如何用特殊字符替换字符串中的多个字符

Question

我有一个与“Ruby gsub multiple characters in string”几乎相同的问题。

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才能使其工作？我想替换字符串中的任何匹配项。

顺便说一句，我正在使用 Rails。

我想要的匹配是：

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：

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

一气呵成：

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，因为Regexp.union 为您完成了所有艰苦的工作（逃避奇怪的字符）。

Answer 3

你可以通过一个电话来完成，正则表达式是/<[^>]+>|[<>&]/

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

Demo

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

正则表达式解释：

• <[^>]+> 匹配 HTML 标记 - 您首先匹配 <，然后是一个或多个不是 > 的字符与 [^>]+，然后是 >
• [<>&] 匹配特殊字符的特殊单次出现，例如 <、> 或 &

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