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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/xml/xpath/Steps.java
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+/* 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., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 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 gnu.java.lang.CPStringBuilder;
+
+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 javax.xml.namespace.QName;
+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<Expr> path;
+
+ public Steps()
+ {
+ this(new LinkedList<Expr>());
+ }
+
+ Steps(LinkedList<Expr> 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);
+ for (Node candidate : possibleContexts(right, context))
+ {
+ 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<Node> possibleContexts(Pattern pattern, Node context)
+ {
+ if (pattern instanceof Selector)
+ {
+ Selector s = (Selector) pattern;
+ Collection<Node> candidates = new LinkedHashSet<Node>();
+ 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.emptySet();
+ }
+
+ @Override
+ public Object evaluate(Node context, int pos, int len)
+ {
+ //System.err.println(toString()+" evaluate");
+ // Left to right
+ Iterator<Expr> i = path.iterator();
+ Expr lhs = 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();
+ /* Suppression is safe, as we know context produces Collection<Node> */
+ @SuppressWarnings("unchecked")
+ Collection<Node> nodes = (Collection<Node>) val;
+ val = rhs.evaluate(context, nodes);
+ //System.err.println("\tevaluate "+rhs+" = "+val);
+ }
+ return val;
+ }
+
+ @Override
+ Collection<Node> evaluate(Node context, Collection<Node> ns)
+ {
+ // Left to right
+ Iterator<Expr> i = path.iterator();
+ Expr lhs = i.next();
+ if (lhs instanceof Path)
+ {
+ ns = ((Path) lhs).evaluate(context, ns);
+ }
+ else
+ {
+ Set<Node> acc = new LinkedHashSet<Node>();
+ int pos = 1, len = ns.size();
+ for (Node node : ns)
+ {
+ Object ret = lhs.evaluate(node, pos++, len);
+ if (ret instanceof Collection)
+ {
+ /* Suppression is safe, as we know context produces Collection<Node> */
+ @SuppressWarnings("unchecked")
+ Collection<Node> nodes = (Collection<Node>) ret;
+ acc.addAll(nodes);
+ }
+ }
+ 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<Expr> path2 = new LinkedList<Expr>();
+ for (int i = 0; i < len; i++)
+ {
+ path2.add(path.get(i).clone(context));
+ }
+ return new Steps(path2);
+ }
+
+ public boolean references(QName var)
+ {
+ for (Iterator<Expr> i = path.iterator(); i.hasNext(); )
+ {
+ if (i.next().references(var))
+ {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ public String toString()
+ {
+ CPStringBuilder buf = new CPStringBuilder();
+ Iterator<Expr> i = path.iterator();
+ Expr expr = i.next();
+ if (!(expr instanceof Root))
+ {
+ buf.append(expr);
+ }
+ while (i.hasNext())
+ {
+ expr = i.next();
+ buf.append('/');
+ buf.append(expr);
+ }
+ return buf.toString();
+ }
+
+}