001/* 002 * Portions of this software was developed by employees of the National Institute 003 * of Standards and Technology (NIST), an agency of the Federal Government and is 004 * being made available as a public service. Pursuant to title 17 United States 005 * Code Section 105, works of NIST employees are not subject to copyright 006 * protection in the United States. This software may be subject to foreign 007 * copyright. Permission in the United States and in foreign countries, to the 008 * extent that NIST may hold copyright, to use, copy, modify, create derivative 009 * works, and distribute this software and its documentation without fee is hereby 010 * granted on a non-exclusive basis, provided that this notice and disclaimer 011 * of warranty appears in all copies. 012 * 013 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER 014 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY 015 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF 016 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM 017 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE 018 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT 019 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT, 020 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM, 021 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY, 022 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR 023 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT 024 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER. 025 */ 026 027package gov.nist.secauto.metaschema.core.metapath; 028 029import gov.nist.secauto.metaschema.core.metapath.item.IItem; 030 031import java.util.List; 032 033import edu.umd.cs.findbugs.annotations.NonNull; 034 035public interface IExpression { 036 /** 037 * Retrieve the child expressions associated with this expression. 038 * 039 * @return a list of expressions, which may be empty 040 */ 041 @NonNull 042 List<? extends IExpression> getChildren(); 043 044 /** 045 * The minimum expected result type to be produced when evaluating the 046 * expression. The result may be a sub-class or sub-interface of this value. 047 * 048 * @return the base result type 049 */ 050 @NonNull 051 default Class<? extends IItem> getBaseResultType() { 052 return IItem.class; 053 } 054 055 /** 056 * The expected result type produced by evaluating the expression. The result 057 * must be the same or a sub-class or sub-interface of the value provided by 058 * {@link #getBaseResultType()}. 059 * <p> 060 * This method can be overloaded to provide static analysis of the expression to 061 * determine a more specific result type. 062 * 063 * @return the result type 064 */ 065 @NonNull 066 default Class<? extends IItem> getStaticResultType() { 067 return getBaseResultType(); 068 } 069 070 /** 071 * Produce a string representation of this expression including the expression's 072 * name. 073 * <p> 074 * This method can be overloaded to provide a more appropriate representation of 075 * the expression. 076 * 077 * @return a string representing the data elements of the expression 078 */ 079 @SuppressWarnings("null") 080 @NonNull 081 default String toASTString() { 082 return String.format("%s[]", getClass().getName()); 083 } 084 085 /** 086 * Provides a double dispatch callback for visitor handling. 087 * 088 * @param dynamicContext 089 * the dynamic evaluation context 090 * @param focus 091 * the outer focus of the expression 092 * @return the result of evaluation 093 */ 094 @NonNull 095 ISequence<? extends IItem> accept(@NonNull DynamicContext dynamicContext, @NonNull ISequence<?> focus); 096 097 /** 098 * Provides a double dispatch callback for visitor handling. 099 * 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}