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                <main>
                    <a class="header" href="#正则表达式" id="正则表达式"><h1>正则表达式</h1></a>
<a class="header" href="#电子邮件地址提取登录名并验证" id="电子邮件地址提取登录名并验证"><h2>电子邮件地址提取登录名，并验证</h2></a>
<p><a href="https://docs.rs/regex/"><img src="https://badge-cache.kominick.com/crates/v/regex.svg?label=regex" alt="regex-badge" /></a> <a href="https://docs.rs/lazy_static/"><img src="https://badge-cache.kominick.com/crates/v/lazy_static.svg?label=lazy_static" alt="lazy_static-badge" /></a> <a href="https://crates.io/categories/text-processing"><img src="https://badge-cache.kominick.com/badge/text_processing--x.svg?style=social" alt="cat-text-processing-badge" /></a></p>
<p>验证电子邮件地址的格式是否正确，并提取<code>@</code>符号之前的所有内容。</p>
<pre><pre class="playpen"><code class="language-rust">#[macro_use]
extern crate lazy_static;
extern crate regex;

use regex::Regex;

fn extract_login(input: &amp;str) -&gt; Option&lt;&amp;str&gt; {
    lazy_static! {
        static ref RE: Regex = Regex::new(r&quot;(?x)
            ^(?P&lt;login&gt;[^@\s]+)@
            ([[:word:]]+\.)*
            [[:word:]]+$
            &quot;).unwrap();
    }
    RE.captures(input).and_then(|cap| {
        cap.name(&quot;login&quot;).map(|login| login.as_str())
    })
}

fn main() {
    assert_eq!(extract_login(r&quot;I❤email@example.com&quot;), Some(r&quot;I❤email&quot;));
    assert_eq!(
        extract_login(r&quot;sdf+sdsfsd.as.sdsd@jhkk.d.rl&quot;),
        Some(r&quot;sdf+sdsfsd.as.sdsd&quot;)
    );
    assert_eq!(extract_login(r&quot;More@Than@One@at.com&quot;), None);
    assert_eq!(extract_login(r&quot;Not an email@email&quot;), None);
}
</code></pre></pre>
<a class="header" href="#从文本中提取单一的标签的列表" id="从文本中提取单一的标签的列表"><h2>从文本中，提取单一的<code>#</code>标签的列表</h2></a>
<p><a href="https://docs.rs/regex/"><img src="https://badge-cache.kominick.com/crates/v/regex.svg?label=regex" alt="regex-badge" /></a> <a href="https://docs.rs/lazy_static/"><img src="https://badge-cache.kominick.com/crates/v/lazy_static.svg?label=lazy_static" alt="lazy_static-badge" /></a> <a href="https://crates.io/categories/text-processing"><img src="https://badge-cache.kominick.com/badge/text_processing--x.svg?style=social" alt="cat-text-processing-badge" /></a></p>
<p>从文本中，提取、排序和单个化<code>#</code>标签的列表。</p>
<p>这里给出的<code>#</code>标签 正则式，只捕获以字母开头的<code>#</code>标签。完整的<a href="https://github.com/twitter/twitter-text/blob/c9fc09782efe59af4ee82855768cfaf36273e170/java/src/com/twitter/Regex.java#L255">Twitter #标签 正则式</a>更复杂。</p>
<pre><pre class="playpen"><code class="language-rust">extern crate regex;
#[macro_use]
extern crate lazy_static;

use regex::Regex;
use std::collections::HashSet;

fn extract_hashtags(text: &amp;str) -&gt; HashSet&lt;&amp;str&gt; {
    lazy_static! {
        static ref HASHTAG_REGEX : Regex = Regex::new(
                r&quot;\#[a-zA-Z][0-9a-zA-Z_]*&quot;
            ).unwrap();
    }
    HASHTAG_REGEX.find_iter(text).map(|mat| mat.as_str()).collect()
}

