46 lines
1017 B
Rust
46 lines
1017 B
Rust
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use darling::{util::Flag, Error, FromDeriveInput, FromMeta};
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use proc_macro2::Ident;
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use syn::parse_quote;
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#[derive(FromMeta)]
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#[darling(and_then = Self::validate)]
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struct Vis {
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public: Flag,
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private: Flag,
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}
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impl Vis {
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fn validate(self) -> darling::Result<Self> {
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if self.public.is_present() && self.private.is_present() {
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return Err(Error::custom("Cannot be both public and private"));
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}
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Ok(self)
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}
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}
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#[derive(FromDeriveInput)]
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#[darling(attributes(sample))]
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#[allow(dead_code)]
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struct Example {
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ident: Ident,
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label: String,
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volume: usize,
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#[darling(flatten)]
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visibility: Vis,
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}
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#[test]
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fn many_errors() {
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let e = Example::from_derive_input(&parse_quote! {
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#[sample(volume = 10, public, private)]
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struct Demo {}
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})
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.map(|_| "Should have failed")
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.unwrap_err();
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// We are expecting an error from the Vis::validate method and an error for the
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// missing `label` field.
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assert_eq!(e.len(), 2);
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}
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