| package org.apache.xpath.axes; |
| |
| import org.apache.xml.dtm.DTM; |
| import org.apache.xml.dtm.DTMIterator; |
| import org.apache.xml.dtm.DTMFilter; |
| import org.apache.xml.dtm.DTMManager; |
| |
| // Xalan imports |
| import org.apache.xpath.res.XPATHErrorResources; |
| import org.apache.xpath.XPath; |
| import org.apache.xpath.compiler.OpMap; |
| import org.apache.xpath.compiler.Compiler; |
| import org.apache.xpath.compiler.OpCodes; |
| import org.apache.xpath.compiler.PsuedoNames; |
| import org.apache.xpath.NodeSetDTM; |
| import org.apache.xpath.Expression; |
| import org.apache.xpath.XPathContext; |
| import org.apache.xpath.objects.XObject; |
| import org.apache.xml.utils.IntStack; |
| import org.apache.xml.utils.PrefixResolver; |
| import org.apache.xml.utils.ObjectPool; |
| import org.apache.xpath.objects.XNodeSet; |
| import org.apache.xpath.axes.AxesWalker; |
| import org.apache.xpath.VariableStack; |
| |
| /** |
| * Location path iterator that uses Walkers. |
| */ |
| |
| public class WalkingIterator extends LocPathIterator |
| { |
| /** |
| * Create a WalkingIterator iterator, including creation |
| * of step walkers from the opcode list, and call back |
| * into the Compiler to create predicate expressions. |
| * |
| * @param compiler The Compiler which is creating |
| * this expression. |
| * @param opPos The position of this iterator in the |
| * opcode list from the compiler. |
| * @param shouldLoadWalkers True if walkers should be |
| * loaded, or false if this is a derived iterator and |
| * it doesn't wish to load child walkers. |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| WalkingIterator( |
| Compiler compiler, int opPos, int analysis, boolean shouldLoadWalkers) |
| throws javax.xml.transform.TransformerException |
| { |
| super(compiler, opPos, analysis, shouldLoadWalkers); |
| |
| int firstStepPos = compiler.getFirstChildPos(opPos); |
| |
| if (shouldLoadWalkers) |
| { |
| m_firstWalker = WalkerFactory.loadWalkers(this, compiler, firstStepPos, 0); |
| m_lastUsedWalker = m_firstWalker; |
| } |
| } |
| |
| /** |
| * Create a WalkingIterator object. |
| * |
| * @param nscontext The namespace context for this iterator, |
| * should be OK if null. |
| */ |
| protected WalkingIterator(PrefixResolver nscontext) |
| { |
| |
| super(nscontext); |
| } |
| |
| |
| /** |
| * Get a cloned WalkingIterator that holds the same |
| * position as this iterator. |
| * |
| * @return A clone of this iterator that holds the same node position. |
| * |
| * @throws CloneNotSupportedException |
| */ |
| public Object clone() throws CloneNotSupportedException |
| { |
| |
| WalkingIterator clone = (WalkingIterator) super.clone(); |
| |
| // clone.m_varStackPos = this.m_varStackPos; |
| // clone.m_varStackContext = this.m_varStackContext; |
| if (null != m_firstWalker) |
| { |
| clone.m_firstWalker = m_firstWalker.cloneDeep(clone, null); |
| } |
| |
| return clone; |
| } |
| |
| /** |
| * Reset the iterator. |
| */ |
| public void reset() |
| { |
| |
| super.reset(); |
| |
| if (null != m_firstWalker) |
| { |
| m_lastUsedWalker = m_firstWalker; |
| |
| m_firstWalker.setRoot(m_context); |
| } |
| |
| } |
| |
| /** |
| * Returns the next node in the set and advances the position of the |
| * iterator in the set. After a NodeIterator is created, the first call |
| * to nextNode() returns the first node in the set. |
| * @return The next <code>Node</code> in the set being iterated over, or |
| * <code>null</code> if there are no more members in that set. |
| */ |
| public int nextNode() |
| { |
| |
| // If the cache is on, and the node has already been found, then |
| // just return from the list. |
| if (null != m_cachedNodes) |
| { |
| if(m_next < m_cachedNodes.size()) |
| { |
| int next = m_lastFetched = m_currentContextNode |
| = m_cachedNodes.elementAt(m_next); |
