Repository navigation
Expand file tree
/
Copy pathmatch.go
More file actions
249 lines (214 loc) · 6.22 KB
/
Copy pathmatch.go
File metadata and controls
249 lines (214 loc) · 6.22 KB
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
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
// Copyright 2014 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.
package eg
import (
"fmt"
"go/ast"
"go/constant"
"go/token"
"go/types"
"log"
"os"
"reflect"
"golang.org/x/tools/go/ast/astutil"
)
// matchExpr reports whether pattern x matches y.
//
// If tr.allowWildcards, Idents in x that refer to parameters are
// treated as wildcards, and match any y that is assignable to the
// parameter type; matchExpr records this correspondence in tr.env.
// Otherwise, matchExpr simply reports whether the two trees are
// equivalent.
//
// A wildcard appearing more than once in the pattern must
// consistently match the same tree.
//
func (tr *Transformer) matchExpr(x, y ast.Expr) bool {
if x == nil && y == nil {
return true
}
if x == nil || y == nil {
return false
}
x = unparen(x)
y = unparen(y)
// Is x a wildcard? (a reference to a 'before' parameter)
if xobj, ok := tr.wildcardObj(x); ok {
return tr.matchWildcard(xobj, y)
}
// Object identifiers (including pkg-qualified ones)
// are handled semantically, not syntactically.
xobj := isRef(x, tr.info)
yobj := isRef(y, tr.info)
if xobj != nil {
return xobj == yobj
}
if yobj != nil {
return false
}
// TODO(adonovan): audit: we cannot assume these ast.Exprs
// contain non-nil pointers. e.g. ImportSpec.Name may be a
// nil *ast.Ident.
if reflect.TypeOf(x) != reflect.TypeOf(y) {
return false
}
switch x := x.(type) {
case *ast.Ident:
log.Fatalf("unexpected Ident: %s", astString(tr.fset, x))
case *ast.BasicLit:
y := y.(*ast.BasicLit)
xval := constant.MakeFromLiteral(x.Value, x.Kind, 0)
yval := constant.MakeFromLiteral(y.Value, y.Kind, 0)
return constant.Compare(xval, token.EQL, yval)
case *ast.FuncLit:
// func literals (and thus statement syntax) never match.
return false
case *ast.CompositeLit:
y := y.(*ast.CompositeLit)
return (x.Type == nil) == (y.Type == nil) &&
(x.Type == nil || tr.matchType(x.Type, y.Type)) &&
tr.matchExprs(x.Elts, y.Elts)
case *ast.SelectorExpr:
y := y.(*ast.SelectorExpr)
return tr.matchSelectorExpr(x, y) &&
tr.info.Selections[x].Obj() == tr.info.Selections[y].Obj()
case *ast.IndexExpr:
y := y.(*ast.IndexExpr)
return tr.matchExpr(x.X, y.X) &&
tr.matchExpr(x.Index, y.Index)
case *ast.SliceExpr:
y := y.(*ast.SliceExpr)
return tr.matchExpr(x.X, y.X) &&
tr.matchExpr(x.Low, y.Low) &&
tr.matchExpr(x.High, y.High) &&
tr.matchExpr(x.Max, y.Max) &&
x.Slice3 == y.Slice3
case *ast.TypeAssertExpr:
y := y.(*ast.TypeAssertExpr)
return tr.matchExpr(x.X, y.X) &&
tr.matchType(x.Type, y.Type)
case *ast.CallExpr:
y := y.(*ast.CallExpr)
match := tr.matchExpr // function call
if tr.info.Types[x.Fun].IsType() {
match = tr.matchType // type conversion
}
return x.Ellipsis.IsValid() == y.Ellipsis.IsValid() &&
match(x.Fun, y.Fun) &&
tr.matchExprs(x.Args, y.Args)
case *ast.StarExpr:
y := y.(*ast.StarExpr)
return tr.matchExpr(x.X, y.X)
case *ast.UnaryExpr:
y := y.(*ast.UnaryExpr)
return x.Op == y.Op &&
tr.matchExpr(x.X, y.X)
case *ast.BinaryExpr:
y := y.(*ast.BinaryExpr)
return x.Op == y.Op &&
tr.matchExpr(x.X, y.X) &&
tr.matchExpr(x.Y, y.Y)
case *ast.KeyValueExpr:
y := y.(*ast.KeyValueExpr)
return tr.matchExpr(x.Key, y.Key) &&
tr.matchExpr(x.Value, y.Value)
}
panic(fmt.Sprintf("unhandled AST node type: %T", x))
}
func (tr *Transformer) matchExprs(xx, yy []ast.Expr) bool {
if len(xx) != len(yy) {
return false
}
for i := range xx {
if !tr.matchExpr(xx[i], yy[i]) {
return false
}
}
return true
}
// matchType reports whether the two type ASTs denote identical types.
