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use crate::ast::{Enum, Field, Struct, Variant}; use syn::{Member, Type}; impl Struct<'_> { pub(crate) fn from_field(&self) -> Option<&Field> { from_field(&self.fields) } pub(crate) fn source_field(&self) -> Option<&Field> { source_field(&self.fields) } pub(crate) fn backtrace_field(&self) -> Option<&Field> { backtrace_field(&self.fields) } } impl Enum<'_> { pub(crate) fn has_source(&self) -> bool { self.variants .iter() .any(|variant| variant.source_field().is_some() || variant.attrs.transparent.is_some()) } pub(crate) fn has_backtrace(&self) -> bool { self.variants .iter() .any(|variant| variant.backtrace_field().is_some()) } pub(crate) fn has_display(&self) -> bool { self.attrs.display.is_some() || self.attrs.transparent.is_some() || self .variants .iter() .any(|variant| variant.attrs.display.is_some()) || self .variants .iter() .all(|variant| variant.attrs.transparent.is_some()) } } impl Variant<'_> { pub(crate) fn from_field(&self) -> Option<&Field> { from_field(&self.fields) } pub(crate) fn source_field(&self) -> Option<&Field> { source_field(&self.fields) } pub(crate) fn backtrace_field(&self) -> Option<&Field> { backtrace_field(&self.fields) } } impl Field<'_> { pub(crate) fn is_backtrace(&self) -> bool { type_is_backtrace(self.ty) } } fn from_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> { for field in fields { if field.attrs.from.is_some() { return Some(field); } } None } fn source_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> { for field in fields { if field.attrs.from.is_some() || field.attrs.source.is_some() { return Some(field); } } for field in fields { match &field.member { Member::Named(ident) if ident == "source" => return Some(field), _ => {} } } None } fn backtrace_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> { for field in fields { if field.attrs.backtrace.is_some() { return Some(field); } } for field in fields { if field.is_backtrace() { return Some(field); } } None } fn type_is_backtrace(ty: &Type) -> bool { let path = match ty { Type::Path(ty) => &ty.path, _ => return false, }; let last = path.segments.last().unwrap(); last.ident == "Backtrace" && last.arguments.is_empty() }