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package bjc.utils.ioutils;
import java.io.LineNumberReader;
import java.io.Reader;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Scanner;
import java.util.function.Consumer;
import java.util.regex.Pattern;
/**
* Implements reading numbered blocks from a source.
*
* A block is a series of characters, separated by some regular expression.
*
* NOTE: The EOF marker is always treated as a delimiter. You are expected to
* handle blocks that may be shorter than you expect.
*
* @author EVE
*
*/
public class BlockReader implements AutoCloseable, Iterator<Block> {
/*
* I/O source for blocks.
*/
private LineNumberReader lnReader;
private Scanner blockReader;
/*
* The current block.
*/
private Block currBlock;
private int blockNo;
/**
* Create a new block reader.
*
* @param blockDelim
* The pattern that separates blocks. Note that the end
* of file is always considered to end a block.
*
* @param source
* The source to read blocks from.
*/
public BlockReader(String blockDelim, Reader source) {
lnReader = new LineNumberReader(source);
blockReader = new Scanner(lnReader);
String pattern = String.format("(?:%s)|\\Z", blockDelim);
Pattern pt = Pattern.compile(pattern, Pattern.MULTILINE);
blockReader.useDelimiter(pt);
}
/**
* Check if this reader has an available block.
*
* @return Whether or not another block is available.
*/
public boolean hasNextBlock() {
return blockReader.hasNext();
}
/**
* Get the current block.
*
* @return The current block, or null if there is no current block.
*/
public Block getBlock() {
return currBlock;
}
/**
* Move to the next block.
*
* @return Whether or not the next block was successfully read.
*/
public boolean nextBlock() {
try {
int blockStartLine = lnReader.getLineNumber();
String blockContents = blockReader.next();
int blockEndLine = lnReader.getLineNumber();
blockNo += 1;
currBlock = new Block(blockNo, blockContents, blockStartLine, blockEndLine);
return true;
} catch (NoSuchElementException nseex) {
return false;
}
}
/**
* Execute an action for each remaining block.
*
* @param action
* The action to execute for each block
*/
public void forEachBlock(Consumer<Block> action) {
while (hasNextBlock()) {
nextBlock();
action.accept(currBlock);
}
}
/**
* Retrieve the number of blocks that have been read so far.
*
* @return The number of blocks read so far.
*/
public int getBlockCount() {
return blockNo;
}
@Override
public void close() throws Exception {
blockReader.close();
lnReader.close();
}
/**
* Set the delimiter used to separate blocks.
*
* @param delim
* The delimiter used to separate blocks.
*/
public void setDelimiter(String delim) {
blockReader.useDelimiter(delim);
}
/*
* Iterator implementation.
*/
@Override
public boolean hasNext() {
return blockReader.hasNext();
}
@Override
public Block next() {
nextBlock();
return getBlock();
}
}
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