ConstantReference (Dataflow Library Distribution Project 6.6.0-111 API)

java.lang.Object
- com.pervasive.datarush.functions.ConstantReference

All Implemented Interfaces:

ScalarValuedFunction
```
public final class ConstantReference
extends Object
implements ScalarValuedFunction
```
A reference to a known value. The defined function returns the value. These can be used to combine constant values with other functions. Note however, that many of the built-in functions provide convenience signatures which do not require direct use of this class.

Constructor Summary

Constructors
Constructor and Description

ConstantReference(ScalarValued v)
Defines a function evaluating to the specified value

Constructors
Constructor and Description
`ConstantReference(ScalarValued v)` Defines a function evaluating to the specified value

Method Summary

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static ScalarValuedFunction`	`constant(BigDecimal value)` Creates a function evaluating to the specified numeric constant.
`static ScalarValuedFunction`	`constant(boolean value)` Creates a function evaluating to the specified boolean constant.
`static ScalarValuedFunction`	`constant(byte[] value)` Creates a function evaluating to the specified binary constant.
`static ScalarValuedFunction`	`constant(char value)` Creates a function evaluating to the specified char constant.
`static ScalarValuedFunction`	`constant(double value)` Creates a function evaluating to the specified double constant.
`static ScalarValuedFunction`	`constant(float value)` Creates a function evaluating to the specified float constant.
`static ScalarValuedFunction`	`constant(int value)` Creates a function evaluating to the specified int constant.
`static ScalarValuedFunction`	`constant(long value)` Creates a function evaluating to the specified long constant.
`static <O> ScalarValuedFunction`	`constant(O value)` Creates a function evaluating to the specified object constant.
`static ScalarValuedFunction`	`constant(ScalarToken value)` Creates a function evaluating to the specified value.
`static ScalarValuedFunction`	`constant(String value)` Creates a function evaluating to the specified string constant.
`boolean`	`equals(Object obj)`
`FunctionEvaluator`	`getEvaluator(RecordValued input, ScalarSettable output)` Constructs an instance of an evaluator for the function.
`Collection<String>`	`getRequiredFields()` Get the input fields required in the function input.
`ScalarValued`	`getSubexpressionEvaluation(EvaluationContext ctx)` Constructs an instance of an evaluation of the function in the context of a larger expression.
`ScalarTokenType`	`getUpperBound()` Gets the upper bound on the output type of the function.
`int`	`hashCode()`
`ScalarValuedFunction`	`mapFieldsToFunctions(Map<String,ScalarValuedFunction> mapping)` Creates a new function, equivalent to the given function, but with specified field references mapped to functions.
`static ScalarValuedFunction`	`nullValue()` Creates a function evaluating to null.
`static ScalarValuedFunction`	`nullValue(ScalarValuedFunction expr)` Deprecated. Untyped null tokens are now supported. Use `nullValue()` to generate a null token without an input type.
`static ScalarValuedFunction`	`nullValue(String fieldName)` Deprecated. Untyped null tokens are now supported. Use `nullValue()` to generate a null token without an input type.
`ScalarValuedFunction`	`remapFieldReferences(Map<String,String> oldToNewMapping)` Creates a new function, equivalent to the given function, but with all field references renamed according to the given mapping.
`String`	`toString()`
`ScalarTokenType`	`validateInputType(RecordTokenType inputType)` Calculates the actual output type of the function given the specified input type.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - ConstantReference
```
public ConstantReference(ScalarValued v)
```
    Defines a function evaluating to the specified value
    
    Parameters:
    
    v - the value to return from the function
- Method Detail
  - getUpperBound
```
public ScalarTokenType getUpperBound()
```
    Description copied from interface: ScalarValuedFunction
    
    Gets the upper bound on the output type of the function. This need not be the exact type of the output, but is expected to be a type to which the actual output type is assignable, as according to TokenType#isAssignableFrom(TokenType).
    This value is used to detect type consistency issues as early as possible. It is always valid to return TokenTypeConstant#SCALAR, in which case no type consistency issues can be caught early.
    
    Specified by:
    
    getUpperBound in interface ScalarValuedFunction
    
    Returns:
    
    the most specific type to which any possible return type is assignable.
  - validateInputType
```
public ScalarTokenType validateInputType(RecordTokenType inputType)
```
    Description copied from interface: ScalarValuedFunction
    
    Calculates the actual output type of the function given the specified input type.
    The type returned must be assignable to the type returned by ScalarValuedFunction.getUpperBound(). If this is not the case, runtime type errors may arise.
    
    Specified by:
    
    validateInputType in interface ScalarValuedFunction
    
    Parameters:
    
    inputType - the type of the record used as input to the function
    
    Returns:
    
    the return type of the function for the given input record schema
  - getEvaluator
```
public FunctionEvaluator getEvaluator(RecordValued input,
                                      ScalarSettable output)
```
    Description copied from interface: ScalarValuedFunction
    Constructs an instance of an evaluator for the function. The evaluator returns the result of the the function applied to the specified input into the given output target.
    Implementations may assume that the input and output are known to be compatible with the function. Normally, this method is only invoked by the DataRush framework, which guarantees this is the case. In general, to satisfy this requirement, callers are expected to:
    - verify that validateInputType(input.getType()) does not throw an exception
    - verify the output type returned is assignable to result.getType()
    Failure to meet this contract may result in runtime exceptions.
    Specified by:
    
    getEvaluator in interface ScalarValuedFunction
    
    Parameters:
    
    input - the record source to use as context for evaluating the function
    
    output - the buffer into which evaluation results are to be stored
    
    Returns:
    
    an evaluator bound to the provided input and output
  - getSubexpressionEvaluation
```
public ScalarValued getSubexpressionEvaluation(EvaluationContext ctx)
```
    Description copied from interface: ScalarValuedFunction
    
    Constructs an instance of an evaluation of the function in the context of a larger expression.
    
