Class Expression

java.lang.Object

org.datanucleus.store.query.expression.Expression

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

ArrayExpression, CaseExpression, ClassExpression, CreatorExpression, DyadicExpression, InvokeExpression, JoinExpression, Literal, OrderExpression, ParameterExpression, PrimaryExpression, SubqueryExpression, TypeExpression, VariableExpression

public abstract class Expression
extends Object
implements Serializable

A Scalar expression in a Query. Used to compute values with a resulting type.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Expression.DyadicOperator	"Dyadic" operator performs operation on one or two operands.
static class	Expression.MonadicOperator	"Monadic" operator performs a function on one operand.
static class	Expression.Operator	Representation of an Operator.

Field Summary

Fields

Modifier and Type	Field	Description
protected String	alias
protected Expression	left
protected Expression.Operator	op
static final Expression.DyadicOperator	OP_ADD	ADD
static final Expression.DyadicOperator	OP_AND	AND
static final Expression.DyadicOperator	OP_BIT_AND	BITWISE AND
static final Expression.DyadicOperator	OP_BIT_OR	BITWISE OR
static final Expression.DyadicOperator	OP_BIT_XOR	BITWISE XOR
static final Expression.DyadicOperator	OP_CAST	IS
static final Expression.MonadicOperator	OP_COM	COM
static final Expression.DyadicOperator	OP_CONCAT	CONCAT
static final Expression.MonadicOperator	OP_DISTINCT	DISTINCT
static final Expression.DyadicOperator	OP_DIV	DIV
static final Expression.DyadicOperator	OP_EQ	EQ
static final Expression.DyadicOperator	OP_GT	GT
static final Expression.DyadicOperator	OP_GTEQ	GTEQ
static final Expression.DyadicOperator	OP_IN	IN
static final Expression.DyadicOperator	OP_IS	IS
static final Expression.DyadicOperator	OP_ISNOT	ISNOT
static final Expression.DyadicOperator	OP_LIKE	LIKE
static final Expression.DyadicOperator	OP_LT	LT
static final Expression.DyadicOperator	OP_LTEQ	LTEQ
static final Expression.DyadicOperator	OP_MOD	MOD
static final Expression.DyadicOperator	OP_MUL	MUL
static final Expression.MonadicOperator	OP_NEG	NEG
static final Expression.MonadicOperator	OP_NOT	NOT
static final Expression.DyadicOperator	OP_NOTEQ	NOTEQ
static final Expression.DyadicOperator	OP_NOTIN	NOTIN
static final Expression.DyadicOperator	OP_OR	OR
static final Expression.DyadicOperator	OP_SUB	SUB
protected Expression	parent	Parent of this expression in the tree (if any).
protected Expression	right
private static final long	serialVersionUID
protected Symbol	symbol

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Expression()	Constructor.
protected	Expression(Expression.MonadicOperator op, Expression operand)	Perform a function op on operand
protected	Expression(Expression operand1, Expression.DyadicOperator op, Expression operand2)	Performs a function on two arguments.

Method Summary

Modifier and Type	Method	Description
abstract Symbol	bind(SymbolTable symtbl)	Method to bind the expression to the symbol table as appropriate.
Object	evaluate(ExpressionEvaluator eval)	Method to evaluate this expression, using the passed evaluator.
String	getAlias()
Expression	getLeft()	Accessor for the left hand expression.
Expression.Operator	getOperator()	The operator to be performed by this expression.
Expression	getParent()	Accessor for the parent expression where this expression is access from.
Expression	getRight()	Accessor for the right hand expression.
Symbol	getSymbol()	Accessor for the symbol for this expression (if set).
void	setAlias(String alias)
void	setLeft(Expression expr)
void	setRight(Expression expr)

Methods inherited from class Object

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

Field Details

serialVersionUID

private static final long serialVersionUID

See Also:

• Constant Field Values

parent

protected Expression parent

Parent of this expression in the tree (if any).

