yang/yang-data-jaxen/src/main/java/org/opendaylight/yangtools/yang/data/jaxen/JaxenXPath.java

   1 /*
   2  * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.yangtools.yang.data.jaxen;
   9
  10 import com.google.common.base.Converter;
  11 import com.google.common.base.Function;
  12 import com.google.common.base.Optional;
  13 import com.google.common.base.Preconditions;
  14 import com.google.common.collect.Lists;
  15 import java.util.Collection;
  16 import java.util.List;
  17 import javax.xml.xpath.XPathExpressionException;
  18 import org.jaxen.BaseXPath;
  19 import org.jaxen.ContextSupport;
  20 import org.jaxen.JaxenException;
  21 import org.jaxen.expr.Expr;
  22 import org.opendaylight.yangtools.yang.common.QNameModule;
  23 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  24 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  25 import org.opendaylight.yangtools.yang.data.api.schema.xpath.XPathBooleanResult;
  26 import org.opendaylight.yangtools.yang.data.api.schema.xpath.XPathDocument;
  27 import org.opendaylight.yangtools.yang.data.api.schema.xpath.XPathExpression;
  28 import org.opendaylight.yangtools.yang.data.api.schema.xpath.XPathNodesetResult;
  29 import org.opendaylight.yangtools.yang.data.api.schema.xpath.XPathNumberResult;
  30 import org.opendaylight.yangtools.yang.data.api.schema.xpath.XPathResult;
  31 import org.opendaylight.yangtools.yang.data.api.schema.xpath.XPathStringResult;
  32 import org.opendaylight.yangtools.yang.model.api.SchemaPath;
  33 import org.slf4j.Logger;
  34 import org.slf4j.LoggerFactory;
  35
  36 final class JaxenXPath implements XPathExpression {
  37     private static final Logger LOG = LoggerFactory.getLogger(JaxenXPath.class);
  38     protected static final Function<NormalizedNodeContext, NormalizedNode<?, ?>> EXTRACT_NODE =
  39             new Function<NormalizedNodeContext, NormalizedNode<?, ?>>() {
  40         @Override
  41         public NormalizedNode<?, ?> apply(final NormalizedNodeContext input) {
  42             return input.getNode();
  43         }
  44     };
  45     private final Converter<String, QNameModule> converter;
  46     private final SchemaPath schemaPath;
  47     private final BaseXPath xpath;
  48
  49     private JaxenXPath(final Converter<String, QNameModule> converter, final SchemaPath schemaPath,
  50             final BaseXPath xpath) {
  51         this.converter = Preconditions.checkNotNull(converter);
  52         this.schemaPath = Preconditions.checkNotNull(schemaPath);
  53         this.xpath = Preconditions.checkNotNull(xpath);
  54     }
  55
  56     static JaxenXPath create(final Converter<String, QNameModule> converter, final SchemaPath schemaPath,
  57             final String xpath) throws JaxenException {
  58         final BaseXPath compiled = new BaseXPath(xpath) {
  59             private static final long serialVersionUID = 1L;
  60
  61             @Override
  62             protected ContextSupport getContextSupport() {
  63                 throw new UnsupportedOperationException(xpath);
  64             }
  65         };
  66
  67         final Expr expr = compiled.getRootExpr();
  68         LOG.debug("Compiled {} to expression {}", xpath, expr);
  69
  70         // FIXME: perform expression introspection to understand things like apex, etc.
  71
  72         return new JaxenXPath(converter, schemaPath, compiled);
  73     }
  74
  75     @Override
  76     public Optional<? extends XPathResult<?>> evaluate(final XPathDocument document, final YangInstanceIdentifier path)
  77             throws XPathExpressionException {
  78         Preconditions.checkArgument(document instanceof JaxenDocument);
  79
  80         final NormalizedNodeContextSupport contextSupport = NormalizedNodeContextSupport.create(
  81             (JaxenDocument)document, converter);
  82
  83         final Object result;
  84         try {
  85             result = xpath.evaluate(contextSupport.createContext(path));
  86         } catch (JaxenException e) {
  87             throw new XPathExpressionException(e);
  88         }
  89
  90         if (result instanceof String) {
  91             return Optional.of(new XPathStringResult() {
  92                 @Override
  93                 public String getValue() {
  94                     return (String)result;
  95                 }
  96             });
  97         } else if (result instanceof Number) {
  98             return Optional.of(new XPathNumberResult() {
  99                 @Override
 100                 public Number getValue() {
 101                     return (Number) result;
 102                 }
 103             });
 104         } else if (result instanceof Boolean) {
 105             return Optional.of(new XPathBooleanResult() {
 106                 @Override
 107                 public Boolean getValue() {
 108                     return (Boolean) result;
 109                 }
 110             });
 111         } else if (result != null){
 112             return Optional.of(new XPathNodesetResult() {
 113                 @SuppressWarnings("unchecked")
 114                 @Override
 115                 public Collection<NormalizedNode<?, ?>> getValue() {
 116                     // XXX: Will this really work, or do we need to perform deep transformation?
 117                     return Lists.transform((List<NormalizedNodeContext>) result, EXTRACT_NODE);
 118                 }
 119             });
 120         } else {
 121             return Optional.absent();
 122         }
 123     }
 124
 125     @Override
 126     public SchemaPath getEvaluationPath() {
 127         return schemaPath;
 128     }
 129
 130     @Override
 131     public SchemaPath getApexPath() {
 132         // TODO: improve this
 133         return SchemaPath.ROOT;
 134     }
 135 }