    Specified by:
    
    getSubexpressionEvaluation in interface ScalarValuedFunction
    
    Parameters:
    
    ctx - the expression context in which the function is being evaluated as a subexpression
    
    Returns:
    
    an object representing the subexpression's current value
  - hashCode
```
public int hashCode()
```
    Description copied from interface: ScalarValuedFunction
    
    ScalarValuedFunctions should override this method in a manner consistent with ScalarValuedFunction.equals(Object).
    
    Specified by:
    
    hashCode in interface ScalarValuedFunction
    
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object obj)
```
    Description copied from interface: ScalarValuedFunction
    
    ScalarValuedFunctions should override this method to indicate whether they are equal to another ScalarValuedFunction.
    
    Specified by:
    
    equals in interface ScalarValuedFunction
    
    Overrides:
    
    equals in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - constant
```
public static ScalarValuedFunction constant(byte[] value)
```
    Creates a function evaluating to the specified binary constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(boolean value)
```
    Creates a function evaluating to the specified boolean constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(char value)
```
    Creates a function evaluating to the specified char constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(int value)
```
    Creates a function evaluating to the specified int constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(long value)
```
    Creates a function evaluating to the specified long constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(float value)
```
    Creates a function evaluating to the specified float constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(double value)
```
    Creates a function evaluating to the specified double constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(BigDecimal value)
```
    Creates a function evaluating to the specified numeric constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(String value)
```
    Creates a function evaluating to the specified string constant.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static <O> ScalarValuedFunction constant(O value)
```
    Creates a function evaluating to the specified object constant.
    
    Type Parameters:
    
    O - the type of the object
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - constant
```
public static ScalarValuedFunction constant(ScalarToken value)
```
    Creates a function evaluating to the specified value.
    
    Parameters:
    
    value - the constant value to return
    
    Returns:
    
    the constant function
  - nullValue
```
@Deprecated
public static ScalarValuedFunction nullValue(String fieldName)
```
    Deprecated. Untyped null tokens are now supported. Use nullValue() to generate a null token without an input type.
    
    Creates a function, of the same type as the specified field, evaluating to null.
    
    Parameters:
    
    fieldName - an input field, the type of which will be used as the result type
    
    Returns:
    
    the null function
  - nullValue
```
@Deprecated
public static ScalarValuedFunction nullValue(ScalarValuedFunction expr)
```
    Deprecated. Untyped null tokens are now supported. Use nullValue() to generate a null token without an input type.
    
    Creates a function, of the same type as the specified expression, evaluating to null.
    
    Parameters:
    
    fieldName - an expression, the type of which will be used as the result type
    
    Returns:
    
    the null function
  - nullValue
```
public static ScalarValuedFunction nullValue()
```
    Creates a function evaluating to null.
    
    Returns:
    
    the null function
  - getRequiredFields
```
public Collection<String> getRequiredFields()
```
    Description copied from interface: ScalarValuedFunction
    
    Get the input fields required in the function input. An empty collection implies no specific fields are required.
    
    Specified by:
    
    getRequiredFields in interface ScalarValuedFunction
    
    Returns:
    
    the names of fields which must be present in the record input schema
  - remapFieldReferences
```
public ScalarValuedFunction remapFieldReferences(Map<String,String> oldToNewMapping)
```
    Description copied from interface: ScalarValuedFunction
    
    Creates a new function, equivalent to the given function, but with all field references renamed according to the given mapping.
    
    Specified by:
    
    remapFieldReferences in interface ScalarValuedFunction
    
    Parameters:
    
    oldToNewMapping - a mapping from old names to new names. If a name is not present in the given mapping, it will remain as-is.
    
    Returns:
    
    a new function with all field reference renamed appropriately
  - mapFieldsToFunctions
```
public ScalarValuedFunction mapFieldsToFunctions(Map<String,ScalarValuedFunction> mapping)
```
    Description copied from interface: ScalarValuedFunction
    
    Creates a new function, equivalent to the given function, but with specified field references mapped to functions.
    
    Specified by:
    
    mapFieldsToFunctions in interface ScalarValuedFunction
    
    Parameters:
    
    mapping - a mapping from field names to functions. If a name is not present in the given mapping, it will remain as-is.
    
    Returns:
    
    a new function with all field reference mapped appropriately

Class ConstantReference

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ConstantReference

Method Detail

getUpperBound

validateInputType

getEvaluator

getSubexpressionEvaluation

hashCode

equals

toString

constant

constant

constant

constant

constant

constant

constant

constant

constant

constant

constant

nullValue

nullValue

nullValue

getRequiredFields

remapFieldReferences

mapFieldsToFunctions