remove empty text nodes

[zkamvar]

This removes empty text nodes that occur before bare links and asis nodes. Two examples below show asis nodes and bare links, respectively from #58

Asis nodes (math)

library(tinkr)
ex <- "- so $\\beta^2 = `r runif(1)`$ works and\n- $\\beta$ works"
f <- textConnection(ex)
y <- yarn$new(f); close(f)
y$protect_math()$show()
#> - so $\beta^2 = `r runif(1)`$ works and
#> - $\beta$ works

this PR removes the empty text node before the “asis” node

cat(as.character(y$body))
#> <?xml version="1.0" encoding="UTF-8"?>
#> <!DOCTYPE document SYSTEM "CommonMark.dtd">
#> <document xmlns="http://commonmark.org/xml/1.0">
#>   <list type="bullet" tight="true">
#>     <item>
#>       <paragraph>
#>         <text xml:space="preserve" latex-pair="1">so $</text>
#>         <text asis="true">\beta^2 = </text>
#>         <code xml:space="preserve" asis="true">r runif(1)</code>
#>         <text asis="true" xml:space="preserve" latex-pair="1">$ works and</text>
#>       </paragraph>
#>     </item>
#>     <item>
#>       <paragraph>
#>         <text xml:space="preserve"/>    <---- THIS ONE GETS REMOVED
#>         <text asis="true">$\beta$</text>
#>         <text> works</text>
#>       </paragraph>
#>     </item>
#>   </list>
#> </document>

^{Created on 2021-10-18 by the reprex package (v2.0.1)}

Bare Links

this PR removes the empty text node before the “link” node

f <- textConnection("## Dataset

The data used for this lesson are in the figshare repository at: 
https://example.com")
y <- tinkr::yarn$new(f, anchor_links = FALSE); close(f)
y$show()
#> ## Dataset
#> 
#> The data used for this lesson are in the figshare repository at:
#> [https://example.com](https://example.com)
cat(as.character(y$body))
#> <?xml version="1.0" encoding="UTF-8"?>
#> <!DOCTYPE document SYSTEM "CommonMark.dtd">
#> <document xmlns="http://commonmark.org/xml/1.0">
#>   <heading level="2">
#>     <text xml:space="preserve">Dataset</text>
#>   </heading>
#>   <paragraph>
#>     <text xml:space="preserve">The data used for this lesson are in the figshare repository at:</text>
#>     <softbreak/>
#>     <text xml:space="preserve"/>    <----- THIS ONE GETS REMOVED
#>     <link destination="https://example.com" title="">
#>       <text xml:space="preserve">https://example.com</text>
#>     </link>
#>   </paragraph>
#> </document>

^{Created on 2021-10-18 by the reprex package (v2.0.1)}

This will fix #58

[maelle]

Thank you! 🕵️

[maelle]

👻

[zkamvar]

keeping with the season 🎃

[maelle]

the comments are so clear ✨

[zkamvar]

🙏

[maelle]

I think it'd be fine to remove the if

library("xml2")
xml <- read_xml("<foo><bar /></foo>")
nodes <- xml2::xml_find_all(xml, ".//fooo")
xml2::xml_remove(nodes)

^{Created on 2021-10-19 by the reprex package (v2.0.0)}

Feel free to disagree, of course.

[zkamvar]

The difference is minuscule, but there is a slight overhead for removing nodes that may or may not exist, so I'm going to leave it.

library("xml2")
xml <- read_xml("<foo><bar /></foo>")
nodes <- xml2::xml_find_all(xml, ".//fooo")
rm <- function(nodes) { xml2::xml_remove(nodes); return(NULL) }
chk <- function(nodes) { if (length(nodes)) xml2::xml_remove(nodes); return(NULL) }
bench::mark(rm(nodes), chk(nodes), iterations = 1e5)
#> # A tibble: 2 × 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 rm(nodes)    1.94µs   2.25µs   372373.    6.21KB     22.3
#> 2 chk(nodes) 599.89ns 696.05ns  1194081.        0B     11.9

^{Created on 2021-10-19 by the reprex package (v2.0.1)}