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| 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 | + | |
| 26 | +package sun.tools.tree; | |
| 27 | + | |
| 28 | +import sun.tools.java.*; | |
| 29 | +import sun.tools.asm.Assembler; | |
| 30 | + | |
| 31 | +/** | |
| 32 | + * WARNING: The contents of this source file are not part of any | |
| 33 | + * supported API. Code that depends on them does so at its own risk: | |
| 34 | + * they are subject to change or removal without notice. | |
| 35 | + */ | |
| 36 | +public | |
| 37 | +class AddExpression extends BinaryArithmeticExpression { | |
| 38 | + /** | |
| 39 | + * constructor | |
| 40 | + */ | |
| 41 | + public AddExpression(long where, Expression left, Expression right) { | |
| 42 | + super(ADD, where, left, right); | |
| 43 | + } | |
| 44 | + | |
| 45 | + /** | |
| 46 | + * Select the type | |
| 47 | + */ | |
| 48 | + void selectType(Environment env, Context ctx, int tm) { | |
| 49 | + if ((left.type == Type.tString) && !right.type.isType(TC_VOID)) { | |
| 50 | + type = Type.tString; | |
| 51 | + return; | |
| 52 | + } else if ((right.type == Type.tString) && !left.type.isType(TC_VOID)) { | |
| 53 | + type = Type.tString; | |
| 54 | + return; | |
| 55 | + } | |
| 56 | + super.selectType(env, ctx, tm); | |
| 57 | + } | |
| 58 | + | |
| 59 | + public boolean isNonNull() { | |
| 60 | + // an addition expression cannot yield a null reference as a result | |
| 61 | + return true; | |
| 62 | + } | |
| 63 | + | |
| 64 | + /** | |
| 65 | + * Evaluate | |
| 66 | + */ | |
| 67 | + Expression eval(int a, int b) { | |
| 68 | + return new IntExpression(where, a + b); | |
| 69 | + } | |
| 70 | + Expression eval(long a, long b) { | |
| 71 | + return new LongExpression(where, a + b); | |
| 72 | + } | |
| 73 | + Expression eval(float a, float b) { | |
| 74 | + return new FloatExpression(where, a + b); | |
| 75 | + } | |
| 76 | + Expression eval(double a, double b) { | |
| 77 | + return new DoubleExpression(where, a + b); | |
| 78 | + } | |
| 79 | + Expression eval(String a, String b) { | |
| 80 | + return new StringExpression(where, a + b); | |
| 81 | + } | |
| 82 | + | |
| 83 | + /** | |
| 84 | + * Inline the value of an AddExpression. If this AddExpression | |
| 85 | + * represents a concatenation of compile-time constant strings, | |
| 86 | + * dispatch to the special method inlineValueSB, which handles | |
| 87 | + * the inlining more efficiently. | |
| 88 | + */ | |
| 89 | + public Expression inlineValue(Environment env, Context ctx) { | |
| 90 | + if (type == Type.tString && isConstant()) { | |
| 91 | + StringBuffer buffer = inlineValueSB(env, ctx, new StringBuffer()); | |
| 92 | + if (buffer != null) { | |
| 93 | + // We were able to evaluate the String concatenation. | |
| 94 | + return new StringExpression(where, buffer.toString()); | |
| 95 | + } | |
| 96 | + } | |
| 97 | + // For some reason inlinValueSB() failed to produce a value. | |
| 98 | + // Use the older, less efficient, inlining mechanism. | |
| 99 | + return super.inlineValue(env, ctx); | |
| 100 | + } | |
| 101 | + | |
| 102 | + /** | |
| 103 | + * Attempt to evaluate this expression. If this expression | |
| 104 | + * yields a value, append it to the StringBuffer `buffer'. | |
| 105 | + * If this expression cannot be evaluated at this time (for | |
| 106 | + * example if it contains a division by zero, a non-constant | |
| 107 | + * subexpression, or a subexpression which "refuses" to evaluate) | |
| 108 | + * then return `null' to indicate failure. | |
| 109 | + * | |
| 110 | + * It is anticipated that this method will be called to evaluate | |
| 111 | + * concatenations of compile-time constant strings. The call | |
| 112 | + * originates from AddExpression#inlineValue(). | |
| 113 | + * | |
| 114 | + * This method does not use associativity to good effect in | |
| 115 | + * folding string concatenations. This is room for improvement. | |
| 116 | + * | |
| 117 | + * ------------- | |
| 118 | + * | |
| 119 | + * A bit of history: this method was added because an | |
| 120 | + * expression like... | |
| 121 | + * | |
| 122 | + * "a" + "b" + "c" + "d" | |
| 123 | + * | |
| 124 | + * ...was evaluated at compile-time as... | |
| 125 | + * | |
| 126 | + * (new StringBuffer((new StringBuffer("a")).append("b").toString())). | |
| 127 | + * append((new StringBuffer("c")).append("d").toString()).toString() | |
| 128 | + * | |
| 129 | + * Alex Garthwaite, in profiling the memory allocation of the | |
| 130 | + * compiler, noticed this and suggested that the method inlineValueSB() | |
| 131 | + * be added to evaluate constant string concatenations in a more | |
| 132 | + * efficient manner. The compiler now builds the string in a | |
| 133 | + * top-down fashion, by accumulating the result in a StringBuffer | |
