fix: keep inline code as a code element in Typst output

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Bug Fixes
 
+- fix: Keep inline code in a Typst document as a code element, so Pandoc writes the syntax highlighting definitions for it. A document with inline code and no code block failed to compile before. (#65)
 - fix: Remove the code-window attributes from a block that sets code-window-enabled="false", and from a block that sets code-window-lines when lines-label is off. They reached the HTML output as data-code-window-* attributes before. (#63)
 - fix: Remove the extension's own label attribute when the output format gets no window chrome, so a writer that keeps attributes no longer prints it. (#63)
 - fix: Check every code block attribute in the code-window group against the schema, so a value nothing validated before, such as code-window-enabled, is now reported when it is wrong. The extension's own duplicate warnings for an invalid code-window-style or code-window-collapse are removed, since the schema already names the same mistake. (#60)

_extensions/code-window/_modules/hotfix/skylighting-typst-fix.lua

@@ -155,44 +155,35 @@ local function build_raw_line_annotation_rule()
 ]==], circled, circled)
 end
 
+--- Shape of the box that holds inline code, after its fill.
+local _inline_box_style = 'inset: (x: 3pt, y: 0pt), outset: (y: 3pt), '
+    .. 'radius: 2pt, stroke: none)['
+
 --- Process inline Code for Typst format.
---- Renders the Code element through Pandoc's Typst writer to get syntax-
---- highlighted output, then wraps it in a box with the theme background colour.
+--- Puts the Code element in a box that carries the theme background colour.
+--- The element itself stays in the document, so Pandoc highlights it and
+--- writes the token definitions for it.
 --- @param el pandoc.Code Inline code element
---- @return pandoc.RawInline|pandoc.Code Transformed or original element
+--- @return pandoc.Inlines The boxed code
 local function process_typst_inline(el)
   local hm = PANDOC_WRITER_OPTIONS and PANDOC_WRITER_OPTIONS.highlight_method
-  local bg_fill = nil
-  local write_opts = nil
-
-  if hm then
-    local bg = hm['background-color']
-    if bg and type(bg) == 'string' then
-      bg_fill = string.format('rgb("%s")', bg)
-    end
-    write_opts = pandoc.WriterOptions({
-      highlight_method = hm,
-    })
-  end
-
-  local rendered = pandoc.write(pandoc.Pandoc({ pandoc.Plain({ el }) }), 'typst', write_opts)
-  rendered = rendered:gsub('%s+$', '')
-  if rendered == '' then return el end
+  local bg = hm and hm['background-color']
+  local opening, closing
 
-  local typst_code
-  if bg_fill then
-    typst_code = string.format(
-      '#box(fill: %s, inset: (x: 3pt, y: 0pt), outset: (y: 3pt), radius: 2pt, stroke: none)[%s]',
-      bg_fill, rendered)
+  if type(bg) == 'string' then
+    opening = string.format('#box(fill: rgb("%s"), ', bg) .. _inline_box_style
+    closing = ']'
   else
-    typst_code = string.format(
-      '#context { let _bg = _cw-page-bg(); let _f = _cw-fg(_bg); '
-      .. 'box(fill: color.mix((_f, 10%%), (_bg, 90%%)), '
-      .. 'inset: (x: 3pt, y: 0pt), outset: (y: 3pt), radius: 2pt, stroke: none)[%s] }',
-      rendered)
+    opening = '#context { let _bg = _cw-page-bg(); let _f = _cw-fg(_bg); '
+      .. 'box(fill: color.mix((_f, 10%), (_bg, 90%)), ' .. _inline_box_style
+    closing = '] }'
   end
 
-  return pandoc.RawInline('typst', typst_code)
+  return pandoc.Inlines({
+    pandoc.RawInline('typst', opening),
+    el,
+    pandoc.RawInline('typst', closing),
+  })
 end
 
 --- Inject Skylighting override at the start of the document.
@@ -245,8 +236,10 @@ local function is_title_scaffold(div)
   return true
 end
 
