public class NullSafeType<T> extends FieldType<T>
FieldType that wraps any other FieldType not supporting null values and adds support for null values.
This class pre-pends a 0x01 to the binary encoding of non-null values, and uses a single 0xff byte to
represent null values. Therefore, null values sort last.
The default value becomes null, for which "null" is the value returned by toParseableString().
Therefore, "null" must not be returned by the wrapped type's toParseableString()
for any value.
This class will automatically "inline" the 0xff for null values and omit the 0x01 for non-null values
if the wrapped FieldType's FieldType.hasPrefix0xff() method returns false.
| Modifier and Type | Field and Description |
|---|---|
protected FieldType<T> |
inner
The inner
FieldType that this instance wraps. |
static int |
NOT_NULL_SENTINEL
Not null sentinel byte value.
|
static int |
NULL_SENTINEL
Null sentinel byte value.
|
name, NAME_PATTERN, REFERENCE_TYPE_NAME, signature, typeToken| Constructor and Description |
|---|
NullSafeType(FieldType<T> inner)
Constructor.
|
NullSafeType(String name,
FieldType<T> inner)
Constructor.
|
| Modifier and Type | Method and Description |
|---|---|
int |
compare(T value1,
T value2)
Order two field values.
|
<S> T |
convert(FieldType<S> type,
S value)
|
boolean |
equals(Object obj) |
T |
fromParseableString(ParseContext context)
Parse a value previously encoded by
toParseableString() as a self-delimited String
and positioned at the start of the given parsing context. |
T |
fromString(String string)
Parse a non-null value previously encoded by
toString(T). |
NullSafeType<T> |
genericizeForIndex()
Remove any information that may differ between instances associated with the same indexed field in the same schema.
|
int |
hashCode() |
boolean |
hasPrefix0x00()
Determine whether any of this field type's encoded values start with a
0x00 byte. |
boolean |
hasPrefix0xff()
Determine whether any of this field type's encoded values start with a
0xff byte. |
T |
read(ByteReader reader)
Read a value from the given input.
|
void |
skip(ByteReader reader)
Read and discard a value from the given input.
|
String |
toParseableString(T value)
Encode a possibly null value as a
String for later decoding by fromParseableString(). |
String |
toString(T value)
Encode a non-null value as a
String for later decoding by fromString(). |
void |
write(ByteWriter writer,
T value)
Write a value to the given output.
|
getDefaultValue, getDefaultValueObject, getEncodingSignature, getKeyRange, getName, getTypeToken, toString, validate, validateAndWriteclone, finalize, getClass, notify, notifyAll, wait, wait, waitcomparing, comparing, comparingDouble, comparingInt, comparingLong, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLongpublic static final int NOT_NULL_SENTINEL
public static final int NULL_SENTINEL
public NullSafeType(String name, FieldType<T> inner)
name - type nameinner - inner type that is not null safepublic NullSafeType(FieldType<T> inner)
inner; therefore, this instance and inner
cannot be both registered in a FieldTypeRegistry.inner - inner type that is not null safepublic T read(ByteReader reader)
FieldTypepublic void write(ByteWriter writer, T value)
FieldTypepublic void skip(ByteReader reader)
FieldTypepublic T fromString(String string)
FieldTypetoString(T).
The implementation in FieldType creates a new ParseContext based on string,
delegates to FieldType.toParseableString(T) to parse it, and verifies that all of string was consumed
during the parse. Subclasses that override this method should also override toString(T).
fromString in class FieldType<T>string - non-null value previously encoded as a String by toString(T)public String toString(T value)
FieldTypeString for later decoding by fromString().
Each of the characters in the returned String must be one of the valid XML characters
(tab, newline, carriage return, \u0020 - \ud7ff, and \ue000 - \fffdf).
The implementation in FieldType checks that value is not null, then delegates to FieldType.toParseableString(T).
Subclasses that override this method should also override fromString().
toString in class FieldType<T>value - actual value, never nullvalue acceptable to fromString()public T fromParseableString(ParseContext context)
FieldTypetoParseableString() as a self-delimited String
and positioned at the start of the given parsing context.fromParseableString in class FieldType<T>context - parse context starting with a string previously encoded via toParseableString()public String toParseableString(T value)
FieldTypeString for later decoding by fromParseableString().
The string value must be self-delimiting, i.e., decodable even when followed by arbitrary additional characters,
and must not start with whitespace or closing square bracket ("]").
In addition, each of the characters in the returned String must be one of the valid XML characters
(tab, newline, carriage return, \u0020 - \ud7ff, and \ue000 - \fffdf).
toParseableString in class FieldType<T>value - actual value (possibly null)value acceptable to fromParseableString()public <S> T convert(FieldType<S> type, S value)
FieldTypeFieldType into a value of this FieldType.
For a non-null value, the implementation in FieldType first checks whether the value is already
a valid value for this type; if so, the value is returned. Otherwise, it invokes type.toString(value) to convert value into a String, and then attempts to parse that string via
this.fromString(); if the parse fails, an IllegalArgumentException is thrown.
If value is null, the implementation in FieldType returns null, unless this type does not support null
values, in which case an IllegalArgumentException is thrown.
Special handling also exists for certain conversions between built-in types:
value != 0char and a String of length one are convertible (other Strings are not)char[] array and a String are convertiblepublic int compare(T value1, T value2)
FieldType
This method must provide a total ordering of all supported Java values that is consistent with the database ordering,
i.e., the unsigned lexicographical ordering of the corresponding byte[] encoded field values.
If null is a supported Java value, then the returned Comparator must accept null parameters without
throwing an exception (note, this is a stronger requirement than the Comparator interface normally requires).
Note: by convention, null values usually sort last.
public boolean hasPrefix0xff()
FieldType0xff byte.
Certain optimizations are possible when this is not the case. It is safe for this method to always return true.
Note: changing the return value of this method usually means changing the binary encoding, resulting in an incompatible type.
The implementation in FieldType returns true.
hasPrefix0xff in class FieldType<T>0xff existspublic boolean hasPrefix0x00()
FieldType0x00 byte.
Certain optimizations are possible when this is not the case. It is safe for this method to always return true.
Note: changing the return value of this method usually means changing the binary encoding, resulting in an incompatible type.
The implementation in FieldType returns true.
hasPrefix0x00 in class FieldType<T>0x00 existspublic NullSafeType<T> genericizeForIndex()
FieldTypeThis operation should be applied before using this instance with index queries.
genericizeForIndex in class FieldType<T>Copyright © 2018. All rights reserved.