diff options
Diffstat (limited to 'libjava/gnu/xml/xpath/Steps.java')
| -rw-r--r-- | libjava/gnu/xml/xpath/Steps.java | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/libjava/gnu/xml/xpath/Steps.java b/libjava/gnu/xml/xpath/Steps.java new file mode 100644 index 0000000..abd30e4 --- /dev/null +++ b/libjava/gnu/xml/xpath/Steps.java @@ -0,0 +1,240 @@ +/* Steps.java -- + Copyright (C) 2004 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA +02111-1307 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package gnu.xml.xpath; + +import java.util.Collection; +import java.util.Collections; +import java.util.Iterator; +import java.util.LinkedHashSet; +import java.util.LinkedList; +import java.util.Set; +import org.w3c.dom.Attr; +import org.w3c.dom.Node; + +/** + * A list of transitions between components in a location path. + * + * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a> + */ +public final class Steps + extends Path +{ + + final LinkedList path; + + public Steps() + { + this(new LinkedList()); + } + + Steps(LinkedList path) + { + this.path = path; + } + + public boolean matches(Node context) + { + // Right to left + return matches(context, path.size() - 1); + } + + boolean matches(Node context, int pos) + { + Pattern right = (Pattern) path.get(pos); + if (!right.matches(context)) + { + return false; + } + if (pos > 0) + { + Pattern left = (Pattern) path.get(pos - 1); + Iterator j = possibleContexts(right, context).iterator(); + while (j.hasNext()) + { + Node candidate = (Node) j.next(); + if (left.matches(candidate) && + matches(candidate, pos - 1)) + { + return true; + } + // keep going, there may be another candidate + } + return false; + } + return true; + } + + /** + * Essentially the reverse of Selector.addCandidates. + * The idea is to determine possible context nodes for a match. + */ + Collection possibleContexts(Pattern pattern, Node context) + { + if (pattern instanceof Selector) + { + Selector s = (Selector) pattern; + Collection candidates = new LinkedHashSet(); + switch (s.axis) + { + case Selector.PARENT: + s.addChildNodes(context, candidates, false); + break; + case Selector.ANCESTOR: + s.addChildNodes(context, candidates, true); + break; + case Selector.ANCESTOR_OR_SELF: + candidates.add (context); + s.addChildNodes(context, candidates, true); + break; + case Selector.CHILD: + s.addParentNode(context, candidates, false); + break; + case Selector.DESCENDANT: + s.addParentNode(context, candidates, true); + break; + case Selector.DESCENDANT_OR_SELF: + candidates.add(context); + s.addParentNode(context, candidates, true); + break; + case Selector.PRECEDING_SIBLING: + s.addFollowingNodes(context, candidates, false); + break; + case Selector.FOLLOWING_SIBLING: + s.addPrecedingNodes(context, candidates, false); + break; + case Selector.PRECEDING: + s.addFollowingNodes(context, candidates, true); + break; + case Selector.FOLLOWING: + s.addPrecedingNodes(context, candidates, true); + break; + case Selector.ATTRIBUTE: + case Selector.NAMESPACE: + if (context.getNodeType() == Node.ATTRIBUTE_NODE) + { + candidates.add(((Attr) context).getOwnerElement()); + } + break; + case Selector.SELF: + candidates.add(context); + break; + } + return candidates; + } + return Collections.EMPTY_SET; + } + + public Object evaluate(Node context, int pos, int len) + { + //System.err.println(toString()+" evaluate"); + // Left to right + Iterator i = path.iterator(); + Expr lhs = (Expr) i.next(); + Object val = lhs.evaluate(context, pos, len); + //System.err.println("\tevaluate "+lhs+" = "+val); + while (val instanceof Collection && i.hasNext()) + { + Path rhs = (Path) i.next(); + val = rhs.evaluate(context, (Collection) val); + //System.err.println("\tevaluate "+rhs+" = "+val); + } + return val; + } + + Collection evaluate(Node context, Collection ns) + { + // Left to right + Iterator i = path.iterator(); + Expr lhs = (Expr) i.next(); + if (lhs instanceof Path) + { + ns = ((Path) lhs).evaluate(context, ns); + } + else + { + Set acc = new LinkedHashSet(); + int pos = 1, len = ns.size(); + for (Iterator j = ns.iterator(); j.hasNext(); ) + { + Node node = (Node) j.next(); + Object ret = lhs.evaluate(node, pos++, len); + if (ret instanceof Collection) + { + acc.addAll((Collection) ret); + } + } + ns = acc; + } + while (i.hasNext()) + { + Path rhs = (Path) i.next(); + ns = rhs.evaluate(context, ns); + } + return ns; + } + + public Expr clone(Object context) + { + int len = path.size(); + LinkedList path2 = new LinkedList(); + for (int i = 0; i < len; i++) + { + path2.add(((Expr) path.get(i)).clone(context)); + } + return new Steps(path2); + } + + public String toString() + { + StringBuffer buf = new StringBuffer(); + Iterator i = path.iterator(); + Expr expr = (Expr) i.next(); + if (!(expr instanceof Root)) + { + buf.append(expr); + } + while (i.hasNext()) + { + expr = (Expr) i.next(); + buf.append('/'); + buf.append(expr); + } + return buf.toString(); + } + +} |