concourse_resource_derive/
lib.rs

1#![deny(
2    warnings,
3    missing_debug_implementations,
4    missing_copy_implementations,
5    trivial_casts,
6    trivial_numeric_casts,
7    unsafe_code,
8    unstable_features,
9    unused_import_braces,
10    unused_qualifications
11)]
12
13//! Helper for [concourse-resource] crate, to derive the `Vec<KV>` struct needed by [Concourse]
14//! for metadata from any struct that `impl Serialize` from serde. Refer to [concourse-resource]
15//! for usage.
16//!
17//! [Concourse]: https://concourse-ci.org
18//! [concourse-resource]: https://github.com/mockersf/concourse-resource-rs
19
20extern crate proc_macro;
21
22use crate::proc_macro::TokenStream;
23use quote::quote;
24
25#[proc_macro_derive(IntoMetadataKV)]
26pub fn metadata_kv_derive(input: TokenStream) -> TokenStream {
27    // Construct a representation of Rust code as a syntax tree
28    // that we can manipulate
29    let ast: syn::DeriveInput = syn::parse(input).unwrap();
30
31    // Build the trait implementation
32
33    match ast.data {
34        syn::Data::Struct(fields) => impl_metadata_kv(ast.ident, fields),
35        _ => panic!("#[derive(IntoMetadataKV)] is only defined for structs"),
36    }
37}
38
39fn impl_metadata_kv(name: syn::Ident, data_struct: syn::DataStruct) -> TokenStream {
40    let md_fields: Vec<_> = data_struct
41        .fields
42        .iter()
43        .filter_map(|field| field.ident.as_ref())
44        .map(|field_name| {
45            let val = quote! {
46                serde_json::to_string(&self.#field_name).unwrap()
47            };
48            quote! {
49                concourse_resource::internal::KV {
50                    name: String::from(stringify!(#field_name)),
51                    value: #val.strip_prefix('"')
52                    .unwrap_or(&#val)
53                    .strip_suffix('"')
54                    .unwrap_or(&#val)
55                    .to_string()
56                }
57            }
58        })
59        .collect();
60
61    let gen = quote! {
62        impl IntoMetadataKV for #name {
63            fn into_metadata_kv(self) -> Vec<concourse_resource::internal::KV> {
64                // let mut md = Vec::new();
65                // md
66                vec![#(#md_fields,)*]
67            }
68        }
69    };
70    gen.into()
71}
concourse_resource_derive/lib.rs

concourse_resource_derive/
lib.rs
