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简单的常规表达问题

regex ruby ruby-on-rails

Sam å±± · 技术社区 · 15 年前

我在博客上有一个这样的标题 Main Idea, key term, key term, keyterm

我希望主要的想法和关键术语有不同的字体大小。首先想到的是搜索第一个逗号和字符串的结尾,并用相同的东西替换该块,但用一个类将跨度标记包围,使字体变小。

计划如下:

HTML(以前)

  <a href="stupidreqexquestion">Main Idea, key term, key term, key term</a>

HTML(后)

  <a href="stupidreqexquestion">Main Idea <span class="smaller_font">, key term, key term key term</span></a>

我正在使用Rails,因此我计划将其添加为帮助函数-例如:

帮手

  def make_key_words_in_title_smaller(title)
      #replace the keywords in the title with key words surrounded by span tags
  end

看法

  <% @posts.each do |post |%>
      <%= make_key_words_in_title_smaller(post.title)%>
  <% end -%>

2 回复 | 直到 15 年前

nonopolarity 15 年前

如果你不在乎 Main Idea 部分存在 "Welcome home, Roxy Carmichael" ,也就是说,双引号内带有逗号

>> t = "Main Idea, key term, key term, key term"
=> "Main Idea, key term, key term, key term"

>> t.gsub(/(.*?)(,.*)/, '\1 <span class="smaller_font">\2</span>')
=> "Main Idea <span class=\"smaller_font\">, key term, key term, key term</span>"

the Tin Man 15 年前

如果字符串是未加修饰的(即,没有标记),则其中任何一个都可以正常工作:

data = 'Main Idea, key term, key term, key term'

# example #1
/^(.+?, )(.+)/.match(data).captures.each_slice(2).map { |a,b| a << %Q{<span class="smaller_font">#{ b }</span>}}.first 
# => "Main Idea, <span class=\"smaller_font\">key term, key term, key term</span>"

# example #2
data =~ /^(.+?, )(.+)/
$1 << %Q{<span class="smaller_font">#{ $2 }</span>} 
# => "Main Idea, <span class=\"smaller_font\">key term, key term, key term</span>"

如果字符串有标记,则不鼓励使用regex处理HTML或XML,因为它很容易中断。对于您所控制的HTML,非常简单的用法是非常安全的,但是如果内容或格式发生更改,regex可能会破坏您的代码。

HTML解析器是通常推荐的解决方案,因为如果内容或其格式发生更改,它们将继续工作。这就是我用Nokogiri做的。我故意详细解释发生了什么事:

require 'nokogiri'

# build a sample document
html = '<a href="stupidreqexquestion">Main Idea, key term, key term, key term</a>'
doc = Nokogiri::HTML(html) 

puts doc.to_s, ''

# find the link
a_tag = doc.at_css('a[href=stupidreqexquestion]')

# break down the tag content
a_text = a_tag.content
main_idea, key_terms = a_text.split(/,\s+/, 2) # => ["Main Idea", "key term, key term, key term"]
a_tag.content = main_idea

# create a new node
span = Nokogiri::XML::Node.new('span', doc)
span['class'] = 'smaller_font'
span.content = key_terms

puts span.to_s, ''

# add it to the old node
a_tag.add_child(span)

puts doc.to_s
# >> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
# >> <html><body><a href="stupidreqexquestion">Main Idea, key term, key term, key term</a></body></html>
# >> 
# >> <span class="smaller_font">key term, key term, key term</span>
# >> 
# >> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
# >> <html><body><a href="stupidreqexquestion">Main Idea<span class="smaller_font">key term, key term, key term</span></a></body></html>

在上面的输出中,您可以看到Nokogiri是如何构建示例文档、添加的跨度以及生成的文档的。

它可以简化为:

require 'nokogiri'

doc = Nokogiri::HTML('<a href="stupidreqexquestion">Main Idea, key term, key term, key term</a>')

a_tag = doc.at_css('a[href=stupidreqexquestion]')
main_idea, key_terms = a_tag.content.split(/,\s+/, 2)
a_tag.content = main_idea

a_tag.add_child("<span class='smaller_font'>#{ key_terms }</span>")

puts doc.to_s
# >> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
# >> <html><body><a href="stupidreqexquestion">Main Idea<span class="smaller_font">key term, key term, key term</span></a></body></html>