standardsqlfunction.java

一个Java持久层类库

//$Id: StandardSQLFunction.java 10774 2006-11-08 16:54:55Z [e-mail] $
package org.hibernate.dialect.function;

import java.util.List;

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

/**
 * Provides a standard implementation that supports the majority of the HQL
 * functions that are translated to SQL. The Dialect and its sub-classes use
 * this class to provide details required for processing of the associated
 * function.
 *
 * @author David Channon
 */
public class StandardSQLFunction implements SQLFunction {
	private final String name;
	private final Type type;

	/**
	 * Construct a standard SQL function definition with a variable return type;
	 * the actual return type will depend on the types to which the function
	 * is applied.
	 * <p/>
	 * Using this form, the return type is considered non-static and assumed
	 * to be the type of the first argument.
	 *
	 * @param name The name of the function.
	 */
	public StandardSQLFunction(String name) {
		this( name, null );
	}

	/**
	 * Construct a standard SQL function definition with a static return type.
	 *
	 * @param name The name of the function.
	 * @param type The static return type.
	 */
	public StandardSQLFunction(String name, Type type) {
		this.name = name;
		this.type = type;
	}

	/**
	 * Function name accessor
	 *
	 * @return The function name.
	 */
	public String getName() {
		return name;
	}

	/**
	 * Function static return type accessor.
	 *
	 * @return The static function return type; or null if return type is
	 * not static.
	 */
	public Type getType() {
		return type;
	}

	/**
	 * {@inheritDoc}
	 */
	public Type getReturnType(Type columnType, Mapping mapping) {
		// return the concrete type, or the underlying type if a concrete type
		// was not specified
		return type == null ? columnType : type;
	}

	/**
	 * {@inheritDoc}
	 */
	public boolean hasArguments() {
		return true;
	}

	/**
	 * {@inheritDoc}
	 */
	public boolean hasParenthesesIfNoArguments() {
		return true;
	}

	/**
	 * {@inheritDoc}
	 */
	public String render(List args, SessionFactoryImplementor factory) {
		StringBuffer buf = new StringBuffer();
		buf.append( name ).append( '(' );
		for ( int i = 0; i < args.size(); i++ ) {
			buf.append( args.get( i ) );
			if ( i < args.size() - 1 ) {
				buf.append( ", " );
			}
		}
		return buf.append( ')' ).toString();
	}

	public String toString() {
		return name;
	}
}