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use crate::ast::{Enum, Field, Struct, Variant};
use crate::span::MemberSpan;
use proc_macro2::Span;
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)
}
pub(crate) fn distinct_backtrace_field(&self) -> Option<&Field> {
let backtrace_field = self.backtrace_field()?;
distinct_backtrace_field(backtrace_field, self.from_field())
}
}
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)
}
pub(crate) fn distinct_backtrace_field(&self) -> Option<&Field> {
let backtrace_field = self.backtrace_field()?;
distinct_backtrace_field(backtrace_field, self.from_field())
}
}
impl Field<'_> {
pub(crate) fn is_backtrace(&self) -> bool {
type_is_backtrace(self.ty)
}
pub(crate) fn source_span(&self) -> Span {
if let Some(source_attr) = &self.attrs.source {
source_attr.path().get_ident().unwrap().span()
} else if let Some(from_attr) = &self.attrs.from {
from_attr.path().get_ident().unwrap().span()
} else {
self.member.member_span()
}
}
}
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
}
// The #[backtrace] field, if it is not the same as the #[from] field.
fn distinct_backtrace_field<'a, 'b>(
backtrace_field: &'a Field<'b>,
from_field: Option<&Field>,
) -> Option<&'a Field<'b>> {
if from_field.map_or(false, |from_field| {
from_field.member == backtrace_field.member
}) {
None
} else {
Some(backtrace_field)
}
}
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()
}