com.scudata.dw.compress.StringColumn 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.dw.compress;

import java.io.IOException;
import java.util.ArrayList;

import com.scudata.common.MessageManager;
import com.scudata.common.RQException;
import com.scudata.dw.BufferReader;
import com.scudata.resources.EngineMessage;

public class StringColumn extends Column {
	private static final int NULL = -1;
	
	// ???ݰ???洢??ÿ????Column.BLOCK_RECORD_COUNT????¼
	private ArrayList blockList = new ArrayList(1024);
	
	// ??????blockList???Ӧ???λ??, -1??ʾnull
	private ArrayList posList = new ArrayList(1024);
	private int lastRecordCount = Column.BLOCK_RECORD_COUNT; // ???һ??ļ?¼??
	private int nextPos = -1; // ??һ??д?뵽buffer?е?λ??
	
	// ?????¿?ʱʹ??buffer??buffer????ʱ????????1.5?????ȵ???buffer?????¼??д????????ʵ?ʵĴ?С???浽blockList??
	private char []buffer = new char[65536];
	
	// ׷??һ?е?????
	public void addData(Object data) {
		if (lastRecordCount == Column.BLOCK_RECORD_COUNT) {
			if (blockList.size() > 0) {
				// ???¼??д??????????СΪʵ?ʴ?С
				char []block = new char[nextPos];
				System.arraycopy(buffer, 0, block, 0, nextPos);
				blockList.set(blockList.size() - 1, block);
			}
			
			int []posBlock = new int[Column.BLOCK_RECORD_COUNT];
			blockList.add(buffer);
			posList.add(posBlock);
			lastRecordCount = 0;
			nextPos = 0;
		}
		
		if (data instanceof String) {
			String str = (String)data;
			int len = str.length();
			int free = buffer.length - nextPos;
			
			// ??????һ??Ļ??????ռ䲻????????????һ???Ļ?????
			if (free < len) {
				char []tmp = new char[buffer.length * 3 / 2];
				System.arraycopy(buffer, 0, tmp, 0, buffer.length);
				buffer = tmp;
				blockList.set(blockList.size() - 1, tmp);
			}
			
			str.getChars(0, len, buffer, nextPos);
			int []posBlock = posList.get(posList.size() - 1);
			posBlock[lastRecordCount++] = nextPos;
			nextPos += len;
		} else if (data == null) {
			int []posBlock = posList.get(posList.size() - 1);
			posBlock[lastRecordCount++] = NULL;
		} else {
			// ???쳣
			MessageManager mm = EngineMessage.get();
			throw new RQException(mm.getMessage("ds.colTypeDif"));
		}
	}
	
	// ȡ??row?е?????
	public Object getData(int row) {
		// row?кţ???1??ʼ????
		row--;
		int b = row / Column.BLOCK_RECORD_COUNT;
		int index = row % Column.BLOCK_RECORD_COUNT;
		
		int []posBlock = posList.get(b);
		int startPos = posBlock[index];
		if (startPos == NULL) {
			return null;
		}
		
		char []block = blockList.get(b);
		int endPos;
		
		// ?Ƿ????һ??
		if (b == blockList.size() - 1) {
			endPos = nextPos;
			for (int i = index + 1, end = lastRecordCount; i < end; ++i) {
				if (posBlock[i] != NULL) {
					endPos = posBlock[i];
					break;
				}
			}
		} else {
			endPos = block.length;
			for (int i = index + 1; i < Column.BLOCK_RECORD_COUNT; ++i) {
				if (posBlock[i] != NULL) {
					endPos = posBlock[i];
					break;
				}
			}
		}
		
		return new String(block, startPos, endPos - startPos);
	}
	
	public Column clone() {
		return new StringColumn();
	}
	
	public void appendData(BufferReader br) throws IOException {
		addData(br.readObject());
	}
}