Package org.apache.qpid.server.query.engine.parsing.expression.function

Class AbstractFunctionExpression<T,R>

java.lang.Object

org.apache.qpid.server.query.engine.parsing.expression.AbstractExpressionNode<T,R>

org.apache.qpid.server.query.engine.parsing.expression.function.AbstractFunctionExpression<T,R>

Type Parameters:

T - Input parameter type

R - Output parameter type

All Implemented Interfaces:

Function<T,R>, Expression<T,R>, ExpressionNode<T,R>

Direct Known Subclasses:

AbsExpression, AbstractAggregationExpression, CoalesceExpression, ConcatExpression, CurrentTimestampExpression, DateAddExpression, DateDiffExpression, DateExpression, ExtractExpression, LeftTrimExpression, LengthExpression, LowerExpression, PositionExpression, ReplaceExpression, RightTrimExpression, RoundExpression, SubstringExpression, TrimExpression, TruncExpression, UpperExpression

public abstract class AbstractFunctionExpression<T,R>
extends AbstractExpressionNode<T,R>

Parent for function expression classes

Field Summary

Fields

Modifier and Type	Field	Description
protected String	_functionName	Function name

Fields inherited from class org.apache.qpid.server.query.engine.parsing.expression.AbstractExpressionNode

_metadata

Constructor Summary

Constructors

Constructor	Description
AbstractFunctionExpression(String alias, List<ExpressionNode<T,?>> args)	Constructor initializes children expression list

Method Summary

Modifier and Type	Method	Description
protected <X,Y> Y	evaluateChild(int index, X value, FunctionParameterTypePredicate<Y> typePredicate)	Evaluates child expression against the value supplied and validates the result against the validator
String	getFunctionName()	Getter for function name
<X,Y> Optional<Y>	getOptionalConstantParameter(int index, Class<Y> type, String message)	Evaluates nullable constant expression.
<X,Y> Optional<Y>	getOptionalParameter(int index, X value, Class<Y> type, String message)	Evaluates nullable expression using value supplied and performs validation checks of result.
<X,Y> Y	getRequiredParameter(int index, X value, Class<Y> type, String message)	Evaluates expression using value supplied and performs validation checks of result.

Methods inherited from class org.apache.qpid.server.query.engine.parsing.expression.AbstractExpressionNode

containsAggregation, ctx, evaluateChild, getAggregations, getAlias, getChild, getChildren, getParent, isAccessor, isInstantlyEvaluable, setAlias, setParent, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.qpid.server.query.engine.parsing.expression.Expression

andThen, apply

Methods inherited from interface java.util.function.Function

andThen, compose

Field Detail

_functionName

protected final String _functionName

Function name

Constructor Detail

AbstractFunctionExpression

public AbstractFunctionExpression(String alias,
                                  List<ExpressionNode<T,?>> args)

Constructor initializes children expression list

Parameters:

alias - Expression alias

args - List of children expressions

Method Detail

getFunctionName

public String getFunctionName()

Getter for function name

Returns:

Function name

evaluateChild

protected <X,Y> Y evaluateChild(int index,
                                      X value,
                                      FunctionParameterTypePredicate<Y> typePredicate)

Evaluates child expression against the value supplied and validates the result against the validator

Type Parameters:

X - Value type

Y - Result type

Parameters:

index - Child expression index

value - Value used to evaluate child expression

typePredicate - Predicate used for result validation

Returns:

Result of child expression evaluation

getRequiredParameter

public <X,Y> Y getRequiredParameter(int index,
                                          X value,
                                          Class<Y> type,
                                          String message)

Evaluates expression using value supplied and performs validation checks of result. Returns result if checks succeeded, throws an exception otherwise.

Type Parameters:

X - Input parameter type

Y - Return parameter type

Parameters:

index - Child expression index to evaluate

value - Value to pass to expression

type - Expected result type

message - Exception message

Returns:

Evaluated result

getOptionalParameter

public <X,Y> Optional<Y> getOptionalParameter(int index,
                                                    X value,
                                                    Class<Y> type,
                                                    String message)

Evaluates nullable expression using value supplied and performs validation checks of result. Returns an empty Optional when expression is null, otherwise returns evaluated result wrapped into Optional.

Type Parameters:

X - Input parameter type

Y - Return parameter type

Parameters:

index - Child expression index to evaluate

value - Value to pass to expression

type - Expected result type

message - Exception message

Returns:

Optional result

getOptionalConstantParameter

public <X,Y> Optional<Y> getOptionalConstantParameter(int index,
                                                            Class<Y> type,
                                                            String message)

Evaluates nullable constant expression. Returns an empty Optional when expression is null, otherwise returns evaluated result wrapped into Optional.

Type Parameters:

X - Input parameter type

Y - Return parameter type

Parameters:

index - Child expression index to evaluate

type - Expected result type

message - Exception message

Returns:

Optional result