1/* 2 * Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package sun.tools.tree; 27 28import sun.tools.java.*; 29import sun.tools.asm.Assembler; 30import java.io.PrintStream; 31import java.util.Hashtable; 32 33/** 34 * WARNING: The contents of this source file are not part of any 35 * supported API. Code that depends on them does so at its own risk: 36 * they are subject to change or removal without notice. 37 */ 38public 39class ArrayAccessExpression extends UnaryExpression { 40 41 /** 42 * The index expression for the array access. Note that 43 * ArrayAccessExpression also `moonlights' as a structure for 44 * storing array types (like Object[]) which are used as part 45 * of cast expressions. For properly formed array types, the 46 * value of index is null. We need to be on the lookout for 47 * null indices in true array accesses, and non-null indices 48 * in array types. We also need to make sure general purpose 49 * methods (like copyInline(), which is called for both) are 50 * prepared to handle either null or non-null indices. 51 */ 52 Expression index; 53 54 /** 55 * constructor 56 */ 57 public ArrayAccessExpression(long where, Expression right, Expression index) { 58 super(ARRAYACCESS, where, Type.tError, right); 59 this.index = index; 60 } 61 62 /** 63 * Check expression type 64 */ 65 public Vset checkValue(Environment env, Context ctx, Vset vset, Hashtable<Object, Object> exp) { 66 vset = right.checkValue(env, ctx, vset, exp); 67 if (index == null) { 68 env.error(where, "array.index.required"); 69 return vset; 70 } 71 vset = index.checkValue(env, ctx, vset, exp); 72 index = convert(env, ctx, Type.tInt, index); 73 74 if (!right.type.isType(TC_ARRAY)) { 75 if (!right.type.isType(TC_ERROR)) { 76 env.error(where, "not.array", right.type); 77 } 78 return vset; 79 } 80 81 type = right.type.getElementType(); 82 return vset; 83 } 84 85 public Vset checkAmbigName(Environment env, Context ctx, 86 Vset vset, Hashtable<Object, Object> exp, 87 UnaryExpression loc) { 88 if (index == null) { 89 vset = right.checkAmbigName(env, ctx, vset, exp, this); 90 if (right.type == Type.tPackage) { 91 FieldExpression.reportFailedPackagePrefix(env, right); 92 return vset; 93 } 94 95 // Nope. Is this field expression a type? 96 if (right instanceof TypeExpression) { 97 Type atype = Type.tArray(right.type); 98 loc.right = new TypeExpression(where, atype); 99 return vset; 100 } 101 102 env.error(where, "array.index.required"); 103 return vset; 104 } 105 return super.checkAmbigName(env, ctx, vset, exp, loc); 106 } 107 108 /* 109 * Check the array if it appears on the LHS of an assignment 110 */ 111 public Vset checkLHS(Environment env, Context ctx, 112 Vset vset, Hashtable<Object, Object> exp) { 113 return checkValue(env, ctx, vset, exp); 114 } 115 116 /* 117 * Check the array if it appears on the LHS of an op= expression 118 */ 119 public Vset checkAssignOp(Environment env, Context ctx, 120 Vset vset, Hashtable<Object, Object> exp, Expression outside) { 121 return checkValue(env, ctx, vset, exp); 122 } 123 124 /** 125 * An array access expression never requires the use of an access method to perform 126 * an assignment to an array element, though an access method may be required to 127 * fetch the array object itself. 128 */ 129 public FieldUpdater getAssigner(Environment env, Context ctx) { 130 return null; 131 } 132 133 /** 134 * An array access expression never requires a field updater. 135 */ 136 public FieldUpdater getUpdater(Environment env, Context ctx) { 137 return null; 138 } 139 140 /** 141 * Convert to a type 142 */ 143 Type toType(Environment env, Context ctx) { 144 return toType(env, right.toType(env, ctx)); 145 } 146 Type toType(Environment env, Type t) { 147 if (index != null) { 148 env.error(index.where, "array.dim.in.type"); 149 } 150 return Type.tArray(t); 151 } 152 153 /** 154 * Inline 155 */ 156 public Expression inline(Environment env, Context ctx) { 157 // It isn't possible to simply replace an array access 158 // with a CommaExpression as happens with many binary 159 // operators, because array accesses may have side effects 160 // such as NullPointerException or IndexOutOfBoundsException. 161 right = right.inlineValue(env, ctx); 162 index = index.inlineValue(env, ctx); 163 return this; 164 } 165 public Expression inlineValue(Environment env, Context ctx) { 166 // inlineValue() should not end up being called when the index is 167 // null. If it is null, we let this method fail with a 168 // NullPointerException. 169 170 right = right.inlineValue(env, ctx); 171 index = index.inlineValue(env, ctx); 172 return this; 173 } 174 public Expression inlineLHS(Environment env, Context ctx) { 175 return inlineValue(env, ctx); 176 } 177 178 /** 179 * Create a copy of the expression for method inlining 180 */ 181 public Expression copyInline(Context ctx) { 182 ArrayAccessExpression e = (ArrayAccessExpression)clone(); 183 e.right = right.copyInline(ctx); 184 if (index == null) { 185 // The index can be null when this node is being used to 186 // represent a type (e.g. Object[]) used in a cast expression. 187 // We need to copy such structures without complaint. 188 e.index = null; 189 } else { 190 e.index = index.copyInline(ctx); 191 } 192 return e; 193 } 194 195 /** 196 * The cost of inlining this expression 197 */ 198 public int costInline(int thresh, Environment env, Context ctx) { 199 // costInline() should not end up being called when the index is 200 // null. If it is null, we let this method fail with a 201 // NullPointerException. 202 203 return 1 + right.costInline(thresh, env, ctx) 204 + index.costInline(thresh, env, ctx); 205 } 206 207 /** 208 * Code 209 */ 210 int codeLValue(Environment env, Context ctx, Assembler asm) { 211 // codeLValue() should not end up being called when the index is 212 // null. If it is null, we let this method fail with a 213 // NullPointerException. 214 215 right.codeValue(env, ctx, asm); 216 index.codeValue(env, ctx, asm); 217 return 2; 218 } 219 void codeLoad(Environment env, Context ctx, Assembler asm) { 220 switch (type.getTypeCode()) { 221 case TC_BOOLEAN: 222 case TC_BYTE: 223 asm.add(where, opc_baload); 224 break; 225 case TC_CHAR: 226 asm.add(where, opc_caload); 227 break; 228 case TC_SHORT: 229 asm.add(where, opc_saload); 230 break; 231 default: 232 asm.add(where, opc_iaload + type.getTypeCodeOffset()); 233 } 234 } 235 void codeStore(Environment env, Context ctx, Assembler asm) { 236 switch (type.getTypeCode()) { 237 case TC_BOOLEAN: 238 case TC_BYTE: 239 asm.add(where, opc_bastore); 240 break; 241 case TC_CHAR: 242 asm.add(where, opc_castore); 243 break; 244 case TC_SHORT: 245 asm.add(where, opc_sastore); 246 break; 247 default: 248 asm.add(where, opc_iastore + type.getTypeCodeOffset()); 249 } 250 } 251 public void codeValue(Environment env, Context ctx, Assembler asm) { 252 codeLValue(env, ctx, asm); 253 codeLoad(env, ctx, asm); 254 } 255 256 257 /** 258 * Print 259 */ 260 public void print(PrintStream out) { 261 out.print("(" + opNames[op] + " "); 262 right.print(out); 263 out.print(" "); 264 if (index != null) { 265 index.print(out); 266 } else { 267 out.print("<empty>"); 268 } 269 out.print(")"); 270 } 271} 272