1 /* 2 * Copyright 2016 Google Inc. All Rights Reserved. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.turbine.types; 18 19 import com.google.common.base.Function; 20 import com.google.common.collect.ImmutableList; 21 import com.google.turbine.binder.bound.SourceTypeBoundClass; 22 import com.google.turbine.binder.sym.TyVarSymbol; 23 import com.google.turbine.type.Type; 24 import com.google.turbine.type.Type.TyVar; 25 26 /** Generic type erasure. */ 27 public class Erasure { 28 public static Type erase(Type ty, Function<TyVarSymbol, SourceTypeBoundClass.TyVarInfo> tenv) { 29 switch (ty.tyKind()) { 30 case PRIM_TY: 31 case VOID_TY: 32 return ty; 33 case CLASS_TY: 34 return eraseClassTy((Type.ClassTy) ty); 35 case ARRAY_TY: 36 return eraseArrayTy((Type.ArrayTy) ty, tenv); 37 case TY_VAR: 38 return eraseTyVar((TyVar) ty, tenv); 39 default: 40 throw new AssertionError(ty.tyKind()); 41 } 42 } 43 44 private static Type eraseTyVar( 45 TyVar ty, Function<TyVarSymbol, SourceTypeBoundClass.TyVarInfo> tenv) { 46 SourceTypeBoundClass.TyVarInfo info = tenv.apply(ty.sym()); 47 if (info.superClassBound() != null) { 48 return erase(info.superClassBound(), tenv); 49 } 50 if (!info.interfaceBounds().isEmpty()) { 51 return erase(info.interfaceBounds().get(0), tenv); 52 } 53 return Type.ClassTy.OBJECT; 54 } 55 56 private static Type.ArrayTy eraseArrayTy( 57 Type.ArrayTy ty, Function<TyVarSymbol, SourceTypeBoundClass.TyVarInfo> tenv) { 58 return new Type.ArrayTy(erase(ty.elementType(), tenv), ty.annos()); 59 } 60 61 public static Type.ClassTy eraseClassTy(Type.ClassTy ty) { 62 ImmutableList.Builder<Type.ClassTy.SimpleClassTy> classes = ImmutableList.builder(); 63 for (Type.ClassTy.SimpleClassTy c : ty.classes) { 64 if (c.targs().isEmpty()) { 65 classes.add(c); 66 } else { 67 classes.add(new Type.ClassTy.SimpleClassTy(c.sym(), ImmutableList.of(), c.annos())); 68 } 69 } 70 return new Type.ClassTy(classes.build()); 71 } 72 } 73