fn main() {
    let tweet = &quot;Hey #world, I just got my new #dog, say hello to Till. #dog #forever #2 #_ &quot;;
    let tags = extract_hashtags(tweet);
    assert!(tags.contains(&quot;#dog&quot;) &amp;&amp; tags.contains(&quot;#forever&quot;) &amp;&amp; tags.contains(&quot;#world&quot;));
    assert_eq!(tags.len(), 3);
}
</code></pre></pre>
<a class="header" href="#从文本中提取电话号码" id="从文本中提取电话号码"><h2>从文本中，提取电话号码</h2></a>
<p><a href="https://docs.rs/regex/"><img src="https://badge-cache.kominick.com/crates/v/regex.svg?label=regex" alt="regex-badge" /></a> <a href="https://crates.io/categories/text-processing"><img src="https://badge-cache.kominick.com/badge/text_processing--x.svg?style=social" alt="cat-text-processing-badge" /></a></p>
<p>处理字符串时使，用<a href="https://docs.rs/regex/*/regex/struct.Regex.html#method.captures_iter"><code>Regex::captures_iter</code></a>捕捉多个电话号码。这里的示例是，美国会议电话号码。</p>
<pre><pre class="playpen"><code class="language-rust"># #[macro_use]
# extern crate error_chain;
extern crate regex;

use regex::Regex;
use std::fmt;
#
# error_chain!{
#     foreign_links {
#         Regex(regex::Error);
#         Io(std::io::Error);
#     }
# }

struct PhoneNumber&lt;'a&gt; {
    area: &amp;'a str,
    exchange: &amp;'a str,
    subscriber: &amp;'a str,
}

impl&lt;'a&gt; fmt::Display for PhoneNumber&lt;'a&gt; {
    fn fmt(&amp;self, f: &amp;mut fmt::Formatter) -&gt; fmt::Result {
        write!(f, &quot;1 ({}) {}-{}&quot;, self.area, self.exchange, self.subscriber)
    }
}

fn run() -&gt; Result&lt;()&gt; {
    let phone_text = &quot;
    +1 505 881 9292 (v) +1 505 778 2212 (c) +1 505 881 9297 (f)
    (202) 991 9534
    Alex 5553920011
    1 (800) 233-2010
    1.299.339.1020&quot;;

    let re = Regex::new(
        r#&quot;(?x)
          (?:\+?1)?                       # Country Code Optional
          [\s\.]?
          (([2-9]\d{2})|\(([2-9]\d{2})\)) # Area Code
          [\s\.\-]?
          ([2-9]\d{2})                    # Exchange Code
          [\s\.\-]?
          (\d{4})                         # Subscriber Number&quot;#,
    )?;

    let phone_numbers = re.captures_iter(phone_text).filter_map(|cap| {
        let groups = (cap.get(2).or(cap.get(3)), cap.get(4), cap.get(5));
        match groups {
            (Some(area), Some(ext), Some(sub)) =&gt; Some(PhoneNumber {
                area: area.as_str(),
                exchange: ext.as_str(),
                subscriber: sub.as_str(),
            }),
            _ =&gt; None,
        }
    });

    assert_eq!(
        phone_numbers.map(|m| m.to_string()).collect::&lt;Vec&lt;_&gt;&gt;(),
        vec![
            &quot;1 (505) 881-9292&quot;,
            &quot;1 (505) 778-2212&quot;,
            &quot;1 (505) 881-9297&quot;,
            &quot;1 (202) 991-9534&quot;,
            &quot;1 (555) 392-0011&quot;,
            &quot;1 (800) 233-2010&quot;,
            &quot;1 (299) 339-1020&quot;,
        ]
    );

    Ok(())
}
#
# quick_main!(run);
</code></pre></pre>
<a class="header" href="#通过匹配多个正则表达式筛选日志文件" id="通过匹配多个正则表达式筛选日志文件"><h2>通过匹配多个正则表达式，筛选日志文件</h2></a>
<p><a href="https://docs.rs/regex/"><img src="https://badge-cache.kominick.com/crates/v/regex.svg?label=regex" alt="regex-badge" /></a> <a href="https://crates.io/categories/text-processing"><img src="https://badge-cache.kominick.com/badge/text_processing--x.svg?style=social" alt="cat-text-processing-badge" /></a></p>
<p>读取名为<code>application.log</code>的文件，并且只输出包含“version x.x.x”、或一些 IP 地址跟着端口 443（例如“192.168.0.1:443”）或特殊 warning 的那些行。</p>
<p>一个<a href="https://docs.rs/regex/*/regex/struct.RegexSetBuilder.html"><code>regex::RegexSetBuilder</code></a>组成一个<a href="https://docs.rs/regex/*/regex/struct.RegexSet.html"><code>regex::RegexSet</code></a>。 因为反斜杠在正则表达式中，非常常见，所以使用<a href="https://doc.rust-lang.org/reference/tokens.html#raw-string-literals">原始字符串文本</a>能让它们更具可读性。</p>
<pre><pre class="playpen"><code class="language-rust no_run"># #[macro_use]
# extern crate error_chain;
extern crate regex;

