1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
//! A mini version of ast::Ty, which is easier to use, and features an explicit `Self` type to use
//! when specifying impls to be derived.

pub use Ty::*;

use rustc_ast::ptr::P;
use rustc_ast::{self as ast, Expr, GenericArg, GenericParamKind, Generics, SelfKind};
use rustc_expand::base::ExtCtxt;
use rustc_span::source_map::{respan, DUMMY_SP};
use rustc_span::symbol::{kw, Ident, Symbol};
use rustc_span::Span;
use thin_vec::ThinVec;

/// A path, e.g., `::std::option::Option::<i32>` (global). Has support
/// for type parameters.
#[derive(Clone)]
pub struct Path {
    path: Vec<Symbol>,
    params: Vec<Box<Ty>>,
    kind: PathKind,
}

#[derive(Clone)]
pub enum PathKind {
    Local,
    Global,
    Std,
}

impl Path {
    pub fn new(path: Vec<Symbol>) -> Path {
        Path::new_(path, Vec::new(), PathKind::Std)
    }
    pub fn new_local(path: Symbol) -> Path {
        Path::new_(vec![path], Vec::new(), PathKind::Local)
    }
    pub fn new_(path: Vec<Symbol>, params: Vec<Box<Ty>>, kind: PathKind) -> Path {
        Path { path, params, kind }
    }

    pub fn to_ty(
        &self,
        cx: &ExtCtxt<'_>,
        span: Span,
        self_ty: Ident,
        self_generics: &Generics,
    ) -> P<ast::Ty> {
        cx.ty_path(self.to_path(cx, span, self_ty, self_generics))
    }
    pub fn to_path(
        &self,
        cx: &ExtCtxt<'_>,
        span: Span,
        self_ty: Ident,
        self_generics: &Generics,
    ) -> ast::Path {
        let mut idents = self.path.iter().map(|s| Ident::new(*s, span)).collect();
        let tys = self.params.iter().map(|t| t.to_ty(cx, span, self_ty, self_generics));
        let params = tys.map(GenericArg::Type).collect();

        match self.kind {
            PathKind::Global => cx.path_all(span, true, idents, params),
            PathKind::Local => cx.path_all(span, false, idents, params),
            PathKind::Std => {
                let def_site = cx.with_def_site_ctxt(DUMMY_SP);
                idents.insert(0, Ident::new(kw::DollarCrate, def_site));
                cx.path_all(span, false, idents, params)
            }
        }
    }
}

/// A type. Supports pointers, Self, and literals.
#[derive(Clone)]
pub enum Ty {
    Self_,
    /// A reference.
    Ref(Box<Ty>, ast::Mutability),
    /// `mod::mod::Type<[lifetime], [Params...]>`, including a plain type
    /// parameter, and things like `i32`
    Path(Path),
    /// For () return types.
    Unit,
}

pub fn self_ref() -> Ty {
    Ref(Box::new(Self_), ast::Mutability::Not)
}

impl Ty {
    pub fn to_ty(
        &self,
        cx: &ExtCtxt<'_>,
        span: Span,
        self_ty: Ident,
        self_generics: &Generics,
    ) -> P<ast::Ty> {
        match self {
            Ref(ty, mutbl) => {
                let raw_ty = ty.to_ty(cx, span, self_ty, self_generics);
                cx.ty_ref(span, raw_ty, None, *mutbl)
            }
            Path(p) => p.to_ty(cx, span, self_ty, self_generics),
            Self_ => cx.ty_path(self.to_path(cx, span, self_ty, self_generics)),
            Unit => {
                let ty = ast::TyKind::Tup(ThinVec::new());
                cx.ty(span, ty)
            }
        }
    }

    pub fn to_path(
        &self,
        cx: &ExtCtxt<'_>,
        span: Span,
        self_ty: Ident,
        generics: &Generics,
    ) -> ast::Path {
        match self {
            Self_ => {
                let params: Vec<_> = generics
                    .params
                    .iter()
                    .map(|param| match param.kind {
                        GenericParamKind::Lifetime { .. } => {
                            GenericArg::Lifetime(ast::Lifetime { id: param.id, ident: param.ident })
                        }
                        GenericParamKind::Type { .. } => {
                            GenericArg::Type(cx.ty_ident(span, param.ident))
                        }
                        GenericParamKind::Const { .. } => {
                            GenericArg::Const(cx.const_ident(span, param.ident))
                        }
                    })
                    .collect();

                cx.path_all(span, false, vec![self_ty], params)
            }
            Path(p) => p.to_path(cx, span, self_ty, generics),
            Ref(..) => cx.span_bug(span, "ref in a path in generic `derive`"),
            Unit => cx.span_bug(span, "unit in a path in generic `derive`"),
        }
    }
}

fn mk_ty_param(
    cx: &ExtCtxt<'_>,
    span: Span,
    name: Symbol,
    bounds: &[Path],
    self_ident: Ident,
    self_generics: &Generics,
) -> ast::GenericParam {
    let bounds = bounds
        .iter()
        .map(|b| {
            let path = b.to_path(cx, span, self_ident, self_generics);
            cx.trait_bound(path, false)
        })
        .collect();
    cx.typaram(span, Ident::new(name, span), bounds, None)
}

/// Bounds on type parameters.
#[derive(Clone)]
pub struct Bounds {
    pub bounds: Vec<(Symbol, Vec<Path>)>,
}

impl Bounds {
    pub fn empty() -> Bounds {
        Bounds { bounds: Vec::new() }
    }
    pub fn to_generics(
        &self,
        cx: &ExtCtxt<'_>,
        span: Span,
        self_ty: Ident,
        self_generics: &Generics,
    ) -> Generics {
        let params = self
            .bounds
            .iter()
            .map(|&(name, ref bounds)| mk_ty_param(cx, span, name, &bounds, self_ty, self_generics))
            .collect();

        Generics {
            params,
            where_clause: ast::WhereClause {
                has_where_token: false,
                predicates: ThinVec::new(),
                span,
            },
            span,
        }
    }
}

pub fn get_explicit_self(cx: &ExtCtxt<'_>, span: Span) -> (P<Expr>, ast::ExplicitSelf) {
    // This constructs a fresh `self` path.
    let self_path = cx.expr_self(span);
    let self_ty = respan(span, SelfKind::Region(None, ast::Mutability::Not));
    (self_path, self_ty)
}