Java LocalVariableGen.getStart方法代码示例

import com.sun.org.apache.bcel.internal.generic.LocalVariableGen; //导入方法依赖的package包/类
/**
 * Determines whether a particular variable is in use at a particular offset
 * in the byte code for this method.
 * <p><b>Preconditions:</b>
 * <ul>
 * <li>The {@link InstructionList#setPositions()} has been called for the
 * {@link InstructionList} associated with this {@link MethodGenerator}.
 * </li></ul></p>
 * @param lvg the {@link LocalVariableGen} for the variable
 * @param offset the position in the byte code
 * @return <code>true</code> if and only if the specified variable is in
 * use at the particular byte code offset.
 */
boolean offsetInLocalVariableGenRange(LocalVariableGen lvg, int offset) {
    InstructionHandle lvgStart = lvg.getStart();
    InstructionHandle lvgEnd = lvg.getEnd();

    // If no start handle is recorded for the LocalVariableGen, it is
    // assumed to be in use from the beginning of the method.
    if (lvgStart == null) {
        lvgStart = getInstructionList().getStart();
    }

    // If no end handle is recorded for the LocalVariableGen, it is assumed
    // to be in use to the end of the method.
    if (lvgEnd == null) {
        lvgEnd = getInstructionList().getEnd();
    }

    // Does the range of the instruction include the specified offset?
    // Note that the InstructionHandle.getPosition method returns the
    // offset of the beginning of an instruction.  A LocalVariableGen's
    // range includes the end instruction itself, so that instruction's
    // length must be taken into consideration in computing whether the
    // varible is in range at a particular offset.
    return ((lvgStart.getPosition() <= offset)
                && (lvgEnd.getPosition()
                        + lvgEnd.getInstruction().getLength() >= offset));
}
 

import com.sun.org.apache.bcel.internal.generic.LocalVariableGen; //导入方法依赖的package包/类
public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
    final ConstantPoolGen cpg = classGen.getConstantPool();
    final InstructionList il = methodGen.getInstructionList();
    final LocalVariableGen local =
        methodGen.addLocalVariable2("ppt",
                                    Util.getJCRefType(NODE_SIG),
                                    null);

    final com.sun.org.apache.bcel.internal.generic.Instruction loadLocal =
        new ILOAD(local.getIndex());
    final com.sun.org.apache.bcel.internal.generic.Instruction storeLocal =
        new ISTORE(local.getIndex());

    if (_right.isWildcard()) {
        il.append(methodGen.loadDOM());
        il.append(SWAP);
    }
    else if (_right instanceof StepPattern) {
        il.append(DUP);
        local.setStart(il.append(storeLocal));

        _right.translate(classGen, methodGen);

        il.append(methodGen.loadDOM());
        local.setEnd(il.append(loadLocal));
    }
    else {
        _right.translate(classGen, methodGen);

        if (_right instanceof AncestorPattern) {
            il.append(methodGen.loadDOM());
            il.append(SWAP);
        }
    }

    final int getParent = cpg.addInterfaceMethodref(DOM_INTF,
                                                    GET_PARENT,
                                                    GET_PARENT_SIG);
    il.append(new INVOKEINTERFACE(getParent, 2));

    final SyntaxTreeNode p = getParent();
    if (p == null || p instanceof Instruction ||
        p instanceof TopLevelElement)
    {
        _left.translate(classGen, methodGen);
    }
    else {
        il.append(DUP);
        InstructionHandle storeInst = il.append(storeLocal);

        if (local.getStart() == null) {
            local.setStart(storeInst);
        }

        _left.translate(classGen, methodGen);

        il.append(methodGen.loadDOM());
        local.setEnd(il.append(loadLocal));
    }

    methodGen.removeLocalVariable(local);

    /*
     * If _right is an ancestor pattern, backpatch _left false
     * list to the loop that searches for more ancestors.
     */
    if (_right instanceof AncestorPattern) {
        final AncestorPattern ancestor = (AncestorPattern) _right;
        _left.backPatchFalseList(ancestor.getLoopHandle());    // clears list
    }

    _trueList.append(_right._trueList.append(_left._trueList));
    _falseList.append(_right._falseList.append(_left._falseList));
}