com.scudata.dm.ComputeStack Maven / Gradle / Ivy

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SPL(Structured Process Language) A programming language specially for structured data computing.
There is a newer version: 20240823
package com.scudata.dm;

import java.util.NoSuchElementException;

/**
 * ?????ջ
 * @author WangXiaoJun
 *
 */
public class ComputeStack {
	private LinkEntry stackHead; // ???ڼ????е????С???¼????ɶ?ջ
	private LinkEntry argHead; // eval?????õ??Ĳ?????ջ
	
	/**
	 * ?Ѳ???ѹջ
	 * @param value Sequence ???????ֵ
	 */
	public void pushArg(Sequence value) {
		if (value != null) {
			argHead = new LinkEntry(new Current(value), argHead);
		} else {
			argHead = new LinkEntry(null, argHead);
		}
	}

	/**
	 * ?Ѳ?????ջ
	 */
	public void popArg() {
		if (argHead != null) {
			argHead = argHead.getNext();
		} else {
			throw new NoSuchElementException();
		}
	}

	/**
	 * ȡ????"arg"??ֵ
	 * @return BaseSequence.Current
	 */
	public Current getArg() {
		if (argHead != null) {
			return argHead.getElement();
		} else {
			throw new NoSuchElementException();
		}
	}

	/**
	 * ??????ѹջ??A.(...), r.(...)
	 * @param obj IComputeItem
	 */
	public void push(IComputeItem obj) {
		stackHead = new LinkEntry(obj, stackHead);
	}

	// ȡ???еĵ?ǰԪ??ֵ
	public Object getCurrentValue(Sequence seq) {
		for (LinkEntry entry = stackHead; entry != null; entry = entry.getNext()) {
			IComputeItem item = entry.getElement();
			if (item.getCurrentSequence() == seq) {
				return item.getCurrent();
			}
		}

		if (seq.length() > 0) {
			return seq.get(1);
		} else {
			return null;
		}
	}

	public Current getSequenceCurrent(Sequence seq) {
		for (LinkEntry entry = stackHead; entry != null; entry = entry.getNext()) {
			IComputeItem item = entry.getElement();
			if (item.getCurrentSequence() == seq) {
				return (Current)item;
			}
		}

		return null;
	}

	// ???????еĵ?ǰ????
	public int getCurrentIndex(Sequence seq) {
		for (LinkEntry entry = stackHead; entry != null; entry = entry.getNext()) {
			IComputeItem item = entry.getElement();
			if (item.getCurrentSequence() == seq) {
				return item.getCurrentIndex();
			}
		}

		return 0;
	}

	/**
	 * ??ջ???Ķ????ջ
	 */
	public void pop() {
		if (stackHead != null) {
			stackHead.getElement().popStack();
			stackHead = stackHead.getNext();
		} else {
			throw new NoSuchElementException();
		}
	}

	/**
	 * ȡջ???Ķ???
	 * @return IComputeItem
	 */
	public IComputeItem getTopObject() {
		if (stackHead != null) {
			return stackHead.getElement();
		} else {
			throw new NoSuchElementException();
		}
	}

	/**
	 * ȡ??˵?????
	 * @return Sequence
	 */
	public Sequence getTopSequence() {
		for (LinkEntry entry = stackHead; entry != null; entry = entry.getNext()) {
			Sequence seq = entry.getElement().getCurrentSequence();
			if (seq != null) {
				return seq;
			}
		}
		
		// ????ִ?е?????
		throw new NoSuchElementException();
	}
	
	/**
	 * ȡ??˵????м??????
	 * @return Sequence
	 */
	public Current getTopCurrent() {
		for (LinkEntry entry = stackHead; entry != null; entry = entry.getNext()) {
			IComputeItem item = entry.getElement();
			if (item instanceof Current) {
				return (Current)item;
			}
		}
		
		// ????ִ?е?????
		throw new NoSuchElementException();
	}
	
	/**
	 * ?ж϶????Ƿ???ջ??
	 * @param obj IComputeItem
	 * @return boolean
	 */
	public boolean isInComputeStack(IComputeItem obj) {
		for (LinkEntry entry = stackHead; entry != null; entry = entry.getNext()) {
			if (entry.getElement() == obj) {
				return true;
			}
		}

		return false;
	}

	/**
	 * ???ض?ջ?Ƿ??
	 * @return boolean
	 */
	public boolean isStackEmpty() {
		return stackHead == null;
	}

	public LinkEntry getStackHeadEntry() {
		return stackHead;
	}

	/**
	 * ??ռ????ջ
	 */
	public void clearStackList() {
		stackHead = null;
	}

	/**
	 * ???arg??ջ
	 */
	public void clearArgStackList() {
		argHead = null;
	}

	public void reset() {
		stackHead = null;
		argHead = null;
	}
}