我如何才能自动从 XML 文件中解析数据？

Question

您可以使用我的 LuaXML 包，顾名思义，它可以使用 LuaTeX 处理 XML 文档。我将使用我关于Mathml 到 LaTeX处理。这是图书馆，transform-xml.lua：

-- adapted code from https://github.com/michal-h21/luaxml-mathml
--
local domobject = require "luaxml-domobject"

-- we need to define different actions for XML elements. The default action is
-- to just process child elements and return the result
local function default_action(element)
  return process_children(element)
end

-- use template string to place the processed children
local function simple_content(s)
  return function(element)
    local content = process_children(element)
    -- process attrubutes
    -- attribute should be marked as @{name}
    local expanded = s:gsub("@{(.-)}", function(name)
      return element:get_attribute(name) or ""
    end)
    return string.format(expanded, content)
  end
end

local function get_child_element(element, count)
  -- return specified child element 
  local i = 0
  for _, el in ipairs(element:get_children()) do
    -- count elements 
    if el:is_element() then
      -- return the desired numbered element
      i = i + 1
      if i == count then return el end
    end
  end
end

-- actions for particular elements
local actions = {
  
}

-- add more complicated action
local function add_custom_action(name, fn)
  actions[name] = fn
end

-- normal actions
local function add_action(name, template)
  actions[name] = simple_content(template)
end

-- convert Unicode characters to TeX sequences
local unicodes = {
  [35] = "\\#",
  [38] = "\\&",
  [60] = "\\textless{}",
  [62] = "\\textgreater{}",
  [92] = "\\textbackslash{}",
  [123] = "\\{",
  [125] = "\\}"
}

local function process_text(text)
  local t = {}
  -- process all Unicode characters and find if they should be replaced
  for _, char in utf8.codes(text) do
    -- construct new string with replacements or original char
    t[#t+1] = unicodes[char] or utf8.char(char)
  end
  return table.concat(t)
end

function process_children(element)
  -- accumulate text from children elements
  local t = {}
  -- sometimes we may get text node
  if type(element) ~= "table" then return element end
  for i, elem in ipairs(element:get_children()) do
    if elem:is_text() then
      -- concat text
      t[#t+1] = process_text(elem:get_text())
    elseif elem:is_element() then
      -- recursivelly process child elements
      t[#t+1] = process_tree(elem)
    end
  end
  return table.concat(t)
end


function process_tree(element)
  -- find specific action for the element, or use the default action
  local element_name = element:get_element_name()
  local action = actions[element_name] or default_action
  return action(element)
end

function parse_xml(content)
  -- parse XML string and process it
  local dom = domobject.parse(content)
  -- start processing of DOM from the root element
  -- return string with TeX content
  return process_tree(dom:root_node())
end

local function load_file(filename)
  local f = io.open(filename, "r")
  local content = f:read("*all")
  f:close()
  return parse_xml(content)
end


function print_tex(content)
  -- we need to replace "\n" characters with calls to tex.sprint
  for s in content:gmatch("([^\n]*)") do
    tex.sprint(s)
  end
end


local M = {
  parse_xml = parse_xml,
  process_children = process_children,
  print_tex = print_tex,
  add_action = add_action,
  add_custom_action = add_custom_action,
  simple_content = simple_content,
  load_file = load_file
}

return M

我不会详细描述它，因为它基本上与来自我的另一个答案，只是更加通用。

它提供的主要功能是transform_xml.add_action。它需要两个参数，第一个是元素的名称，第二个是将插入到文档中的 TeX 模板。

该模板可以使用文本从所有子元素插入%s文本。您应该在所有可以包含任何文本的元素中使用它。可以使用@{attribute name}占位符访问属性。

示例模板可能如下所示：

xmltransform.add_action("section", [[\section{@{title}}
%s
\par]])

注意我们使用[[ ... ]]来指定模板，是为了方便输入换行符和反斜杠。\par插入段落时也需要使用命令。

我们可以在自定义 TeX 包中指定必要的操作myarticle.sty：

\ProvidesPackage{myarticle}
\RequirePackage{luacode}
\RequirePackage{graphicx}
\RequirePackage{xparse}


\begin{luacode*}
xmltransform = require "transform_xml.lua" 


xmltransform.add_action("article", [[
\chapter{@{title}}
by \emph{@{author}}\par

%s
]])

xmltransform.add_action("section", [[\section{@{title}}
%s
\par]])

xmltransform.add_action("image", '\\includegraphics{@{source}}')

function article_load(filename)
  local transformed = xmltransform.load_file(filename)
  if transformed then
    xmltransform.print_tex(transformed)
  else
    tex.sprint("Error in parsing of the XML file " .. filename)
  end
end

\end{luacode*}


\NewDocumentCommand\processarticle{m}{%
  \directlua{article_load("#1")}
}
 

\endinput

为所有需要的元素（文章、章节、图像）指定操作。当没有为元素指定操作时，例如<body>，它的内容将被处理并插入到 TeX 文档中。

包还声明了一个新命令\processarticle。它获取 XML 文件名并使用对其进行处理transform_xml。

我们现在可以尝试一个示例文档：

\documentclass{book}
\usepackage{myarticle}
\begin{document}
\processarticle{article.xml}
\end{document}

最终的 PDF 结果如下：

Answer 1