wherror_impl/
prop.rs

1use crate::ast::{Enum, Field, Struct, Variant};
2use crate::unraw::MemberUnraw;
3use proc_macro2::Span;
4use syn::Type;
5use syn::{
6    AngleBracketedGenericArguments, GenericArgument, Lifetime, PathArguments, TypeReference,
7};
8
9impl Struct<'_> {
10    pub(crate) fn from_field(&self) -> Option<&Field> {
11        from_field(&self.fields)
12    }
13
14    pub(crate) fn source_field(&self) -> Option<&Field> {
15        source_field(&self.fields)
16    }
17
18    pub(crate) fn backtrace_field(&self) -> Option<&Field> {
19        backtrace_field(&self.fields)
20    }
21
22    pub(crate) fn location_field(&self) -> Option<&Field> {
23        location_field(&self.fields)
24    }
25
26    pub(crate) fn distinct_backtrace_field(&self) -> Option<&Field> {
27        let backtrace_field = self.backtrace_field()?;
28        distinct_backtrace_field(backtrace_field, self.from_field())
29    }
30}
31
32impl Enum<'_> {
33    pub(crate) fn has_source(&self) -> bool {
34        self.variants
35            .iter()
36            .any(|variant| variant.source_field().is_some() || variant.attrs.transparent.is_some())
37    }
38
39    pub(crate) fn has_backtrace(&self) -> bool {
40        self.variants
41            .iter()
42            .any(|variant| variant.backtrace_field().is_some())
43    }
44
45    pub(crate) fn has_display(&self) -> bool {
46        self.attrs.display.is_some()
47            || self.attrs.transparent.is_some()
48            || self.attrs.fmt.is_some()
49            || self
50                .variants
51                .iter()
52                .any(|variant| variant.attrs.display.is_some() || variant.attrs.fmt.is_some())
53            || self
54                .variants
55                .iter()
56                .all(|variant| variant.attrs.transparent.is_some())
57    }
58}
59
60impl Variant<'_> {
61    pub(crate) fn from_field(&self) -> Option<&Field> {
62        from_field(&self.fields)
63    }
64
65    pub(crate) fn source_field(&self) -> Option<&Field> {
66        source_field(&self.fields)
67    }
68
69    pub(crate) fn backtrace_field(&self) -> Option<&Field> {
70        backtrace_field(&self.fields)
71    }
72
73    pub(crate) fn location_field(&self) -> Option<&Field> {
74        location_field(&self.fields)
75    }
76
77    pub(crate) fn distinct_backtrace_field(&self) -> Option<&Field> {
78        let backtrace_field = self.backtrace_field()?;
79        distinct_backtrace_field(backtrace_field, self.from_field())
80    }
81}
82
83impl Field<'_> {
84    pub(crate) fn is_backtrace(&self) -> bool {
85        type_is_backtrace(self.ty)
86    }
87
88    pub(crate) fn is_location(&self) -> bool {
89        type_is_location(self.ty)
90    }
91
92    pub(crate) fn source_span(&self) -> Span {
93        if let Some(source_attr) = &self.attrs.source {
94            source_attr.span
95        } else if let Some(from_attr) = &self.attrs.from {
96            from_attr.span
97        } else {
98            self.member.span()
99        }
100    }
101}
102
103fn from_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> {
104    for field in fields {
105        if field.attrs.from.is_some() {
106            return Some(field);
107        }
108    }
109    None
110}
111
112fn source_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> {
113    for field in fields {
114        if field.attrs.from.is_some() || field.attrs.source.is_some() {
115            return Some(field);
116        }
117    }
118    for field in fields {
119        match &field.member {
120            MemberUnraw::Named(ident) if ident == "source" => return Some(field),
121            _ => {}
122        }
123    }
124    None
125}
126
127fn backtrace_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> {
128    for field in fields {
129        if field.attrs.backtrace.is_some() {
130            return Some(field);
131        }
132    }
133    for field in fields {
134        if field.is_backtrace() {
135            return Some(field);
136        }
137    }
138    None
139}
140
141fn location_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> {
142    for field in fields {
143        if field.attrs.location.is_some() {
144            return Some(field);
145        }
146    }
147    for field in fields {
148        if field.is_location() {
149            return Some(field);
150        }
151    }
152    None
153}
154
155// The #[backtrace] field, if it is not the same as the #[from] field.
156fn distinct_backtrace_field<'a, 'b>(
157    backtrace_field: &'a Field<'b>,
158    from_field: Option<&Field>,
159) -> Option<&'a Field<'b>> {
160    if from_field.map_or(false, |from_field| {
161        from_field.member == backtrace_field.member
162    }) {
163        None
164    } else {
165        Some(backtrace_field)
166    }
167}
168
169fn type_is_backtrace(ty: &Type) -> bool {
170    let path = match ty {
171        Type::Path(ty) => &ty.path,
172        _ => return false,
173    };
174
175    let last = path.segments.last().unwrap();
176    last.ident == "Backtrace" && last.arguments.is_empty()
177}
178
179fn type_is_location(ty: &Type) -> bool {
180    let path = match ty {
181        Type::Reference(TypeReference {
182            lifetime: Some(Lifetime { ident: ltident, .. }),
183            elem, // TODO: replace with `elem: box Type::Path(path)` once box_patterns stabalizes
184            ..
185        }) if ltident == "static" => match &**elem {
186            Type::Path(ty) => &ty.path,
187            _ => return false,
188        },
189        _ => return false,
190    };
191
192    let last = path.segments.last().unwrap();
193
194    last.ident == "Location"
195        && match &last.arguments {
196            PathArguments::AngleBracketed(AngleBracketedGenericArguments { args, .. }) => {
197                match args.first() {
198                    Some(GenericArgument::Lifetime(Lifetime { ident, .. })) => ident == "static",
199                    _ => false,
200                }
201            }
202            _ => false,
203        }
204}
wherror_impl/prop.rs

wherror_impl/
prop.rs
