| /* |
| * Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package sun.tools.tree; |
| |
| import sun.tools.java.*; |
| import sun.tools.asm.Assembler; |
| |
| /** |
| * WARNING: The contents of this source file are not part of any |
| * supported API. Code that depends on them does so at its own risk: |
| * they are subject to change or removal without notice. |
| */ |
| public |
| class AddExpression extends BinaryArithmeticExpression { |
| /** |
| * constructor |
| */ |
| public AddExpression(long where, Expression left, Expression right) { |
| super(ADD, where, left, right); |
| } |
| |
| /** |
| * Select the type |
| */ |
| void selectType(Environment env, Context ctx, int tm) { |
| if ((left.type == Type.tString) && !right.type.isType(TC_VOID)) { |
| type = Type.tString; |
| return; |
| } else if ((right.type == Type.tString) && !left.type.isType(TC_VOID)) { |
| type = Type.tString; |
| return; |
| } |
| super.selectType(env, ctx, tm); |
| } |
| |
| public boolean isNonNull() { |
| // an addition expression cannot yield a null reference as a result |
| return true; |
| } |
| |
| /** |
| * Evaluate |
| */ |
| Expression eval(int a, int b) { |
| return new IntExpression(where, a + b); |
| } |
| Expression eval(long a, long b) { |
| return new LongExpression(where, a + b); |
| } |
| Expression eval(float a, float b) { |
| return new FloatExpression(where, a + b); |
| } |
| Expression eval(double a, double b) { |
| return new DoubleExpression(where, a + b); |
| } |
| Expression eval(String a, String b) { |
| return new StringExpression(where, a + b); |
| } |
| |
| /** |
| * Inline the value of an AddExpression. If this AddExpression |
| * represents a concatenation of compile-time constant strings, |
| * dispatch to the special method inlineValueSB, which handles |
| * the inlining more efficiently. |
| */ |
| public Expression inlineValue(Environment env, Context ctx) { |
| if (type == Type.tString && isConstant()) { |
| StringBuffer buffer = inlineValueSB(env, ctx, new StringBuffer()); |
| if (buffer != null) { |
| // We were able to evaluate the String concatenation. |
| return new StringExpression(where, buffer.toString()); |
| } |
| } |
| // For some reason inlinValueSB() failed to produce a value. |
| // Use the older, less efficient, inlining mechanism. |
| return super.inlineValue(env, ctx); |
| } |
| |
| /** |
| * Attempt to evaluate this expression. If this expression |
| * yields a value, append it to the StringBuffer `buffer'. |
| * If this expression cannot be evaluated at this time (for |
| * example if it contains a division by zero, a non-constant |
| * subexpression, or a subexpression which "refuses" to evaluate) |
| * then return `null' to indicate failure. |
| * |
| * It is anticipated that this method will be called to evaluate |
| * concatenations of compile-time constant strings. The call |
| * originates from AddExpression#inlineValue(). |
| * |
| * This method does not use associativity to good effect in |
| * folding string concatenations. This is room for improvement. |
| * |
| * ------------- |
| * |
| * A bit of history: this method was added because an |
| * expression like... |
| * |
| * "a" + "b" + "c" + "d" |
| * |
| * ...was evaluated at compile-time as... |
| * |
| * (new StringBuffer((new StringBuffer("a")).append("b").toString())). |
| * append((new StringBuffer("c")).append("d").toString()).toString() |
| * |
| * Alex Garthwaite, in profiling the memory allocation of the |
| * compiler, noticed this and suggested that the method inlineValueSB() |
| * be added to evaluate constant string concatenations in a more |
| * efficient manner. The compiler now builds the string in a |
