?? sequencevalue.java
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/*
* Copyright 2004-2008 H2 Group. Licensed under the H2 License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.expression;
import java.sql.SQLException;
import org.h2.engine.Session;
import org.h2.message.Message;
import org.h2.schema.Sequence;
import org.h2.table.ColumnResolver;
import org.h2.table.TableFilter;
import org.h2.value.Value;
import org.h2.value.ValueInt;
import org.h2.value.ValueLong;
/**
* Wraps a sequence when used in a statement.
*/
public class SequenceValue extends Expression {
private Sequence sequence;
public SequenceValue(Sequence sequence) {
this.sequence = sequence;
}
public Value getValue(Session session) throws SQLException {
long value = sequence.getNext();
session.setLastIdentity(ValueLong.get(value));
return ValueLong.get(value);
}
public int getType() {
return Value.LONG;
}
public void mapColumns(ColumnResolver resolver, int level) {
// nothing to do
}
public void checkMapped() {
// nothing to do
}
public Expression optimize(Session session) {
return this;
}
public void setEvaluatable(TableFilter tableFilter, boolean b) {
// nothing to do
}
public int getScale() {
return 0;
}
public long getPrecision() {
return ValueInt.PRECISION;
}
public int getDisplaySize() {
return ValueInt.DISPLAY_SIZE;
}
public String getSQL() {
return "(NEXT VALUE FOR " + sequence.getSQL() +")";
}
public void updateAggregate(Session session) {
// nothing to do
}
public boolean isEverything(ExpressionVisitor visitor) {
switch(visitor.type) {
case ExpressionVisitor.OPTIMIZABLE_MIN_MAX_COUNT_ALL:
return true;
case ExpressionVisitor.DETERMINISTIC:
case ExpressionVisitor.READONLY:
return false;
case ExpressionVisitor.INDEPENDENT:
return false;
case ExpressionVisitor.EVALUATABLE:
return true;
case ExpressionVisitor.SET_MAX_DATA_MODIFICATION_ID:
visitor.addDataModificationId(sequence.getModificationId());
return true;
case ExpressionVisitor.NOT_FROM_RESOLVER:
return true;
case ExpressionVisitor.GET_DEPENDENCIES:
visitor.addDependency(sequence);
return true;
default:
throw Message.getInternalError("type="+visitor.type);
}
}
public int getCost() {
return 1;
}
}
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