add pagebreak script

Signed-off-by: Christine Dodrill <me@christine.website>

src/00_overhead/overhead.md

@@ -1,4 +1,4 @@
-<div style="page-break-before:always;"></div>
+\pagebreak
 
 <center>
 

src/build.sh

@@ -7,7 +7,12 @@ FILES="$(ls ./**/*.md | grep -v plans)"
 
 echo $FILES
 
-pandoc -o ../out/Spellblade.epub --resource-path=. --css style.css title.txt $FILES
+pandoc \
+    -o ../out/Spellblade.epub \
+    --resource-path=. \
+    --css style.css \
+    --lua-filter ./pagebreak.lua \
+    title.txt $FILES
 ebook-convert ../out/Spellblade.epub ../out/Spellblade.mobi
 
 pandoc --lua-filter wordcount.lua $FILES

src/pagebreak.lua

@@ -0,0 +1,109 @@
+--[[
+pagebreak – convert raw LaTeX page breaks to other formats
+
+Copyright © 2017-2021 Benct Philip Jonsson, Albert Krewinkel
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+]]
+local stringify_orig = (require 'pandoc.utils').stringify
+
+local function stringify(x)
+  return type(x) == 'string' and x or stringify_orig(x)
+end
+
+--- configs – these are populated in the Meta filter.
+local pagebreak = {
+  asciidoc = '<<<\n\n',
+  context = '\\page',
+  epub = '<p style="page-break-after: always;"> </p>',
+  html = '<div style="page-break-after: always;"></div>',
+  latex = '\\newpage{}',
+  ms = '.bp',
+  ooxml = '<w:p><w:r><w:br w:type="page"/></w:r></w:p>',
+  odt = '<text:p text:style-name="Pagebreak"/>'
+}
+
+local function pagebreaks_from_config (meta)
+  local html_class =
+    (meta.newpage_html_class and stringify(meta.newpage_html_class))
+    or os.getenv 'PANDOC_NEWPAGE_HTML_CLASS'
+  if html_class and html_class ~= '' then
+    pagebreak.html = string.format('<div class="%s"></div>', html_class)
+  end
+
+  local odt_style =
+    (meta.newpage_odt_style and stringify(meta.newpage_odt_style))
+    or os.getenv 'PANDOC_NEWPAGE_ODT_STYLE'
+  if odt_style and odt_style ~= '' then
+    pagebreak.odt = string.format('<text:p text:style-name="%s"/>', odt_style)
+  end
+end
+
+--- Return a block element causing a page break in the given format.
+local function newpage(format)
+  if format:match 'asciidoc' then
+    return pandoc.RawBlock('asciidoc', pagebreak.asciidoc)
+  elseif format == 'context' then
+    return pandoc.RawBlock('context', pagebreak.context)
+  elseif format == 'docx' then
+    return pandoc.RawBlock('openxml', pagebreak.ooxml)
+  elseif format:match 'epub' then
+    return pandoc.RawBlock('html', pagebreak.epub)
+  elseif format:match 'html.*' then
+    return pandoc.RawBlock('html', pagebreak.html)
+  elseif format:match 'latex' then
+    return pandoc.RawBlock('tex', pagebreak.latex)
+  elseif format:match 'ms' then
+    return pandoc.RawBlock('ms', pagebreak.ms)
+  elseif format:match 'odt' then
+    return pandoc.RawBlock('opendocument', pagebreak.odt)
+  else
+    -- fall back to insert a form feed character
+    return pandoc.Para{pandoc.Str '\f'}
+  end
+end
+
+local function is_newpage_command(command)
+  return command:match '^\\newpage%{?%}?$'
+    or command:match '^\\pagebreak%{?%}?$'
+end
+
+-- Filter function called on each RawBlock element.
+function RawBlock (el)
+  -- Don't do anything if the output is TeX
+  if FORMAT:match 'tex$' then
+    return nil
+  end
+  -- check that the block is TeX or LaTeX and contains only
+  -- \newpage or \pagebreak.
+  if el.format:match 'tex' and is_newpage_command(el.text) then
+    -- use format-specific pagebreak marker. FORMAT is set by pandoc to
+    -- the targeted output format.
+    return newpage(FORMAT)
+  end
+  -- otherwise, leave the block unchanged
+  return nil
+end
+
+-- Turning paragraphs which contain nothing but a form feed
+-- characters into line breaks.
+function Para (el)
+  if #el.content == 1 and el.content[1].text == '\f' then
+    return newpage(FORMAT)
+  end
+end
+
+return {
+  {Meta = pagebreaks_from_config},
+  {RawBlock = RawBlock, Para = Para}
+}