File Module: Incorporate changes

[ChristianGruen]

The EXPath File Module must be revised in several steps. First of all, several functions need to be incorporated that were added to the initial version (details: https://docs.basex.org/12/File_Functions).

[michaelhkay]

file:descendants: seems reasonable. In the BaseX documentation, the example using matches($file, '.txt', 'i') is surely wrong: the regex pattern should be \.txt$. Perhaps a function file:extension() is needed.

file:is-absolute: are Windows UNC file names absolute?

file:list-roots similar question about UNC file names.

file:read-text and file:read-text-lines - options should be aligned with fn:unparsed-text. Not sure whether $offset and $length are needed - can use slice() or subsequence() to restrict the range.

file:resolve-path - seems OK.

Note, when considering Windows, a concept that seems to be missing is that each drive has a current directory.

[ChristianGruen]

file:descendants: seems reasonable. In the BaseX documentation, the example using matches($file, '.txt', 'i') is surely wrong: the regex pattern should be \.txt$. Perhaps a function file:extension() is needed.

Thanks (changed to matches($file, '.txt', 'iq')).

file:is-absolute: are Windows UNC file names absolute?

Yes, and true, it needs to be clarified in the documentation.

file:list-roots similar question about UNC file names.

I am not sure how easy it would be to also return available UNC paths, as this would include network discovery. Currently, it is only defined to return static root directories.

file:read-text and file:read-text-lines - options should be aligned with fn:unparsed-text.

It could become tricky to do this without compromising backward-compatibility, but we could possibly introduce an options parameter, and still support the old parameters, as it was e.g. done with fn:deep-equals and the collations parameter.

Not sure whether $offset and $length are needed - can use slice() or subsequence() to restrict the range.

At first glance, it’s »just an optimization issue«, but we decided to add the offset and length parameters as it can be very tricky to support partial reads when input it streamed and needs to be properly closed. Instead, we do it the other way round and rewrite code like head(file:read-text-lines(...)) to file:read-text-lines(..., 0, 1).

Note, when considering Windows, a concept that seems to be missing is that each drive has a current directory.

The “current working directory” concept is certainly a controversial one. In the spec, it is defined as a single directory, but it is up to the implementation to decide which one it is:

“The current working directory is implementation-defined: It can e. g. be the file system directory from which a query processor was started.”