1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 /* 19 * $Id: WalkingIteratorSorted.java 468655 2006-10-28 07:12:06Z minchau $ 20 */ 21 package org.apache.xpath.axes; 22 23 import org.apache.xml.dtm.Axis; 24 import org.apache.xml.utils.PrefixResolver; 25 import org.apache.xpath.compiler.Compiler; 26 27 /** 28 * This class iterates over set of nodes that needs to be sorted. 29 * @xsl.usage internal 30 */ 31 public class WalkingIteratorSorted extends WalkingIterator 32 { 33 static final long serialVersionUID = -4512512007542368213L; 34 35 // /** True if the nodes will be found in document order */ 36 // protected boolean m_inNaturalOrder = false; 37 38 /** True if the nodes will be found in document order, and this can 39 * be determined statically. */ 40 protected boolean m_inNaturalOrderStatic = false; 41 42 /** 43 * Create a WalkingIteratorSorted object. 44 * 45 * @param nscontext The namespace context for this iterator, 46 * should be OK if null. 47 */ 48 public WalkingIteratorSorted(PrefixResolver nscontext) 49 { 50 super(nscontext); 51 } 52 53 /** 54 * Create a WalkingIterator iterator, including creation 55 * of step walkers from the opcode list, and call back 56 * into the Compiler to create predicate expressions. 57 * 58 * @param compiler The Compiler which is creating 59 * this expression. 60 * @param opPos The position of this iterator in the 61 * opcode list from the compiler. 62 * @param shouldLoadWalkers True if walkers should be 63 * loaded, or false if this is a derived iterator and 64 * it doesn't wish to load child walkers. 65 * 66 * @throws javax.xml.transform.TransformerException 67 */ 68 WalkingIteratorSorted( 69 Compiler compiler, int opPos, int analysis, boolean shouldLoadWalkers) 70 throws javax.xml.transform.TransformerException 71 { 72 super(compiler, opPos, analysis, shouldLoadWalkers); 73 } 74 75 /** 76 * Returns true if all the nodes in the iteration well be returned in document 77 * order. 78 * 79 * @return true as a default. 80 */ 81 public boolean isDocOrdered() 82 { 83 return m_inNaturalOrderStatic; 84 } 85 86 87 /** 88 * Tell if the nodeset can be walked in doc order, via static analysis. 89 * 90 * 91 * @return true if the nodeset can be walked in doc order, without sorting. 92 */ 93 boolean canBeWalkedInNaturalDocOrderStatic() 94 { 95 96 if (null != m_firstWalker) 97 { 98 AxesWalker walker = m_firstWalker; 99 int prevAxis = -1; 100 boolean prevIsSimpleDownAxis = true; 101 102 for(int i = 0; null != walker; i++) 103 { 104 int axis = walker.getAxis(); 105 106 if(walker.isDocOrdered()) 107 { 108 boolean isSimpleDownAxis = ((axis == Axis.CHILD) 109 || (axis == Axis.SELF) 110 || (axis == Axis.ROOT)); 111 // Catching the filtered list here is only OK because 112 // FilterExprWalker#isDocOrdered() did the right thing. 113 if(isSimpleDownAxis || (axis == -1)) 114 walker = walker.getNextWalker(); 115 else 116 { 117 boolean isLastWalker = (null == walker.getNextWalker()); 118 if(isLastWalker) 119 { 120 if(walker.isDocOrdered() && (axis == Axis.DESCENDANT || 121 axis == Axis.DESCENDANTORSELF || axis == Axis.DESCENDANTSFROMROOT 122 || axis == Axis.DESCENDANTSORSELFFROMROOT) || (axis == Axis.ATTRIBUTE)) 123 return true; 124 } 125 return false; 126 } 127 } 128 else 129 return false; 130 } 131 return true; 132 } 133 return false; 134 } 135 136 137 // /** 138 // * NEEDSDOC Method canBeWalkedInNaturalDocOrder 139 // * 140 // * 141 // * NEEDSDOC (canBeWalkedInNaturalDocOrder) @return 142 // */ 143 // boolean canBeWalkedInNaturalDocOrder() 144 // { 145 // 146 // if (null != m_firstWalker) 147 // { 148 // AxesWalker walker = m_firstWalker; 149 // int prevAxis = -1; 150 // boolean prevIsSimpleDownAxis = true; 151 // 152 // for(int i = 0; null != walker; i++) 153 // { 154 // int axis = walker.getAxis(); 155 // 156 // if(walker.isDocOrdered()) 157 // { 158 // boolean isSimpleDownAxis = ((axis == Axis.CHILD) 159 // || (axis == Axis.SELF) 160 // || (axis == Axis.ROOT)); 161 // // Catching the filtered list here is only OK because 162 // // FilterExprWalker#isDocOrdered() did the right thing. 163 // if(isSimpleDownAxis || (axis == -1)) 164 // walker = walker.getNextWalker(); 165 // else 166 // { 167 // boolean isLastWalker = (null == walker.getNextWalker()); 168 // if(isLastWalker) 169 // { 170 // if(walker.isDocOrdered() && (axis == Axis.DESCENDANT || 171 // axis == Axis.DESCENDANTORSELF || axis == Axis.DESCENDANTSFROMROOT 172 // || axis == Axis.DESCENDANTSORSELFFROMROOT) || (axis == Axis.ATTRIBUTE)) 173 // return true; 174 // } 175 // return false; 176 // } 177 // } 178 // else 179 // return false; 180 // } 181 // return true; 182 // } 183 // return false; 184 // } 185 186 /** 187 * This function is used to perform some extra analysis of the iterator. 188 * 189 * @param vars List of QNames that correspond to variables. This list 190 * should be searched backwards for the first qualified name that 191 * corresponds to the variable reference qname. The position of the 192 * QName in the vector from the start of the vector will be its position 193 * in the stack frame (but variables above the globalsTop value will need 194 * to be offset to the current stack frame). 195 */ 196 public void fixupVariables(java.util.Vector vars, int globalsSize) 197 { 198 super.fixupVariables(vars, globalsSize); 199 200 int analysis = getAnalysisBits(); 201 if(WalkerFactory.isNaturalDocOrder(analysis)) 202 { 203 m_inNaturalOrderStatic = true; 204 } 205 else 206 { 207 m_inNaturalOrderStatic = false; 208 // System.out.println("Setting natural doc order to false: "+ 209 // WalkerFactory.getAnalysisString(analysis)); 210 } 211 212 } 213 214 } 215
