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/*
* Copyright 2004-2019 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.condition;
import org.h2.engine.Session;
import org.h2.expression.Expression;
import org.h2.expression.ExpressionVisitor;
import org.h2.expression.ValueExpression;
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;
/**
* Additional condition for index only.
*/
private Expression added;
public ConditionAndOr(int andOrType, Expression left, Expression right) {
if (left == null || right == null) {
DbException.throwInternalError(left + " " + right);
}
this.andOrType = andOrType;
this.left = left;
this.right = right;
}
@Override
public StringBuilder getSQL(StringBuilder builder, boolean alwaysQuote) {
builder.append('(');
left.getSQL(builder, alwaysQuote);
switch (andOrType) {
case AND:
builder.append("\n AND ");
break;
case OR:
builder.append("\n OR ");
break;
default:
throw DbException.throwInternalError("andOrType=" + andOrType);
}
return right.getSQL(builder, alwaysQuote).append(')');
}
@Override
public void createIndexConditions(Session session, TableFilter filter) {
if (andOrType == AND) {
left.createIndexConditions(session, filter);
right.createIndexConditions(session, filter);
if (added != null) {
added.createIndexConditions(session, filter);
}
}
}
@Override
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);
}
@Override
public Value getValue(Session session) {
Value l = left.getValue(session);
Value r;
switch (andOrType) {
case AND: {
if (l != ValueNull.INSTANCE && !l.getBoolean()) {
return ValueBoolean.FALSE;
}
r = right.getValue(session);
if (r != ValueNull.INSTANCE && !r.getBoolean()) {
return ValueBoolean.FALSE;
}
if (l == ValueNull.INSTANCE || r == ValueNull.INSTANCE) {
return ValueNull.INSTANCE;
}
return ValueBoolean.TRUE;
}
case OR: {
if (l.getBoolean()) {
return ValueBoolean.TRUE;
}
r = right.getValue(session);
if (r.getBoolean()) {
return ValueBoolean.TRUE;
}
if (l == ValueNull.INSTANCE || r == ValueNull.INSTANCE) {
return ValueNull.INSTANCE;
}
return ValueBoolean.FALSE;
}
default:
throw DbException.throwInternalError("type=" + andOrType);
}
}
@Override
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;
}
switch (andOrType) {
case AND:
if (!session.getDatabase().getSettings().optimizeTwoEquals) {
break;
}
// 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
// try to add conditions (A=B AND B=1: add A=1)
if (left instanceof Comparison && right instanceof Comparison) {
// try to add conditions (A=B AND B=1: add A=1)
Expression added = ((Comparison) left).getAdditionalAnd(session, (Comparison) right);
if (added != null) {
this.added = added.optimize(session);
}
}
break;
case OR:
if (!session.getDatabase().getSettings().optimizeOr) {
break;
}
Expression reduced;
if (left instanceof Comparison && right instanceof Comparison) {
reduced = ((Comparison) left).optimizeOr(session, (Comparison) right);
} else if (left instanceof ConditionIn && right instanceof Comparison) {
reduced = ((ConditionIn) left).getAdditional((Comparison) right);
} else if (right instanceof ConditionIn && left instanceof Comparison) {
reduced = ((ConditionIn) right).getAdditional((Comparison) left);
} else if (left instanceof ConditionInConstantSet && right instanceof Comparison) {
reduced = ((ConditionInConstantSet) left).getAdditional(session, (Comparison) right);
} else if (right instanceof ConditionInConstantSet && left instanceof Comparison) {
reduced = ((ConditionInConstantSet) right).getAdditional(session, (Comparison) left);
} else if (left instanceof ConditionAndOr && right instanceof ConditionAndOr) {
reduced = optimizeConditionAndOr((ConditionAndOr)left, (ConditionAndOr)right);
} else {
// TODO optimization: convert .. OR .. to UNION if the cost is lower
break;
}
if (reduced != null) {
return reduced.optimize(session);
}
}
return optimizeConstant(session, this, andOrType, left, right);
}
/**
* Optimize the expression if at least one part is constant.
