org.hibernate.dialect.function.SQLFunctionTemplate.java Source code

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Here is the source code for org.hibernate.dialect.function.SQLFunctionTemplate.java

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.dialect.function;

import java.util.List;

import org.hibernate.QueryException;
import org.hibernate.engine.spi.Mapping;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.type.Type;

/**
 * Represents HQL functions that can have different representations in different SQL dialects where that
 * difference can be handled via a template/pattern.
 * <p/>
 * E.g. in HQL we can define function <code>concat(?1, ?2)</code> to concatenate two strings
 * p1 and p2.  Dialects would register different versions of this class *using the same name* (concat) but with
 * different templates or patterns; <code>(?1 || ?2)</code> for Oracle, <code>concat(?1, ?2)</code> for MySql,
 * <code>(?1 + ?2)</code> for MS SQL.  Each dialect will define a template as a string (exactly like above) marking function
 * parameters with '?' followed by parameter's index (first index is 1).
 *
 * @author <a href="mailto:alex@jboss.org">Alexey Loubyansky</a>
 */
public class SQLFunctionTemplate implements SQLFunction {
    private final Type type;
    private final TemplateRenderer renderer;
    private final boolean hasParenthesesIfNoArgs;

    /**
     * Constructs a SQLFunctionTemplate
     *
     * @param type The functions return type
     * @param template The function template
     */
    public SQLFunctionTemplate(Type type, String template) {
        this(type, template, true);
    }

    /**
     * Constructs a SQLFunctionTemplate
     *
     * @param type The functions return type
     * @param template The function template
     * @param hasParenthesesIfNoArgs If there are no arguments, are parentheses required?
     */
    public SQLFunctionTemplate(Type type, String template, boolean hasParenthesesIfNoArgs) {
        this.type = type;
        this.renderer = new TemplateRenderer(template);
        this.hasParenthesesIfNoArgs = hasParenthesesIfNoArgs;
    }

    @Override
    public String render(Type argumentType, List args, SessionFactoryImplementor factory) {
        return renderer.render(args, factory);
    }

    @Override
    public Type getReturnType(Type argumentType, Mapping mapping) throws QueryException {
        return type;
    }

    @Override
    public boolean hasArguments() {
        return renderer.getAnticipatedNumberOfArguments() > 0;
    }

    @Override
    public boolean hasParenthesesIfNoArguments() {
        return hasParenthesesIfNoArgs;
    }

    @Override
    public String toString() {
        return renderer.getTemplate();
    }
}