require "nokogiri" require "pathname" files = ARGV[0..-1] class LineInfo attr_accessor :links def initialize @links = [] end end class Handler def initialize @file_infos = {} end # Traverse the preformatted Agda block in the given Agda HTML file # and find which textual ranges have IDs and links to other ranges. # Store this information in a hash, line => LineInfo. def process_agda_html_file(file) return @file_infos[file] if @file_infos.include? file @file_infos[file] = line_infos = {} unless File.exists?(file) return line_infos end document = Nokogiri::HTML.parse(File.open(file)) pre_code = document.css("pre.Agda")[0] # The traversal postorder; we always visit children before their # parents, and we visit leaves in sequence. offset = 0 line = 1 pre_code.traverse do |at| # Text nodes are always leaves; visiting a new leaf means we've advanced # in the text by the length of that text. However, if there are newlines # -- since this is a preformatted block -- we also advanced by a line. # At this time, do not support links that span multiple lines, but # Agda doesn't produce those either. if at.text? if at.content.include? "\n" # This textual leaf is at least part whitespace. The logic # assumes that links can't span multiple pages, and that links # aren't nested, so ensure that the parent of the textual node # is the preformatted block itself. raise "unsupported Agda HTML output" if at.parent.name != "pre" # Increase the line and track the final offset. Written as a loop # in case we eventually want to add some handling for the pieces # sandwiched between newlines. at.content.split("\n", -1).each_with_index do |bit, idx| line += 1 unless idx == 0 offset = bit.length end else # It's not a newline node, so it could be anywhere. All we need to # do is adjust the offset within the full pre block's text. offset += at.content.length end elsif at.name == "a" # We found a link. Agda emits both links and "things to link to" as # 'a' nodes, so check for either, and record them. Even if # the link is nested, the .content.length accessor will only # retrieve the textual content, and thus -- assuming the link # isn't split across lines -- will find the proper from-to range. line_info = line_infos.fetch(line) { line_infos[line] = LineInfo.new } href = at.attribute("href") id = at.attribute("id") if href or id new_link = { :from => offset-at.content.length, :to => offset } new_link[:href] = href if href new_link[:id] = id if id line_info.links << new_link end end end return line_infos end # Given a Hugo HTML file which references potentially several Agda modules # in code blocks, insert links into the code blocks. # # There are several things we need to take care of: # 1. Finding the HTML files associated with each referenced Agda module. # For this, we make use of the data-base-path etc. attributes that # the vanilla theme inserts. # 2. "zipping together" the Agda and Hugo HTML representations. Each of # them encode the code, but they use different HTML elements and structures. # So, given a Hugo HTML code block, traverse its textual contents # and find any that are covered by links in the related Agda HTML file. # 3. Fixing up links: the Agda HTML links assume each module has its own HTML # file. This isn't true for us: multiple modules are stitched into # one Hugo HTML file. Also, we don't include the entire Agda HTML # file in the Hugo HTML, so some links may be broken. So, find IDs # that are visible in the Hugo file, rename them to be globally unique, # and re-write cross-file links that reference these IDs to point # inside the Hugo file. def process_source_file(file) nodes_referencing_href = {} # Agda HTML ID -> all (Hugo HTML) nodes that link to it seen_hrefs = {} # Agda HTML ID -> its new ID in Hugo-land id_counter = 0 # Process each highlight group that's been marked as an Agda file. document = Nokogiri::HTML.parse(File.open(file)) document.css('div[data-agda-block]').each do |t| first_line, last_line = nil, nil if first_line_attr = t.attribute("data-first-line") first_line = first_line_attr.to_s.to_i end if last_line_attr = t.attribute("data-last-line") last_line = last_line_attr.to_s.to_i end # The name of an Agda module is determined from its directory # structure: A/B/C.agda creates A.B.C.html. Assume that the # base path is the Agda module root, and use the remaining directories # to build the HTML file name. base_path = t.attribute("data-base-path").to_s base_path_dirs = Pathname(base_path).each_filename.to_a full_path = t.attribute("data-file-path").to_s full_path_dirs = Pathname(full_path).each_filename.to_a dirs_in_base = full_path_dirs[base_path_dirs.length..