com.cronutils.model.time.generator.EveryFieldValueGenerator.java Source code

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Here is the source code for com.cronutils.model.time.generator.EveryFieldValueGenerator.java

Source

package com.cronutils.model.time.generator;

import com.cronutils.model.field.CronField;
import com.cronutils.model.field.expression.Every;
import com.cronutils.model.field.expression.FieldExpression;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.Lists;
import org.joda.time.DateTime;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.List;

/*
 * Copyright 2015 jmrozanec
 * 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.
 */
class EveryFieldValueGenerator extends FieldValueGenerator {
    private static final Logger log = LoggerFactory.getLogger(EveryFieldValueGenerator.class);

    public EveryFieldValueGenerator(CronField cronField) {
        super(cronField);
        log.trace(String.format("processing \"%s\" at %s", cronField.getExpression().asString(), DateTime.now()));
    }

    @Override
    public int generateNextValue(int reference) throws NoSuchValueException {
        //intuition: for valid values, we have: offset+period*i
        if (reference >= cronField.getConstraints().getEndRange()) {
            throw new NoSuchValueException();
        }
        Every every = (Every) cronField.getExpression();
        int referenceWithoutOffset = reference - offset();
        int period = every.getPeriod().getValue();
        int remainder = referenceWithoutOffset % period;

        int next = reference + (period - remainder);
        if (next < cronField.getConstraints().getStartRange()) {
            return cronField.getConstraints().getStartRange();
        }
        if (next > cronField.getConstraints().getEndRange()) {
            throw new NoSuchValueException();
        }
        return next;
    }

    @Override
    public int generatePreviousValue(int reference) throws NoSuchValueException {
        Every every = (Every) cronField.getExpression();
        int period = every.getPeriod().getValue();
        int remainder = reference % period;
        if (remainder == 0) {
            return reference - period;
        } else {
            return reference - remainder;
        }
    }

    @Override
    protected List<Integer> generateCandidatesNotIncludingIntervalExtremes(int start, int end) {
        List<Integer> values = Lists.newArrayList();
        try {
            int reference = generateNextValue(start);
            while (reference < end) {
                values.add(reference);
                reference = generateNextValue(reference);
            }
        } catch (NoSuchValueException ignored) {
        } //we just skip, since we generate values until we get the exception
        return values;
    }

    @Override
    public boolean isMatch(int value) {
        Every every = (Every) cronField.getExpression();
        int start = cronField.getConstraints().getStartRange();
        return ((value - start) % every.getPeriod().getValue()) == 0;
    }

    @Override
    protected boolean matchesFieldExpressionClass(FieldExpression fieldExpression) {
        return fieldExpression instanceof Every;
    }

    @VisibleForTesting
    int offset() {
        return cronField.getConstraints().getStartRange();
    }
}