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.
-
-
Field Summary
Fields Modifier and Type Field Description private static int
EXPONENT_DENORMALISATION_CORR_LIMIT
private static double
EXPONENT_DENORMALISATION_FACTOR
private boolean
foundSign
Did we find a sign last time we checked?private static int
INFINITY_LENGTH
private static byte[]
INFINITY_LOWER
private static int
INFINITY_SHORTCUT_LENGTH
private static byte[]
INFINITY_UPPER
private byte[]
input
Array being parsedprivate static int
NOT_A_NUMBER_LENGTH
private static byte[]
NOT_A_NUMBER_LOWER
private static byte[]
NOT_A_NUMBER_UPPER
private static int
NUMBER_BASE
The underlying number base used in this class.private static double
NUMBER_BASE_DOUBLE
The underlying number base used in this class as a double value.private int
numberLength
Length of last parsed valueprivate int
offset
Current offset into input.
-
Constructor Summary
Constructors Constructor Description ByteParser(byte[] input)
Construct a parser.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private int
checkSign()
Find the sign for a number .private double
getBareInteger(int length)
Get the integer value starting at the current position.boolean
getBoolean()
boolean
getBoolean(int length)
byte[]
getBuffer()
double
getDouble()
Read in the buffer until a double is read.double
getDouble(int length)
float
getFloat()
float
getFloat(int length)
int
getInt()
int
getInt(int length)
long
getLong(int length)
int
getNumberLength()
int
getOffset()
Get the current offset.java.lang.String
getString(int length)
private boolean
isCaseInsensitiv(int length, int constantLength, byte[] lowerConstant, byte[] upperConstant)
void
setBuffer(byte[] buf)
Set the buffer for the parser.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.
-
-
-
Field Detail
-
EXPONENT_DENORMALISATION_CORR_LIMIT
private static final int EXPONENT_DENORMALISATION_CORR_LIMIT
- See Also:
- Constant Field Values
-
EXPONENT_DENORMALISATION_FACTOR
private static final double EXPONENT_DENORMALISATION_FACTOR
- See Also:
- Constant Field Values
-
INFINITY_LOWER
private static final byte[] INFINITY_LOWER
-
INFINITY_UPPER
private static final byte[] INFINITY_UPPER
-
INFINITY_LENGTH
private static final int INFINITY_LENGTH
-
INFINITY_SHORTCUT_LENGTH
private static final int INFINITY_SHORTCUT_LENGTH
- See Also:
- Constant Field Values
-
NOT_A_NUMBER_LOWER
private static final byte[] NOT_A_NUMBER_LOWER
-
NOT_A_NUMBER_UPPER
private static final byte[] NOT_A_NUMBER_UPPER
-
NOT_A_NUMBER_LENGTH
private static final int NOT_A_NUMBER_LENGTH
-
NUMBER_BASE
private static final int NUMBER_BASE
The underlying number base used in this class.- See Also:
- Constant Field Values
-
NUMBER_BASE_DOUBLE
private static final double NUMBER_BASE_DOUBLE
The underlying number base used in this class as a double value.- See Also:
- Constant Field Values
-
foundSign
private boolean foundSign
Did we find a sign last time we checked?
-
input
private byte[] input
Array being parsed
-
numberLength
private int numberLength
Length of last parsed value
-
offset
private int offset
Current offset into input.
-
-
Method Detail
-
checkSign
private int checkSign()
Find the sign for a number . This routine looks for a sign (+/-) at the current location and return +1/-1 if one is found, or +1 if not. The foundSign boolean is set if a sign is found and offset is incremented.
-
getBareInteger
private double getBareInteger(int length)
Get the integer value starting at the current position. This routine returns a double rather than an int/long to enable it to read very long integers (with reduced precision) such as 111111111111111111111111111111111111111111. Note that this routine does set numberLength.- Parameters:
length
- The maximum number of characters to use.
-
getBoolean
public boolean getBoolean() throws FormatException
- Returns:
- a boolean value from the beginning of the buffer.
- Throws:
FormatException
- if the double was in an unknown format
-
getBoolean
public boolean getBoolean(int length) throws FormatException
- Parameters:
length
- The maximum number of characters used to parse this boolean.- Returns:
- a boolean value from a specified region of the buffer
- Throws:
FormatException
- if the double was in an unknown format
-
getBuffer
public byte[] getBuffer()
- Returns:
- the buffer being used by the parser
-
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
- if the double was in an unknown format
-
getDouble
public double getDouble(int length) throws FormatException
- 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.- Returns:
- a parsed double from the buffer. Leading spaces are ignored.
- Throws:
FormatException
- if the double was in an unknown format
-
getFloat
public float getFloat() throws FormatException
- Returns:
- a floating point value from the buffer. (see getDouble(int())
- Throws:
FormatException
- if the float was in an unknown format
-
getFloat
public float getFloat(int length) throws FormatException
- Parameters:
length
- The maximum number of characters used to parse this float.- Returns:
- a floating point value in a region of the buffer
- Throws:
FormatException
- if the float was in an unknown format
-
getInt
public int getInt() throws FormatException
- Returns:
- an integer at the beginning of the buffer
- Throws:
FormatException
- if the integer was in an unknown format
-
getInt
public int getInt(int length) throws FormatException
- Parameters:
length
- The maximum number of characters used to parse this integer. @throws FormatException if the integer was in an unknown format- Returns:
- a region of the buffer to an integer
- Throws:
FormatException
- if the integer was in an unknown format
-
getLong
public long getLong(int length) throws FormatException
- Parameters:
length
- The maximum number of characters used to parse this long.- Returns:
- a long in a specified region of the buffer
- Throws:
FormatException
- if the long was in an unknown format
-
getNumberLength
public int getNumberLength()
- Returns:
- the number of characters used to parse the previous number (or the length of the previous String returned).
-
getOffset
public int getOffset()
Get the current offset.- Returns:
- The current offset within the buffer.
-
getString
public java.lang.String getString(int length)
- Parameters:
length
- The length of the string.- Returns:
- a string.
-
isCaseInsensitiv
private boolean isCaseInsensitiv(int length, int constantLength, byte[] lowerConstant, byte[] upperConstant)
-
setBuffer
public void setBuffer(byte[] buf)
Set the buffer for the parser.- Parameters:
buf
- buffer to set
-
setOffset
public void setOffset(int offset)
Set the offset into the array.- Parameters:
offset
- The desired offset from the beginning of the array.
-
skip
public void skip(int nBytes)
Skip bytes in the buffer.- Parameters:
nBytes
- number of bytes to skip
-
skipWhite
public int skipWhite(int length)
Skip white space. This routine skips with space in the input .- Parameters:
length
- The maximum number of characters to skip.- Returns:
- the number of character skipped. White space is defined as ' ', '\t', '\n' or '\r'
-
-