-1] html_file = dirs_in_base.join(".").gsub(/\.agda$/, ".html") html_path = File.join(["code", base_path, "html", html_file]) agda_info = process_agda_html_file(html_path) # Hugo conveniently generates a bunch of spans, each encoding a line # of code output. We can iterate over these and match them up with # the line numbers we got from reading the Agda HTML output. lines = t.css("pre.chroma code[data-lang] .line") lines.zip((first_line..last_line)).each do |line, line_no| line_info = agda_info[line_no] next unless line_info offset = 0 line.traverse do |lt| if lt.text? content = lt.content new_offset = offset + content.length # The span/a/etc. structure of the Agda and Hugo HTML files # need not line up; it's possible for there to be a single link # in the Agda file that's broken up across multiple HTML nodes # in the Hugo output. For now, just don't link those, since inserting # such overlapping links is relatively complicated. Instead, # require links to fit fully within a current text node (and thus, # not overlap the boundaries of any HTML). matching_links = line_info.links.filter do |link| link[:from] >= offset and link[:to] <= new_offset end # A given text node can be broken into any number of sub-nodes, # where some sub-nodes are still text, and others have been turned # into links. Store the new pieces in replace_with. E.g., # # Original: # abc # # New: # abc # # replace_with: # ["a", , "c"] # # match_offset represents how much of the original text we've # already converted. The below iteration assumes that matching # links are in order, and don't overlap. replace_with = [] replace_offset = 0 matching_links.each do |match| # The link's range is an offset from the beginning of the line, # but the text piece we're splitting up might be partway into # the line. Convert the link coordinates to piece-relative ones. relative_from = match[:from] - offset relative_to = match[:to] - offset # If the previous link ended some time before the new link # began (or if the current link is the first one, and is not # at the beginning), ensure that the plain text "in between" # is kept. replace_with << content[replace_offset...relative_from] tag = (match.include? :href) ? 'a' : 'span' new_link = Nokogiri::XML::Node.new(tag, document) if match.include? :href # For nodes with links, note what they're referring to, so # we can adjust their hrefs when we assign global IDs. href = match[:href].to_s new_link['href'] = href ref_list = nodes_referencing_href.fetch(href) { nodes_referencing_href[href] = [] } ref_list << new_link end if match.include? :id # For nodes with IDs visible in the current Hugo file, we'll # want to redirect links that previously go to other Agda # module HTML files. So, note the ID that we want to redirect, # and pick a new unique ID to replace it with. id = match[:id].to_s uniq_id = "agda-unique-ident-#{id_counter}" id_counter += 1 new_link['id'] = uniq_id seen_hrefs["#{html_file}##{id}"] = uniq_id end new_link.content = content[relative_from...relative_to] replace_with << new_link replace_offset = relative_to end replace_with << content[replace_offset..-1] # Finally, replace the node under consideration with the new # pieces. replace_with.each do |replacement| lt.add_previous_sibling replacement end lt.remove offset = new_offset end end end end # Now, we have a complete list of all the IDs visible in scope. # Redirect relevant links to these IDs. This achieves within-post # links. seen_hrefs.each do |agda_id, hugo_id| nodes_to_rewrite = nodes_referencing_href[agda_id] next unless nodes_to_rewrite nodes_to_rewrite.each do |node| node['href'] = "##{hugo_id}" end nodes_referencing_href.delete agda_id end # The remaining nodes reference symbols not in the current Hugo document, # so just replace them with their contents for now (we'd need some # external hosting to make this work otherwise). nodes_referencing_href.each do |href, nodes| nodes.each do |node| node.replace node.content end end File.write(file, document.to_html(encoding: 'UTF-8')) end end handler = Handler.new files.each do |file| handler.process_source_file file end