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48 package org.jaxen.expr;
49
50 import java.util.Iterator;
51 import java.util.List;
52
53 import org.jaxen.Context;
54 import org.jaxen.ContextSupport;
55 import org.jaxen.JaxenException;
56 import org.jaxen.UnsupportedAxisException;
57
58 /***
59 * <p>Represents a location step in a LocationPath. The node-set selected by
60 * the location step is the node-set that results from generating an initial
61 * node-set from the axis and node-test, and then filtering that node-set by
62 * each of the predicates in turn.</p>
63 *
64 * <p>
65 * The initial node-set consists of the nodes having the relationship to the
66 * context node specified by the axis, and having the node type and expanded-name
67 * specified by the node test.</p>
68 */
69 public interface Step extends Predicated
70 {
71
72 /***
73 * Performs the node-test part of evaluating the step for the given node
74 * (which must be on the axis).
75 *
76 * @return true if the node matches this step; false if it doesn't
77 */
78 boolean matches(Object node,
79 ContextSupport contextSupport) throws JaxenException;
80
81 /***
82 * Returns a <code>String</code> containing the XPath expression.
83 *
84 * @return the text form of this step
85 */
86 String getText();
87
88 /***
89 * Simplifies the XPath step. In practice, this is usually a noop.
90 * Jaxen does not currently perform any simplification.
91 */
92 void simplify();
93
94 /***
95 * Get an identifier for the current axis.
96 *
97 * @return the axis identifier
98 * @see org.jaxen.saxpath.Axis
99 */
100 public int getAxis();
101
102 /***
103 * Get an Iterator for the current axis starting in the given contextNode.
104 *
105 * @param contextNode the node from which to follow this step
106 * @param support the remaining context for the traversal
107 * @return an iterator over the nodes along the axis
108 * @throws UnsupportedAxisException if the navigator does not support this step's axis
109 *
110 */
111 Iterator axisIterator(Object contextNode,
112 ContextSupport support) throws UnsupportedAxisException;
113
114
115 /***
116 * For each node in the given context calls matches() for every node on the
117 * axis, then filters the result by each of the predicates.
118 *
119 * @return a list of matching nodes
120 */
121 List evaluate(Context context) throws JaxenException;
122
123 }
124