[transformation] alt text with both single and double quotes has double-escaped double quotes

[zkamvar]

tmp <- withr::local_tempfile()
writeLines(c("![\"data\" is a 3 by 3 numpy 'array'](../fig/python-zero-index.svg)"), tmp)
pegboard::Episode$new(tmp)$use_sandpaper()$show()
#> ---
#> ~
#> ---
#> 
#> ![](fig/python-zero-index.svg){alt="\\"data\\" is a 3 by 3 numpy 'array'"}

^{Created on 2023-03-28 with reprex v2.0.2}

[zkamvar]

use case in https://github.com/swcarpentry/python-novice-inflammation/blob/8994f5607577d40df272adcee88a54c0dad0a05f/_episodes/02-numpy.md?plain=1#LL235-L239C64

[zkamvar]

The reason this is not working is because we find the attributes curly brace and then take those attributes, insert them into an HTML block so that we can use {xml2}'s HTML parsing capabilities to extract the alt text in set_alt_attr():

pegboard/R/get_images.R

Lines 80 to 98 in e815ea1

	set_alt_attr <- function(images, xpath, ns) {
	attrs <- xml2::xml_find_all(images, glue::glue("./{xpath}"), ns = ns)
	# We have the text of the alt text here, but it's possible that the alt text
	# was separated on different lines
	attr_texts <- xml2::xml_text(attrs)
	no_closing <- !grepl("[}]", attr_texts)
	if (any(no_closing)) {
	fixed_text <- purrr::map_chr(attrs[no_closing], get_broken_attr_text, ns)
	attr_texts[no_closing] <- fixed_text
	}
	htmls <- paste(gsub("[{](.+)[}]", "<img \\1/>", attr_texts), collapse = "\n")
	htmls <- xml2::read_html(htmls)
	alts <- xml2::xml_find_all(htmls, ".//img")
	alts <- xml2::xml_attr(alts, "alt")
	purrr::walk2(images, alts, function(img, alt) {
	if (!is.na(alt)) xml2::xml_set_attr(img, "alt", alt)
	})
	invisible(images)
	}

The problem is that because we are going from XML -> HTML, the quotes are already escaped in the XML, so they look like normal quotes in HTML, which causes it to truncate on the attributes.

One solution is to rewrite this so that we search for the boundaries between elements (e.g. splitting on =["']) and then reconstructing from there, but it's a big enough undertaking that I am willing to hold off on this until we have the lessons transformed.