1 //! Functions to derive `darling`'s traits from well-formed input, without directly depending
2 //! on `proc_macro`.
3
4 use proc_macro2::TokenStream;
5 use quote::ToTokens;
6 use syn::DeriveInput;
7
8 use crate::options;
9
10 /// Run an expression which returns a `darling::Result`, then either return the tokenized
11 /// representation of the `Ok` value, or the tokens of the compiler errors in the `Err` case.
12 macro_rules! emit_impl_or_error {
13 ($e:expr) => {
14 match $e {
15 Ok(val) => val.into_token_stream(),
16 Err(err) => err.write_errors(),
17 }
18 };
19 }
20
21 /// Create tokens for a `darling::FromMeta` impl from a `DeriveInput`. If
22 /// the input cannot produce a valid impl, the returned tokens will contain
23 /// compile errors instead.
from_meta(input: &DeriveInput) -> TokenStream24 pub fn from_meta(input: &DeriveInput) -> TokenStream {
25 emit_impl_or_error!(options::FromMetaOptions::new(input))
26 }
27
28 /// Create tokens for a `darling::FromAttributes` impl from a `DeriveInput`. If
29 /// the input cannot produce a valid impl, the returned tokens will contain
30 /// compile errors instead.
from_attributes(input: &DeriveInput) -> TokenStream31 pub fn from_attributes(input: &DeriveInput) -> TokenStream {
32 emit_impl_or_error!(options::FromAttributesOptions::new(input))
33 }
34
35 /// Create tokens for a `darling::FromDeriveInput` impl from a `DeriveInput`. If
36 /// the input cannot produce a valid impl, the returned tokens will contain
37 /// compile errors instead.
from_derive_input(input: &DeriveInput) -> TokenStream38 pub fn from_derive_input(input: &DeriveInput) -> TokenStream {
39 emit_impl_or_error!(options::FdiOptions::new(input))
40 }
41
42 /// Create tokens for a `darling::FromField` impl from a `DeriveInput`. If
43 /// the input cannot produce a valid impl, the returned tokens will contain
44 /// compile errors instead.
from_field(input: &DeriveInput) -> TokenStream45 pub fn from_field(input: &DeriveInput) -> TokenStream {
46 emit_impl_or_error!(options::FromFieldOptions::new(input))
47 }
48
49 /// Create tokens for a `darling::FromTypeParam` impl from a `DeriveInput`. If
50 /// the input cannot produce a valid impl, the returned tokens will contain
51 /// compile errors instead.
from_type_param(input: &DeriveInput) -> TokenStream52 pub fn from_type_param(input: &DeriveInput) -> TokenStream {
53 emit_impl_or_error!(options::FromTypeParamOptions::new(input))
54 }
55
56 /// Create tokens for a `darling::FromVariant` impl from a `DeriveInput`. If
57 /// the input cannot produce a valid impl, the returned tokens will contain
58 /// compile errors instead.
from_variant(input: &DeriveInput) -> TokenStream59 pub fn from_variant(input: &DeriveInput) -> TokenStream {
60 emit_impl_or_error!(options::FromVariantOptions::new(input))
61 }
62