Fix bom

[pawelru]

I have a package that imports lzstring. I test my package on different OS including windows machines using RHub workflows. I got errors in (r-release-windows-x86_64) (R-release) and (r-oldrel-windows-x86_64) (R-oldrel).
The traceback is as follows:

Error: Error: Invalid byte order mark (BOM).
Backtrace:
    ▆
(...)
 5.   └─lzstring::compressToEncodedURIComponent(as.character(files_json)) at roxy.shinylive/R/parse_url.R:31:3
 6.     └─lzstring:::safe_compress(string, compressToEncodedURIComponent_)
 7.       └─lzstring (local) f(string_utf16)

It took me a while to find out what's going on. Even a simple lzstring::compressToEncodedURIComponent("Hello World!") failed.
I made a print the source of the lzstring:::convert_to_utf16le function and this is what I got:

function (string) 
{
    string <- enc2utf8(string)
    string_utf16 <- iconv(string, from = "UTF-8", to = "UTF-16LE", 
        toRaw = TRUE)[[1]]
    bom_le <- charToRaw("ÿþ")
    if (!identical(string_utf16[1:2], bom_le)) {
        string_utf16 <- c(bom_le, string_utf16)
    }
    string_utf16
}
<bytecode: 0x000001e0e794fc00>
<environment: namespace:lzstring>

In particular: bom_le <- charToRaw("ÿþ").

Then this happens:

> print(charToRaw("ÿþ"))
 [1] c3 bf c3 be

Then the if is false and c3 bf c3 be is appended:

> print(lzstring:::convert_to_utf16le("test"))
 [1] c3 bf c3 be 74 00 65 00 73 00 74 00

(as opposed to the expected ff fe 74 00 65 00 73 00 74 00 value)
Then this throws.

This PR is an attempt to fix this.

[parmsam]

Thanks for making the PR, @pawelru! I'll review this soon and merge it into the main branch. Will try to get a new version release onto CRAN before the end of the month.

[parmsam]

Plan to update pkgdown site manually. Will add you in the description file as a contributor. Merging into main now.

[pawelru]

Thanks for the prompt reply! I am definitely looking forward a CRAN release of that. I'm also planning to do CRAN release of my package and for this I might need that fix.

[parmsam-pfizer]

That’s awesome! I have a PR that would add Shinylive URL encode and decode functions into the Shinylive R package: posit-dev/r-shinylive#92 You may have seen it already. Hopefully, that’ll get reviewed and merged in before the end of the year.