| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| /* |
| * $Id: WalkingIterator.java 469314 2006-10-30 23:31:59Z minchau $ |
| */ |
| package org.apache.xpath.axes; |
| |
| import org.apache.xml.dtm.DTM; |
| import org.apache.xml.utils.PrefixResolver; |
| import org.apache.xpath.Expression; |
| import org.apache.xpath.ExpressionOwner; |
| import org.apache.xpath.VariableStack; |
| import org.apache.xpath.XPathVisitor; |
| import org.apache.xpath.compiler.Compiler; |
| import org.apache.xpath.compiler.OpMap; |
| |
| /** |
| * Location path iterator that uses Walkers. |
| */ |
| |
| public class WalkingIterator extends LocPathIterator implements ExpressionOwner |
| { |
| static final long serialVersionUID = 9110225941815665906L; |
| /** |
| * 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 = OpMap.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. |
| */ |
| public WalkingIterator(PrefixResolver nscontext) |
| { |
| |
| super(nscontext); |
| } |
| |
| |
| /** |
| * Get the analysis bits for this walker, as defined in the WalkerFactory. |
| * @return One of WalkerFactory#BIT_DESCENDANT, etc. |
| */ |
| public int getAnalysisBits() |
| { |
| int bits = 0; |
| if (null != m_firstWalker) |
| { |
| AxesWalker walker = m_firstWalker; |
| |
| while (null != walker) |
| { |
| int bit = walker.getAnalysisBits(); |
| bits |= bit; |
| walker = walker.getNextWalker(); |
| } |
| } |
| return bits; |
| } |
| |
| /** |
| * 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); |
| } |
| |
| } |
| |
| /** |
| * Initialize the context values for this expression |
| * after it is cloned. |
| * |
| * @param context The XPath runtime context for this |
| * transformation. |
| */ |
| public void setRoot(int context, Object environment) |
| { |
| |
| super.setRoot(context, environment); |
| |
| if(null != m_firstWalker) |
| { |
| m_firstWalker.setRoot(context); |
| m_lastUsedWalker = m_firstWalker; |
| } |
| } |
| |
| /** |
| * 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(m_foundLast) |
| 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) |
| { |
| 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); |
| |
| int n = returnNextNode(m_firstWalker.nextNode()); |
| |
| // These two statements need to be combined into one operation. |
| vars.setStackFrame(savedStart); |
| |
| return n; |
| } |
| } |
| |
| |
| /** |
| * Get the head of the walker list. |
| * |
| * @return The head of the walker list, or null |
| * if this iterator does not implement walkers. |
| * @xsl.usage advanced |
| */ |
| public final AxesWalker getFirstWalker() |
| { |
| return m_firstWalker; |
| } |
| |
| /** |
| * Set the head of the walker list. |
| * |
| * @param walker Should be a valid AxesWalker. |
| * @xsl.usage advanced |
| */ |
| public final void setFirstWalker(AxesWalker walker) |
| { |
| m_firstWalker = walker; |
| } |
| |
| |
| /** |
| * Set the last used walker. |
| * |
| * @param walker The last used walker, or null. |
| * @xsl.usage advanced |
| */ |
| public final void setLastUsedWalker(AxesWalker walker) |
| { |
| m_lastUsedWalker = walker; |
| } |
| |
| /** |
| * Get the last used walker. |
| * |
| * @return The last used walker, or null. |
| * @xsl.usage advanced |
| */ |
| 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() |
| { |
| if(m_allowDetach) |
| { |
| AxesWalker walker = m_firstWalker; |
| while (null != walker) |
| { |
| walker.detach(); |
| walker = walker.getNextWalker(); |
| } |
| |
| 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(); |
| } |
| } |
| |
| /** |
| * @see org.apache.xpath.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor) |
| */ |
| public void callVisitors(ExpressionOwner owner, XPathVisitor visitor) |
| { |
| if(visitor.visitLocationPath(owner, this)) |
| { |
| if(null != m_firstWalker) |
| { |
| m_firstWalker.callVisitors(this, visitor); |
| } |
| } |
| } |
| |
| |
| /** 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; |
| |
| /** |
| * @see ExpressionOwner#getExpression() |
| */ |
| public Expression getExpression() |
| { |
| return m_firstWalker; |
| } |
| |
| /** |
| * @see ExpressionOwner#setExpression(Expression) |
| */ |
| public void setExpression(Expression exp) |
| { |
| exp.exprSetParent(this); |
| m_firstWalker = (AxesWalker)exp; |
| } |
| |
| /** |
| * @see Expression#deepEquals(Expression) |
| */ |
| public boolean deepEquals(Expression expr) |
| { |
| if (!super.deepEquals(expr)) |
| return false; |
| |
| AxesWalker walker1 = m_firstWalker; |
| AxesWalker walker2 = ((WalkingIterator)expr).m_firstWalker; |
| while ((null != walker1) && (null != walker2)) |
| { |
| if(!walker1.deepEquals(walker2)) |
| return false; |
| walker1 = walker1.getNextWalker(); |
| walker2 = walker2.getNextWalker(); |
| } |
| |
| if((null != walker1) || (null != walker2)) |
| return false; |
| |
| return true; |
| } |
| |
| } |