| 134 | + * which is allocated once and passed in as a parameter. The new | |
| 135 | + * evaluation scheme is equivalent to... | |
| 136 | + * | |
| 137 | + * (new StringBuffer("a")).append("b").append("c").append("d") | |
| 138 | + * .toString() | |
| 139 | + * | |
| 140 | + * ...which is more efficient. Since then, the code has been modified | |
| 141 | + * to fix certain problems. Now, for example, it can return `null' | |
| 142 | + * when it encounters a concatenation which it is not able to | |
| 143 | + * evaluate. | |
| 144 | + * | |
| 145 | + * See also Expression#inlineValueSB() and ExprExpression#inlineValueSB(). | |
| 146 | + */ | |
| 147 | + protected StringBuffer inlineValueSB(Environment env, | |
| 148 | + Context ctx, | |
| 149 | + StringBuffer buffer) { | |
| 150 | + if (type != Type.tString) { | |
| 151 | + // This isn't a concatenation. It is actually an addition | |
| 152 | + // of some sort. Call the generic inlineValueSB() | |
| 153 | + return super.inlineValueSB(env, ctx, buffer); | |
| 154 | + } | |
| 155 | + | |
| 156 | + buffer = left.inlineValueSB(env, ctx, buffer); | |
| 157 | + if (buffer != null) { | |
| 158 | + buffer = right.inlineValueSB(env, ctx, buffer); | |
| 159 | + } | |
| 160 | + return buffer; | |
| 161 | + } | |
| 162 | + | |
| 163 | + /** | |
| 164 | + * Simplify | |
| 165 | + */ | |
| 166 | + Expression simplify() { | |
| 167 | + if (!type.isType(TC_CLASS)) { | |
| 168 | + // Can't simplify floating point add because of -0.0 strangeness | |
| 169 | + if (type.inMask(TM_INTEGER)) { | |
| 170 | + if (left.equals(0)) { | |
| 171 | + return right; | |
| 172 | + } | |
| 173 | + if (right.equals(0)) { | |
| 174 | + return left; | |
| 175 | + } | |
| 176 | + } | |
| 177 | + } else if (right.type.isType(TC_NULL)) { | |
| 178 | + right = new StringExpression(right.where, "null"); | |
| 179 | + } else if (left.type.isType(TC_NULL)) { | |
| 180 | + left = new StringExpression(left.where, "null"); | |
| 181 | + } | |
| 182 | + return this; | |
| 183 | + } | |
| 184 | + | |
| 185 | + /** | |
| 186 | + * The cost of inlining this expression | |
| 187 | + */ | |
| 188 | + public int costInline(int thresh, Environment env, Context ctx) { | |
| 189 | + return (type.isType(TC_CLASS) ? 12 : 1) | |
| 190 | + + left.costInline(thresh, env, ctx) | |
| 191 | + + right.costInline(thresh, env, ctx); | |
| 192 | + } | |
| 193 | + | |
| 194 | + /** | |
| 195 | + * Code | |
| 196 | + */ | |
| 197 | + void codeOperation(Environment env, Context ctx, Assembler asm) { | |
| 198 | + asm.add(where, opc_iadd + type.getTypeCodeOffset()); | |
| 199 | + } | |
| 200 | + | |
| 201 | + /** | |
| 202 | + * Convert this expression to a string and append it to the string | |
| 203 | + * buffer on the top of the stack. | |
| 204 | + * If the needBuffer argument is true, the string buffer needs to be | |
| 205 | + * created, initialized, and pushed on the stack, first. | |
| 206 | + */ | |
| 207 | + void codeAppend(Environment env, Context ctx, Assembler asm, | |
| 208 | + ClassDeclaration sbClass, boolean needBuffer) | |
| 209 | + throws ClassNotFound, AmbiguousMember { | |
| 210 | + if (type.isType(TC_CLASS)) { | |
| 211 | + left.codeAppend(env, ctx, asm, sbClass, needBuffer); | |
| 212 | + right.codeAppend(env, ctx, asm, sbClass, false); | |
| 213 | + } else { | |
| 214 | + super.codeAppend(env, ctx, asm, sbClass, needBuffer); | |
| 215 | + } | |
| 216 | + } | |
| 217 | + | |
| 218 | + public void codeValue(Environment env, Context ctx, Assembler asm) { | |
| 219 | + if (type.isType(TC_CLASS)) { | |
| 220 | + try { | |
| 221 | + // optimize (""+foo) or (foo+"") to String.valueOf(foo) | |
| 222 | + if (left.equals("")) { | |
| 223 | + right.codeValue(env, ctx, asm); | |
| 224 | + right.ensureString(env, ctx, asm); | |
| 225 | + return; | |
| 226 | + } | |
| 227 | + if (right.equals("")) { | |
| 228 | + left.codeValue(env, ctx, asm); | |
| 229 | + left.ensureString(env, ctx, asm); | |
| 230 | + return; | |
| 231 | + } | |
| 232 | + | |
| 233 | + ClassDeclaration sbClass = | |
| 234 | + env.getClassDeclaration(idJavaLangStringBuffer); | |
| 235 | + ClassDefinition sourceClass = ctx.field.getClassDefinition(); | |
| 236 | + // Create the string buffer and append to it. | |
| 237 | + codeAppend(env, ctx, asm, sbClass, true); | |
| 238 | + // Convert the string buffer to a string | |
| 239 | + MemberDefinition f = | |
| 240 | + sbClass.getClassDefinition(env).matchMethod(env, | |
| 241 | + sourceClass, | |
| 242 | + idToString); | |
| 243 | + asm.add(where, opc_invokevirtual, f); | |
| 244 | + } catch (ClassNotFound e) { | |
| 245 | + throw new CompilerError(e); | |
| 246 | + } catch (AmbiguousMember e) { | |
| 247 | + throw new CompilerError(e); | |
| 248 | + } | |
| 249 | + } else { | |
| 250 | + super.codeValue(env, ctx, asm); | |
| 251 | + } | |
| 252 | + } | |
| 253 | +} | |