*
* @param session the session
* @param condition the condition
* @param andOrType the type
* @param left the left part of the condition
* @param right the right part of the condition
* @return the optimized expression
*/
static Expression optimizeConstant(Session session, Expression condition, int andOrType, Expression left,
Expression right) {
Value l = left.isConstant() ? left.getValue(session) : null;
Value r = right.isConstant() ? right.getValue(session) : null;
if (l == null && r == null) {
return condition;
}
if (l != null && r != null) {
return ValueExpression.getBoolean(condition.getValue(session));
}
switch (andOrType) {
case AND:
if (l != null) {
if (l != ValueNull.INSTANCE && !l.getBoolean()) {
return ValueExpression.getBoolean(false);
} else if (l.getBoolean()) {
return castToBoolean(session, right);
}
} else if (r != null) {
if (r != ValueNull.INSTANCE && !r.getBoolean()) {
return ValueExpression.getBoolean(false);
} else if (r.getBoolean()) {
return castToBoolean(session, left);
}
}
break;
case OR:
if (l != null) {
if (l.getBoolean()) {
return ValueExpression.getBoolean(true);
} else if (l != ValueNull.INSTANCE) {
return castToBoolean(session, right);
}
} else if (r != null) {
if (r.getBoolean()) {
return ValueExpression.getBoolean(true);
} else if (r != ValueNull.INSTANCE) {
return castToBoolean(session, left);
}
}
break;
default:
DbException.throwInternalError("type=" + andOrType);
}
return condition;
}
@Override
public void addFilterConditions(TableFilter filter) {
if (andOrType == AND) {
left.addFilterConditions(filter);
right.addFilterConditions(filter);
} else {
super.addFilterConditions(filter);
}
}
@Override
public void mapColumns(ColumnResolver resolver, int level, int state) {
left.mapColumns(resolver, level, state);
right.mapColumns(resolver, level, state);
}
@Override
public void setEvaluatable(TableFilter tableFilter, boolean b) {
left.setEvaluatable(tableFilter, b);
right.setEvaluatable(tableFilter, b);
}
@Override
public void updateAggregate(Session session, int stage) {
left.updateAggregate(session, stage);
right.updateAggregate(session, stage);
}
@Override
public boolean isEverything(ExpressionVisitor visitor) {
return left.isEverything(visitor) && right.isEverything(visitor);
}
@Override
public int getCost() {
return left.getCost() + right.getCost();
}
@Override
public int getSubexpressionCount() {
return 2;
}
@Override
public Expression getSubexpression(int index) {
switch (index) {
case 0:
return left;
case 1:
return right;
default:
throw new IndexOutOfBoundsException();
}
}
/**
* Optimize query according to the given condition. Example:
* (A AND B) OR (C AND B), the new condition B AND (A OR C) is returned
*
* @param left the session
* @param right the second condition
* @return null or the third condition
*/
private static Expression optimizeConditionAndOr(ConditionAndOr left, ConditionAndOr right) {
if (left.andOrType != AND || right.andOrType != AND) {
return null;
}
Expression leftLeft = left.getSubexpression(0), leftRight = left.getSubexpression(1);
Expression rightLeft = right.getSubexpression(0), rightRight = right.getSubexpression(1);
String leftLeftSQL = leftLeft.getSQL(true), rightLeftSQL = rightLeft.getSQL(true);
Expression combinedExpression;
if (leftLeftSQL.equals(rightLeftSQL)) {
combinedExpression = new ConditionAndOr(OR, leftRight, rightRight);
return new ConditionAndOr(AND, leftLeft, combinedExpression);
}
String rightRightSQL = rightRight.getSQL(true);
if (leftLeftSQL.equals(rightRightSQL)) {
combinedExpression = new ConditionAndOr(OR, leftRight, rightLeft);
return new ConditionAndOr(AND, leftLeft, combinedExpression);
}
String leftRightSQL = leftRight.getSQL(true);
if (leftRightSQL.equals(rightLeftSQL)) {
combinedExpression = new ConditionAndOr(OR, leftLeft, rightRight);
return new ConditionAndOr(AND, leftRight, combinedExpression);
} else if (leftRightSQL.equals(rightRightSQL)) {
combinedExpression = new ConditionAndOr(OR, leftLeft, rightLeft);
return new ConditionAndOr(AND, leftRight, combinedExpression);
}
return null;
}
}