op

protected Expression.Operator op

left

protected Expression left

right

protected Expression right

symbol

protected Symbol symbol

alias

protected String alias

OP_OR

public static final Expression.DyadicOperator OP_OR

OR

OP_AND

public static final Expression.DyadicOperator OP_AND

AND

OP_NOT

public static final Expression.MonadicOperator OP_NOT

NOT

OP_EQ

public static final Expression.DyadicOperator OP_EQ

EQ

OP_NOTEQ

public static final Expression.DyadicOperator OP_NOTEQ

NOTEQ

OP_LT

public static final Expression.DyadicOperator OP_LT

LT

OP_LTEQ

public static final Expression.DyadicOperator OP_LTEQ

LTEQ

OP_GT

public static final Expression.DyadicOperator OP_GT

GT

OP_GTEQ

public static final Expression.DyadicOperator OP_GTEQ

GTEQ

OP_LIKE

public static final Expression.DyadicOperator OP_LIKE

LIKE

OP_IS

public static final Expression.DyadicOperator OP_IS

IS

OP_ISNOT

public static final Expression.DyadicOperator OP_ISNOT

ISNOT

OP_CAST

public static final Expression.DyadicOperator OP_CAST

IS

OP_IN

public static final Expression.DyadicOperator OP_IN

IN

OP_NOTIN

public static final Expression.DyadicOperator OP_NOTIN

NOTIN

OP_BIT_OR

public static final Expression.DyadicOperator OP_BIT_OR

BITWISE OR

OP_BIT_XOR

public static final Expression.DyadicOperator OP_BIT_XOR

BITWISE XOR

OP_BIT_AND

public static final Expression.DyadicOperator OP_BIT_AND

BITWISE AND

OP_ADD

public static final Expression.DyadicOperator OP_ADD

ADD

OP_SUB

public static final Expression.DyadicOperator OP_SUB

SUB

OP_CONCAT

public static final Expression.DyadicOperator OP_CONCAT

CONCAT

OP_MUL

public static final Expression.DyadicOperator OP_MUL

MUL

OP_DIV

public static final Expression.DyadicOperator OP_DIV

DIV

OP_MOD

public static final Expression.DyadicOperator OP_MOD

MOD

OP_NEG

public static final Expression.MonadicOperator OP_NEG

NEG

OP_COM

public static final Expression.MonadicOperator OP_COM

COM

OP_DISTINCT

public static final Expression.MonadicOperator OP_DISTINCT

DISTINCT

Constructor Details

Expression

protected Expression()

Constructor.

Expression

protected Expression(Expression.MonadicOperator op,
 Expression operand)

Perform a function op on operand

Parameters:

op - operator

operand - operand

Expression

protected Expression(Expression operand1,
 Expression.DyadicOperator op,
 Expression operand2)

Performs a function on two arguments. op(operand1,operand2) operand1 op operand2

Parameters:

operand1 - the first expression

op - the operator between operands

operand2 - the second expression

Method Details

getParent

public Expression getParent()

Accessor for the parent expression where this expression is access from.

Returns:

Parent expression

setLeft

public void setLeft(Expression expr)

setRight

public void setRight(Expression expr)

getOperator

public Expression.Operator getOperator()

The operator to be performed by this expression. See the OP_{name} final static properties of this class.

Returns:

Operator

getLeft

public Expression getLeft()

Accessor for the left hand expression.

Returns:

Left expression

getRight

public Expression getRight()

Accessor for the right hand expression.

Returns:

Right expression

getSymbol

public Symbol getSymbol()

Accessor for the symbol for this expression (if set).

Returns:

The symbol

setAlias

public void setAlias(String alias)

getAlias

public String getAlias()

evaluate

public Object evaluate(ExpressionEvaluator eval)

Method to evaluate this expression, using the passed evaluator.

Parameters:

eval - Evaluator

Returns:

The result

bind

public abstract Symbol bind(SymbolTable symtbl)

Method to bind the expression to the symbol table as appropriate.

Parameters:

symtbl - Symbol table

Returns:

The symbol for this expression