com.google.debugging.sourcemap

Class Base64VLQ

java.lang.Object

com.google.debugging.sourcemap.Base64VLQ

final class Base64VLQ
extends java.lang.Object

We encode our variable length numbers as base64 encoded strings with the least significant digit coming first. Each base64 digit encodes a 5-bit value (0-31) and a continuation bit. Signed values can be represented by using the least significant bit of the value as the sign bit.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static interface	Base64VLQ.CharIterator A simple interface for advancing through a sequence of characters, that communicates that advance back to the source.

Field Summary

Fields

Modifier and Type	Field and Description
private static int	VLQ_BASE
private static int	VLQ_BASE_MASK
private static int	VLQ_BASE_SHIFT
private static int	VLQ_CONTINUATION_BIT

Constructor Summary

Constructors

Modifier	Constructor and Description
private	Base64VLQ()

Method Summary

Modifier and Type	Method and Description
static int	decode(Base64VLQ.CharIterator in) Decodes the next VLQValue from the provided CharIterator.
static void	encode(java.lang.Appendable out, int value) Writes a VLQ encoded value to the provide appendable.
private static int	fromVLQSigned(int value) Converts to a two-complement value from a value where the sign bit is is placed in the least significant bit.
private static int	toVLQSigned(int value) Converts from a two-complement value to a value where the sign bit is is placed in the least significant bit.

Methods inherited from class java.lang.Object

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

Field Detail

VLQ_BASE_SHIFT

private static final int VLQ_BASE_SHIFT

See Also:

Constant Field Values

VLQ_BASE

private static final int VLQ_BASE

See Also:

Constant Field Values

VLQ_BASE_MASK

private static final int VLQ_BASE_MASK

See Also:

Constant Field Values

VLQ_CONTINUATION_BIT

private static final int VLQ_CONTINUATION_BIT

See Also:

Constant Field Values

Constructor Detail

Base64VLQ

private Base64VLQ()

Method Detail

toVLQSigned

private static int toVLQSigned(int value)

Converts from a two-complement value to a value where the sign bit is is placed in the least significant bit. For example, as decimals: 1 becomes 2 (10 binary), -1 becomes 3 (11 binary) 2 becomes 4 (100 binary), -2 becomes 5 (101 binary)

fromVLQSigned

private static int fromVLQSigned(int value)

Converts to a two-complement value from a value where the sign bit is is placed in the least significant bit. For example, as decimals: 2 (10 binary) becomes 1, 3 (11 binary) becomes -1 4 (100 binary) becomes 2, 5 (101 binary) becomes -2

encode

public static void encode(java.lang.Appendable out,
                          int value)
                   throws java.io.IOException

Writes a VLQ encoded value to the provide appendable.

Throws:

java.io.IOException

decode

public static int decode(Base64VLQ.CharIterator in)

Decodes the next VLQValue from the provided CharIterator.