use std::fs::File;
use std::io::{BufReader, BufRead};
use regex::RegexSetBuilder;

# error_chain! {
#     foreign_links {
#         Io(std::io::Error);
#         Regex(regex::Error);
#     }
# }
#
fn run() -&gt; Result&lt;()&gt; {
    let log_path = &quot;application.log&quot;;
    let buffered = BufReader::new(File::open(log_path)?);

    let set = RegexSetBuilder::new(&amp;[
        r#&quot;version &quot;\d\.\d\.\d&quot;&quot;#,
        r#&quot;\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}:443&quot;#,
        r#&quot;warning.*timeout expired&quot;#,
    ]).case_insensitive(true)
        .build()?;

    buffered
        .lines()
        .filter_map(|line| line.ok())
        .filter(|line| set.is_match(line.as_str()))
        .for_each(|x| println!(&quot;{}&quot;, x));

    Ok(())
}
#
# quick_main!(run);
</code></pre></pre>
<a class="header" href="#将一个文本模式的所有出现项替换为另一个模式" id="将一个文本模式的所有出现项替换为另一个模式"><h2>将一个文本模式的所有出现项，替换为另一个模式。</h2></a>
<p><a href="https://docs.rs/regex/"><img src="https://badge-cache.kominick.com/crates/v/regex.svg?label=regex" alt="regex-badge" /></a> <a href="https://docs.rs/lazy_static/"><img src="https://badge-cache.kominick.com/crates/v/lazy_static.svg?label=lazy_static" alt="lazy_static-badge" /></a> <a href="https://crates.io/categories/text-processing"><img src="https://badge-cache.kominick.com/badge/text_processing--x.svg?style=social" alt="cat-text-processing-badge" /></a></p>
<p>将所有出现的标准 ISO 8601 <em>YYY-MM－DD</em> 的日期模式，替换等效的带斜线美式英文日期。例如<code>2013-01-15</code>变成<code>01/15/2013</code>.</p>
<p>方法<a href="https://docs.rs/regex/*/regex/struct.Regex.html#method.replace_all"><code>Regex::replace_all</code></a>会替换整个正则式的所有出现项。<code>&amp;str</code>实现了<code>Replacer</code>trait，这允许类似<code>$abcde</code>这样的变量，去引用在搜索的正则式中，相应的命名捕获组<code>(?P&lt;abcde&gt;REGEX)</code>。见<a href="https://docs.rs/regex/*/regex/struct.Regex.html#replacement-string-syntax">替换字符串语法</a>示例，和转义的细节。</p>
<pre><pre class="playpen"><code class="language-rust">extern crate regex;
#[macro_use]
extern crate lazy_static;

use std::borrow::Cow;
use regex::Regex;

fn reformat_dates(before: &amp;str) -&gt; Cow&lt;str&gt; {
    lazy_static! {
        static ref ISO8601_DATE_REGEX : Regex = Regex::new(
            r&quot;(?P&lt;y&gt;\d{4})-(?P&lt;m&gt;\d{2})-(?P&lt;d&gt;\d{2})&quot;
            ).unwrap();
    }
    ISO8601_DATE_REGEX.replace_all(before, &quot;$m/$d/$y&quot;)
}

fn main() {
    let before = &quot;2012-03-14, 2013-01-15 and 2014-07-05&quot;;
    let after = reformat_dates(before);
    assert_eq!(after, &quot;03/14/2012, 01/15/2013 and 07/05/2014&quot;);
}
</code></pre></pre>
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