lmdbjava/src/main/java/org/lmdbjava/MaskedFlag.java at gh-267 · lmdbjava/lmdbjava · GitHub

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* 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 org.lmdbjava;

import static java.util.Objects.requireNonNull;

import java.util.Objects;

import java.util.function.Predicate;

import java.util.stream.Stream;

/** Indicates an enum that can provide integers for each of its values. */

public interface MaskedFlag {

/**

* Obtains the integer value for this enum which can be included in a mask.

* @return the integer value for combination into a mask

int getMask();

/**

* Indicates if the flag must be propagated to the underlying C code of LMDB or not.

* @return the boolean value indicating the propagation

default boolean isPropagatedToLmdb() {

return true;

}

/**

* Fetch the integer mask for all presented flags.

* @param <M> flag type

* @param flags to mask (null or empty returns zero)

* @return the integer mask for use in C

@SafeVarargs

static <M extends MaskedFlag> int mask(final M... flags) {

return mask(false, flags);

}

/**

* Fetch the integer mask for all presented flags.

* @param <M> flag type

* @param flags to mask (null or empty returns zero)

* @return the integer mask for use in C

static <M extends MaskedFlag> int mask(final Stream<M> flags) {

return mask(false, flags);

}

/**

* Fetch the integer mask for the presented flags.

* @param <M> flag type

* @param onlyPropagatedToLmdb if to include only the flags which are also propagate to the C code

* or all of them

* @param flags to mask (null or empty returns zero)

* @return the integer mask for use in C

@SafeVarargs

static <M extends MaskedFlag> int mask(final boolean onlyPropagatedToLmdb, final M... flags) {

if (flags == null || flags.length == 0) {

return 0;

}

int result = 0;

for (final M flag : flags) {

if (flag == null) {

continue;

}

if (!onlyPropagatedToLmdb || flag.isPropagatedToLmdb()) {

result |= flag.getMask();

}

return result;

}

/**

* Fetch the integer mask for all presented flags.

* @param <M> flag type

* @param onlyPropagatedToLmdb if to include only the flags which are also propagate to the C code

* or all of them

* @param flags to mask

* @return the integer mask for use in C

static <M extends MaskedFlag> int mask(

final boolean onlyPropagatedToLmdb, final Stream<M> flags) {

final Predicate<M> filter = onlyPropagatedToLmdb ? MaskedFlag::isPropagatedToLmdb : f -> true;

return flags == null

? 0

: flags

.filter(Objects::nonNull)

.filter(filter)

.map(M::getMask)

.reduce(0, (f1, f2) -> f1 | f2);

}

/**

* Indicates whether the passed flag has the relevant masked flag high.

* @param flags to evaluate (usually produced by {@link #mask(org.lmdbjava.MaskedFlag...)}

* @param test the flag being sought (required)

* @return true if set.

static boolean isSet(final int flags, final MaskedFlag test) {

requireNonNull(test);

return (flags & test.getMask()) == test.getMask();

}

lmdbjava/src/main/java/org/lmdbjava/MaskedFlag.java at gh-267 · lmdbjava/lmdbjava · GitHub

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