/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.expression;
import org.h2.constant.SysProperties;
import org.h2.engine.Session;
import org.h2.message.DbException;
import org.h2.table.ColumnResolver;
import org.h2.table.TableFilter;
import org.h2.value.Value;
import org.h2.value.ValueBoolean;
import org.h2.value.ValueNull;
/**
* An 'and' or 'or' condition as in WHERE ID=1 AND NAME=?
*/
public class ConditionAndOr extends Condition {
/**
* The AND condition type as in ID=1 AND NAME='Hello'.
*/
public static final int AND = 0;
/**
* The OR condition type as in ID=1 OR NAME='Hello'.
*/
public static final int OR = 1;
private final int andOrType;
private Expression left, right;
public ConditionAndOr(int andOrType, Expression left, Expression right) {
this.andOrType = andOrType;
this.left = left;
this.right = right;
if (SysProperties.CHECK && (left == null || right == null)) {
DbException.throwInternalError();
}
}
public String getSQL() {
String sql;
switch (andOrType) {
case AND:
sql = left.getSQL() + "\n AND " + right.getSQL();
break;
case OR:
sql = left.getSQL() + "\n OR " + right.getSQL();
break;
default:
throw DbException.throwInternalError("andOrType=" + andOrType);
}
return "(" + sql + ")";
}
public void createIndexConditions(Session session, TableFilter filter) {
if (andOrType == AND) {
left.createIndexConditions(session, filter);
right.createIndexConditions(session, filter);
}
}
public Expression getNotIfPossible(Session session) {
// (NOT (A OR B)): (NOT(A) AND NOT(B))
// (NOT (A AND B)): (NOT(A) OR NOT(B))
Expression l = left.getNotIfPossible(session);
if (l == null) {
l = new ConditionNot(left);
}
Expression r = right.getNotIfPossible(session);
if (r == null) {
r = new ConditionNot(right);
}
int reversed = andOrType == AND ? OR : AND;
return new ConditionAndOr(reversed, l, r);
}
public Value getValue(Session session) {
Value l = left.getValue(session);
Value r;
switch (andOrType) {
case AND: {
if (Boolean.FALSE.equals(l.getBoolean())) {
return l;
}
r = right.getValue(session);
if (Boolean.FALSE.equals(r.getBoolean())) {
return r;
}
if (l == ValueNull.INSTANCE) {
return l;
}
if (r == ValueNull.INSTANCE) {
return r;
}
return ValueBoolean.get(true);
}
case OR: {
if (Boolean.TRUE.equals(l.getBoolean())) {
return l;
}
r = right.getValue(session);
if (Boolean.TRUE.equals(r.getBoolean())) {
return r;
}
if (l == ValueNull.INSTANCE) {
return l;
}
if (r == ValueNull.INSTANCE) {
return r;
}
return ValueBoolean.get(false);
}
default:
throw DbException.throwInternalError("type=" + andOrType);
}
}
public Expression optimize(Session session) {
// NULL handling: see wikipedia,
// http://www-cs-students.stanford.edu/~wlam/compsci/sqlnulls
left = left.optimize(session);
right = right.optimize(session);
int lc = left.getCost(), rc = right.getCost();
if (rc < lc) {
Expression t = left;
left = right;
right = t;
}
// this optimization does not work in the following case,
// but NOT is optimized before:
// CREATE TABLE TEST(A INT, B INT);
// INSERT INTO TEST VALUES(1, NULL);
// SELECT * FROM TEST WHERE NOT (B=A AND B=0); // no rows
// SELECT * FROM TEST WHERE NOT (B=A AND B=0 AND A=0); // 1, NULL
if (session.getDatabase().getSettings().optimizeTwoEquals && andOrType == AND) {
// try to add conditions (A=B AND B=1: add A=1)
if (left instanceof Comparison && right instanceof Comparison) {
Comparison compLeft = (Comparison) left;
Comparison compRight = (Comparison) right;
Expression added = compLeft.getAdditional(session, compRight, true);
if (added != null) {
added = added.optimize(session);
ConditionAndOr a = new ConditionAndOr(AND, this, added);
return a;
}
}
}
// TODO optimization: convert ((A=1 AND B=2) OR (A=1 AND B=3)) to
// (A=1 AND (B=2 OR B=3))
if (andOrType == OR && session.getDatabase().getSettings().optimizeOr) {
// try to add conditions (A=B AND B=1: add A=1)
if (left instanceof Comparison && right instanceof Comparison) {
Comparison compLeft = (Comparison) left;
Comparison compRight = (Comparison) right;
Expression added = compLeft.getAdditional(session, compRight, false);
if (added != null) {
return added.optimize(session);
}
} else if (left instanceof ConditionIn && right instanceof Comparison) {
Expression added = ((ConditionIn) left).getAdditional(session, (Comparison) right);
if (added != null) {
return added.optimize(session);
}
} else if (right instanceof ConditionIn && left instanceof Comparison) {
Expression added = ((ConditionIn) right).getAdditional(session, (Comparison) left);
if (added != null) {
return added.optimize(session);
}
}
}
// TODO optimization: convert .. OR .. to UNION if the cost is lower
Value l = left.isConstant() ? left.getValue(session) : null;
Value r = right.isConstant() ? right.getValue(session) : null;
if (l == null && r == null) {
return this;
}
if (l != null && r != null) {
return ValueExpression.get(getValue(session));
}
switch (andOrType) {
case AND:
if (l != null) {
if (Boolean.FALSE.equals(l.getBoolean())) {
return ValueExpression.get(l);
} else if (Boolean.TRUE.equals(l.getBoolean())) {
return right;
}
} else if (r != null) {
if (Boolean.FALSE.equals(r.getBoolean())) {
return ValueExpression.get(r);
} else if (Boolean.TRUE.equals(r.getBoolean())) {
return left;
}
}
break;
case OR:
if (l != null) {
if (Boolean.TRUE.equals(l.getBoolean())) {
return ValueExpression.get(l);
} else if (Boolean.FALSE.equals(l.getBoolean())) {
return right;
}
} else if (r != null) {
if (Boolean.TRUE.equals(r.getBoolean())) {
return ValueExpression.get(r);
} else if (Boolean.FALSE.equals(r.getBoolean())) {
return left;
}
}
break;
default:
DbException.throwInternalError("type=" + andOrType);
}
return this;
}
public void addFilterConditions(TableFilter filter, boolean outerJoin) {
if (andOrType == AND) {
left.addFilterConditions(filter, outerJoin);
right.addFilterConditions(filter, outerJoin);
} else {
super.addFilterConditions(filter, outerJoin);
}
}
public void mapColumns(ColumnResolver resolver, int level) {
left.mapColumns(resolver, level);
right.mapColumns(resolver, level);
}
public void setEvaluatable(TableFilter tableFilter, boolean b) {
left.setEvaluatable(tableFilter, b);
right.setEvaluatable(tableFilter, b);
}
public void updateAggregate(Session session) {
left.updateAggregate(session);
right.updateAggregate(session);
}
public boolean isEverything(ExpressionVisitor visitor) {
return left.isEverything(visitor) && right.isEverything(visitor);
}
public int getCost() {
return left.getCost() + right.getCost();
}
/**
* Get the left or the right sub-expression of this condition.
*
* @param getLeft true to get the left sub-expression, false to get the right
* sub-expression.
* @return the sub-expression
*/
public Expression getExpression(boolean getLeft) {
return getLeft ? this.left : right;
}
}