Compatibility and limits

Lesath validates spreadsheet packages against a documented subset. Unknown parts, unsupported XML, and features outside that subset produce errors. There is no option to import a workbook while silently dropping its content.

On this page

• Supported content
• Unsupported features
  • String whitespace
• Workbook limits
• Package limits
• Errors
• Rukbat integration

Supported content

Formula text can round-trip within its format, but Lesath never evaluates it. Cross-format formula export is rejected. See the formula guide.

Unsupported features

The subset excludes styles and formatting, rich text, date/time value types, merged cells, comments, charts, images, macros, validations, protection, hyperlinks, named ranges, external links, embedded objects, signatures, and encryption. Shared strings and shared formulas are outside the XLSX subset. ODS populated rows or cells with repetition attributes are rejected.

Many files generated by Excel or LibreOffice contain default style or metadata parts, even when their visible cells look simple. Such files may be rejected. Lesath does not promise round trips for general office files or implement the whole XLSX or ODS specification.

XLSX numbers have no date inference. A numeric date serial with no unsupported style remains a number. Do not treat it as a Date or Time automatically.

String whitespace

XLSX inline strings preserve leading and trailing whitespace, repeated spaces, tabs, and line breaks through xml:space="preserve" where needed.

ODS rejects strings with leading or trailing ASCII spaces, consecutive ASCII spaces, tabs, carriage returns, or line feeds. These require text:s, tab, or line-break markup that Lesath does not support. The restriction applies to both imported strings and exported values, including formula caches. An empty string and a single interior space are supported.

Workbook limits

Floats must be finite. Ruby strings must be convertible to valid UTF-8 and cannot contain disallowed XML control characters. An emoji may occupy two UTF-16 code units, so the string limit is not a simple character count.

Package limits

The generated ZIP is checked against the same package limits before the target path is created. Highly repetitive data can exceed the compression ratio limit even when it stays below the cell and byte limits.

Output paths must not already exist. Choose a new filename when saving edits; Lesath does not offer an overwrite flag.

Errors

UnsupportedFeature and InvalidPackage inherit from Lesath::Error. Catch the specific exceptions first if you want to give different messages:

begin
  book = Lesath.read("input.xlsx")
  Lesath.write(book, "output.xlsx")
rescue Lesath::UnsupportedFeature => error
  warn "Unsupported spreadsheet content: #{error.message}"
rescue Lesath::InvalidPackage => error
  warn "Invalid spreadsheet package: #{error.message}"
rescue Lesath::Error => error
  warn "Workbook error: #{error.message}"
end

Filesystem failures during export, such as a missing parent directory or insufficient write permissions, can raise Ruby SystemCallError subclasses. Handle these where your application manages output files.

Rukbat integration

Rukbat::Workbook is not directly accepted. Lesath has its own workbook model, and Rukbat formatting, comments, and formula semantics need an explicit adapter and loss policy. CSV remains the broader interchange path until such an adapter exists.

The design rationale and source standards are documented in ADR 001.