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

Interface Expression<T>

All Known Implementing Classes:

AbstractExpression, LogicalExpression, NotLogicalExpression, RelationalExpression

public interface Expression<T>

Expression representation. There are two types of expressions, relational and logical. Each expression has an operator and either 2 operands for binary expressions or 1 operand for unary expressions.

Method Summary

Modifier and Type	Method and Description
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.
Predicate	toPredicate() Get the predicate representation of the expression.

Method Detail

merge

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

Merge expression with surrounding expressions.

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.

toPredicate

Predicate toPredicate()
               throws InvalidQueryException

Get the predicate representation of the expression.

Returns:

a predicate instance for the expression

Throws:

InvalidQueryException

setLeftOperand

void setLeftOperand(T left)

Set the expressions left operand.

Parameters:

left - the left operand

setRightOperand

void setRightOperand(T right)

Set the expressions right operand.

Parameters:

right - the right operand

getLeftOperand

T getLeftOperand()

Get the left operand expression.

Returns:

the left operand

getRightOperand

T getRightOperand()

Get the right operand expression.

Returns:

the right operand.

getOperator

Operator getOperator()

Get the expression operator.

Returns:

the logical operator for the expression