1//! Special types handling
2
3use super::spanned::Sp;
4
5use syn::{
6 spanned::Spanned, GenericArgument, Path, PathArguments, PathArguments::AngleBracketed,
7 PathSegment, Type, TypePath,
8};
9
10#[derive(Copy, Clone, PartialEq, Eq, Debug)]
11pub(crate) enum Ty {
12 Unit,
13 Vec,
14 VecVec,
15 Option,
16 OptionOption,
17 OptionVec,
18 OptionVecVec,
19 Other,
20}
21
22impl Ty {
23 pub(crate) fn from_syn_ty(ty: &Type) -> Sp<Self> {
24 use self::Ty::{Option, OptionOption, OptionVec, OptionVecVec, Other, Unit, Vec, VecVec};
25 let t = |kind| Sp::new(kind, ty.span());
26
27 if is_unit_ty(ty) {
28 t(Unit)
29 } else if let Some(vt) = get_vec_ty(ty, Vec, VecVec) {
30 t(vt)
31 } else if let Some(subty) = subty_if_name(ty, "Option") {
32 if is_generic_ty(subty, "Option") {
33 t(OptionOption)
34 } else if let Some(vt) = get_vec_ty(subty, OptionVec, OptionVecVec) {
35 t(vt)
36 } else {
37 t(Option)
38 }
39 } else {
40 t(Other)
41 }
42 }
43
44 pub(crate) fn as_str(&self) -> &'static str {
45 match self {
46 Self::Unit => "()",
47 Self::Vec => "Vec<T>",
48 Self::Option => "Option<T>",
49 Self::OptionOption => "Option<Option<T>>",
50 Self::OptionVec => "Option<Vec<T>>",
51 Self::VecVec => "Vec<Vec<T>>",
52 Self::OptionVecVec => "Option<Vec<Vec<T>>>",
53 Self::Other => "...other...",
54 }
55 }
56}
57
58pub(crate) fn inner_type(field_ty: &Type) -> &Type {
59 let ty: Sp = Ty::from_syn_ty(field_ty);
60 match *ty {
61 Ty::Vec | Ty::Option => sub_type(field_ty).unwrap_or(default:field_ty),
62 Ty::OptionOption | Ty::OptionVec | Ty::VecVec => {
63 sub_type(field_ty).and_then(sub_type).unwrap_or(default:field_ty)
64 }
65 Ty::OptionVecVec => sub_type(field_ty)
66 .and_then(sub_type)
67 .and_then(sub_type)
68 .unwrap_or(default:field_ty),
69 _ => field_ty,
70 }
71}
72
73pub(crate) fn sub_type(ty: &Type) -> Option<&Type> {
74 subty_if(ty, |_| true)
75}
76
77fn only_last_segment(mut ty: &Type) -> Option<&PathSegment> {
78 while let Type::Group(syn::TypeGroup { elem: &Box, .. }) = ty {
79 ty = elem;
80 }
81 match ty {
82 Type::Path(TypePath {
83 qself: None,
84 path:
85 Path {
86 leading_colon: None,
87 segments: &Punctuated,
88 },
89 }) => only_one(segments.iter()),
90
91 _ => None,
92 }
93}
94
95fn subty_if<F>(ty: &Type, f: F) -> Option<&Type>
96where
97 F: FnOnce(&PathSegment) -> bool,
98{
99 only_last_segmentOption<&PathSegment>(ty)
100 .filter(|segment: &&PathSegment| f(segment))
101 .and_then(|segment: &PathSegment| {
102 if let AngleBracketed(args: &AngleBracketedGenericArguments) = &segment.arguments {
103 only_one(args.args.iter()).and_then(|genneric: &GenericArgument| {
104 if let GenericArgument::Type(ty: &Type) = genneric {
105 Some(ty)
106 } else {
107 None
108 }
109 })
110 } else {
111 None
112 }
113 })
114}
115
116pub(crate) fn subty_if_name<'a>(ty: &'a Type, name: &str) -> Option<&'a Type> {
117 subty_if(ty, |seg: &PathSegment| seg.ident == name)
118}
119
120pub(crate) fn is_simple_ty(ty: &Type, name: &str) -> bool {
121 only_last_segment(ty)
122 .map(|segment| {
123 if let PathArguments::None = segment.arguments {
124 segment.ident == name
125 } else {
126 false
127 }
128 })
129 .unwrap_or(default:false)
130}
131
132fn is_generic_ty(ty: &Type, name: &str) -> bool {
133 subty_if_name(ty, name).is_some()
134}
135
136fn is_unit_ty(ty: &Type) -> bool {
137 if let Type::Tuple(tuple: &TypeTuple) = ty {
138 tuple.elems.is_empty()
139 } else {
140 false
141 }
142}
143
144fn only_one<I, T>(mut iter: I) -> Option<T>
145where
146 I: Iterator<Item = T>,
147{
148 iter.next().filter(|_| iter.next().is_none())
149}
150
151#[cfg(feature = "unstable-v5")]
152fn get_vec_ty(ty: &Type, vec_ty: Ty, vecvec_ty: Ty) -> Option<Ty> {
153 subty_if_name(ty, "Vec").map(|subty| {
154 if is_generic_ty(subty, "Vec") {
155 vecvec_ty
156 } else {
157 vec_ty
158 }
159 })
160}
161
162#[cfg(not(feature = "unstable-v5"))]
163fn get_vec_ty(ty: &Type, vec_ty: Ty, _vecvec_ty: Ty) -> Option<Ty> {
164 is_generic_ty(ty, name:"Vec").then_some(vec_ty)
165}
166