/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.phoenix.expression.function;
import java.io.DataInput;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.LiteralExpression;
import org.apache.phoenix.parse.FunctionParseNode.Argument;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.schema.PDataType;
import org.apache.phoenix.schema.SortOrder;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.util.StringUtil;
/**
*
* Implementation of the SUBSTR(<string>,<offset>[,<length>]) built-in function
* where <offset> is the offset from the start of <string>. A positive offset
* is treated as 1-based, a zero offset is treated as 0-based, and a negative
* offset starts from the end of the string working backwards. The optional
* <length> argument is the number of characters to return. In the absence of the
* <length> argument, the rest of the string starting from <offset> is returned.
* If <length> is less than 1, null is returned.
*
*
* @since 0.1
*/
@BuiltInFunction(name=SubstrFunction.NAME, args={
@Argument(allowedTypes={PDataType.VARCHAR}),
@Argument(allowedTypes={PDataType.LONG}), // These are LONG because negative numbers end up as longs
@Argument(allowedTypes={PDataType.LONG},defaultValue="null")} )
public class SubstrFunction extends PrefixFunction {
public static final String NAME = "SUBSTR";
private boolean hasLengthExpression;
private boolean isOffsetConstant;
private boolean isLengthConstant;
private boolean isFixedWidth;
private Integer maxLength;
public SubstrFunction() {
}
public SubstrFunction(List<Expression> children) {
super(children);
init();
}
private void init() {
isOffsetConstant = getOffsetExpression() instanceof LiteralExpression;
isLengthConstant = getLengthExpression() instanceof LiteralExpression;
hasLengthExpression = !isLengthConstant || ((LiteralExpression)getLengthExpression()).getValue() != null;
isFixedWidth = getStrExpression().getDataType().isFixedWidth() && ((hasLengthExpression && isLengthConstant) || (!hasLengthExpression && isOffsetConstant));
if (hasLengthExpression && isLengthConstant) {
Integer maxLength = ((Number)((LiteralExpression)getLengthExpression()).getValue()).intValue();
this.maxLength = maxLength >= 0 ? maxLength : 0;
} else if (isOffsetConstant) {
Number offsetNumber = (Number)((LiteralExpression)getOffsetExpression()).getValue();
if (offsetNumber != null) {
int offset = offsetNumber.intValue();
PDataType type = getStrExpression().getDataType();
if (type.isFixedWidth()) {
if (offset >= 0) {
Integer maxLength = getStrExpression().getMaxLength();
this.maxLength = maxLength - offset + (offset == 0 ? 0 : 1);
} else {
this.maxLength = -offset;
}
}
}
}
}
@Override
public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
Expression offsetExpression = getOffsetExpression();
if (!offsetExpression.evaluate(tuple, ptr)) {
return false;
}
int offset = offsetExpression.getDataType().getCodec().decodeInt(ptr, offsetExpression.getSortOrder());
int length = -1;
if (hasLengthExpression) {
Expression lengthExpression = getLengthExpression();
if (!lengthExpression.evaluate(tuple, ptr)) {
return false;
}
length = lengthExpression.getDataType().getCodec().decodeInt(ptr, lengthExpression.getSortOrder());
if (length <= 0) {
return false;
}
}
if (!getStrExpression().evaluate(tuple, ptr)) {
return false;
}
boolean isCharType = getStrExpression().getDataType() == PDataType.CHAR;
SortOrder sortOrder = getStrExpression().getSortOrder();
int strlen = isCharType ? ptr.getLength() : StringUtil.calculateUTF8Length(ptr.get(), ptr.getOffset(), ptr.getLength(), sortOrder);
// Account for 1 versus 0-based offset
offset = offset - (offset <= 0 ? 0 : 1);
if (offset < 0) { // Offset < 0 means get from end
offset = strlen + offset;
}
if (offset < 0 || offset >= strlen) {
return false;
}
int maxLength = strlen - offset;
length = length == -1 ? maxLength : Math.min(length,maxLength);
int byteOffset = isCharType ? offset : StringUtil.getByteLengthForUtf8SubStr(ptr.get(), ptr.getOffset(), offset, sortOrder);
int byteLength = isCharType ? length : StringUtil.getByteLengthForUtf8SubStr(ptr.get(), ptr.getOffset() + byteOffset, length, sortOrder);
ptr.set(ptr.get(), ptr.getOffset() + byteOffset, byteLength);
return true;
}
@Override
public PDataType getDataType() {
// If fixed width, then return child expression type.
// If not fixed width, then we don't know how big this will be across the board
return isFixedWidth ? getStrExpression().getDataType() : PDataType.VARCHAR;
}
@Override
public boolean isNullable() {
return getStrExpression().isNullable() || !isFixedWidth || getOffsetExpression().isNullable();
}
@Override
public Integer getMaxLength() {
return maxLength;
}
@Override
public SortOrder getSortOrder() {
return getStrExpression().getSortOrder();
}
@Override
public void readFields(DataInput input) throws IOException {
super.readFields(input);
init();
}
private Expression getStrExpression() {
return children.get(0);
}
private Expression getOffsetExpression() {
return children.get(1);
}
private Expression getLengthExpression() {
return children.get(2);
}
@Override
public OrderPreserving preservesOrder() {
if (isOffsetConstant) {
LiteralExpression literal = (LiteralExpression) getOffsetExpression();
Number offsetNumber = (Number) literal.getValue();
if (offsetNumber != null) {
int offset = offsetNumber.intValue();
if ((offset == 0 || offset == 1) && (!hasLengthExpression || isLengthConstant)) {
return OrderPreserving.YES_IF_LAST;
}
}
}
return OrderPreserving.NO;
}
@Override
protected boolean extractNode() {
return true;
}
@Override
public String getName() {
return NAME;
}
}