net.named_data.jndn.encoding

Class BinaryXmlDecoder

java.lang.Object

net.named_data.jndn.encoding.BinaryXmlDecoder

public class BinaryXmlDecoder
extends Object

A BinaryXmlDecoder has methods to decode an input according to Binary XML.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	BinaryXmlDecoder.TypeAndValue

Constructor Summary

Constructors

Constructor and Description
BinaryXmlDecoder(ByteBuffer input) Create a new BinaryXmlDecoder to decode the input.

Method Summary

Methods

Modifier and Type	Method and Description
BinaryXmlDecoder.TypeAndValue	decodeTypeAndValue() Decode the header's type and value from the input starting at its position.
int	getOffset() Get the current position of the input, used for the next read.
boolean	peekDTag(int expectedTag) Decode the header from the input starting at its position, and if it is a DTAG where the value is the expectedTag, then set return true.
ByteBuffer	readBinaryDTagElement(int expectedTag) Decode the header from the input starting its position, expecting the type to be DTAG and the value to be expectedTag.
ByteBuffer	readBinaryDTagElement(int expectedTag, boolean allowNull) Decode the header from the input starting its position, expecting the type to be DTAG and the value to be expectedTag.
void	readElementClose() Read one byte from the input starting at its position, expecting it to be the element close.
void	readElementStartDTag(int expectedTag) Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag.
ByteBuffer	readOptionalBinaryDTagElement(int expectedTag) Peek at the next element and if it is the expectedTag, call readBinaryDTagElement.
ByteBuffer	readOptionalBinaryDTagElement(int expectedTag, boolean allowNull) Peek at the next element and if it is the expectedTag, call readBinaryDTagElement.
double	readOptionalTimeMillisecondsDTagElement(int expectedTag) Peek at the next element, and if it has the expectedTag then call readTimeMillisecondsDTagElement.
ByteBuffer	readOptionalUDataDTagElement(int expectedTag) Peek at the next element and if it is the expectedTag, call readUDataDTagElement.
int	readOptionalUnsignedIntegerDTagElement(int expectedTag) Peek at the next element, and if it has the expectedTag then call readUnsignedIntegerDTagElement.
double	readTimeMillisecondsDTagElement(int expectedTag) Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag.
ByteBuffer	readUDataDTagElement(int expectedTag) Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag.
int	readUnsignedIntegerDTagElement(int expectedTag) Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag.
void	seek(int position) Set the position of the input, used for the next read.
double	unsignedBigEndianToDouble(ByteBuffer bytes) Interpret the bytes as an unsigned big endian integer and convert to a double.

Methods inherited from class java.lang.Object

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

Constructor Detail

BinaryXmlDecoder

public BinaryXmlDecoder(ByteBuffer input)

Create a new BinaryXmlDecoder to decode the input.

Parameters:

input - The input ByteBuffer whose position and limit are set to the desired bytes to decode. This calls input.duplicate(), but does not copy the underlying buffer whose contents must remain valid during the life of this object.

Method Detail

decodeTypeAndValue

public BinaryXmlDecoder.TypeAndValue decodeTypeAndValue()
                                                 throws EncodingException

Decode the header's type and value from the input starting at its position. Update the input's position.

Returns:

a TypeAndValue with the header's type and value

Throws:

EncodingException - For invalid encoding including if the first head octet is zero.

readElementStartDTag

public final void readElementStartDTag(int expectedTag)
                                throws EncodingException

Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag. Update the input's position.

Parameters:

expectedTag - The expected value for DTAG.

Throws:

EncodingException - For invalid encoding including if did not get the expected DTAG.

readElementClose

public final void readElementClose()
                            throws EncodingException

Read one byte from the input starting at its position, expecting it to be the element close. Update the input's position.

Throws:

EncodingException - For invalid encoding including if did not get the expected element close.

peekDTag

public final boolean peekDTag(int expectedTag)
                       throws EncodingException

Decode the header from the input starting at its position, and if it is a DTAG where the value is the expectedTag, then set return true. Do not update the input's position.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

True if the tag is the expected tag, otherwise false.

Throws:

EncodingException - For invalid encoding including if did not get the expected DTAG.

readBinaryDTagElement

public final ByteBuffer readBinaryDTagElement(int expectedTag,
                               boolean allowNull)
                                       throws EncodingException

Decode the header from the input starting its position, expecting the type to be DTAG and the value to be expectedTag. Then read one item of any type (presumably BLOB, UDATA, TAG or ATTR) and return a ByteBuffer. However, if allowNull is true, then the item may be absent. Finally, read the element close. Update the input's position.

Parameters:

expectedTag - The expected value for DTAG.

allowNull - True if the binary item may be missing.

Returns:

a ByteBuffer which is a slice on the data inside the input buffer. However, if allowNull is true and the binary data item is absent, then return null.

