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this work for additional information regarding copyright ownership.
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(the "License"); you may not use this file except in compliance with
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package org.apache.poi.ss.formula.functions;
import org.apache.poi.ss.formula.eval.AreaEval;
import org.apache.poi.ss.formula.eval.ErrorEval;
import org.apache.poi.ss.formula.eval.EvaluationException;
import org.apache.poi.ss.formula.eval.MissingArgEval;
import org.apache.poi.ss.formula.eval.OperandResolver;
import org.apache.poi.ss.formula.eval.RefEval;
import org.apache.poi.ss.formula.eval.ValueEval;
/**
* Implementation for Excel function OFFSET()
*
* OFFSET returns an area reference that is a specified number of rows and columns from a
* reference cell or area.
*
* Syntax:
* OFFSET(reference, rows, cols, height, width)
* reference is the base reference.
* rows is the number of rows up or down from the base reference.
* cols is the number of columns left or right from the base reference.
* height (default same height as base reference) is the row count for the returned area reference.
* width (default same width as base reference) is the column count for the returned area reference.
*
* @author Josh Micich
*/
public final class Offset implements Function {
// These values are specific to BIFF8
private static final int LAST_VALID_ROW_INDEX = 0xFFFF;
private static final int LAST_VALID_COLUMN_INDEX = 0xFF;
/**
* A one dimensional base + offset. Represents either a row range or a column range.
* Two instances of this class together specify an area range.
*/
/* package */ static final class LinearOffsetRange {
private final int _offset;
private final int _length;
public LinearOffsetRange(int offset, int length) {
if(length == 0) {
// handled that condition much earlier
throw new RuntimeException("length may not be zero");
}
_offset = offset;
_length = length;
}
public short getFirstIndex() {
return (short) _offset;
}
public short getLastIndex() {
return (short) (_offset + _length - 1);
}
/**
* Moves the range by the specified translation amount.
*
* This method also 'normalises' the range: Excel specifies that the width and height
* parameters (length field here) cannot be negative. However, OFFSET() does produce
* sensible results in these cases. That behavior is replicated here.
*
* @param translationAmount may be zero negative or positive
*
* @return the equivalent LinearOffsetRange with a positive length, moved by the
* specified translationAmount.
*/
public LinearOffsetRange normaliseAndTranslate(int translationAmount) {
if (_length > 0) {
if(translationAmount == 0) {
return this;
}
return new LinearOffsetRange(translationAmount + _offset, _length);
}
return new LinearOffsetRange(translationAmount + _offset + _length + 1, -_length);
}
public boolean isOutOfBounds(int lowValidIx, int highValidIx) {
if(_offset < lowValidIx) {
return true;
}
if(getLastIndex() > highValidIx) {
return true;
}
return false;
}
public String toString() {
StringBuilder sb = new StringBuilder(64);
sb.append(getClass().getName()).append(" [");
sb.append(_offset).append("...").append(getLastIndex());
sb.append("]");
return sb.toString();
}
}
/**
* Encapsulates either an area or cell reference which may be 2d or 3d.