| * top-down fashion, by accumulating the result in a StringBuffer |
| * which is allocated once and passed in as a parameter. The new |
| * evaluation scheme is equivalent to... |
| * |
| * (new StringBuffer("a")).append("b").append("c").append("d") |
| * .toString() |
| * |
| * ...which is more efficient. Since then, the code has been modified |
| * to fix certain problems. Now, for example, it can return `null' |
| * when it encounters a concatenation which it is not able to |
| * evaluate. |
| * |
| * See also Expression#inlineValueSB() and ExprExpression#inlineValueSB(). |
| */ |
| protected StringBuffer inlineValueSB(Environment env, |
| Context ctx, |
| StringBuffer buffer) { |
| if (type != Type.tString) { |
| // This isn't a concatenation. It is actually an addition |
| // of some sort. Call the generic inlineValueSB() |
| return super.inlineValueSB(env, ctx, buffer); |
| } |
| |
| buffer = left.inlineValueSB(env, ctx, buffer); |
| if (buffer != null) { |
| buffer = right.inlineValueSB(env, ctx, buffer); |
| } |
| return buffer; |
| } |
| |
| /** |
| * Simplify |
| */ |
| Expression simplify() { |
| if (!type.isType(TC_CLASS)) { |
| // Can't simplify floating point add because of -0.0 strangeness |
| if (type.inMask(TM_INTEGER)) { |
| if (left.equals(0)) { |
| return right; |
| } |
| if (right.equals(0)) { |
| return left; |
| } |
| } |
| } else if (right.type.isType(TC_NULL)) { |
| right = new StringExpression(right.where, "null"); |
| } else if (left.type.isType(TC_NULL)) { |
| left = new StringExpression(left.where, "null"); |
| } |
| return this; |
| } |
| |
| /** |
| * The cost of inlining this expression |
| */ |
| public int costInline(int thresh, Environment env, Context ctx) { |
| return (type.isType(TC_CLASS) ? 12 : 1) |
| + left.costInline(thresh, env, ctx) |
| + right.costInline(thresh, env, ctx); |
| } |
| |
| /** |
| * Code |
| */ |
| void codeOperation(Environment env, Context ctx, Assembler asm) { |
| asm.add(where, opc_iadd + type.getTypeCodeOffset()); |
| } |
| |
| /** |
| * Convert this expression to a string and append it to the string |
| * buffer on the top of the stack. |
| * If the needBuffer argument is true, the string buffer needs to be |
| * created, initialized, and pushed on the stack, first. |
| */ |
| void codeAppend(Environment env, Context ctx, Assembler asm, |
| ClassDeclaration sbClass, boolean needBuffer) |
| throws ClassNotFound, AmbiguousMember { |
| if (type.isType(TC_CLASS)) { |
| left.codeAppend(env, ctx, asm, sbClass, needBuffer); |
| right.codeAppend(env, ctx, asm, sbClass, false); |
| } else { |
| super.codeAppend(env, ctx, asm, sbClass, needBuffer); |
| } |
| } |
| |
| public void codeValue(Environment env, Context ctx, Assembler asm) { |
| if (type.isType(TC_CLASS)) { |
| try { |
| // optimize (""+foo) or (foo+"") to String.valueOf(foo) |
| if (left.equals("")) { |
| right.codeValue(env, ctx, asm); |
| right.ensureString(env, ctx, asm); |
| return; |
| } |
| if (right.equals("")) { |
| left.codeValue(env, ctx, asm); |
| left.ensureString(env, ctx, asm); |
| return; |
| } |
| |
| ClassDeclaration sbClass = |
| env.getClassDeclaration(idJavaLangStringBuffer); |
| ClassDefinition sourceClass = ctx.field.getClassDefinition(); |
| // Create the string buffer and append to it. |
| codeAppend(env, ctx, asm, sbClass, true); |
| // Convert the string buffer to a string |
| MemberDefinition f = |
| sbClass.getClassDefinition(env).matchMethod(env, |
| sourceClass, |
| idToString); |
| asm.add(where, opc_invokevirtual, f); |
| } catch (ClassNotFound e) { |
| throw new CompilerError(e); |
| } catch (AmbiguousMember e) { |
| throw new CompilerError(e); |
| } |
| } else { |
| super.codeValue(env, ctx, asm); |
| } |
| } |
| } |