如何用特殊字符替换字符串中的多个字符

Question

我有一个问题几乎与“ Ruby gsub字符串中的多个字符 ”相同。

但是，我的字符串包含特殊字符：

a = "<p>text</p> <strong>bold</strong> and <em>italic</em>"

使用/\\w+/对我不起作用。 我尝试了许多不同的组合，但没有运气。 我应该在下面输入什么正则表达式匹配项才能使其正常工作？ 我想替换字符串中任何位置的那些匹配项。

顺便说一句，我正在使用Rails。

我想要的比赛是：

a.gsub({{WHAT REGEX EXP?}},
  "\r\n" => "",
  "<p>" => "",
  "</p>" => "\n\n",
  "<br />" => "\n",
  "<strong>" => "*",
  "</strong>" => "*",
  "<em>" => "_",
  "</em>" => "_",
  "<s>" => "~",
  "</s>" => "~",
  "<blockquote>" => ">",
  "</blockquote>" => ">",
  "&" => "&amp;",
  "<" => "&lt;",
  ">" => "&gt;"
)

Answer 1

#gsub工作原理：

replacements = {
  "\r\n" => "",
  "<p>" => "",
  "</p>" => "\n\n",
  "<br />" => "\n",
  "<strong>" => "*",
  "</strong>" => "*",
  "<em>" => "_",
  "</em>" => "_",
  "<s>" => "~",
  "</s>" => "~",
  "<blockquote>" => ">",
  "</blockquote>" => ">",
  "&" => "&amp;",
  "<" => "&lt;",
  ">" => "&gt;"
}

a = "<p>text</p> <strong>bold</strong> and <em>italic</em>"

replacements.each do |find, replace|
  a.gsub!(find, replace)
end

a # => "text\n\n *bold* and _italic_"

Answer 2

可以一次性完成：

replacements = {
  "\r\n" => "",
  "<p>" => "",
  "</p>" => "\n\n",
  "<br />" => "\n",
  "<strong>" => "*",
  "</strong>" => "*",
  "<em>" => "_",
  "</em>" => "_",
  "<s>" => "~",
  "</s>" => "~",
  "<blockquote>" => ">",
  "</blockquote>" => ">",
  "&" => "&amp;",
  "<" => "&lt;",
  ">" => "&gt;"
}

keys = Regexp.union(replacements.keys)
a    = "<p>text</p> <strong>bold</strong> and <em>italic</em>"

p a.gsub(keys, replacements) # => "text\n\n *bold* and _italic_"

这很容易工作，因为Regexp.union为您完成了所有艰苦的工作（转义了奇怪的字符）。

Answer 3

您只需一次调用即可完成，正则表达式为/<[^>]+>|[<>&]/

a = "<p>text</p> <strong>bold</strong> and <em>italic</em> & <>"
a.gsub(/(<[^>]+>|[<>&])/, replacements)
# => "text\n\n *bold* and _italic_ &amp; &lt;&gt;"

演示版

String#gsub(pattern, hash) → new_str如果第二个参数是Hash，并且匹配的文本是其键之一，则对应的值是替换字符串。 文件

正则表达式说明：

• <[^>]+>匹配HTML标记-您首先匹配< ，然后使用[^>]+匹配不是>一个或多个字符，然后>
• [<>&]匹配特殊字符如< ， >或&特殊单次出现

也就是说，正则表达式不是处理HTML的最佳工具，最好使用HTML解析器（例如Nokogiri）。