Interval.java

package jef.database.jsqlparser.expression;

import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;

import jef.database.jsqlparser.visitor.Expression;
import jef.database.jsqlparser.visitor.ExpressionType;
import jef.database.jsqlparser.visitor.ExpressionVisitor;
import jef.database.jsqlparser.visitor.SqlValue;
import jef.database.query.SqlExpression;

import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.StringUtils;

/**
 * 这个是专门为了解析MYSQL日期时间操作中的INTERVAL关键字的
 * @author jiyi
 *
 */
public class Interval implements Expression,SqlValue{
	private String unit;
	private Expression value;
	private static final String[] MYSQL_ALL_DATEUNIT={"microsecond",
		"second","minute","hour","day","week","month","quarter","year",
		"second_microsecond", 
		"minute_microsecond",
		"minute_second",
		"hour_microsecond",
		"hour_second",
		"hour_minute",
		"day_microsecond",
		"day_second",
		"day_minute",
		"day_hour",
		"year_month"};
		
	private static final Map<String,String> alias=new HashMap<String,String>();
	
	static{
		alias.put("years", "year");
		alias.put("months", "month");
		alias.put("weeks", "week");
		alias.put("days", "day");
		alias.put("hours", "hour");
		alias.put("minutes", "minute");
		alias.put("seconds", "second");
		alias.put("y", "year");
		alias.put("m", "month");
		alias.put("d", "day");
		alias.put("one", "1");
	}
	
	public Interval(){}
	
	/**
	 * postgres模式下，没有value，value和unit都被引号变为常量
	 * @return
	 */
	public boolean isPostgreMode(){
		return value==null && unit.charAt(0)=='\'';
	}
	
	public boolean isMySQLMode(){
		return ArrayUtils.contains(MYSQL_ALL_DATEUNIT, unit.toLowerCase());
	}
	
	public boolean toMySqlMode(){
		if(isPostgreMode()){
			unit=StringUtils.substringBetween(unit, "'", "'");
			int space=unit.indexOf(' ');
			if(space>-1){
				value=new SqlExpression(unit.substring(0,space));
				String u=unit.substring(space+1);
				String fixed=alias.get(u.toLowerCase());
				unit=fixed==null?u:fixed;
			}
			return true;
		}else{
			return isMySQLMode();
		}
	}
	
	public boolean toPostgresMode(){
		if(isMySQLMode()){
			unit="'"+value.toString()+" "+unit+"'";
			value=null;
			return true;
		}else{
			return isPostgreMode();
		}
	}
	
	
	
	public Interval(String valueAndUnit){
		this.unit=valueAndUnit;
	}
	
	public Interval(Expression value,String unit){
		this.value=value;
		this.unit=unit;
	}
	
	public void accept(ExpressionVisitor expressionVisitor) {
		expressionVisitor.visit(this);
	}
	
	@Override
	public String toString() {
		StringBuilder sb=new StringBuilder(64);
		appendTo(sb);
		return sb.toString();
	}
	
	public void appendTo(StringBuilder sb) {
		sb.append("INTERVAL ");
		if(value!=null){
			value.appendTo(sb);
			sb.append(' ');
		}
		sb.append(unit);
	}
	
	

	public String getUnit() {
		return unit;
	}

	public Expression getValue() {
		return value;
	}
	
	/**
MICROSECOND MICROSECONDS  毫秒
SECOND SECONDS            秒
MINUTE MINUTES            分
HOUR HOURS                时
DAY DAYS                  天
WEEK WEEKS                周
MONTH MONTHS              月
QUARTER QUARTERS          季
YEAR YEARS                年
SECOND_MICROSECOND 'SECONDS.MICROSECONDS' 
MINUTE_MICROSECOND 'MINUTES:SECONDS.MICROSECONDS' 
MINUTE_SECOND 'MINUTES:SECONDS' 
HOUR_MICROSECOND 'HOURS:MINUTES:SECONDS.MICROSECONDS' 
HOUR_SECOND 'HOURS:MINUTES:SECONDS' 
HOUR_MINUTE 'HOURS:MINUTES' 
DAY_MICROSECOND 'DAYS HOURS:MINUTES:SECONDS.MICROSECONDS' 
DAY_SECOND 'DAYS HOURS:MINUTES:SECONDS' 
DAY_MINUTE 'DAYS HOURS:MINUTES' 
DAY_HOUR 'DAYS HOURS' 
YEAR_MONTH 'YEARS-MONTHS' 

	 * @return
	 */
	public long toMills(){
		return 0;
	}

	public ExpressionType getType() {
		return ExpressionType.value;
	}

	public Object formatNumber(BigDecimal negate) {
		return negate.longValue();
	}
}