org.springframework.data.solr.core.query.Function.java Source code

Introduction

Here is the source code for org.springframework.data.solr.core.query.Function.java

Source

/*
 * Copyright 2012 - 2018 the original author or authors.
 *
 * 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
 *
 * https://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.springframework.data.solr.core.query;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import org.apache.commons.lang3.StringUtils;
import org.springframework.util.Assert;

/**
 * @author Christoph Strobl
 * @since 1.1
 */
public interface Function {

    /**
     * solr readable representation of function
     *
     * @return
     */
    String getOperation();

    /**
     * @return
     */
    Iterable<?> getArguments();

    /**
     * @return true if {@link #getArguments()} is not empty
     */
    boolean hasArguments();

    /**
     * Convert the Function to a Solr readable {@link String} in the given {@link Context}.
     *
     * @param context must not be {@literal null}.
     * @return never {@literal null}.
     * @since 4.1
     */
    default String toSolrFunction(Context context) {

        StringBuilder sb = new StringBuilder();

        sb.append("{!func}");
        sb.append(getOperation());
        sb.append('(');

        if (hasArguments()) {

            List<String> solrReadableArguments = new ArrayList<>();
            for (Object arg : getArguments()) {

                Assert.notNull(arg, "Unable to parse 'null' within function arguments.");
                solrReadableArguments.add(context.convert(arg));
            }
            sb.append(StringUtils.join(solrReadableArguments, ','));
        }
        sb.append(')');

        return sb.toString();
    }

    /**
     * Get the {@link Map} of already Solr readable (converted) arguments for this {@link Function} in the given
     * {@link Context}.
     *
     * @param context must not be {@literal null}.
     * @return never {@literal null}.
     * @since 4.1
     */
    default Map<String, String> getArgumentMap(Context context) {
        return Collections.emptyMap();
    }

    /**
     * The {@link Context} the {@link Function} is used in.
     * 
     * @since 4.1
     */
    interface Context {

        /**
         * Convert the given value into a Solr readable {@link String} argument.
         *
         * @param value must not be {@literal null}.
         * @return the Solr readable representation of the given value.
         */
        String convert(Object value);

        Target getTarget();

        /**
         * The actual context target.
         */
        enum Target {
            SORT, PROJECTION, QUERY
        }
    }

}