/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.expression;
import org.h2.engine.SessionLocal;
import org.h2.expression.condition.Comparison;
import org.h2.index.IndexCondition;
import org.h2.table.TableFilter;
import org.h2.value.TypeInfo;
import org.h2.value.Value;
import org.h2.value.ValueBoolean;
import org.h2.value.ValueNull;
/**
* An expression representing a constant value.
*/
public class ValueExpression extends Operation0 {
/**
* The expression represents ValueNull.INSTANCE.
*/
public static final ValueExpression NULL = new ValueExpression(ValueNull.INSTANCE);
/**
* This special expression represents the default value. It is used for
* UPDATE statements of the form SET COLUMN = DEFAULT. The value is
* ValueNull.INSTANCE, but should never be accessed.
*/
public static final ValueExpression DEFAULT = new ValueExpression(ValueNull.INSTANCE);
/**
* The expression represents ValueBoolean.TRUE.
*/
public static final ValueExpression TRUE = new ValueExpression(ValueBoolean.TRUE);
/**
* The expression represents ValueBoolean.FALSE.
*/
public static final ValueExpression FALSE = new ValueExpression(ValueBoolean.FALSE);
/**
* The value.
*/
final Value value;
ValueExpression(Value value) {
this.value = value;
}
/**
* Create a new expression with the given value.
*
* @param value the value
* @return the expression
*/
public static ValueExpression get(Value value) {
if (value == ValueNull.INSTANCE) {
return NULL;
}
if (value.getValueType() == Value.BOOLEAN) {
return getBoolean(value.getBoolean());
}
return new ValueExpression(value);
}
/**
* Create a new expression with the given boolean value.
*
* @param value the boolean value
* @return the expression
*/
public static ValueExpression getBoolean(Value value) {
if (value == ValueNull.INSTANCE) {
return TypedValueExpression.UNKNOWN;
}
return getBoolean(value.getBoolean());
}
/**
* Create a new expression with the given boolean value.
*
* @param value the boolean value
* @return the expression
*/
public static ValueExpression getBoolean(boolean value) {
return value ? TRUE : FALSE;
}
@Override
public Value getValue(SessionLocal session) {
return value;
}
@Override
public TypeInfo getType() {
return value.getType();
}
@Override
public void createIndexConditions(SessionLocal session, TableFilter filter) {
if (value.getValueType() == Value.BOOLEAN && !value.getBoolean()) {
filter.addIndexCondition(IndexCondition.get(Comparison.FALSE, null, this));
}
}
@Override
public Expression getNotIfPossible(SessionLocal session) {
if (value == ValueNull.INSTANCE) {
return TypedValueExpression.UNKNOWN;
}
return getBoolean(!value.getBoolean());
}
@Override
public boolean isConstant() {
return true;
}
@Override
public boolean isNullConstant() {
return this == NULL;
}
@Override
public boolean isValueSet() {
return true;
}
@Override
public StringBuilder getUnenclosedSQL(StringBuilder builder, int sqlFlags) {
if (this == DEFAULT) {
builder.append("DEFAULT");
} else {
value.getSQL(builder, sqlFlags);
}
return builder;
}
@Override
public boolean isEverything(ExpressionVisitor visitor) {
return true;
}
@Override
public int getCost() {
return 0;
}
}