IIndex.java
/*
* Portions of this software was developed by employees of the National Institute
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* being made available as a public service. Pursuant to title 17 United States
* Code Section 105, works of NIST employees are not subject to copyright
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* copyright. Permission in the United States and in foreign countries, to the
* extent that NIST may hold copyright, to use, copy, modify, create derivative
* works, and distribute this software and its documentation without fee is hereby
* granted on a non-exclusive basis, provided that this notice and disclaimer
* of warranty appears in all copies.
*
* THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
* EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
* THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
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package gov.nist.secauto.metaschema.core.model.constraint;
import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
import gov.nist.secauto.metaschema.core.metapath.InvalidTypeMetapathException;
import gov.nist.secauto.metaschema.core.metapath.MetapathException;
import gov.nist.secauto.metaschema.core.metapath.MetapathExpression;
import gov.nist.secauto.metaschema.core.metapath.MetapathExpression.ResultType;
import gov.nist.secauto.metaschema.core.metapath.function.library.FnData;
import gov.nist.secauto.metaschema.core.metapath.item.node.INodeItem;
import gov.nist.secauto.metaschema.core.util.CollectionUtil;
import gov.nist.secauto.metaschema.core.util.ObjectUtils;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
public interface IIndex {
/**
* Construct a new index using the provided key field components to generate
* keys.
*
* @param keyFields
* the key field components to use to generate keys by default
* @return the new index
*/
@NonNull
static IIndex newInstance(@NonNull List<? extends IKeyField> keyFields) {
return new DefaultIndex(keyFields);
}
/**
* Check if a key contains information other than {@code null} Strings.
*
* @param key
* the key to check
* @return {@code true} if the series of key values contains only {@code null}
* values, or {@code false} otherwise
*/
static boolean isAllNulls(@NonNull Iterable<String> key) {
for (String value : key) {
if (value != null) {
return false; // NOPMD readability
}
}
return true;
}
/**
* Retrieve the key field components used to generate a key for this index.
*
* @return the key field components
*/
@NonNull
List<IKeyField> getKeyFields();
/**
* Store the provided item in the index using the index's key field components
* to generate the key.
*
* @param item
* the item to store in the index
* @param dynamicContext
* the Metapath evaluation context
* @return the previous item stored in the index, or {@code null} otherwise
*/
@Nullable
default INodeItem put(@NonNull INodeItem item, @NonNull DynamicContext dynamicContext) {
List<String> key = toKey(item, getKeyFields(), dynamicContext);
return put(item, key);
}
/**
* Store the provided item using the provided key.
*
* @param item
* the item to store
* @param key
* the key to store the item with
* @return the previous item stored in the index using the key, or {@code null}
* otherwise
*/
@Nullable
INodeItem put(@NonNull INodeItem item, @NonNull List<String> key);
/**
* Retrieve the item from the index that matches the key generated by evaluating
* the index's default key field components against the provided item.
*
* @param item
* the item to store in the index
* @param dynamicContext
* the Metapath evaluation context
* @return the previous item stored in the index, or {@code null} otherwise
*/
@Nullable
default INodeItem get(@NonNull INodeItem item, @NonNull DynamicContext dynamicContext) {
List<String> key = toKey(item, getKeyFields(), dynamicContext);
return get(key);
}
/**
* Retrieve the item from the index that matches the provided key.
*
* @param key
* the key to use for lookup
* @return the item with the matching key or {@code null} if no matching item
* was found
*/
INodeItem get(List<String> key);
/**
* Construct a key by evaluating the provided key field components against the
* provided item.
*
* @param item
* the item to generate the key from
* @param keyFields
* the key field components used to generate the key
* @param dynamicContext
* the Metapath evaluation context
* @return a new key
*/
@NonNull
static List<String> toKey(@NonNull INodeItem item, @NonNull List<? extends IKeyField> keyFields,
@NonNull DynamicContext dynamicContext) {
return CollectionUtil.unmodifiableList(
ObjectUtils.notNull(keyFields.stream()
.map(keyField -> {
assert keyField != null;
return buildKeyItem(item, keyField, dynamicContext);
})
.collect(Collectors.toCollection(ArrayList::new))));
}
/**
* Evaluates the provided key field component against the item to generate a key
* value.
*
* @param item
* the item to generate the key value from
* @param keyField
* the key field component used to generate the key value
* @param dynamicContext
* the Metapath evaluation context
* @return the key value or {@code null} if the evaluation resulted in no value
*/
@Nullable
private static String buildKeyItem(
@NonNull INodeItem item,
@NonNull IKeyField keyField,
@NonNull DynamicContext dynamicContext) {
MetapathExpression keyPath = keyField.getTarget();
INodeItem keyItem;
try {
keyItem = keyPath.evaluateAs(item, ResultType.NODE, dynamicContext);
} catch (InvalidTypeMetapathException ex) {
throw new MetapathException("Key path did not result in a single node", ex);
}
String keyValue = null;
if (keyItem != null) {
keyValue = FnData.fnDataItem(keyItem).asString();
Pattern pattern = keyField.getPattern();
if (pattern != null) {
keyValue = applyPattern(keyItem, keyValue, pattern);
}
} // empty key
return keyValue;
}
/**
* Apply the key value pattern, if configured, to generate the final key value.
*
* @param keyItem
* the node item used to form the key field
* @param pattern
* the key field pattern configuration from the constraint
* @param keyValue
* the current key value
* @return the final key value
*/
private static String applyPattern(@NonNull INodeItem keyItem, @NonNull String keyValue,
@NonNull Pattern pattern) {
Matcher matcher = pattern.matcher(keyValue);
if (!matcher.matches()) {
throw new MetapathException(
String.format("Key field declares the pattern '%s' which does not match the value '%s' of node '%s'",
pattern.pattern(), keyValue, keyItem.getMetapath()));
}
if (matcher.groupCount() != 1) {
throw new MetapathException(String.format(
"The first group was not a match for value '%s' of node '%s' for key field pattern '%s'",
keyValue, keyItem.getMetapath(), pattern.pattern()));
}
return matcher.group(1);
}
}