1 //! Special types handling
2
3 use super::spanned::Sp;
4
5 use syn::{
6 spanned::Spanned, GenericArgument, Path, PathArguments, PathArguments::AngleBracketed,
7 PathSegment, Type, TypePath,
8 };
9
10 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
11 pub enum Ty {
12 Unit,
13 Vec,
14 VecVec,
15 Option,
16 OptionOption,
17 OptionVec,
18 OptionVecVec,
19 Other,
20 }
21
22 impl Ty {
from_syn_ty(ty: &syn::Type) -> Sp<Self>23 pub fn from_syn_ty(ty: &syn::Type) -> Sp<Self> {
24 use self::Ty::*;
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
as_str(&self) -> &'static str44 pub 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
inner_type(field_ty: &syn::Type) -> &syn::Type58 pub fn inner_type(field_ty: &syn::Type) -> &syn::Type {
59 let ty = Ty::from_syn_ty(field_ty);
60 match *ty {
61 Ty::Vec | Ty::Option => sub_type(field_ty).unwrap_or(field_ty),
62 Ty::OptionOption | Ty::OptionVec | Ty::VecVec => {
63 sub_type(field_ty).and_then(sub_type).unwrap_or(field_ty)
64 }
65 Ty::OptionVecVec => sub_type(field_ty)
66 .and_then(sub_type)
67 .and_then(sub_type)
68 .unwrap_or(field_ty),
69 _ => field_ty,
70 }
71 }
72
sub_type(ty: &syn::Type) -> Option<&syn::Type>73 pub fn sub_type(ty: &syn::Type) -> Option<&syn::Type> {
74 subty_if(ty, |_| true)
75 }
76
only_last_segment(mut ty: &syn::Type) -> Option<&PathSegment>77 fn only_last_segment(mut ty: &syn::Type) -> Option<&PathSegment> {
78 while let syn::Type::Group(syn::TypeGroup { elem, .. }) = 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,
88 },
89 }) => only_one(segments.iter()),
90
91 _ => None,
92 }
93 }
94
subty_if<F>(ty: &syn::Type, f: F) -> Option<&syn::Type> where F: FnOnce(&PathSegment) -> bool,95 fn subty_if<F>(ty: &syn::Type, f: F) -> Option<&syn::Type>
96 where
97 F: FnOnce(&PathSegment) -> bool,
98 {
99 only_last_segment(ty)
100 .filter(|segment| f(segment))
101 .and_then(|segment| {
102 if let AngleBracketed(args) = &segment.arguments {
103 only_one(args.args.iter()).and_then(|genneric| {
104 if let GenericArgument::Type(ty) = genneric {
105 Some(ty)
106 } else {
107 None
108 }
109 })
110 } else {
111 None
112 }
113 })
114 }
115
subty_if_name<'a>(ty: &'a syn::Type, name: &str) -> Option<&'a syn::Type>116 pub fn subty_if_name<'a>(ty: &'a syn::Type, name: &str) -> Option<&'a syn::Type> {
117 subty_if(ty, |seg| seg.ident == name)
118 }
119
is_simple_ty(ty: &syn::Type, name: &str) -> bool120 pub fn is_simple_ty(ty: &syn::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(false)
130 }
131
is_generic_ty(ty: &syn::Type, name: &str) -> bool132 fn is_generic_ty(ty: &syn::Type, name: &str) -> bool {
133 subty_if_name(ty, name).is_some()
134 }
135
is_unit_ty(ty: &syn::Type) -> bool136 fn is_unit_ty(ty: &syn::Type) -> bool {
137 if let syn::Type::Tuple(tuple) = ty {
138 tuple.elems.is_empty()
139 } else {
140 false
141 }
142 }
143
only_one<I, T>(mut iter: I) -> Option<T> where I: Iterator<Item = T>,144 fn only_one<I, T>(mut iter: I) -> Option<T>
145 where
146 I: Iterator<Item = T>,
147 {
148 iter.next().filter(|_| iter.next().is_none())
149 }
150
151 #[cfg(feature = "unstable-v5")]
get_vec_ty(ty: &Type, vec_ty: Ty, vecvec_ty: Ty) -> Option<Ty>152 fn 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"))]
get_vec_ty(ty: &Type, vec_ty: Ty, _vecvec_ty: Ty) -> Option<Ty>163 fn get_vec_ty(ty: &Type, vec_ty: Ty, _vecvec_ty: Ty) -> Option<Ty> {
164 is_generic_ty(ty, "Vec").then_some(vec_ty)
165 }
166