org.apache.ambari.server.api.predicate.expressions

Class AbstractExpression<T>

java.lang.Object

org.apache.ambari.server.api.predicate.expressions.AbstractExpression<T>

All Implemented Interfaces:

Expression<T>

Direct Known Subclasses:

LogicalExpression, RelationalExpression

public abstract class AbstractExpression<T>
extends Object
implements Expression<T>

Base class for expressions.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractExpression(Operator op) Constructor.

Method Summary

Modifier and Type	Method and Description
protected List<Expression>	defaultMerge(Expression left, Expression right) Base merge implementation.
T	getLeftOperand() Get the left operand expression.
Operator	getOperator() Get the expression operator.
T	getRightOperand() Get the right operand expression.
List<Expression>	merge(Expression left, Expression right, int precedence) Merge expression with surrounding expressions.
void	setLeftOperand(T left) Set the expressions left operand.
void	setRightOperand(T right) Set the expressions right operand.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.ambari.server.api.predicate.expressions.Expression

toPredicate

Constructor Detail

AbstractExpression

protected AbstractExpression(Operator op)

Constructor.

Parameters:

op - the expressions operator

Method Detail

setLeftOperand

public void setLeftOperand(T left)

Description copied from interface: Expression

Set the expressions left operand.

Specified by:

setLeftOperand in interface Expression<T>

Parameters:

left - the left operand

setRightOperand

public void setRightOperand(T right)

Description copied from interface: Expression

Set the expressions right operand.

Specified by:

setRightOperand in interface Expression<T>

Parameters:

right - the right operand

getLeftOperand

public T getLeftOperand()

Description copied from interface: Expression

Get the left operand expression.

Specified by:

getLeftOperand in interface Expression<T>

Returns:

the left operand

getRightOperand

public T getRightOperand()

Description copied from interface: Expression

Get the right operand expression.

Specified by:

getRightOperand in interface Expression<T>

Returns:

the right operand.

getOperator

public Operator getOperator()

Description copied from interface: Expression

Get the expression operator.

Specified by:

getOperator in interface Expression<T>

Returns:

the logical operator for the expression

merge

public List<Expression> merge(Expression left,
                              Expression right,
                              int precedence)

Description copied from interface: Expression

Merge expression with surrounding expressions.

Specified by:

merge in interface Expression<T>

Parameters:

left - the preceding expression

right - the following expression

precedence - the precedence level being merged. Only expressions at this precedence level should be merged. Others should simply return the left expression, themselves and the right expression in that order.

Returns:

a list of expressions after merging. Do not return any null elements.

defaultMerge

protected List<Expression> defaultMerge(Expression left,
                                        Expression right)

Base merge implementation. No merge is done, simply returns the left expression, this and the right expression.

Parameters:

left - the expression to the left of this expression

right - the expression to the right of this expression

Returns:

a list containing the un-merged left expression, this and right expression