asia.redact.bracket.properties.line

Class LineScanner

java.lang.Object

java.io.Reader

asia.redact.bracket.properties.line.LineScanner

All Implemented Interfaces:

Closeable, AutoCloseable, Readable

public class LineScanner
extends Reader

 
 This is an augmented version of java.io.BufferedReader from the Apache Harmony implementation. Source:
 http://www.java2s.com/Open-Source/Java-Document/Apache-Harmony-Java-SE/java-package/java/io/BufferedReader.java.htm
 
 Scan a properties file conforming to the description at
 http://download.oracle.com/javase/6/docs/api/java/util/Properties.html#load(java.io.Reader)
 into tokens.
 
 The idea here is that as we read lines, we return not just the line text but a Line object which
 has knowledge of its internal parts, such as if the line has a key, etc. This allows for streaming
 parsing and hopefully can handle very large properties files.
 
 
 There is one additional extension: a comment line which starts with #;; is treated 
 as transient (not read in). This is used later to generate a transient header and footer
 
 This class tracks the absolute offset of lines in the file, and the line() method works like
 readLine() but returns extra info in addition to the String. The Line object returned
 by "line()" provides tokenization methods and also an absolute index of the line into the file.
 PropertiesParser2 "pulls" the lines using this BufferedReader implementation.
 
 Note: because this is a Reader, you must call close() on it when done.
 
 

See Also:

Line

Field Summary

Fields

Modifier and Type	Field and Description
private char[]	buf The characters that can be read and refilled in bulk.
private LineEnding	delimiter
private int	delimiterLength
private int	end
private Reader	in
private int	mark
private int	markLimit
private int	pos
private long	totalRead

Fields inherited from class java.io.Reader

lock

Constructor Summary

Constructors

Constructor and Description
LineScanner(Reader in) Constructs a new BufferedReader on the Reader in.
LineScanner(Reader in, int size) Constructs a new BufferedReader on the Reader in.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes this reader.
private int	fillBuf() Populates the buffer with data.
LineEnding	getDelimiter()
long	getTotalRead()
private boolean	isClosed() Indicates whether or not this reader is closed.
Line	line()
void	mark(int markLimit) Sets a mark position in this reader.
boolean	markSupported() Indicates whether this reader supports the mark() and reset() methods.
int	read() Reads a single character from this reader and returns it with the two higher-order bytes set to 0.
int	read(char[] buffer, int offset, int length) Reads at most length characters from this reader and stores them at offset in the character array buffer.
String	readLine() Returns the next line of text available from this reader.
boolean	ready() Indicates whether this reader is ready to be read without blocking.
void	reset() Resets this reader's position to the last mark() location.
long	skip(long amount) Skips amount characters in this reader.

Methods inherited from class java.io.Reader

read, read

Methods inherited from class java.lang.Object

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

Field Detail

in

private final Reader in

buf

private char[] buf

The characters that can be read and refilled in bulk. We maintain three indices into this buffer:

     { X X X X X X X X X X X X - - }
           ^     ^             ^
           |     |             |
         mark   pos           end

Pos points to the next readable character. End is one greater than the last readable character. When pos == end, the buffer is empty and must be filled before characters can be read.

Mark is the value pos will be set to on calls to reset(). Its value is in the range [0...pos]. If the mark is -1, the buffer cannot be reset.

MarkLimit limits the distance between the mark and the pos. When this limit is exceeded, reset() is permitted (but not required) to throw an exception. For shorter distances, reset() shall not throw (unless the reader is closed).

pos

private int pos

end

private int end

mark

private int mark

markLimit

private int markLimit

totalRead

private long totalRead

delimiterLength

private int delimiterLength

delimiter

private LineEnding delimiter

Constructor Detail

LineScanner

public LineScanner(Reader in)

Constructs a new BufferedReader on the Reader in. The buffer gets the default size (8 KB).

Parameters:

in - the Reader that is buffered.

LineScanner

public LineScanner(Reader in,
           int size)

Constructs a new BufferedReader on the Reader in. The buffer size is specified by the parameter size.

Parameters:

in - the Reader that is buffered.

size - the size of the buffer to allocate.

Throws:

IllegalArgumentException - if size <= 0.

