ConditionNot.java

/*
 * Copyright 2014-2015 the original author or authors
 *
 * Licensed under the Apache License, Version 2.0 (the “License”);
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an “AS IS” BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.wplatform.ddal.command.expression;

import java.util.List;

import com.wplatform.ddal.dbobject.table.ColumnResolver;
import com.wplatform.ddal.dbobject.table.TableFilter;
import com.wplatform.ddal.engine.Session;
import com.wplatform.ddal.value.Value;
import com.wplatform.ddal.value.ValueNull;

/**
 * A NOT condition.
 */
public class ConditionNot extends Condition {

    private Expression condition;

    public ConditionNot(Expression condition) {
        this.condition = condition;
    }

    @Override
    public Expression getNotIfPossible(Session session) {
        return condition;
    }

    @Override
    public Value getValue(Session session) {
        Value v = condition.getValue(session);
        if (v == ValueNull.INSTANCE) {
            return v;
        }
        return v.convertTo(Value.BOOLEAN).negate();
    }

    @Override
    public void mapColumns(ColumnResolver resolver, int level) {
        condition.mapColumns(resolver, level);
    }

    @Override
    public Expression optimize(Session session) {
        Expression e2 = condition.getNotIfPossible(session);
        if (e2 != null) {
            return e2.optimize(session);
        }
        Expression expr = condition.optimize(session);
        if (expr.isConstant()) {
            Value v = expr.getValue(session);
            if (v == ValueNull.INSTANCE) {
                return ValueExpression.getNull();
            }
            return ValueExpression.get(v.convertTo(Value.BOOLEAN).negate());
        }
        condition = expr;
        return this;
    }

    @Override
    public void setEvaluatable(TableFilter tableFilter, boolean b) {
        condition.setEvaluatable(tableFilter, b);
    }

    @Override
    public String getSQL() {
        return "(NOT " + condition.getSQL() + ")";
    }

    @Override
    public void updateAggregate(Session session) {
        condition.updateAggregate(session);
    }

    @Override
    public void addFilterConditions(TableFilter filter, boolean outerJoin) {
        if (outerJoin) {
            // can not optimize:
            // select * from test t1 left join test t2 on t1.id = t2.id where
            // not t2.id is not null
            // to
            // select * from test t1 left join test t2 on t1.id = t2.id and
            // t2.id is not null
            return;
        }
        super.addFilterConditions(filter, outerJoin);
    }

    @Override
    public boolean isEverything(ExpressionVisitor visitor) {
        return condition.isEverything(visitor);
    }

    @Override
    public int getCost() {
        return condition.getCost();
    }

    @Override
    public String exportParameters(TableFilter filter, List<Value> container) {
        return "(NOT " + condition.exportParameters(filter, container) + ")";
    }

}