import com.sun.org.apache.xerces.internal.impl.dtd.models.CMStateSet; //导入依赖的package包/类
protected void calcFirstPos(CMStateSet toSet) {
    if (type() == XSModelGroupImpl.MODELGROUP_CHOICE) {
        // Its the the union of the first positions of our children.
        toSet.setTo(fLeftChild.firstPos());
        toSet.union(fRightChild.firstPos());
    }
     else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE) {
        //
        //  If our left child is nullable, then its the union of our
        //  children's first positions. Else is our left child's first
        //  positions.
        //
        toSet.setTo(fLeftChild.firstPos());
        if (fLeftChild.isNullable())
            toSet.union(fRightChild.firstPos());
    }
     else {
        throw new RuntimeException("ImplementationMessages.VAL_BST");
    }
}
 

import com.sun.org.apache.xerces.internal.impl.dtd.models.CMStateSet; //导入依赖的package包/类
protected void calcLastPos(CMStateSet toSet) {
    if (type() == XSModelGroupImpl.MODELGROUP_CHOICE) {
        // Its the the union of the first positions of our children.
        toSet.setTo(fLeftChild.lastPos());
        toSet.union(fRightChild.lastPos());
    }
    else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE) {
        //
        //  If our right child is nullable, then its the union of our
        //  children's last positions. Else is our right child's last
        //  positions.
        //
        toSet.setTo(fRightChild.lastPos());
        if (fRightChild.isNullable())
            toSet.union(fLeftChild.lastPos());
    }
    else {
        throw new RuntimeException("ImplementationMessages.VAL_BST");
    }
}
 

import com.sun.org.apache.xerces.internal.impl.dtd.models.CMStateSet; //导入依赖的package包/类
protected void calcFirstPos(CMStateSet toSet) {
    // If we are an epsilon node, then the first pos is an empty set
    if (fPosition == -1)
        toSet.zeroBits();

    // Otherwise, its just the one bit of our position
    else
        toSet.setBit(fPosition);
}
 

import com.sun.org.apache.xerces.internal.impl.dtd.models.CMStateSet; //导入依赖的package包/类
protected void calcLastPos(CMStateSet toSet) {
    // If we are an epsilon node, then the last pos is an empty set
    if (fPosition == -1)
        toSet.zeroBits();

    // Otherwise, its just the one bit of our position
    else
        toSet.setBit(fPosition);
}
 

import com.sun.org.apache.xerces.internal.impl.dtd.models.CMStateSet; //导入依赖的package包/类
protected void calcFirstPos(CMStateSet toSet) {
    // Its just based on our child node's first pos
    toSet.setTo(fChild.firstPos());
}
 

import com.sun.org.apache.xerces.internal.impl.dtd.models.CMStateSet; //导入依赖的package包/类
protected void calcLastPos(CMStateSet toSet) {
    // Its just based on our child node's last pos
    toSet.setTo(fChild.lastPos());
}