private ParseNode parseRangeable()

in poi/src/main/java/org/apache/poi/ss/formula/FormulaParser.java [466:584]
100 lines of code
31 McCabe index (conditional complexity)

    private ParseNode parseRangeable() {
        skipWhite();
        int savePointer = _pointer;
        SheetIdentifier sheetIden = parseSheetName(false);

        if (sheetIden == null) {
            resetPointer(savePointer);
        } else {
            skipWhite();
            savePointer = _pointer;
        }

        SimpleRangePart part1 = parseSimpleRangePart();
        if (part1 == null) {
            if (sheetIden != null) {
                if(look == '#'){  // error ref like MySheet!#REF!
                    return new ParseNode(ErrPtg.valueOf(parseErrorLiteral()));
                } else {
                    // Is it a named range?
                    String name = parseAsName();
                    if (name.length() == 0) {
                        throw new FormulaParseException("Cell reference or Named Range "
                                + "expected after sheet name at index " + _pointer + ".");
                    }
                    Ptg nameXPtg = _book.getNameXPtg(name, sheetIden);
                    if (nameXPtg == null) {
                        throw new FormulaParseException("Specified name '" + name +
                                "' for sheet " + sheetIden.asFormulaString() + " not found");
                    }
                    return new ParseNode(nameXPtg);
                }
            }
            return parseNonRange(savePointer);
        }
        boolean whiteAfterPart1 = isWhite(look);
        if (whiteAfterPart1) {
            skipWhite();
        }

        if (look == ':') {
            int colonPos = _pointer;
            nextChar();
            skipWhite();
            SimpleRangePart part2 = parseSimpleRangePart();
            if (part2 != null && !part1.isCompatibleForArea(part2)) {
                // second part is not compatible with an area ref e.g. S!A1:S!B2
                // where S might be a sheet name (that looks like a column name)

                part2 = null;
            }
            if (part2 == null) {
                // second part is not compatible with an area ref e.g. A1:OFFSET(B2, 1, 2)
                // reset and let caller use explicit range operator
                resetPointer(colonPos);
                if (!part1.isCell()) {
                    String prefix = "";
                    if (sheetIden != null) {
                        prefix = "'" + sheetIden.getSheetIdentifier().getName() + '!';
                    }
                    throw new FormulaParseException(prefix + part1.getRep() + "' is not a proper reference.");
                }
            }
            return createAreaRefParseNode(sheetIden, part1, part2);
        }

        if (look == '.') {
            nextChar();
            int dotCount = 1;
            while (look =='.') {
                dotCount ++;
                nextChar();
            }
            boolean whiteBeforePart2 = isWhite(look);

            skipWhite();
            SimpleRangePart part2 = parseSimpleRangePart();
            String part1And2 = _formulaString.substring(savePointer-1, _pointer-1);
            if (part2 == null) {
                if (sheetIden != null) {
                    throw new FormulaParseException("Complete area reference expected after sheet name at index "
                            + _pointer + ".");
                }
                return parseNonRange(savePointer);
            }


            if (whiteAfterPart1 || whiteBeforePart2) {
                if (part1.isRowOrColumn() || part2.isRowOrColumn()) {
                    // "A .. B" not valid syntax for "A:B"
                    // and there's no other valid expression that fits this grammar
                    throw new FormulaParseException("Dotted range (full row or column) expression '"
                            + part1And2 + "' must not contain whitespace.");
                }
                return createAreaRefParseNode(sheetIden, part1, part2);
            }

            if (dotCount == 1 && part1.isRow() && part2.isRow()) {
                // actually, this is looking more like a number
                return parseNonRange(savePointer);
            }

            if (part1.isRowOrColumn() || part2.isRowOrColumn()) {
                if (dotCount != 2) {
                    throw new FormulaParseException("Dotted range (full row or column) expression '" + part1And2
                            + "' must have exactly 2 dots.");
                }
            }
            return createAreaRefParseNode(sheetIden, part1, part2);
        }
        if (part1.isCell() && isValidCellReference(part1.getRep())) {
            return createAreaRefParseNode(sheetIden, part1, null);
        }
        if (sheetIden != null) {
            throw new FormulaParseException("Second part of cell reference expected after sheet name at index "
                    + _pointer + ".");
        }

        return parseNonRange(savePointer);
    }