Pandoc lua 过滤器强制压缩列表

Question

我想编写一个 lua 过滤器，在从 markdown 转换为 PDF 时强制 Pandoc 使用紧凑列表。我注意到带有嵌套表/文本/div 的列表不会使用 \tightlist 选项，因为 Pandoc AST 对每个列表项使用 Para 而不是 Plain。我尝试修改示例here 以强制所有BulletList 和OrderedList 项目为Plain，但当项目包含嵌套内容时我无法使其工作。 pandoc mwe.txt -f markdown -t native --lua-filter the-filter.lua 为第一个列表项返回 Para：

[BulletList
 [[Plain [Str "list",Space,Str "1"]]
 ,[Plain [Str "list",Space,Str "1"]]
 ,[Plain [Str "list",Space,Str "1"]]]
,Para [Str "Some",Space,Str "paragraph"]
,BulletList
 [[Para [Str "list",Space,Str "2"]
  ,Div ("",["class"],[])
   [Para [Str "Nested",Space,Str "div"]]]
 ,[Plain [Str "list",Space,Str "2"]]
 ,[Plain [Str "list",Space,Str "2"]]]]

我不知道如何处理这个问题：

• 我是否应该使用walk_block 并将每个列表项更改为Plain？
• 如何处理#blocks > 1 的情况？如何将Para 更改为Plain，然后包含任何嵌套内容（比如我有两个嵌套的 div）？

mwe.txt

- list 1
- list 1
- list 1

Some paragraph

- list 2

  ::: {.class}
  Nested div
  :::

- list 2
- list 2

the-filter.lua

local List = require 'pandoc.List'

function compactifyItem2 (blocks)
  if (#blocks == 1) then
    if (blocks[1].t == 'Para') then
      return {pandoc.Plain(blocks[1].content)}
    else
      return blocks
    end
  elseif (#blocks == 2) then -- I assume I have to change the Para and nest the child content
    if (blocks[1].t == 'Para') then
      blocks.content = pandoc.Plain(blocks[1].content) .. blocks[2].content
      return {blocks.content}
    end
  else
    return blocks
  end
end

function compactifyList (l)
  l.content = List.map(l.content, compactifyItem2)
  return l
end

return {{
    BulletList = compactifyList,
    OrderedList = compactifyList
}}

Answer 1

你已经很亲近了。我相信以下应该适用于一般情况：

--- Iterate over all blocks in an item, converting 'top-level'
-- Para into Plain blocks.
function compactifyItem (blocks)
  -- step through the list of blocks step-by-step, keeping track of the
  -- element's index in the list in variable `i`, and assign the current
  -- block to `blk`.
  -- 
  for i, blk in ipairs(blocks) do
    if blk.t == 'Para' then
      -- update in item's block list.
      blocks[i] = pandoc.Plain(blk.content)
    end
  end
  return blocks
end

function compactifyList (l)
  -- l.content is an instance of pandoc.List, so the following is equivalent
  -- to pandoc.List.map(l.content, compactifyItem)
  l.content = l.content:map(compactifyItem)
  return l
end

return {{
    BulletList = compactifyList,
    OrderedList = compactifyList
}}

多块项目的情况是链接帖子中的遗漏。然而，对于何时应该使列表紧凑，可能存在不同的意见。以上应该压缩所有列表。

使用 walk_blocks 会产生意想不到的副作用，因为它会影响 所有 块，包括嵌套在 Div 下方的 Para 块。

Answer 2

上面的原始答案不适用于 Pandoc 2.11 和从 Google Docs 导出的 docx 文件。有关详细信息，请参阅this issue。这是我对原始答案的修改版本。

-- Source: https://stackoverflow.com/a/57943159/7361270
-- Modified by makeworld

-- Iterate over all blocks in an item, converting 'top-level'
-- Para into Plain blocks.
function compactifyItem (blocks)
  -- step through the list of blocks step-by-step, keeping track of the
  -- element's index in the list in variable `i`, and assign the current
  -- block to `blk`.
  -- 
  for i, blk in ipairs(blocks) do
    if blk.t == 'Para' then
      -- update in item's block list.
      blocks[i] = pandoc.Plain(blk.content)
    elseif blk.t == 'BlockQuote' then
      -- It's a Google Doc thing, where each bullet is in a blockquote
      -- https://github.com/jgm/pandoc/issues/6824
      blocks[i] = pandoc.Plain(blk.content[1].content)
    end
  end
  return blocks
end

function compactifyList (l)
  -- l.content is an instance of pandoc.List, so the following is equivalent
  -- to pandoc.List.map(l.content, compactifyItem)
  l.content = l.content:map(compactifyItem)
  return l
end

return {{
    BulletList = compactifyList,
    OrderedList = compactifyList
}}