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/*
* Copyright 2000-2022 Vaadin Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.vaadin.data.provider;
import java.util.Comparator;
import java.util.Locale;
import java.util.Objects;
import com.vaadin.data.ValueProvider;
import com.vaadin.server.SerializableBiPredicate;
import com.vaadin.server.SerializableComparator;
import com.vaadin.server.SerializablePredicate;
import com.vaadin.server.SerializableSupplier;
import com.vaadin.shared.data.sort.SortDirection;
import com.vaadin.ui.UI;
/**
* A class containing a number of static helper methods for implementing
* {@link InMemoryDataProvider}s.
* <p>
* This class is intended primarily for internal use.
*
* @author Vaadin Ltd
* @since 8.1
*/
public class InMemoryDataProviderHelpers {
/**
* Supplier that attempts to resolve a locale from the current UI. Returns
* the system's default locale as a fallback.
*/
public static final SerializableSupplier<Locale> CURRENT_LOCALE_SUPPLIER = () -> {
UI currentUi = UI.getCurrent();
if (currentUi != null) {
return currentUi.getLocale();
}
return Locale.getDefault();
};
/**
* Wraps a given data provider so that its filter ignores null items
* returned by the given value provider.
*
* @param dataProvider
* the data provider to wrap
* @param valueProvider
* the value provider for providing values to filter
* @param predicate
* the predicate to combine null filtering with
* @return the wrapped data provider
*/
public static <T, V, Q> DataProvider<T, Q> filteringByIgnoreNull(
InMemoryDataProvider<T> dataProvider,
ValueProvider<T, V> valueProvider,
SerializableBiPredicate<V, Q> predicate) {
Objects.requireNonNull(predicate, "Predicate cannot be null");
return dataProvider.filteringBy(valueProvider,
(itemValue, queryFilter) -> itemValue != null
&& predicate.test(itemValue, queryFilter));
}
/**
* Wraps a given data provider so that its filter tests the given predicate
* with the lower case string provided by the given value provider.
*
* @param dataProvider
* the data provider to wrap
* @param valueProvider
* the value provider for providing string values to filter
* @param predicate
* the predicate to use for comparing the resulting lower case
* strings
* @param localeSupplier
* the locale to use when converting strings to lower case
* @return the wrapped data provider
*/
public static <T> DataProvider<T, String> filteringByCaseInsensitiveString(
InMemoryDataProvider<T> dataProvider,
ValueProvider<T, String> valueProvider,
SerializableBiPredicate<String, String> predicate,
SerializableSupplier<Locale> localeSupplier) {
// Only assert since these are only passed from our own code
assert predicate != null;
assert localeSupplier != null;
return filteringByIgnoreNull(dataProvider, valueProvider,
(itemString, filterString) -> {
Locale locale = localeSupplier.get();
assert locale != null;
return predicate.test(itemString.toLowerCase(locale),
filterString.toLowerCase(locale));
});
}
/**
* Creates a comparator for the return type of the given
* {@link ValueProvider}, sorted in the direction specified by the given
* {@link SortDirection}.
*
* @param valueProvider
* the value provider to use
* @param sortDirection
* the sort direction to use
* @return the created comparator
*/
public static <V extends Comparable<? super V>, T> SerializableComparator<T> propertyComparator(
ValueProvider<T, V> valueProvider, SortDirection sortDirection) {
Objects.requireNonNull(valueProvider, "Value provider cannot be null");
Objects.requireNonNull(sortDirection, "Sort direction cannot be null");
Comparator<V> comparator = getNaturalSortComparator(sortDirection);
return (a, b) -> comparator.compare(valueProvider.apply(a),
valueProvider.apply(b));
}
/**
* Gets the natural order comparator for the type argument, or the natural
* order comparator reversed if the given sorting direction is
* {@link SortDirection#DESCENDING}.
*
* @param sortDirection
* the sort direction to use
* @return the natural comparator, with ordering defined by the given sort
* direction
*/
public static <V extends Comparable<? super V>> Comparator<V> getNaturalSortComparator(
SortDirection sortDirection) {
Comparator<V> comparator = Comparator.naturalOrder();
if (sortDirection == SortDirection.DESCENDING) {
comparator = comparator.reversed();
}
return comparator;
}
/**
* Creates a new predicate from the given predicate and value provider. This
* allows using a predicate of the value providers return type with objects
* of the value providers type.
*
* @param valueProvider
* the value provider to use
* @param valueFilter
* the original predicate
* @return the created predicate
*/
public static <T, V> SerializablePredicate<T> createValueProviderFilter(
ValueProvider<T, V> valueProvider,
SerializablePredicate<V> valueFilter) {
return item -> valueFilter.test(valueProvider.apply(item));
}
/**
* Creates a predicate that compares equality of the given required value to
* the value the given value provider obtains.
*
* @param valueProvider
* the value provider to use
* @param requiredValue
* the required value
* @return the created predicate
*/
public static <T, V> SerializablePredicate<T> createEqualsFilter(
ValueProvider<T, V> valueProvider, V requiredValue) {
Objects.requireNonNull(valueProvider, "Value provider cannot be null");
return item -> Objects.equals(valueProvider.apply(item), requiredValue);
}
}
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