| |
| incrementNextPosition(); |
| |
| return next; |
| } |
| else if(m_foundLast) |
| { |
| m_lastFetched = DTM.NULL; |
| return DTM.NULL; |
| } |
| } |
| |
| // If the variable stack position is not -1, we'll have to |
| // set our position in the variable stack, so our variable access |
| // will be correct. Iterators that are at the top level of the |
| // expression need to reset the variable stack, while iterators |
| // in predicates do not need to, and should not, since their execution |
| // may be much later than top-level iterators. |
| // m_varStackPos is set in setRoot, which is called |
| // from the execute method. |
| if (-1 == m_stackFrame) |
| { |
| if (DTM.NULL == m_firstWalker.getRoot()) |
| { |
| this.setNextPosition(0); |
| m_firstWalker.setRoot(m_context); |
| |
| m_lastUsedWalker = m_firstWalker; |
| } |
| |
| return returnNextNode(m_firstWalker.nextNode()); |
| } |
| else |
| { |
| VariableStack vars = m_execContext.getVarStack(); |
| |
| // These three statements need to be combined into one operation. |
| int savedStart = vars.getStackFrame(); |
| |
| vars.setStackFrame(m_stackFrame); |
| |
| if (DTM.NULL == m_firstWalker.getRoot()) |
| { |
| this.setNextPosition(0); |
| m_firstWalker.setRoot(m_context); |
| |
| m_lastUsedWalker = m_firstWalker; |
| } |
| |
| int n = returnNextNode(m_firstWalker.nextNode()); |
| |
| // These two statements need to be combined into one operation. |
| vars.setStackFrame(savedStart); |
| |
| return n; |
| } |
| } |
| |
| /** |
| * <meta name="usage" content="advanced"/> |
| * Get the head of the walker list. |
| * |
| * @return The head of the walker list, or null |
| * if this iterator does not implement walkers. |
| */ |
| public final AxesWalker getFirstWalker() |
| { |
| return m_firstWalker; |
| } |
| |
| /** |
| * <meta name="usage" content="advanced"/> |
| * Set the last used walker. |
| * |
| * @param walker The last used walker, or null. |
| */ |
| public final void setLastUsedWalker(AxesWalker walker) |
| { |
| m_lastUsedWalker = walker; |
| } |
| |
| /** |
| * <meta name="usage" content="advanced"/> |
| * Get the last used walker. |
| * |
| * @return The last used walker, or null. |
| */ |
| public final AxesWalker getLastUsedWalker() |
| { |
| return m_lastUsedWalker; |
| } |
| |
| /** |
| * Detaches the iterator from the set which it iterated over, releasing |
| * any computational resources and placing the iterator in the INVALID |
| * state. After<code>detach</code> has been invoked, calls to |
| * <code>nextNode</code> or<code>previousNode</code> will raise the |
| * exception INVALID_STATE_ERR. |
| */ |
| public void detach() |
| { |
| m_lastUsedWalker = null; |
| |
| // Always call the superclass detach last! |
| super.detach(); |
| } |
| |
| /** |
| * This function is used to fixup variables from QNames to stack frame |
| * indexes at stylesheet build time. |
| * @param vars List of QNames that correspond to variables. This list |
| * should be searched backwards for the first qualified name that |
| * corresponds to the variable reference qname. The position of the |
| * QName in the vector from the start of the vector will be its position |
| * in the stack frame (but variables above the globalsTop value will need |
| * to be offset to the current stack frame). |
| */ |
| public void fixupVariables(java.util.Vector vars, int globalsSize) |
| { |
| m_predicateIndex = -1; |
| |
| AxesWalker walker = m_firstWalker; |
| |
| while (null != walker) |
| { |
| walker.fixupVariables(vars, globalsSize); |
| walker = walker.getNextWalker(); |
| } |
| } |
| |
| |
| /** The last used step walker in the walker list. |
| * @serial */ |
| protected AxesWalker m_lastUsedWalker; |
| |
| /** The head of the step walker list. |
| * @serial */ |
| protected AxesWalker m_firstWalker; |
| |
| } |