Method Detail

close

public void close()
           throws IOException

Closes this reader. This implementation closes the buffered source reader and releases the buffer. Nothing is done if this reader has already been closed.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in class Reader

Throws:

IOException - if an error occurs while closing this reader.

fillBuf

private int fillBuf()
             throws IOException

Populates the buffer with data. It is an error to call this method when the buffer still contains data; ie. if pos < end.

Returns:

the number of bytes read into the buffer, or -1 if the end of the source stream has been reached.

Throws:

IOException

isClosed

private boolean isClosed()

Indicates whether or not this reader is closed.

Returns:

true if this reader is closed, false otherwise.

mark

public void mark(int markLimit)
          throws IOException

Sets a mark position in this reader. The parameter markLimit indicates how many characters can be read before the mark is invalidated. Calling reset() will reposition the reader back to the marked position if markLimit has not been surpassed.

Overrides:

mark in class Reader

Parameters:

markLimit - the number of characters that can be read before the mark is invalidated.

Throws:

IllegalArgumentException - if markLimit < 0.

IOException - if an error occurs while setting a mark in this reader.

See Also:

markSupported(), reset()

markSupported

public boolean markSupported()

Indicates whether this reader supports the mark() and reset() methods. This implementation returns true.

Overrides:

markSupported in class Reader

Returns:

true for BufferedReader.

See Also:

mark(int), reset()

read

public int read()
         throws IOException

Reads a single character from this reader and returns it with the two higher-order bytes set to 0. If possible, BufferedReader returns a character from the buffer. If there are no characters available in the buffer, it fills the buffer and then returns a character. It returns -1 if there are no more characters in the source reader.

Overrides:

read in class Reader

Returns:

the character read or -1 if the end of the source reader has been reached.

Throws:

IOException - if this reader is closed or some other I/O error occurs.

read

public int read(char[] buffer,
       int offset,
       int length)
         throws IOException

Reads at most length characters from this reader and stores them at offset in the character array buffer. Returns the number of characters actually read or -1 if the end of the source reader has been reached. If all the buffered characters have been used, a mark has not been set and the requested number of characters is larger than this readers buffer size, BufferedReader bypasses the buffer and simply places the results directly into buffer.

Specified by:

read in class Reader

Parameters:

buffer - the character array to store the characters read.

offset - the initial position in buffer to store the bytes read from this reader.

length - the maximum number of characters to read, must be non-negative.

Returns:

number of characters read or -1 if the end of the source reader has been reached.

Throws:

IndexOutOfBoundsException - if offset < 0 or length < 0, or if offset + length is greater than the size of buffer.

IOException - if this reader is closed or some other I/O error occurs.

line

public Line line()

readLine

public String readLine()
                throws IOException

Returns the next line of text available from this reader. A line is represented by zero or more characters followed by '\n', '\r', "\r\n" or the end of the reader. The string does not include the newline sequence.

Returns:

the contents of the line or null if no characters were read before the end of the reader has been reached.

Throws:

IOException - if this reader is closed or some other I/O error occurs.

ready

public boolean ready()
              throws IOException

Indicates whether this reader is ready to be read without blocking.

Overrides:

ready in class Reader

Returns:

true if this reader will not block when read is called, false if unknown or blocking will occur.

Throws:

IOException - if this reader is closed or some other I/O error occurs.

See Also:

read(), read(char[], int, int), readLine()

reset

public void reset()
           throws IOException

Resets this reader's position to the last mark() location. Invocations of read() and skip() will occur from this new location.

Overrides:

reset in class Reader

Throws:

IOException - if this reader is closed or no mark has been set.

See Also:

mark(int), markSupported()

skip

public long skip(long amount)
          throws IOException

Skips amount characters in this reader. Subsequent read()s will not return these characters unless reset() is used. Skipping characters may invalidate a mark if markLimit is surpassed.

Overrides:

skip in class Reader

Parameters:

amount - the maximum number of characters to skip.

Returns:

the number of characters actually skipped.

Throws:

IllegalArgumentException - if amount < 0.

IOException - if this reader is closed or some other I/O error occurs.

See Also:

mark(int), markSupported(), reset()

getTotalRead

public long getTotalRead()

getDelimiter

public LineEnding getDelimiter()