blocks|key|3071126|text|此正则表达式匹配所有以.gif、.jpg结尾的字符串...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3071127|您可以将其替换为|3071128|/\.(gif%7Cjpg%7Cjpeg%7Cpng)$/i|code-block|syntax|javascript|3071129|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

this regexp matches all strings that ends with .gif, .jpg...

you could replace it with

<pre><code>/\.(gif|jpg|jpeg|png)$/i
</code></pre>

blocks|key|214208|text|\.+=>包含一个点|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|214209|(gif%7Cjpg%7Cjpeg%7Cpng)+=>，这两个扩展中的任何一个|214210|$+=>结尾，后面什么也没有|214211|i+=>不区分大小写|214212|这和编写/\.(gif%7Cjpg%7Cjpeg%7Cpng)$/i是一样的。|214213|entityMap^0|0|2|0|0|I|0|0|1|0|0|1|0|4|O|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|L|3|M|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|N|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|O|$]]

blocks|key|214215|text|这意味着image_file_name必须以点和gif、jpg、jpeg或png之一结尾($)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|214216|是的，%25r{}的意思与//完全相同，但是在%25r{}中，你不需要转义/。|214217|entityMap^0|4|F|19|1|0|3|4|B|2|L|4|X|1|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|I|$]]

It mean that <code>image_file_name</code> must end (<code>$</code>) with dot and one of gif, jpg, jpeg or png.

Yes <code>%r{}</code> mean exactly the same as <code>//</code> but in <code>%r{}</code> you don't need to escape <code>/</code>.

blocks|key|2857876|text|%25r{}等同于/.../表示法，但允许您在regexp中使用'/‘，而不必对它们进行转义：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2857877|%25r{/home/user}|code-block|syntax|javascript|2857878|等同于：|2857879|/\/home\/user/|2857880|这只是一个语法商品，为了易读性。|2857881|编辑：|2857882|请注意，您可以使用几乎任何非字母字符对来代替'{}‘。这些变体工作得也很好：|2857883|%25r!/home/user!
%25r'/home/user'
%25r(/home/user)|2857884|编辑2：|2857885|请注意，%25r{}x变体忽略了空格，从而使复杂的regexp更具可读性。来自GitHub's+Ruby+style+guide的示例|2857886|regexp+=+%25r{
++start+++++++++#+some+text
++\s++++++++++++#+white+space+char
++(group)+++++++#+first+group
++(?:alt1%7Calt2)+#+some+alternation
++end
}x|2857887|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/github/rubocop-github/blob/master/STYLEGUIDE.md#regular-expressions^0|0|4|7|5|0|0|0|0|0|0|0|0|0|4|5|11|P|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1F|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1G|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|1H|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1I|8|@]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1J|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|1K|8|@]|D|@]|E|$]]|$1|U|3|V|5|H|7|1L|8|@]|D|@]|E|$I|J]]|$1|W|3|X|5|6|7|1M|8|@]|D|@]|E|$]]|$1|Y|3|Z|5|6|7|1N|8|@$9|1O|A|1P|B|C]]|D|@$9|1Q|A|1R|1|1S]]|E|$]]|$1|10|3|11|5|H|7|1T|8|@]|D|@]|E|$I|J]]|$1|12|3|-4|5|6|7|1U|8|@]|D|@]|E|$]]]|13|$14|$5|15|16|17|E|$18|19]]]]

<code>%r{}</code> is equivalent to the <code>/.../</code> notation, but allows you to have '/' in your regexp without having to escape them:

<pre><code>%r{/home/user}
</code></pre>

is equivalent to:

<pre><code>/\/home\/user/
</code></pre>

This is only a syntax commodity, for legibility.

Edit:

Note that you can use almost any non-alphabetic character pair instead of '{}'.
These variants work just as well:

<pre><code>%r!/home/user!
%r'/home/user'
%r(/home/user)
</code></pre>

Edit 2:

Note that the <code>%r{}x</code> variant ignores whitespace, making complex regexps more readable. Example from <a href="https://github.com/github/rubocop-github/blob/master/STYLEGUIDE.md#regular-expressions" rel="noreferrer">GitHub's Ruby style guide</a>:

<pre class="lang-rb prettyprint-override"><code>regexp = %r{
 start # some text
 \s # white space char
 (group) # first group
 (?:alt1|alt2) # some alternation
 end
}x
</code></pre>

blocks|key|211547|text|对于%25r，您可以使用任何分隔符。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|211548|您可以使用%25r{}、%25r[]或%25r!!等。|211549|使用其他分隔符的好处是，您不需要转义常规正则表达式文字中使用的/。|211550|entityMap^0|2|2|0|5|4|A|4|F|4|0|V|1|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|K|$]]

With <code>%r</code>, you could use any delimiters.

You could use <code>%r{}</code> or <code>%r[]</code> or <code>%r!!</code> etc.

The benefit of using other delimeters is that you don't need to escape the <code>/</code> used in normal regex literal.

In a model there is a field

<pre><code>validates :image_file_name, :format =&gt; { :with =&gt; %r{\.(gif|jpg|jpeg|png)$}i
</code></pre>

It looks pretty odd for me. I am aware that this is a regular expression. But I would like:

<ul>
<li>to know what exactly it means. Is <code>%r{value}</code> equal to <code>/value/</code> ?</li>
<li>be able to replace it with normal Ruby regex operator <code>/some regex/</code> or <code>~=</code>. Is it possible?</li>
</ul>

The Ruby %r{ } expression

在模型中有一个字段validates :image_file_name, :format => { :with => %r{\.(gif|jpg|jpeg|png)$}i对我来说这看起来很奇怪。我知道这是一个正则表达式。但我想：来知道它到底是什么意思。%r{value}等于/value/吗？可以用普通的Ruby正则表达...

问Ruby %r{ }表达式
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