---- Walk the document tree and convert inline Code to RawInline with
---- background styling. Code in title scaffolds is converted to plain
+--- Walk the document tree and box inline Code with background styling.
+--- The extension contributes the pass once, so it sees each Code element
+--- once and boxes it once.
+--- Code in title scaffolds is converted to plain
 --- Typst backtick code to avoid Skylighting tokens with inner quotes
 --- that would break the string parameter Quarto generates.
 --- The typst-title-fix post-quarto filter then evaluates the string

tests/fixtures/inline-code-no-theme.qmd

@@ -0,0 +1,17 @@
+---
+title: "Inline code, no theme"
+filters:
+  - code-window
+highlight-style: none
+format:
+  typst:
+    keep-typ: true
+---
+
+The document below turns syntax highlighting off, so the theme gives no
+background colour.
+
+The filter then boxes the inline code with a colour it mixes from the page,
+and that box has to compile too.
+
+A paragraph with `inline code` in it.

tests/fixtures/inline-code-only.qmd

@@ -0,0 +1,15 @@
+---
+title: "Inline code, no block"
+filters:
+  - code-window
+format:
+  typst:
+    keep-typ: true
+---
+
+The document below has inline code and no code block.
+
+The filter boxes the inline code and leaves the element in place, so Pandoc
+writes the token definitions for it.
+
+A paragraph with `inline code` in it.

tests/fixtures/inline-code-with-block.qmd

@@ -0,0 +1,19 @@
+---
+title: "Inline code and a block"
+filters:
+  - code-window
+format:
+  typst:
+    keep-typ: true
+---
+
+The document below has inline code and a code block.
+
+The boxed inline code and the block that goes through the Skylighting
+override share one document, and that document has to compile.
+
+A paragraph with `inline code` in it.
+
+```python
+x = 1
+```

tests/run.sh

@@ -85,6 +85,50 @@ for fixture in cell-output-bare cell-output-classed; do
 	fi
 done
 
+# ============================================================================
+# Inline code keeps the token definitions in a document with no code block
+# ============================================================================
+
+# The filter boxes inline code and leaves the element itself in place, so
+# Pandoc highlights it and writes the token definitions. The render fails to
+# compile when they are missing, and the grep says why.
+render inline-code-only typst
+if grep -q '^#let NormalTok(' "${work_dir}/inline-code-only.typ"; then
+	report pass "inline-code-only: the token definitions reach the document"
+else
+	report fail "inline-code-only: the token definitions reach the document" \
+		"a #let NormalTok( definition in inline-code-only.typ"
+fi
+
+# A theme with a background colour takes the box that names the colour.
+if grep -q 'box(fill: rgb(' "${work_dir}/inline-code-only.typ"; then
+	report pass "inline-code-only: the box takes the colour of the theme"
+else
+	report fail "inline-code-only: the box takes the colour of the theme" \
+		"a box(fill: rgb( call in inline-code-only.typ"
+fi
+
+# A code block goes through the Skylighting override, and the inline code
+# keeps its own box in the same document.
+render inline-code-with-block typst
+if grep -q '^#Skylighting(' "${work_dir}/inline-code-with-block.typ" &&
+	grep -q 'box(fill: rgb(' "${work_dir}/inline-code-with-block.typ"; then
+	report pass "inline-code-with-block: the block and the inline code share the document"
+else
+	report fail "inline-code-with-block: the block and the inline code share the document" \
+		"a #Skylighting( call and a box(fill: rgb( call in inline-code-with-block.typ"
+fi
+
+# A theme that gives no background colour takes the other box, which mixes its
+# colour from the page. The render compiles that box.
+render inline-code-no-theme typst
+if grep -q 'box(fill: color.mix' "${work_dir}/inline-code-no-theme.typ"; then
+	report pass "inline-code-no-theme: the box takes its colour from the page"
+else
+	report fail "inline-code-no-theme: the box takes its colour from the page" \
+		"a box(fill: color.mix call in inline-code-no-theme.typ"
+fi
+
 # ============================================================================
 # A per-block style override reaches the output
 # ============================================================================