org.apache.pig.newplan.logical.expression
Class ProjectExpression

java.lang.Object
  org.apache.pig.newplan.Operator
      org.apache.pig.newplan.logical.expression.LogicalExpression
          org.apache.pig.newplan.logical.expression.ColumnExpression
              org.apache.pig.newplan.logical.expression.ProjectExpression

public class ProjectExpression
extends ColumnExpression

Projection of columns in an expression.

Field Summary

Fields inherited from class org.apache.pig.newplan.logical.expression.LogicalExpression

fieldSchema, uidOnlyFieldSchema

Fields inherited from class org.apache.pig.newplan.Operator

annotations, hashPrime, location, name, plan

Constructor Summary

ProjectExpression(OperatorPlan plan, int inputNum, int colNum, LogicalRelationalOperator attachedRelationalOp)
Adds projection to the plan.

ProjectExpression(OperatorPlan plan, int inputNum, LogicalRelationalOperator attachedRelationalOp)
Constructor for range projection Adds projection to the plan.

ProjectExpression(OperatorPlan plan, int inputNum, String alias, Operator projectedOp, LogicalRelationalOperator attachedRelationalOp)
Adds projection to the plan.

ProjectExpression(ProjectExpression projExpr, OperatorPlan plan)
like a copy constructor, but with a plan argument

Method Summary

void	accept(PlanVisitor v) Accept a visitor at this node in the graph.
LogicalExpression	deepCopy(LogicalExpressionPlan lgExpPlan) Create the deep copy of this expression and add that into the passed LogicalExpressionPlan Return the copy of this expression with updated logical expression plan.
LogicalRelationalOperator	findReferent() Find the LogicalRelationalOperator that this projection refers to.
LogicalRelationalOperator	getAttachedRelationalOp()
String	getColAlias()
int	getColNum() Column number this project references.
int	getEndCol()
LogicalSchema.LogicalFieldSchema	getFieldSchema() Get the field schema for the output of this expression operator.
int	getInputNum() Input number this project references.
Operator	getProjectedOperator()
int	getStartCol()
byte	getType() Get the data type for this expression.
boolean	isEqual(Operator other) This is like a shallow equals comparison.
boolean	isProjectStar()
boolean	isRangeOrStarProject()
boolean	isRangeProject()
void	setAttachedRelationalOp(LogicalRelationalOperator attachedRelationalOp)
void	setColNum(int colNum) Set the column number for this project.
void	setColumnNumberFromAlias() If there is an alias, finds the column number from it.
void	setEndAlias(String endAlias)
void	setEndCol(int endCol)
void	setInputNum(int inputNum)
void	setStartAlias(String startAlias)
void	setStartCol(int startCol)
String	toString()

Methods inherited from class org.apache.pig.newplan.logical.expression.LogicalExpression

getNextUid, hasFieldSchema, neverUseForRealSetFieldSchema, resetFieldSchema, resetNextUid, resetUid

Methods inherited from class org.apache.pig.newplan.Operator

annotate, getAnnotation, getLocation, getName, getPlan, removeAnnotation, setLocation, setPlan

Methods inherited from class java.lang.Object

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

Constructor Detail

ProjectExpression

public ProjectExpression(OperatorPlan plan,
                         int inputNum,
                         int colNum,
                         LogicalRelationalOperator attachedRelationalOp)

Adds projection to the plan.

Parameters:

plan - LogicalExpressionPlan this projection will be a part of

inputNum - Input number this project references.

colNum - Column number this project references.

attachedRelationalOp -

ProjectExpression

public ProjectExpression(OperatorPlan plan,
                         int inputNum,
                         String alias,
                         Operator projectedOp,
                         LogicalRelationalOperator attachedRelationalOp)

Adds projection to the plan.

Parameters:

plan -

inputNum -

alias -

attachedRelationalOp -

Throws:

FrontendException

ProjectExpression

public ProjectExpression(OperatorPlan plan,
                         int inputNum,
                         LogicalRelationalOperator attachedRelationalOp)

Constructor for range projection Adds projection to the plan. The start and end alias/column-number should be set separately.

