/*
* 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.api.ErrorCode;
import org.h2.engine.SessionLocal;
import org.h2.message.DbException;
import org.h2.mvstore.db.Store;
import org.h2.util.json.JSONArray;
import org.h2.util.json.JSONValue;
import org.h2.value.TypeInfo;
import org.h2.value.Value;
import org.h2.value.ValueArray;
import org.h2.value.ValueJson;
import org.h2.value.ValueNull;
/**
* Array element reference.
*/
public final class ArrayElementReference extends Operation2 {
public ArrayElementReference(Expression left, Expression right) {
super(left, right);
}
@Override
public StringBuilder getUnenclosedSQL(StringBuilder builder, int sqlFlags) {
left.getSQL(builder, sqlFlags, AUTO_PARENTHESES).append('[');
return right.getUnenclosedSQL(builder, sqlFlags).append(']');
}
@Override
public Value getValue(SessionLocal session) {
Value l = left.getValue(session);
Value r = right.getValue(session);
if (l != ValueNull.INSTANCE && r != ValueNull.INSTANCE) {
int element = r.getInt();
if (left.getType().getValueType() == Value.ARRAY) {
Value[] list = ((ValueArray) l).getList();
int cardinality = list.length;
if (element >= 1 && element <= cardinality) {
return list[element - 1];
}
throw DbException.get(ErrorCode.ARRAY_ELEMENT_ERROR_2, Integer.toString(element), "1.." + cardinality);
} else {
JSONValue value = l.convertToAnyJson().getDecomposition();
if (value instanceof JSONArray) {
JSONValue jsonValue = ((JSONArray) value).getElement(element - 1);
if (jsonValue != null) {
return ValueJson.fromJson(jsonValue);
}
}
}
}
return ValueNull.INSTANCE;
}
@Override
public Expression optimize(SessionLocal session) {
left = left.optimize(session);
right = right.optimize(session);
TypeInfo leftType = left.getType();
switch (leftType.getValueType()) {
case Value.NULL:
return ValueExpression.NULL;
case Value.JSON:
type = TypeInfo.TYPE_JSON;
if (left.isConstant() && right.isConstant()) {
return TypedValueExpression.getTypedIfNull(getValue(session), type);
}
break;
case Value.ARRAY:
type = (TypeInfo) leftType.getExtTypeInfo();
if (left.isConstant() && right.isConstant()) {
return TypedValueExpression.get(getValue(session), type);
}
break;
default:
throw Store.getInvalidExpressionTypeException("Array", left);
}
return this;
}
}