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https://github.com/OMGeeky/confique.git
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ebd8aba2fa
Regarding nested fields: I cannot imagine a situation where that distinction is useful. Also, specifying an empty nested object looks stupid in TOML and YAML anyway. Regarding default fields: If there is a default value, then the field should not be declared as optional to begin with.
47 lines
1.3 KiB
Rust
47 lines
1.3 KiB
Rust
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/// Checks if the given type is an `Option` and if so, return the inner type.
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///
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/// Note: this function clearly shows one of the major shortcomings of proc
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/// macros right now: we do not have access to the compiler's type tables and
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/// can only check if it "looks" like an `Option`. Of course, stuff can go
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/// wrong. But that's the best we can do and it's highly unlikely that someone
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/// shadows `Option`.
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pub(crate) fn unwrap_option(ty: &syn::Type) -> Option<&syn::Type> {
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let ty = match ty {
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syn::Type::Path(path) => path,
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_ => return None,
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};
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if ty.qself.is_some() || ty.path.leading_colon.is_some() {
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return None;
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}
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let valid_paths = [
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&["Option"] as &[_],
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&["std", "option", "Option"],
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&["core", "option", "Option"],
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];
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if !valid_paths.iter().any(|vp| ty.path.segments.iter().map(|s| &s.ident).eq(*vp)) {
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return None;
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}
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let args = match &ty.path.segments.last().unwrap().arguments {
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syn::PathArguments::AngleBracketed(args) => args,
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_ => return None,
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};
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if args.args.len() != 1 {
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return None;
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}
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match &args.args[0] {
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syn::GenericArgument::Type(t) => Some(t),
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_ => None,
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}
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}
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/// Returns `true` if the given type is `Option<_>`.
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pub(crate) fn is_option(ty: &syn::Type) -> bool {
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unwrap_option(ty).is_some()
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}
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