org.apache.tajo.plan.expr

Class AlgebraicUtil

java.lang.Object

org.apache.tajo.plan.expr.AlgebraicUtil

public class AlgebraicUtil
extends Object

Constructor Summary

Constructors

Constructor and Description
AlgebraicUtil()

Method Summary

Methods

Modifier and Type	Method and Description
static BinaryEval	commutate(BinaryEval inputExpr) Commutate two terms which are added, subtracted and multiplied.
static boolean	containSingleVar(EvalNode expr)
static EvalNode	createSingletonExprFromCNF(EvalNode... cnfExprs) Convert a list of conjunctive normal forms into a singleton expression.
static EvalNode	createSingletonExprFromDNF(EvalNode... cnfExprs) Convert a list of conjunctive normal forms into a singleton expression.
static EvalNode	eliminateConstantExprs(EvalNode expr) Simplify the given expr.
static EvalType	inverseOperator(EvalType type) Inverse a given operator (+, -, *, /)
static boolean	isIndexableOperator(EvalNode expr)
static PartialBinaryExpr	splitLeftTerm(BinaryEval binary) Split the left term and transform it into the right deep expression.
static PartialBinaryExpr	splitRightTerm(BinaryEval binary) Split the left term and transform it into the right deep expression.
static EvalNode[]	toConjunctiveNormalFormArray(EvalNode expr) Transforms a expression to an array of conjunctive normal formed expressions.
static EvalNode[]	toDisjunctiveNormalFormArray(EvalNode... exprs) Transforms a expression to an array of disjunctive normal formed expressions.
static EvalNode	transpose(EvalNode evalNode, Column target) Transpose a given comparison expression into the expression where the variable corresponding to the target is placed on the left-hand side.

Methods inherited from class java.lang.Object

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

Constructor Detail

AlgebraicUtil

public AlgebraicUtil()

Method Detail

transpose

public static EvalNode transpose(EvalNode evalNode,
                 Column target)

Transpose a given comparison expression into the expression where the variable corresponding to the target is placed on the left-hand side.

Parameters:

evalNode -

target -

Returns:

Transposed expression

inverseOperator

public static EvalType inverseOperator(EvalType type)

Inverse a given operator (+, -, *, /)

Parameters:

type -

Returns:

inversed operator type

eliminateConstantExprs

public static EvalNode eliminateConstantExprs(EvalNode expr)

Simplify the given expr. That is, all subexprs consisting of only constants are calculated immediately.

Parameters:

expr - to be simplified

Returns:

the simplified expr

containSingleVar

public static boolean containSingleVar(EvalNode expr)

Parameters:

expr - to be evaluated if the expr includes one variable

Returns:

true if expr has only one field

splitLeftTerm

public static PartialBinaryExpr splitLeftTerm(BinaryEval binary)

Split the left term and transform it into the right deep expression.

Parameters:

binary - - notice the left term of this expr will be eliminated after done.

Returns:

the separated expression changed into the right deep expression. For example, the expr 'x * y' is transformed into '* x'.

splitRightTerm

public static PartialBinaryExpr splitRightTerm(BinaryEval binary)

Split the left term and transform it into the right deep expression.

Parameters:

binary - - to be splited

Returns:

the separated expression changed into the right deep expression. For example, the expr 'x * y' is transformed into '* y'.

Throws:

CloneNotSupportedException

commutate

public static BinaryEval commutate(BinaryEval inputExpr)

Commutate two terms which are added, subtracted and multiplied.

Parameters:

inputExpr -

Returns:

isIndexableOperator

public static boolean isIndexableOperator(EvalNode expr)

createSingletonExprFromCNF

public static EvalNode createSingletonExprFromCNF(EvalNode... cnfExprs)

Convert a list of conjunctive normal forms into a singleton expression.

Parameters:

cnfExprs -

Returns:

The EvalNode object that merges all CNF-formed expressions.

toConjunctiveNormalFormArray

public static EvalNode[] toConjunctiveNormalFormArray(EvalNode expr)

Transforms a expression to an array of conjunctive normal formed expressions.

Parameters:

expr - The expression to be transformed to an array of CNF-formed expressions.

Returns:

An array of CNF-formed expressions

createSingletonExprFromDNF

public static EvalNode createSingletonExprFromDNF(EvalNode... cnfExprs)

Convert a list of conjunctive normal forms into a singleton expression.

Parameters:

cnfExprs -

Returns:

The EvalNode object that merges all CNF-formed expressions.

toDisjunctiveNormalFormArray

public static EvalNode[] toDisjunctiveNormalFormArray(EvalNode... exprs)

Transforms a expression to an array of disjunctive normal formed expressions.

Parameters:

exprs - The expressions to be transformed to an array of CNF-formed expressions.

Returns:

An array of CNF-formed expressions