*/
private static final class BaseRef {
private final int _firstRowIndex;
private final int _firstColumnIndex;
private final int _width;
private final int _height;
private final RefEval _refEval;
private final AreaEval _areaEval;
public BaseRef(RefEval re) {
_refEval = re;
_areaEval = null;
_firstRowIndex = re.getRow();
_firstColumnIndex = re.getColumn();
_height = 1;
_width = 1;
}
public BaseRef(AreaEval ae) {
_refEval = null;
_areaEval = ae;
_firstRowIndex = ae.getFirstRow();
_firstColumnIndex = ae.getFirstColumn();
_height = ae.getLastRow() - ae.getFirstRow() + 1;
_width = ae.getLastColumn() - ae.getFirstColumn() + 1;
}
public int getWidth() {
return _width;
}
public int getHeight() {
return _height;
}
public int getFirstRowIndex() {
return _firstRowIndex;
}
public int getFirstColumnIndex() {
return _firstColumnIndex;
}
public AreaEval offset(int relFirstRowIx, int relLastRowIx,
int relFirstColIx, int relLastColIx) {
if (_refEval == null) {
return _areaEval.offset(relFirstRowIx, relLastRowIx, relFirstColIx, relLastColIx);
}
return _refEval.offset(relFirstRowIx, relLastRowIx, relFirstColIx, relLastColIx);
}
}
@SuppressWarnings("fallthrough")
public ValueEval evaluate(ValueEval[] args, int srcCellRow, int srcCellCol) {
if(args.length < 1 || args.length > 5) {
return ErrorEval.VALUE_INVALID;
}
try {
BaseRef baseRef = evaluateBaseRef(args[0]);
// optional arguments
// If offsets are omitted, it is assumed to be 0.
int rowOffset = (args[1] instanceof MissingArgEval) ? 0 : evaluateIntArg(args[1], srcCellRow, srcCellCol);
int columnOffset = (args[2] instanceof MissingArgEval) ? 0 : evaluateIntArg(args[2], srcCellRow, srcCellCol);
int height = baseRef.getHeight();
int width = baseRef.getWidth();
// optional arguments
// If height or width are omitted, it is assumed to be the same height or width as reference.
switch(args.length) {
case 5:
if(!(args[4] instanceof MissingArgEval)) {
width = evaluateIntArg(args[4], srcCellRow, srcCellCol);
}
// fall-through to pick up height
case 4:
if(!(args[3] instanceof MissingArgEval)) {
height = evaluateIntArg(args[3], srcCellRow, srcCellCol);
}
break;
//case 3:
// nothing to do
default:
break;
}
// Zero height or width raises #REF! error
if(height == 0 || width == 0) {
return ErrorEval.REF_INVALID;
}
LinearOffsetRange rowOffsetRange = new LinearOffsetRange(rowOffset, height);
LinearOffsetRange colOffsetRange = new LinearOffsetRange(columnOffset, width);
return createOffset(baseRef, rowOffsetRange, colOffsetRange);
} catch (EvaluationException e) {
return e.getErrorEval();
}
}
private static AreaEval createOffset(BaseRef baseRef,
LinearOffsetRange orRow, LinearOffsetRange orCol) throws EvaluationException {
LinearOffsetRange absRows = orRow.normaliseAndTranslate(baseRef.getFirstRowIndex());
LinearOffsetRange absCols = orCol.normaliseAndTranslate(baseRef.getFirstColumnIndex());
if(absRows.isOutOfBounds(0, LAST_VALID_ROW_INDEX)) {
throw new EvaluationException(ErrorEval.REF_INVALID);
}
if(absCols.isOutOfBounds(0, LAST_VALID_COLUMN_INDEX)) {
throw new EvaluationException(ErrorEval.REF_INVALID);
}
return baseRef.offset(orRow.getFirstIndex(), orRow.getLastIndex(), orCol.getFirstIndex(), orCol.getLastIndex());
}
private static BaseRef evaluateBaseRef(ValueEval eval) throws EvaluationException {
if(eval instanceof RefEval) {
return new BaseRef((RefEval)eval);
}
if(eval instanceof AreaEval) {
return new BaseRef((AreaEval)eval);
}
if (eval instanceof ErrorEval) {
throw new EvaluationException((ErrorEval) eval);
}
throw new EvaluationException(ErrorEval.VALUE_INVALID);
}
/**
* OFFSET's numeric arguments (2..5) have similar processing rules
*/
static int evaluateIntArg(ValueEval eval, int srcCellRow, int srcCellCol) throws EvaluationException {
ValueEval ve = OperandResolver.getSingleValue(eval, srcCellRow, srcCellCol);
return OperandResolver.coerceValueToInt(ve);
}
}