Module com.github.marschall.lineparser

Package com.github.marschall.lineparser

Class LineParser

java.lang.Object

com.github.marschall.lineparser.LineParser

public final class LineParser
extends Object

Parses a file into multiple lines.

Intended for cases where:

• the start position in the file of a line is required
• the length in bytes of a line is required
• only a few character of every line is required

Offers a fast paths for:

• single byte character sets
• ISO 8859-1 compatible character sets

They can be combined for maximum performance.

Algorithm

The following algorithm is used to parse files:

1. map the file into memory
2. encode CR, LF and CR LF to bytes using the give character set
3. while not done
   1. scan the file byte by byte for cr of lf
   2. create a line object and invoke the callback
4. unmap the file from memory

If the file is larger can 2GB then it is mapped into memory multiple times. This has to be done because Java does not support file mappings larger than 2GB.

Unmapping the file from memory is controversial and can only be done using semi-official APIs. The alternative would be to rely on finalization to close file handles.

This class is thread safe.

See Also:

Line

Constructor Summary

Constructors

Constructor	Description
LineParser()

Method Summary

Modifier and Type	Method	Description
void	forEach(Path path, Charset cs, Consumer<Line> lineCallback)	Internal iterator over every line in a file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LineParser

public LineParser()

Method Detail

forEach

public void forEach(Path path,
                    Charset cs,
                    Consumer<Line> lineCallback)
             throws IOException

Internal iterator over every line in a file.

This method is thread safe.

Parameters:

path - the file to parse

cs - the character set to use

lineCallback - callback executed for every line

Throws:

IOException - if an exception happens when reading

UnmapFailedException - if unampping fails, this can happen on non OpenJDK JREs or JREs that are newer than expected or security managers