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package com.salesforce.phoenix.expression.function;
import java.io.UnsupportedEncodingException;
import java.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import com.salesforce.phoenix.expression.Expression;
import com.salesforce.phoenix.parse.FunctionParseNode.Argument;
import com.salesforce.phoenix.parse.FunctionParseNode.BuiltInFunction;
import com.salesforce.phoenix.schema.PDataType;
import com.salesforce.phoenix.schema.tuple.Tuple;
import com.salesforce.phoenix.util.ByteUtil;
import com.salesforce.phoenix.util.StringUtil;
/**
*
* Implementation of the LENGTH(<string>) build-in function. <string> is the string
* of characters we want to find the length of. If <string> is NULL or empty, null
* is returned.
*
* @author zhuang
* @since 0.1
*/
@BuiltInFunction(name=LengthFunction.NAME, args={
@Argument(allowedTypes={PDataType.VARCHAR})} )
public class LengthFunction extends ScalarFunction {
public static final String NAME = "LENGTH";
public LengthFunction() { }
public LengthFunction(List<Expression> children) throws SQLException {
super(children);
}
private Expression getStringExpression() {
return children.get(0);
}
@Override
public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
Expression child = getStringExpression();
if (!child.evaluate(tuple, ptr)) {
return false;
}
if (ptr.getLength() == 0) {
ptr.set(ByteUtil.EMPTY_BYTE_ARRAY);
return true;
}
int len;
if (child.getDataType() == PDataType.CHAR) {
// Only single-byte characters allowed in CHAR
len = ptr.getLength();
} else {
try {
len = StringUtil.calculateUTF8Length(ptr.get(), ptr.getOffset(), ptr.getLength(), child.getColumnModifier());
} catch (UnsupportedEncodingException e) {
return false;
}
}
ptr.set(PDataType.INTEGER.toBytes(len));
return true;
}
@Override
public PDataType getDataType() {
return PDataType.INTEGER;
}
@Override
public String getName() {
return NAME;
}
}