author | ntoda |
Thu, 31 Jul 2014 17:01:24 -0700 | |
changeset 25799 | 1afc4675dc75 |
parent 5506 | 202f599c92aa |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package sun.tools.tree; |
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import sun.tools.java.*; |
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import sun.tools.asm.Assembler; |
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import sun.tools.asm.Label; |
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import java.io.PrintStream; |
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import java.util.Hashtable; |
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/** |
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* WARNING: The contents of this source file are not part of any |
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* supported API. Code that depends on them does so at its own risk: |
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* they are subject to change or removal without notice. |
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*/ |
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public |
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class IfStatement extends Statement { |
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Expression cond; |
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Statement ifTrue; |
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Statement ifFalse; |
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/** |
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* Constructor |
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*/ |
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public IfStatement(long where, Expression cond, Statement ifTrue, Statement ifFalse) { |
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super(IF, where); |
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this.cond = cond; |
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this.ifTrue = ifTrue; |
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this.ifFalse = ifFalse; |
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} |
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/** |
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* Check statement |
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*/ |
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25799
1afc4675dc75
8044867: Fix raw and unchecked lint warnings in sun.tools.*
ntoda
parents:
5506
diff
changeset
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Vset check(Environment env, Context ctx, Vset vset, Hashtable<Object, Object> exp) { |
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checkLabel(env, ctx); |
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CheckContext newctx = new CheckContext(ctx, this); |
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// Vset vsExtra = vset.copy(); // See comment below. |
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ConditionVars cvars = |
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cond.checkCondition(env, newctx, reach(env, vset), exp); |
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cond = convert(env, newctx, Type.tBoolean, cond); |
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// The following code, now deleted, was apparently an erroneous attempt |
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// at providing better error diagnostics. The comment read: 'If either |
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// the true clause or the false clause is unreachable, do a reasonable |
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// check on the child anyway.' |
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// Vset vsTrue = cvars.vsTrue.isDeadEnd() ? vsExtra : cvars.vsTrue; |
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// Vset vsFalse = cvars.vsFalse.isDeadEnd() ? vsExtra : cvars.vsFalse; |
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// Unfortunately, this violates the rules laid out in the JLS, and leads to |
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// blatantly incorrect results. For example, 'i' will not be recognized |
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// as definitely assigned following the statement 'if (true) i = 1;'. |
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// It is best to slavishly follow the JLS here. A cleverer approach could |
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// only correctly issue warnings, as JLS 16.2.6 is quite explicit, and it |
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// is OK for a dead branch of an if-statement to omit an assignment that |
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// would be required in the other branch. A complication: This code also |
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// had the effect of implementing the special-case rules for 'if-then' and |
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// 'if-then-else' in JLS 14.19, "Unreachable Statements". We now use |
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// 'Vset.clearDeadEnd' to remove the dead-end status of unreachable branches |
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// without affecting the definite-assignment status of the variables, thus |
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// maintaining a correct implementation of JLS 16.2.6. Fixes 4094353. |
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// Note that the code below will not consider the branches unreachable if |
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// the entire statement is unreachable. This is consistent with the error |
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// recovery policy that reports the only the first unreachable statement |
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// along an acyclic execution path. |
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Vset vsTrue = cvars.vsTrue.clearDeadEnd(); |
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Vset vsFalse = cvars.vsFalse.clearDeadEnd(); |
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vsTrue = ifTrue.check(env, newctx, vsTrue, exp); |
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if (ifFalse != null) |
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vsFalse = ifFalse.check(env, newctx, vsFalse, exp); |
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vset = vsTrue.join(vsFalse.join(newctx.vsBreak)); |
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return ctx.removeAdditionalVars(vset); |
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} |
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/** |
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* Inline |
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*/ |
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public Statement inline(Environment env, Context ctx) { |
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ctx = new Context(ctx, this); |
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cond = cond.inlineValue(env, ctx); |
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// The compiler currently needs to perform inlining on both |
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// branches of the if statement -- even if `cond' is a constant |
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// true or false. Why? The compiler will later try to compile |
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// all classes that it has seen; this includes classes that |
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// appear in dead code. If we don't inline the dead branch here |
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// then the compiler will never perform inlining on any local |
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// classes appearing on the dead code. When the compiler tries |
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// to compile an un-inlined local class with uplevel references, |
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// it dies. (bug 4059492) |
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// |
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// A better solution to this would be to walk the dead branch and |
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// mark any local classes appearing therein as unneeded. Then the |
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// compilation phase could skip these classes. |
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if (ifTrue != null) { |
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ifTrue = ifTrue.inline(env, ctx); |
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} |
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if (ifFalse != null) { |
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ifFalse = ifFalse.inline(env, ctx); |
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} |
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if (cond.equals(true)) { |
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return eliminate(env, ifTrue); |
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} |
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if (cond.equals(false)) { |
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return eliminate(env, ifFalse); |
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} |
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if ((ifTrue == null) && (ifFalse == null)) { |
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return eliminate(env, new ExpressionStatement(where, cond).inline(env, ctx)); |
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} |
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if (ifTrue == null) { |
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cond = new NotExpression(cond.where, cond).inlineValue(env, ctx); |
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return eliminate(env, new IfStatement(where, cond, ifFalse, null)); |
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} |
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return this; |
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} |
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/** |
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* Create a copy of the statement for method inlining |
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*/ |
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public Statement copyInline(Context ctx, boolean valNeeded) { |
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IfStatement s = (IfStatement)clone(); |
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s.cond = cond.copyInline(ctx); |
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if (ifTrue != null) { |
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s.ifTrue = ifTrue.copyInline(ctx, valNeeded); |
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} |
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if (ifFalse != null) { |
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s.ifFalse = ifFalse.copyInline(ctx, valNeeded); |
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} |
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return s; |
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} |
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/** |
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* The cost of inlining this statement |
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*/ |
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public int costInline(int thresh, Environment env, Context ctx) { |
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int cost = 1 + cond.costInline(thresh, env, ctx); |
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if (ifTrue != null) { |
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cost += ifTrue.costInline(thresh, env, ctx); |
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} |
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if (ifFalse != null) { |
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cost += ifFalse.costInline(thresh, env, ctx); |
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} |
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return cost; |
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} |
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/** |
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* Code |
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*/ |
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public void code(Environment env, Context ctx, Assembler asm) { |
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CodeContext newctx = new CodeContext(ctx, this); |
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Label l1 = new Label(); |
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cond.codeBranch(env, newctx, asm, l1, false); |
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ifTrue.code(env, newctx, asm); |
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if (ifFalse != null) { |
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Label l2 = new Label(); |
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asm.add(true, where, opc_goto, l2); |
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asm.add(l1); |
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ifFalse.code(env, newctx, asm); |
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asm.add(l2); |
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} else { |
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asm.add(l1); |
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} |
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asm.add(newctx.breakLabel); |
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} |
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/** |
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*/ |
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public void print(PrintStream out, int indent) { |
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super.print(out, indent); |
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out.print("if "); |
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cond.print(out); |
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out.print(" "); |
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ifTrue.print(out, indent); |
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if (ifFalse != null) { |
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out.print(" else "); |
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ifFalse.print(out, indent); |
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} |
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} |
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} |