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package com.salesforce.phoenix.expression.function;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.io.WritableUtils;
import com.google.common.collect.Lists;
import com.salesforce.phoenix.expression.Expression;
import com.salesforce.phoenix.expression.LiteralExpression;
import com.salesforce.phoenix.schema.IllegalDataException;
import com.salesforce.phoenix.schema.PDataType;
import com.salesforce.phoenix.schema.tuple.Tuple;
/**
*
* Class encapsulating the process for rounding off a column/literal of
* type {@link com.salesforce.phoenix.schema.PDataType#DECIMAL}
*
* @author samarth.jain
* @since 3.0.0
*/
public class RoundDecimalExpression extends ScalarFunction {
private int scale;
/**
* Creates a {@link RoundDecimalExpression} with rounding scale given by @param scale.
*
*/
public static Expression create(Expression expr, int scale) throws SQLException {
if (expr.getDataType().isCoercibleTo(PDataType.LONG)) {
return expr;
}
Expression scaleExpr = LiteralExpression.newConstant(scale, PDataType.INTEGER, true);
List<Expression> expressions = Lists.newArrayList(expr, scaleExpr);
return new RoundDecimalExpression(expressions);
}
/**
* Creates a {@link RoundDecimalExpression} with a default scale of 0 used for rounding.
*
*/
public static Expression create(Expression expr) throws SQLException {
return create(expr, 0);
}
public RoundDecimalExpression() {}
public RoundDecimalExpression(List<Expression> children) {
super(children);
LiteralExpression scaleChild = (LiteralExpression)children.get(1);
PDataType scaleType = scaleChild.getDataType();
Object scaleValue = scaleChild.getValue();
if(scaleValue != null) {
if (scaleType.isCoercibleTo(PDataType.INTEGER, scaleValue)) {
int scale = (Integer)PDataType.INTEGER.toObject(scaleValue, scaleType);
if (scale >=0 && scale <= PDataType.MAX_PRECISION) {
this.scale = scale;
return;
}
}
throw new IllegalDataException("Invalid second argument for scale: " + scaleValue + ". The scale must be between 0 and " + PDataType.MAX_PRECISION + " inclusive.");
}
}
@Override
public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
Expression childExpr = children.get(0);
if(childExpr.evaluate(tuple, ptr)) {
BigDecimal value = (BigDecimal)PDataType.DECIMAL.toObject(ptr, childExpr.getColumnModifier());
BigDecimal scaledValue = value.setScale(scale, getRoundingMode());
ptr.set(getDataType().toBytes(scaledValue));
return true;
}
return false;
}
@Override
public PDataType getDataType() {
return children.get(0).getDataType();
}
protected RoundingMode getRoundingMode() {
return RoundingMode.HALF_UP;
}
@Override
public void readFields(DataInput input) throws IOException {
super.readFields(input);
scale = WritableUtils.readVInt(input);
}
@Override
public void write(DataOutput output) throws IOException {
super.write(output);
WritableUtils.writeVInt(output, scale);
}
@Override
public String getName() {
return RoundFunction.NAME;
}
@Override
public OrderPreserving preservesOrder() {
return OrderPreserving.YES;
}
}