org.apache.flink.table.expressions

Class ValueLiteralExpression

java.lang.Object

org.apache.flink.table.expressions.ValueLiteralExpression

All Implemented Interfaces:

Expression, ResolvedExpression

@PublicEvolving
public final class ValueLiteralExpression
extends Object
implements ResolvedExpression

Expression for constant literal values.

By design, this class can take any value described by a DataType. However, it is recommended to use instances with default conversion (see DataType.getConversionClass().

Equals/hashCode support of this expression depends on the equals/hashCode support of the value.

The data type can be extracted automatically from non-null values using value-based extraction (see ValueDataTypeConverter).

Symbols (enums extending from TableSymbol) are considered as literal values.

Constructor Summary

Constructors

Constructor and Description
ValueLiteralExpression(Object value)
ValueLiteralExpression(Object value, DataType dataType)

Method Summary

Modifier and Type	Method and Description
<R> R	accept(ExpressionVisitor<R> visitor)
String	asSerializableString() Returns a string that fully serializes this instance.
String	asSummaryString() Returns a string that summarizes this expression for printing to a console.
boolean	equals(Object o)
List<Expression>	getChildren()
DataType	getOutputDataType() Returns the data type of the computation result.
List<ResolvedExpression>	getResolvedChildren()
<T> Optional<T>	getValueAs(Class<T> clazz) Returns the value (excluding null) as an instance of the given class.
int	hashCode()
boolean	isNull()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ValueLiteralExpression

public ValueLiteralExpression(@Nonnull
                              Object value)

ValueLiteralExpression

public ValueLiteralExpression(@Nullable
                              Object value,
                              DataType dataType)

Method Detail

isNull

public boolean isNull()

getValueAs

public <T> Optional<T> getValueAs(Class<T> clazz)

Returns the value (excluding null) as an instance of the given class.

It supports conversions to default conversion classes of LogicalTypes and additionally to BigDecimal for all types of LogicalTypeFamily.NUMERIC. This method should not be called with other classes.

Note to implementers: Whenever we add a new class here, make sure to also update the planner for supporting the class via CallContext.getArgumentValue(int, Class).

getOutputDataType

public DataType getOutputDataType()

Description copied from interface: ResolvedExpression

Returns the data type of the computation result.

Specified by:

getOutputDataType in interface ResolvedExpression

getResolvedChildren

public List<ResolvedExpression> getResolvedChildren()

Specified by:

getResolvedChildren in interface ResolvedExpression

asSummaryString

public String asSummaryString()

Description copied from interface: Expression

Returns a string that summarizes this expression for printing to a console. An implementation might skip very specific properties.

Specified by:

asSummaryString in interface Expression

Returns:

summary string of this expression for debugging purposes

asSerializableString

public String asSerializableString()

Description copied from interface: ResolvedExpression

Returns a string that fully serializes this instance. The serialized string can be used for storing the query in, for example, a Catalog as a view.

Specified by:

asSerializableString in interface ResolvedExpression

Returns:

detailed string for persisting in a catalog

getChildren

public List<Expression> getChildren()

Specified by:

getChildren in interface Expression

accept

public <R> R accept(ExpressionVisitor<R> visitor)

Specified by:

accept in interface Expression

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object