/*
* Bytecode Analysis Framework
* Copyright (C) 2003-2005 University of Maryland
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package edu.umd.cs.findbugs.ba.type;
import java.util.BitSet;
import org.apache.bcel.generic.Type;
import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
import edu.umd.cs.findbugs.ba.Frame;
/**
* A specialization of {@link Frame} for determining the types
* of values in the Java stack frame (locals and operand stack).
*
* @author David Hovemeyer
* @see Frame
* @see TypeAnalysis
*/
public class TypeFrame extends Frame<Type> {
private BitSet exactTypeSet;
/**
* Constructor.
*/
public TypeFrame(int numLocals) {
super(numLocals);
this.exactTypeSet = new BitSet();
}
/**
* Set whether or not a type in a given slot is exact.
*
* @param slot the slot
* @param isExact true if the slot contains an exact type, false if just an upper bound
*/
public void setExact(int slot, boolean isExact) {
exactTypeSet.set(slot, isExact);
}
/**
* Get whether or not a type in a given slot is exact.
*
* @param slot the slot
* @return true if the slot contains an exact type, false if just an upper bound
*/
public boolean isExact(int slot) {
return exactTypeSet.get(slot);
}
/**
* Clear the exact type set.
* The result is that all slots will be assumed <em>not</em> to
* contain an exact type.
*/
public void clearExactSet() {
exactTypeSet.clear();
}
@Override
public void setTop() {
super.setTop();
clearExactSet();
}
@Override
public void copyFrom(Frame<Type> other_) {
clearExactSet();
TypeFrame other = (TypeFrame) other_;
this.exactTypeSet.or(other.exactTypeSet);
super.copyFrom(other_);
}
@Override
protected String valueToString(Type value) {
return value.toString() + ",";
}
/**
* Get the single instance of the "Top" type.
*/
public static Type getTopType() {
return TopType.instance();
}
/**
* Get the single instance of the "Bottom" type.
*/
public static Type getBottomType() {
return BottomType.instance();
}
/**
* Get the single instance of the "LongExtra" type.
*/
public static Type getLongExtraType() {
return LongExtraType.instance();
}
/**
* Get the single instance of the "DoubleExtra" type.
*/
public static Type getDoubleExtraType() {
return DoubleExtraType.instance();
}
/**
* Get the single instance of the "Null" type.
*/
public static Type getNullType() {
return NullType.instance();
}
@Override
public void pushValue(Type value) {
super.pushValue(value);
try {
exactTypeSet.clear(getStackLocation(0));
} catch (DataflowAnalysisException e) {
assert false;
}
}
/**
* Pop a value off of the Java operand stack.
*
* @return the value that was popped
* @throws DataflowAnalysisException
* if the Java operand stack is empty
*/
@Override
public Type popValue() throws DataflowAnalysisException {
exactTypeSet.clear(getStackLocation(0));
return super.popValue();
}
@Override
public String toString() {
if (isTop())
return "[TOP]";
if (isBottom())
return "[BOTTOM]";
StringBuilder buf = new StringBuilder();
buf.append('[');
int numSlots = getNumSlots();
int start = 0;
for (int i = start; i < numSlots; ++i) {
if (i == getNumLocals()) {
// Use a "|" character to visually separate locals from
// the operand stack.
int last = buf.length() - 1;
if (last >= 0) {
if (buf.charAt(last) == ',')
buf.deleteCharAt(last);
}
buf.append(" | ");
}
if (isExact(i))
buf.append("!");
String value = valueToString(getValue(i));
if (i == numSlots - 1 && value.endsWith(","))
value = value.substring(0, value.length() - 1);
buf.append(value);
// buf.append(' ');
}
buf.append(']');
return buf.toString();
}
}
// vim:ts=4