com.scudata.dm.cursor.SinglepathCursor Maven / Gradle / Ivy

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SPL(Structured Process Language) A programming language specially for structured data computing.

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package com.scudata.dm.cursor;

import com.scudata.dm.Context;
import com.scudata.dm.Sequence;

/**
 * ???ڰѶ?·?α??ɵ?·?α?
 * ??װ??cs.groups???????㲻???ٲ??ö??߳?????
 * @author RunQian
 *
 */
public class SinglepathCursor extends ICursor {
	private ICursor cursor; // ??·?α?

	public SinglepathCursor(ICursor cursor) {
		this.cursor = cursor;
		setDataStruct(cursor.getDataStruct());
	}
	
	// ???м???ʱ??Ҫ?ı???????
	// ?̳???????õ??˱???ʽ????Ҫ?????????????½???????ʽ
	public void resetContext(Context ctx) {
		if (this.ctx != ctx) {
			cursor.resetContext(ctx);
			super.resetContext(ctx);
		}
	}

	/**
	 * ??ȡָ???????????ݷ???
	 * @param n ????
	 * @return Sequence
	 */
	protected Sequence get(int n) {
		return cursor.fetch(n);
	}

	/**
	 * ????ָ????????????
	 * @param n ????
	 * @return long ʵ????????????
	 */
	protected long skipOver(long n) {
		return cursor.skip();
	}

	/**
	 * ?ر??α?
	 */
	public synchronized void close() {
		super.close();
		cursor.close();
	}
	
	/**
	 * ?????α?
	 * @return ?????Ƿ?ɹ???true???α???Դ?ͷ????ȡ????false???????Դ?ͷ????ȡ??
	 */
	public boolean reset() {
		close();
		return cursor.reset();
	}
}