1 files changed, 129 insertions, 0 deletions
diff --git a/src/proguard/classfile/editor/VariableEditor.java b/src/proguard/classfile/editor/VariableEditor.java
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+++ b/src/proguard/classfile/editor/VariableEditor.java
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+/*
+ * ProGuard -- shrinking, optimization, obfuscation, and preverification
+ *             of Java bytecode.
+ *
+ * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program 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 for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+package proguard.classfile.editor;
+
+import proguard.classfile.*;
+import proguard.classfile.attribute.*;
+import proguard.classfile.attribute.visitor.AttributeVisitor;
+import proguard.classfile.util.SimplifiedVisitor;
+
+/**
+ * This AttributeVisitor accumulates specified changes to local variables, and
+ * then applies these accumulated changes to the code attributes that it visits.
+ *
+ * @author Eric  Lafortune
+ */
+public class VariableEditor
+extends      SimplifiedVisitor
+implements   AttributeVisitor
+{
+    private boolean   modified;
+
+    private boolean[] deleted     = new boolean[ClassConstants.TYPICAL_VARIABLES_SIZE];
+    private int[]     variableMap = new int[ClassConstants.TYPICAL_VARIABLES_SIZE];
+
+    private final VariableRemapper variableRemapper = new VariableRemapper();
+
+
+    /**
+     * Resets the accumulated code changes.
+     * @param maxLocals the length of the local variable frame that will be
+     *                  edited next.
+     */
+    public void reset(int maxLocals)
+    {
+        // Try to reuse the previous array.
+        if (deleted.length < maxLocals)
+        {
+            deleted = new boolean[maxLocals];
+        }
+        else
+        {
+            for (int index = 0; index < maxLocals; index++)
+            {
+                deleted[index] = false;
+            }
+        }
+
+        modified = false;
+    }
+
+
+    /**
+     * Remembers to delete the given variable.
+     * @param variableIndex the index of the variable to be deleted.
+     */
+    public void deleteVariable(int variableIndex)
+    {
+        deleted[variableIndex] = true;
+
+        modified = true;
+    }
+
+
+    /**
+     * Returns whether the given variable at the given offset has deleted.
+     */
+    public boolean isDeleted(int instructionOffset)
+    {
+        return deleted[instructionOffset];
+    }
+
+
+    // Implementations for AttributeVisitor.
+
+    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
+
+
+    public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
+    {
+        // Avoid doing any work if nothing is changing anyway.
+        if (!modified)
+        {
+            return;
+        }
+
+        int oldMaxLocals = codeAttribute.u2maxLocals;
+
+        // Make sure there is a sufficiently large variable map.
+        if (variableMap.length < oldMaxLocals)
+        {
+            variableMap = new int[oldMaxLocals];
+        }
+
+        // Fill out the variable map.
+        int newVariableIndex = 0;
+        for (int oldVariableIndex = 0; oldVariableIndex < oldMaxLocals; oldVariableIndex++)
+        {
+            variableMap[oldVariableIndex] = deleted[oldVariableIndex] ?
+                -1 : newVariableIndex++;
+        }
+
+        // Set the map.
+        variableRemapper.setVariableMap(variableMap);
+
+        // Remap the variables.
+        variableRemapper.visitCodeAttribute(clazz, method, codeAttribute);
+
+        // Update the length of local variable frame.
+        codeAttribute.u2maxLocals = newVariableIndex;
+    }
+}