nom.tam.util
Class ByteParser

java.lang.Object
  nom.tam.util.ByteParser

public class ByteParser
extends java.lang.Object

This class provides routines for efficient parsing of data stored in a byte array. This routine is optimized (in theory at least!) for efficiency rather than accuracy. The values read in for doubles or floats may differ in the last bit or so from the standard input utilities, especially in the case where a float is specified as a very long string of digits (substantially longer than the precision of the type).

The get methods generally are available with or without a length parameter specified. When a length parameter is specified only the bytes with the specified range from the current offset will be search for the number. If no length is specified, the entire buffer from the current offset will be searched.

The getString method returns a string with leading and trailing white space left intact. For all other get calls, leading white space is ignored. If fillFields is set, then the get methods check that only white space follows valid data and a FormatException is thrown if that is not the case. If fillFields is not set and valid data is found, then the methods return having read as much as possible. E.g., for the sequence "T123.258E13", a getBoolean, getInteger and getFloat call would return true, 123, and 2.58e12 when called in succession.

Constructor Summary

ByteParser(byte[] input)
Construct a parser.

Method Summary

boolean	getBoolean() Get a boolean value from the beginning of the buffer
boolean	getBoolean(int length) Get a boolean value from a specified region of the buffer
byte[]	getBuffer() Get the buffer being used by the parser
double	getDouble() Read in the buffer until a double is read.
double	getDouble(int length) Look for a double in the buffer.
float	getFloat() Get a floating point value from the buffer.
float	getFloat(int length) Get a floating point value in a region of the buffer
int	getInt() Look for an integer at the beginning of the buffer
int	getInt(int length) Convert a region of the buffer to an integer
long	getLong(int length) Look for a long in a specified region of the buffer
int	getNumberLength() Get the number of characters used to parse the previous number (or the length of the previous String returned).
int	getOffset() Get the current offset
java.lang.String	getString(int length) Get a string
void	setBuffer(byte[] buf) Set the buffer for the parser
void	setFillFields(boolean flag) Do we require a field to completely fill up the specified length (with optional leading and trailing white space.
void	setOffset(int offset) Set the offset into the array.
void	skip(int nBytes) Skip bytes in the buffer
int	skipWhite(int length) Skip white space.

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteParser

public ByteParser(byte[] input)

Construct a parser.

Parameters:

input - The byte array to be parsed. Note that the array can be re-used by refilling its contents and resetting the offset.

Method Detail

setBuffer

public void setBuffer(byte[] buf)

Set the buffer for the parser

getBuffer

public byte[] getBuffer()

Get the buffer being used by the parser

setOffset

public void setOffset(int offset)

Set the offset into the array.

Parameters:

offset - The desired offset from the beginning of the array.

setFillFields

public void setFillFields(boolean flag)

Do we require a field to completely fill up the specified length (with optional leading and trailing white space.

Parameters:

flag - Is filling required?

getOffset

public int getOffset()

Get the current offset

Returns:

The current offset within the buffer.

getNumberLength

public int getNumberLength()

Get the number of characters used to parse the previous number (or the length of the previous String returned).

getDouble

public double getDouble()
                 throws FormatException

Read in the buffer until a double is read. This will read the entire buffer if fillFields is set.

Returns:

The value found.

Throws:

FormatException

getDouble

public double getDouble(int length)
                 throws FormatException

Look for a double in the buffer. Leading spaces are ignored.

Parameters:

length - The maximum number of characters used to parse this number. If fillFields is specified then exactly only whitespace may follow a valid double value.

Throws:

FormatException

getFloat

public float getFloat()
               throws FormatException

Get a floating point value from the buffer. (see getDouble(int())

Throws:

FormatException

getFloat

public float getFloat(int length)
               throws FormatException

Get a floating point value in a region of the buffer

Throws:

FormatException

getInt

public int getInt(int length)
           throws FormatException

Convert a region of the buffer to an integer

Throws:

FormatException

getInt

public int getInt()
           throws FormatException

Look for an integer at the beginning of the buffer

Throws:

FormatException

getLong

public long getLong(int length)
             throws FormatException

Look for a long in a specified region of the buffer

Throws:

FormatException

getString

public java.lang.String getString(int length)

Get a string

Parameters:

length - The length of the string.

getBoolean

public boolean getBoolean()
                   throws FormatException

Get a boolean value from the beginning of the buffer

Throws:

FormatException

getBoolean

public boolean getBoolean(int length)
                   throws FormatException

Get a boolean value from a specified region of the buffer

Throws:

FormatException

skip

public void skip(int nBytes)

Skip bytes in the buffer

skipWhite

public int skipWhite(int length)

Skip white space. This routine skips with space in the input and returns the number of character skipped. White space is defined as ' ', '\t', '\n' or '\r'

Parameters:

length - The maximum number of characters to skip.