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
|
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements Selections.
package types2
import (
"bytes"
"fmt"
)
// SelectionKind describes the kind of a selector expression x.f
// (excluding qualified identifiers).
type SelectionKind int
const (
FieldVal SelectionKind = iota // x.f is a struct field selector
MethodVal // x.f is a method selector
MethodExpr // x.f is a method expression
)
// A Selection describes a selector expression x.f.
// For the declarations:
//
// type T struct{ x int; E }
// type E struct{}
// func (e E) m() {}
// var p *T
//
// the following relations exist:
//
// Selector Kind Recv Obj Type Index Indirect
//
// p.x FieldVal T x int {0} true
// p.m MethodVal *T m func() {1, 0} true
// T.m MethodExpr T m func(T) {1, 0} false
//
type Selection struct {
kind SelectionKind
recv Type // type of x
obj Object // object denoted by x.f
index []int // path from x to x.f
indirect bool // set if there was any pointer indirection on the path
}
// Kind returns the selection kind.
func (s *Selection) Kind() SelectionKind { return s.kind }
// Recv returns the type of x in x.f.
func (s *Selection) Recv() Type { return s.recv }
// Obj returns the object denoted by x.f; a *Var for
// a field selection, and a *Func in all other cases.
func (s *Selection) Obj() Object { return s.obj }
// Type returns the type of x.f, which may be different from the type of f.
// See Selection for more information.
func (s *Selection) Type() Type {
switch s.kind {
case MethodVal:
// The type of x.f is a method with its receiver type set
// to the type of x.
sig := *s.obj.(*Func).typ.(*Signature)
recv := *sig.recv
recv.typ = s.recv
sig.recv = &recv
return &sig
case MethodExpr:
// The type of x.f is a function (without receiver)
// and an additional first argument with the same type as x.
// TODO(gri) Similar code is already in call.go - factor!
// TODO(gri) Compute this eagerly to avoid allocations.
sig := *s.obj.(*Func).typ.(*Signature)
arg0 := *sig.recv
sig.recv = nil
arg0.typ = s.recv
var params []*Var
if sig.params != nil {
params = sig.params.vars
}
sig.params = NewTuple(append([]*Var{&arg0}, params...)...)
return &sig
}
// In all other cases, the type of x.f is the type of x.
return s.obj.Type()
}
// Index describes the path from x to f in x.f.
// The last index entry is the field or method index of the type declaring f;
// either:
//
// 1) the list of declared methods of a named type; or
// 2) the list of methods of an interface type; or
// 3) the list of fields of a struct type.
//
// The earlier index entries are the indices of the embedded fields implicitly
// traversed to get from (the type of) x to f, starting at embedding depth 0.
func (s *Selection) Index() []int { return s.index }
// Indirect reports whether any pointer indirection was required to get from
// x to f in x.f.
func (s *Selection) Indirect() bool { return s.indirect }
func (s *Selection) String() string { return SelectionString(s, nil) }
// SelectionString returns the string form of s.
// The Qualifier controls the printing of
// package-level objects, and may be nil.
//
// Examples:
// "field (T) f int"
// "method (T) f(X) Y"
// "method expr (T) f(X) Y"
//
func SelectionString(s *Selection, qf Qualifier) string {
var k string
switch s.kind {
case FieldVal:
k = "field "
case MethodVal:
k = "method "
case MethodExpr:
k = "method expr "
default:
unreachable()
}
var buf bytes.Buffer
buf.WriteString(k)
buf.WriteByte('(')
WriteType(&buf, s.Recv(), qf)
fmt.Fprintf(&buf, ") %s", s.obj.Name())
if T := s.Type(); s.kind == FieldVal {
buf.WriteByte(' ')
WriteType(&buf, T, qf)
} else {
WriteSignature(&buf, T.(*Signature), qf)
}
return buf.String()
}
|
