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
|
/*
* Copyright 2016 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.turbine.types;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.turbine.binder.bound.TypeBoundClass.TyVarInfo;
import com.google.turbine.binder.sym.TyVarSymbol;
import com.google.turbine.type.Type;
import com.google.turbine.type.Type.ArrayTy;
import com.google.turbine.type.Type.ClassTy;
import com.google.turbine.type.Type.ClassTy.SimpleClassTy;
import com.google.turbine.type.Type.IntersectionTy;
import com.google.turbine.type.Type.MethodTy;
import com.google.turbine.type.Type.TyVar;
import com.google.turbine.type.Type.WildTy;
/** Generic type erasure. */
public final class Erasure {
public static Type erase(Type ty, Function<TyVarSymbol, TyVarInfo> tenv) {
switch (ty.tyKind()) {
case CLASS_TY:
return eraseClassTy((Type.ClassTy) ty);
case ARRAY_TY:
return eraseArrayTy((Type.ArrayTy) ty, tenv);
case TY_VAR:
return eraseTyVar((TyVar) ty, tenv);
case INTERSECTION_TY:
return eraseIntersectionTy((Type.IntersectionTy) ty, tenv);
case WILD_TY:
return eraseWildTy((Type.WildTy) ty, tenv);
case METHOD_TY:
return erasureMethodTy((Type.MethodTy) ty, tenv);
case PRIM_TY:
case VOID_TY:
case ERROR_TY:
case NONE_TY:
return ty;
}
throw new AssertionError(ty.tyKind());
}
private static ImmutableList<Type> erase(
ImmutableList<Type> types, Function<TyVarSymbol, TyVarInfo> tenv) {
ImmutableList.Builder<Type> result = ImmutableList.builder();
for (Type type : types) {
result.add(erase(type, tenv));
}
return result.build();
}
private static Type eraseIntersectionTy(
IntersectionTy ty, Function<TyVarSymbol, TyVarInfo> tenv) {
return ty.bounds().isEmpty() ? ClassTy.OBJECT : erase(ty.bounds().get(0), tenv);
}
private static Type eraseTyVar(TyVar ty, Function<TyVarSymbol, TyVarInfo> tenv) {
TyVarInfo info = tenv.apply(ty.sym());
return erase(info.upperBound(), tenv);
}
private static Type.ArrayTy eraseArrayTy(Type.ArrayTy ty, Function<TyVarSymbol, TyVarInfo> tenv) {
return ArrayTy.create(erase(ty.elementType(), tenv), ty.annos());
}
public static Type.ClassTy eraseClassTy(Type.ClassTy ty) {
ImmutableList.Builder<Type.ClassTy.SimpleClassTy> classes = ImmutableList.builder();
for (Type.ClassTy.SimpleClassTy c : ty.classes()) {
if (c.targs().isEmpty()) {
classes.add(c);
} else {
classes.add(SimpleClassTy.create(c.sym(), ImmutableList.of(), c.annos()));
}
}
return ClassTy.create(classes.build());
}
private static Type eraseWildTy(WildTy ty, Function<TyVarSymbol, TyVarInfo> tenv) {
switch (ty.boundKind()) {
case NONE:
case LOWER:
return ClassTy.OBJECT;
case UPPER:
return erase(ty.bound(), tenv);
}
throw new AssertionError(ty.boundKind());
}
private static Type erasureMethodTy(MethodTy ty, Function<TyVarSymbol, TyVarInfo> tenv) {
return MethodTy.create(
/* tyParams= */ ImmutableSet.of(),
erase(ty.returnType(), tenv),
ty.receiverType() != null ? erase(ty.receiverType(), tenv) : null,
erase(ty.parameters(), tenv),
erase(ty.thrown(), tenv));
}
private Erasure() {}
}
|