Parameters:

plan -

inputNum -

attachedRelationalOp -

ProjectExpression

public ProjectExpression(ProjectExpression projExpr,
                         OperatorPlan plan)

like a copy constructor, but with a plan argument

Parameters:

projExpr -

plan -

Method Detail

setColumnNumberFromAlias

public void setColumnNumberFromAlias()
                              throws FrontendException

If there is an alias, finds the column number from it.

Throws:

FrontendException - if there is no such alias

accept

public void accept(PlanVisitor v)
            throws FrontendException

Description copied from class: Operator

Accept a visitor at this node in the graph.

Specified by:

accept in class Operator

Parameters:

v - Visitor to accept.

Throws:

FrontendException

getInputNum

public int getInputNum()

Input number this project references. This is the input number for the relational operator that contains this expression. The count is zero based.

Returns:

input number

setInputNum

public void setInputNum(int inputNum)

getColNum

public int getColNum()

Column number this project references. The column number is the column in the relational operator that contains this expression. The count is zero based.

Returns:

column number

getColAlias

public String getColAlias()

getProjectedOperator

public Operator getProjectedOperator()

setColNum

public void setColNum(int colNum)

Set the column number for this project. This should only be called by ProjectionPatcher. Stupid Java needs friends.

Parameters:

colNum - new column number for projection

isProjectStar

public boolean isProjectStar()

isRangeProject

public boolean isRangeProject()

isRangeOrStarProject

public boolean isRangeOrStarProject()

getFieldSchema

public LogicalSchema.LogicalFieldSchema getFieldSchema()
                                                throws FrontendException

Description copied from class: LogicalExpression

Get the field schema for the output of this expression operator. This does not merely return the field schema variable. If schema is not yet set, this will attempt to construct it. Therefore it is abstract since each operator will need to construct its field schema differently.

Specified by:

getFieldSchema in class LogicalExpression

Returns:

the FieldSchema

Throws:

FrontendException

findReferent

public LogicalRelationalOperator findReferent()
                                       throws FrontendException

Find the LogicalRelationalOperator that this projection refers to.

Returns:

LRO this projection refers to

Throws:

FrontendException

isEqual

public boolean isEqual(Operator other)
                throws FrontendException

Description copied from class: Operator

This is like a shallow equals comparison. It returns true if two operators have equivalent properties even if they are different objects. Here properties mean equivalent plan and equivalent name.

Specified by:

isEqual in class Operator

Returns:

true if two object have equivalent properties, else false

Throws:

FrontendException

toString

public String toString()

Overrides:

toString in class LogicalExpression

getAttachedRelationalOp

public LogicalRelationalOperator getAttachedRelationalOp()

setAttachedRelationalOp

public void setAttachedRelationalOp(LogicalRelationalOperator attachedRelationalOp)

getType

public byte getType()
             throws FrontendException

Description copied from class: LogicalExpression

Get the data type for this expression.

Overrides:

getType in class LogicalExpression

Returns:

data type, one of the static bytes of DataType

Throws:

FrontendException

getStartCol

public int getStartCol()

Returns:

the startCol

setStartCol

public void setStartCol(int startCol)

Parameters:

startCol - the startCol to set

getEndCol

public int getEndCol()

Returns:

the endCol

setEndCol

public void setEndCol(int endCol)

Parameters:

endCol - the endCol to set

setStartAlias

public void setStartAlias(String startAlias)
                   throws FrontendException

Parameters:

startAlias -

Throws:

FrontendException

setEndAlias

public void setEndAlias(String endAlias)
                 throws FrontendException

Parameters:

endAlias -

Throws:

FrontendException

deepCopy

public LogicalExpression deepCopy(LogicalExpressionPlan lgExpPlan)
                           throws FrontendException

Description copied from class: LogicalExpression

Create the deep copy of this expression and add that into the passed LogicalExpressionPlan Return the copy of this expression with updated logical expression plan.

Specified by:

deepCopy in class LogicalExpression

Parameters:

lgExpPlan - LogicalExpressionPlan in which this expression will be added.

Returns:

LogicalExpression with its own logical expression plan.

Throws:

FrontendException