func (tr *Transformer) matchType(x, y ast.Expr) bool {
tx := tr.info.Types[x].Type
ty := tr.info.Types[y].Type
return types.Identical(tx, ty)
}
func (tr *Transformer) wildcardObj(x ast.Expr) (*types.Var, bool) {
if x, ok := x.(*ast.Ident); ok && x != nil && tr.allowWildcards {
if xobj, ok := tr.info.Uses[x].(*types.Var); ok && tr.wildcards[xobj] {
return xobj, true
}
}
return nil, false
}
func (tr *Transformer) matchSelectorExpr(x, y *ast.SelectorExpr) bool {
if xobj, ok := tr.wildcardObj(x.X); ok {
field := x.Sel.Name
yt := tr.info.TypeOf(y.X)
o, _, _ := types.LookupFieldOrMethod(yt, true, tr.currentPkg, field)
if o != nil {
tr.env[xobj.Name()] = y.X // record binding
return true
}
}
return tr.matchExpr(x.X, y.X)
}
func (tr *Transformer) matchWildcard(xobj *types.Var, y ast.Expr) bool {
name := xobj.Name()
if tr.verbose {
fmt.Fprintf(os.Stderr, "%s: wildcard %s -> %s?: ",
tr.fset.Position(y.Pos()), name, astString(tr.fset, y))
}
// Check that y is assignable to the declared type of the param.
yt := tr.info.TypeOf(y)
if yt == nil {
// y has no type.
// Perhaps it is an *ast.Ellipsis in [...]T{}, or
// an *ast.KeyValueExpr in T{k: v}.
// Clearly these pseudo-expressions cannot match a
// wildcard, but it would nice if we had a way to ignore
// the difference between T{v} and T{k:v} for structs.
return false
}
if !types.AssignableTo(yt, xobj.Type()) {
if tr.verbose {
fmt.Fprintf(os.Stderr, "%s not assignable to %s\n", yt, xobj.Type())
}
return false
}
// A wildcard matches any expression.
// If it appears multiple times in the pattern, it must match
// the same expression each time.
if old, ok := tr.env[name]; ok {
// found existing binding
tr.allowWildcards = false
r := tr.matchExpr(old, y)
if tr.verbose {
fmt.Fprintf(os.Stderr, "%t secondary match, primary was %s\n",
r, astString(tr.fset, old))
}
tr.allowWildcards = true
return r
}
if tr.verbose {
fmt.Fprintf(os.Stderr, "primary match\n")
}
tr.env[name] = y // record binding
return true
}
// -- utilities --------------------------------------------------------
func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
// isRef returns the object referred to by this (possibly qualified)
// identifier, or nil if the node is not a referring identifier.
func isRef(n ast.Node, info *types.Info) types.Object {
switch n := n.(type) {
case *ast.Ident:
return info.Uses[n]
case *ast.SelectorExpr:
if _, ok := info.Selections[n]; !ok {
// qualified ident
return info.Uses[n.Sel]
}
}
return nil
}