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package com.salesforce.phoenix.expression.function;
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.ColumnModifier;
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 LTrim(<string>) build-in function. It removes from the left end of
* <string> space character and other function bytes in single byte utf8 characters
* set.
*
* @author zhuang
* @since 0.1
*/
@BuiltInFunction(name=LTrimFunction.NAME, args={
@Argument(allowedTypes={PDataType.VARCHAR})})
public class LTrimFunction extends ScalarFunction {
public static final String NAME = "LTRIM";
private Integer byteSize;
public LTrimFunction() { }
public LTrimFunction(List<Expression> children) throws SQLException {
super(children);
if (getStringExpression().getDataType().isFixedWidth()) {
byteSize = getStringExpression().getByteSize();
}
}
private Expression getStringExpression() {
return children.get(0);
}
@Override
public ColumnModifier getColumnModifier() {
return children.get(0).getColumnModifier();
}
@Override
public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
// Starting from the front of the byte, look for all single bytes at the end of the string
// that is below SPACE_UTF8 (space and control characters) or 0x7f (control chars).
if (!getStringExpression().evaluate(tuple, ptr)) {
return false;
}
if (ptr.getLength() == 0) {
ptr.set(ByteUtil.EMPTY_BYTE_ARRAY);
return true;
}
byte[] string = ptr.get();
int offset = ptr.getOffset();
int length = ptr.getLength();
ColumnModifier columnModifier = getStringExpression().getColumnModifier();
// TODO: when we have ColumnModifier.REVERSE, we'll need to trim from the end instead of
// the beginning (just delegate to RTrimFunction or replace from ExpressionCompiler instead?)
int i = StringUtil.getFirstNonBlankCharIdxFromStart(string, offset, length, columnModifier);
if (i == offset + length) {
ptr.set(ByteUtil.EMPTY_BYTE_ARRAY);
return true;
}
ptr.set(string, i, offset + length - i);
return true;
}
@Override
public Integer getByteSize() {
return byteSize;
}
@Override
public PDataType getDataType() {
return PDataType.VARCHAR;
}
@Override
public String getName() {
return NAME;
}
}