, by_index, index_initializers))
}

/// Create methods for an index.
fn create_methods(
    field_name: &Ident,
    type_name: &syn::Type,
    name: &Ident,
) -> proc_macro2::TokenStream {
    let find_method = syn::Ident::new(&format!("find_by_{}", field_name), field_name.span());
    let delete_method = syn::Ident::new(&format!("delete_by_{}", field_name), field_name.span());
    let update_method = syn::Ident::new(&format!("update_by_{}", field_name), field_name.span());

    quote! {
        pub fn #find_method(&self, #field_name: #type_name) -> tinybase::result::DbResult<Vec<tinybase::Record<#name>>> {
            self.#field_name.select(&#field_name)
        }

        pub fn #delete_method(&self, #field_name: #type_name) -> tinybase::result::DbResult<Vec<tinybase::Record<#name>>> {
            self.#field_name.delete(&#field_name)
        }

        pub fn #update_method(&self, #field_name: #type_name, value: #name) -> tinybase::result::DbResult<Vec<tinybase::Record<#name>>> {
            self.#field_name.update(&#field_name, value)
        }
    }
}