Import thiserror-impl-1.0.16

Change-Id: If439e1c68f7afb772354f3c07ebfec7a94b01300

1 files changed, 111 insertions, 0 deletions

diff --git a/src/prop.rs b/src/prop.rs
new file mode 100644
index 0000000..e011848
--- /dev/null
+++ b/src/prop.rs
@@ -0,0 +1,111 @@
+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()
+}