Throws:

EncodingException - For invalid encoding including if did not get the expected DTAG.

readBinaryDTagElement

public final ByteBuffer readBinaryDTagElement(int expectedTag)
                                       throws EncodingException

Decode the header from the input starting its position, expecting the type to be DTAG and the value to be expectedTag. Then read one item of any type (presumably BLOB, UDATA, TAG or ATTR) and return a ByteBuffer. Finally, read the element close. Update the input's position.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

a ByteBuffer which is a slice on the data inside the input buffer.

Throws:

EncodingException - For invalid encoding including if did not get the expected DTAG.

readOptionalBinaryDTagElement

public final ByteBuffer readOptionalBinaryDTagElement(int expectedTag,
                                       boolean allowNull)
                                               throws EncodingException

Peek at the next element and if it is the expectedTag, call readBinaryDTagElement. Otherwise, return null.

Parameters:

expectedTag - The expected value for DTAG.

allowNull - True if the binary item may be missing.

Returns:

a ByteBuffer which is a slice on the data inside the input buffer. However, if the next element is not the expectedTag, or allowNull is true and the binary data item is absent, then return null.

Throws:

EncodingException - For invalid encoding.

readOptionalBinaryDTagElement

public final ByteBuffer readOptionalBinaryDTagElement(int expectedTag)
                                               throws EncodingException

Peek at the next element and if it is the expectedTag, call readBinaryDTagElement. Otherwise, return null.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

a ByteBuffer which is a slice on the data inside the input buffer.

Throws:

EncodingException - For invalid encoding.

readUDataDTagElement

public final ByteBuffer readUDataDTagElement(int expectedTag)
                                      throws EncodingException

Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag. Then read one item expecting it to be type UDATA, and return a ByteBuffer. Finally, read the element close. Update the input's position.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

a ByteBuffer which is a slice on the data inside the input buffer.

Throws:

EncodingException - For invalid encoding including if did not get the expected DTAG.

readOptionalUDataDTagElement

public final ByteBuffer readOptionalUDataDTagElement(int expectedTag)
                                              throws EncodingException

Peek at the next element and if it is the expectedTag, call readUDataDTagElement. Otherwise, return null.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

a ByteBuffer which is a slice on the data inside the input buffer. However, if the next element is not the expectedTag, return null.

Throws:

EncodingException - For invalid encoding.

readUnsignedIntegerDTagElement

public final int readUnsignedIntegerDTagElement(int expectedTag)
                                         throws EncodingException

Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag. Then read one item expecting it to be type UDATA, parse it as an unsigned decimal integer and return the integer. Finally, read the element close. Update the input's position.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

The parsed integer.

Throws:

EncodingException - For invalid encoding including if did not get the expected DTAG or can't parse the decimal integer.

readOptionalUnsignedIntegerDTagElement

public final int readOptionalUnsignedIntegerDTagElement(int expectedTag)
                                                 throws EncodingException

Peek at the next element, and if it has the expectedTag then call readUnsignedIntegerDTagElement. Otherwise, return -1.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

The parsed integer, or -1 if the next element doesn't have expectedTag.

Throws:

EncodingException - For invalid encoding including if can't parse the decimal integer.

readTimeMillisecondsDTagElement

public final double readTimeMillisecondsDTagElement(int expectedTag)
                                             throws EncodingException

Decode the header from the input starting at its position, expecting the type to be DTAG and the value to be expectedTag. Then read one item, parse it as an unsigned big endian integer in 4096 ticks per second, and convert it to milliseconds. Finally, read the element close. Update the input's position.

Parameters:

expectedTag - The expected value for DTAG.

Returns:

The number of milliseconds.

Throws:

EncodingException - For invalid encoding including if did not get the expected DTAG.

readOptionalTimeMillisecondsDTagElement

public final double readOptionalTimeMillisecondsDTagElement(int expectedTag)
                                                     throws EncodingException

Peek at the next element, and if it has the expectedTag then call readTimeMillisecondsDTagElement. Otherwise, return -1.0 .

Parameters:

expectedTag - The expected value for DTAG.

Returns:

The number of milliseconds, or -1.0 if the next element doesn't have expectedTag.

Throws:

EncodingException - For invalid encoding.

unsignedBigEndianToDouble

public final double unsignedBigEndianToDouble(ByteBuffer bytes)

Interpret the bytes as an unsigned big endian integer and convert to a double. Don't check for overflow. We use a double because it is large enough to represent NDN time (4096 ticks per second since 1970).

Parameters:

bytes - The ByteBuffer with the value. This reads from position() to limit().

Returns:

The double value.

getOffset

public final int getOffset()

Get the current position of the input, used for the next read.

Returns:

The position.

seek

public final void seek(int position)

Set the position of the input, used for the next read.

Parameters:

position - The new position.