org.vanilladb.core.sql.predicate

Class Term

java.lang.Object

org.vanilladb.core.sql.predicate.Term

public class Term
extends Object

A comparison between two expressions.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Term.Operator

Field Summary

Fields

Modifier and Type	Field and Description
static Term.Operator	OP_EQ
static Term.Operator	OP_GT
static Term.Operator	OP_GTE
static Term.Operator	OP_LT
static Term.Operator	OP_LTE

Constructor Summary

Constructors

Constructor and Description
Term(Expression lhs, Term.Operator op, Expression rhs)

Method Summary

Modifier and Type	Method and Description
boolean	isApplicableTo(Schema sch) Returns true if both expressions of this term apply to the specified schema.
boolean	isSatisfied(Record rec) Returns true if, given the specified record, the two expressions evaluate to matching values.
Term.Operator	operator(String fldName) Determines if this term is of the form "F<OP>E" where F is the specified field, <OP> is an operator, and E is an expression.
Constant	oppositeConstant(String fldName) Determines if this term is of the form "F<OP>C" where F is the specified field, <OP> is an operator, and C is some constant.
String	oppositeField(String fldName) Determines if this term is of the form "F1<OP>F2" where F1 is the specified field, <OP> is an operator, and F2 is another field.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

OP_EQ

public static final Term.Operator OP_EQ

OP_LT

public static final Term.Operator OP_LT

OP_LTE

public static final Term.Operator OP_LTE

OP_GT

public static final Term.Operator OP_GT

OP_GTE

public static final Term.Operator OP_GTE

Constructor Detail

Term

public Term(Expression lhs,
            Term.Operator op,
            Expression rhs)

Method Detail

operator

public Term.Operator operator(String fldName)

Determines if this term is of the form "F<OP>E" where F is the specified field, <OP> is an operator, and E is an expression. If so, the method returns <OP>. If not, the method returns null.

Parameters:

fldName - the name of the field

Returns:

either the operator or null

oppositeConstant

public Constant oppositeConstant(String fldName)

Determines if this term is of the form "F<OP>C" where F is the specified field, <OP> is an operator, and C is some constant. If so, the method returns C. If not, the method returns null.

Parameters:

fldName - the name of the field

Returns:

either the constant or null

oppositeField

public String oppositeField(String fldName)

Determines if this term is of the form "F1<OP>F2" where F1 is the specified field, <OP> is an operator, and F2 is another field. If so, the method returns F2. If not, the method returns null.

Parameters:

fldName - the name of F1

Returns:

either the name of the other field, or null

isApplicableTo

public boolean isApplicableTo(Schema sch)

Returns true if both expressions of this term apply to the specified schema.

Parameters:

sch - the schema

Returns:

true if both expressions apply to the schema

isSatisfied

public boolean isSatisfied(Record rec)

Returns true if, given the specified record, the two expressions evaluate to matching values.

Parameters:

rec - the record

Returns:

true if both expressions evaluate to matching values based on the record

toString

public String toString()

Overrides:

toString in class Object