1 /*
2 * Portions of this software was developed by employees of the National Institute
3 * of Standards and Technology (NIST), an agency of the Federal Government and is
4 * being made available as a public service. Pursuant to title 17 United States
5 * Code Section 105, works of NIST employees are not subject to copyright
6 * protection in the United States. This software may be subject to foreign
7 * copyright. Permission in the United States and in foreign countries, to the
8 * extent that NIST may hold copyright, to use, copy, modify, create derivative
9 * works, and distribute this software and its documentation without fee is hereby
10 * granted on a non-exclusive basis, provided that this notice and disclaimer
11 * of warranty appears in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
14 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
15 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
17 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
18 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
19 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
20 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
21 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
22 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
23 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
24 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
25 */
26
27 package gov.nist.secauto.metaschema.core.metapath;
28
29 import gov.nist.secauto.metaschema.core.metapath.item.IItem;
30
31 import java.util.List;
32
33 import edu.umd.cs.findbugs.annotations.NonNull;
34
35 public interface IExpression {
36 /**
37 * Retrieve the child expressions associated with this expression.
38 *
39 * @return a list of expressions, which may be empty
40 */
41 @NonNull
42 List<? extends IExpression> getChildren();
43
44 /**
45 * The minimum expected result type to be produced when evaluating the
46 * expression. The result may be a sub-class or sub-interface of this value.
47 *
48 * @return the base result type
49 */
50 @NonNull
51 default Class<? extends IItem> getBaseResultType() {
52 return IItem.class;
53 }
54
55 /**
56 * The expected result type produced by evaluating the expression. The result
57 * must be the same or a sub-class or sub-interface of the value provided by
58 * {@link #getBaseResultType()}.
59 * <p>
60 * This method can be overloaded to provide static analysis of the expression to
61 * determine a more specific result type.
62 *
63 * @return the result type
64 */
65 @NonNull
66 default Class<? extends IItem> getStaticResultType() {
67 return getBaseResultType();
68 }
69
70 /**
71 * Produce a string representation of this expression including the expression's
72 * name.
73 * <p>
74 * This method can be overloaded to provide a more appropriate representation of
75 * the expression.
76 *
77 * @return a string representing the data elements of the expression
78 */
79 @SuppressWarnings("null")
80 @NonNull
81 default String toASTString() {
82 return String.format("%s[]", getClass().getName());
83 }
84
85 /**
86 * Provides a double dispatch callback for visitor handling.
87 *
88 * @param dynamicContext
89 * the dynamic evaluation context
90 * @param focus
91 * the outer focus of the expression
92 * @return the result of evaluation
93 */
94 @NonNull
95 ISequence<? extends IItem> accept(@NonNull DynamicContext dynamicContext, @NonNull ISequence<?> focus);
96
97 /**
98 * Provides a double dispatch callback for visitor handling.
99 *
100 * @param <RESULT>
101 * the type of the evaluation result
102 * @param <CONTEXT>
103 * the type of the visitor context
104 * @param visitor
105 * the visitor calling this method
106 * @param context
107 * the visitor context
108 * @return the result of evaluation
109 */
110 <RESULT, CONTEXT> RESULT accept(@NonNull IExpressionVisitor<RESULT, CONTEXT> visitor, @NonNull CONTEXT context);
111 }