LocalsArray.java revision f6c387128427e121477c1b32ad35cdcaa5101ba3
1/* 2 * Copyright (C) 2007 The Android Open Source Project 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 17package com.android.dx.cf.code; 18 19import com.android.dx.rop.code.RegisterSpec; 20import com.android.dx.rop.type.Type; 21import com.android.dx.rop.type.TypeBearer; 22import com.android.dx.util.ExceptionWithContext; 23import com.android.dx.util.Hex; 24import com.android.dx.util.MutabilityControl; 25import com.android.dx.util.ToHuman; 26 27/** 28 * Representation of an array of local variables, with Java semantics. 29 * 30 * <p><b>Note:</b> For the most part, the documentation for this class 31 * ignores the distinction between {@link Type} and {@link 32 * TypeBearer}.</p> 33 */ 34public abstract class LocalsArray extends MutabilityControl implements ToHuman { 35 36 /** 37 * Constructs an instance, explicitly indicating the mutability. 38 * 39 * @param mutable <code>true</code> if this instance is mutable 40 */ 41 protected LocalsArray(boolean mutable) { 42 super(mutable); 43 } 44 45 /** 46 * Makes and returns a mutable copy of this instance. 47 * 48 * @return non-null; the copy 49 */ 50 public abstract LocalsArray copy(); 51 52 /** 53 * Annotates (adds context to) the given exception with information 54 * about this instance. 55 * 56 * @param ex non-null; the exception to annotate 57 */ 58 public abstract void annotate(ExceptionWithContext ex); 59 60 /** 61 * Replaces all the occurrences of the given uninitialized type in 62 * this array with its initialized equivalent. 63 * 64 * @param type non-null; type to replace 65 */ 66 public abstract void makeInitialized(Type type); 67 68 /** 69 * Gets the maximum number of locals this instance can refer to. 70 * 71 * @return the max locals 72 */ 73 public abstract int getMaxLocals(); 74 /** 75 * Sets the type stored at the given local index. If the given type 76 * is category-2, then (a) the index must be at least two less than 77 * <code>getMaxLocals()</code> and (b) the next index gets invalidated 78 * by the operation. In case of either category, if the <i>previous</i> 79 * local contains a category-2 value, then it too is invalidated by 80 * this operation. 81 * 82 * @param idx >= 0, < getMaxLocals(); which local 83 * @param type non-null; new type for the local at <code>idx</code> 84 */ 85 public abstract void set(int idx, TypeBearer type); 86 87 /** 88 * Sets the type for the local indicated by the given register spec 89 * to that register spec (which includes type and optional name 90 * information). This is identical to calling 91 * <code>set(spec.getReg(), spec)</code>. 92 * 93 * @param spec non-null; register spec to use as the basis for the update 94 */ 95 public abstract void set(RegisterSpec spec); 96 97 /** 98 * Invalidates the local at the given index. 99 * 100 * @param idx >= 0, < getMaxLocals(); which local 101 */ 102 public abstract void invalidate(int idx); 103 104 /** 105 * Gets the type stored at the given local index, or <code>null</code> 106 * if the given local is uninitialized / invalid. 107 * 108 * @param idx >= 0, < getMaxLocals(); which local 109 * @return null-ok; the type of value stored in that local 110 */ 111 public abstract TypeBearer getOrNull(int idx); 112 113 /** 114 * Gets the type stored at the given local index, only succeeding if 115 * the given local contains a valid type (though it is allowed to 116 * be an uninitialized instance). 117 * 118 * @param idx >= 0, < getMaxLocals(); which local 119 * @return non-null; the type of value stored in that local 120 * @throws SimException thrown if <code>idx</code> is valid, but 121 * the contents are invalid 122 */ 123 public abstract TypeBearer get(int idx); 124 125 /** 126 * Gets the type stored at the given local index, which is expected 127 * to be an initialized category-1 value. 128 * 129 * @param idx >= 0, < getMaxLocals(); which local 130 * @return non-null; the type of value stored in that local 131 * @throws SimException thrown if <code>idx</code> is valid, but 132 * one of the following holds: (a) the local is invalid; (b) the local 133 * contains an uninitialized instance; (c) the local contains a 134 * category-2 value 135 */ 136 public abstract TypeBearer getCategory1(int idx); 137 138 /** 139 * Gets the type stored at the given local index, which is expected 140 * to be a category-2 value. 141 * 142 * @param idx >= 0, < getMaxLocals(); which local 143 * @return non-null; the type of value stored in that local 144 * @throws SimException thrown if <code>idx</code> is valid, but 145 * one of the following holds: (a) the local is invalid; (b) the local 146 * contains a category-1 value 147 */ 148 public abstract TypeBearer getCategory2(int idx); 149 150 /** 151 * Merges this instance with <code>other</code>. If the merged result is 152 * the same as this instance, then this is returned (not a copy). 153 * 154 * @param other non-null; another LocalsArray 155 * @return non-null; the merge result, a new instance or this 156 */ 157 public abstract LocalsArray merge(LocalsArray other); 158 159 /** 160 * Merges this instance with a <code>LocalsSet</code> from a subroutine 161 * caller. To be used when merging in the first block of a subroutine. 162 * 163 * @param other other non-null; another LocalsArray. The final locals 164 * state of a subroutine caller. 165 * @param predLabel the label of the subroutine caller block. 166 * @return non-null; the merge result, a new instance or this 167 */ 168 public abstract LocalsArraySet mergeWithSubroutineCaller 169 (LocalsArray other, int predLabel); 170 171 /** 172 * Gets the locals set appropriate for the current execution context. 173 * That is, if this is a <code>OneLocalsArray</code> instance, then return 174 * <code>this</code>, otherwise return <code>LocalsArraySet</code>'s 175 * primary. 176 * 177 * @return locals for this execution context. 178 */ 179 protected abstract OneLocalsArray getPrimary(); 180 181} 182