ei.ne.ke.cassandra.cql3.template.SelectStatementBuilder.java Source code

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Here is the source code for ei.ne.ke.cassandra.cql3.template.SelectStatementBuilder.java

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/*
 * Copyright 2013 EK3 Technologies, Inc.
 *
 * 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 ei.ne.ke.cassandra.cql3.template;

import java.util.Collection;

import org.apache.commons.lang.StringUtils;
import org.springframework.data.domain.Sort;
import org.springframework.data.domain.Sort.Order;

import com.google.common.base.Functions;
import com.google.common.base.Preconditions;
import com.google.common.collect.Collections2;
import com.google.common.collect.Lists;

/**
 *
 */
public class SelectStatementBuilder implements Preserving {

    private static final long VALUE_NOT_SET = -1;

    private Collection<Identifier> selection;
    private Identifier table;
    private Collection<Relation> relations;
    private Collection<Ordering> orderings;
    private long limit;
    private boolean allowFiltering;

    /**
     *
     *
     * @param selection
     */
    SelectStatementBuilder() {
        this.selection = Lists.newArrayList();
        this.table = null;
        this.relations = Lists.newArrayList();
        this.orderings = Lists.newArrayList();
        this.limit = VALUE_NOT_SET;
        this.allowFiltering = false;
    }

    /**
     * A short-hand for getting the count.
     * @return this builder.
     */
    public SelectStatementBuilder count() {
        selection.add(Identifier.COUNT);
        return this;
    }

    /**
     * A short-hand for selecting all columns.
     * @return this builder.
     */
    public SelectStatementBuilder all() {
        selection.add(Identifier.ALL);
        return this;
    }

    /**
     *
     *
     * @param value
     */
    public SelectStatementBuilder columns(String... columns) {
        if (columns != null) {
            for (String column : columns) {
                selection.add(new Identifier(column));
            }
        }
        return this;
    }

    /**
     *
     *
     * @param value
     * @return this builder.
     */
    public SelectStatementBuilder columns(Collection<String> columns) {
        if (columns != null) {
            for (String column : columns) {
                selection.add(new Identifier(column));
            }
        }
        return this;
    }

    /**
     *
     *
     * @param identifier
     * @return this builder.
     */
    public SelectStatementBuilder from(String identifier) {
        this.table = new Identifier(identifier);
        return this;
    }

    /**
     *
     *
     * @param identifier
     * @param comparator
     * @return this builder.
     */
    public SelectStatementBuilder where(String identifier, String comparator) {
        relations.add(new Relation(new Identifier(identifier), Comparator.getEnum(comparator)));
        return this;
    }

    /**
     * Adds a relation for each of the given column name with the given
     * comparator and a variable value.
     *
     * @param identifiers
     * @param comparator
     * @return this builder.
     */
    public SelectStatementBuilder where(Collection<String> identifiers, String comparator) {
        if (identifiers != null) {
            for (String identifier : identifiers) {
                relations.add(new Relation(new Identifier(identifier), Comparator.getEnum(comparator)));
            }
        }
        return this;
    }

    /**
     *
     *
     * @param identifier
     * @param comparator
     * @param value
     * @return this builder.
     */
    public SelectStatementBuilder where(String identifier, String comparator, String value) {
        relations.add(new Relation(new Identifier(identifier), Comparator.getEnum(comparator), new Term(value)));
        return this;
    }

    /**
     *
     *
     * @param identifier
     * @param strTerms
     * @return this builder.
     */
    public SelectStatementBuilder where(String identifier, Collection<String> ins) {
        Collection<Term> terms = Lists.newArrayListWithExpectedSize(ins.size());
        for (String in : ins) {
            terms.add(new Term(in));
        }
        relations.add(new In(new Identifier(identifier), terms));
        return this;
    }

    /**
     *
     *
     * @param ordering
     * @return this builder.
     */
    public SelectStatementBuilder orderBy(String ordering) {
        orderings.add(new Ordering(new Identifier(ordering)));
        return this;
    }

    /**
     *
     *
     * @param ordering
     * @param direction
     * @return this builder.
     */
    public SelectStatementBuilder orderBy(String ordering, String direction) {
        orderings.add(new Ordering(new Identifier(ordering), new Identifier(direction)));
        return this;
    }

    /**
     *
     *
     * @param sort
     * @return this builder.
     */
    public SelectStatementBuilder orderBy(Sort sort) {
        if (sort != null) {
            for (Order order : sort) {
                orderings.add(new Ordering(new Identifier(order.getProperty()),
                        new Identifier(order.getDirection().toString())));
            }
        }
        return this;
    }

    /**
     *
     *
     * @param value
     * @return this builder.
     */
    public SelectStatementBuilder limit(long value) {
        limit = value;
        return this;
    }

    /**
     *
     *
     * @return this builder.
     */
    public SelectStatementBuilder allowFiltering(boolean value) {
        allowFiltering = value;
        return this;
    }

    /**
     *
     *
     * @return this builder.
     */
    @Override
    public String build() {
        Preconditions.checkNotNull(selection);
        Preconditions.checkArgument(selection.size() > 0, "You must select at least one column");
        Preconditions.checkNotNull(table, "You must set the name of a table");
        StringBuilder sb = new StringBuilder();
        sb.append("SELECT ");
        sb.append(StringUtils.join(selection, ", "));
        sb.append(" FROM ");
        sb.append(table);
        if (relations.size() > 0) {
            sb.append(" WHERE ");
            sb.append(StringUtils.join(Collections2.transform(relations, Functions.toStringFunction()), " AND "));
        }
        if (orderings.size() > 0) {
            sb.append(" ORDER BY ");
            sb.append(StringUtils.join(Collections2.transform(orderings, Functions.toStringFunction()), ", "));
        }
        if (limit > VALUE_NOT_SET) {
            sb.append(" LIMIT ");
            sb.append(limit);
        }
        if (allowFiltering) {
            sb.append(" ALLOW FILTERING");
        }
        sb.append(";");
        return sb.toString();
    }

}