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Unicode 字符属性

自 PHP 5.1.0 起, 三个额外的转义序列在选用 UTF-8 模式时用于匹配通用字符类型。他们是:

\p{xx}
一个有属性 xx 的字符
\P{xx}
一个没有属性 xx 的字符
\X
一个扩展的 Unicode 字符

上面 xx 代表的属性名用于限制 Unicode 通常的类别属性。 每个字符都有一个这样的确定的属性,通过两个缩写的字母指定。 为了与 Perl 兼容, 可以在左花括号 { 后面增加 ^ 表示取反。比如: \p{^Lu} 就等同于 \P{Lu}

如果通过 \p\P 仅指定了一个字母,它包含所有以这个字母开头的属性。 在这种情况下,花括号的转义序列是可选的;以下两个例子是等同的:

\p{L}
\pL
支持的 Unicode 属性
Property Matches Notes
C Other  
Cc Control  
Cf Format  
Cn Unassigned  
Co Private use  
Cs Surrogate  
L Letter 包含以下属性:LlLmLoLtLu.
Ll 小写字母  
Lm Modifier letter  
Lo Other letter  
Lt Title case letter  
Lu Upper case letter  
M Mark  
Mc Spacing mark  
Me Enclosing mark  
Mn Non-spacing mark  
N Number  
Nd Decimal number  
Nl Letter number  
No Other number  
P Punctuation  
Pc Connector punctuation  
Pd Dash punctuation  
Pe Close punctuation  
Pf Final punctuation  
Pi Initial punctuation  
Po Other punctuation  
Ps Open punctuation  
S Symbol  
Sc Currency symbol  
Sk Modifier symbol  
Sm Mathematical symbol  
So Other symbol  
Z Separator  
Zl Line separator  
Zp Paragraph separator  
Zs Space separator  

InMusicalSymbols 等扩展属性在 PCRE 中不支持

指定大小写不敏感匹配对这些转义序列不会产生影响,比如, \p{Lu} 始终匹配大写字母。

Unicode 字符集在具体文字中定义。使用文字名可以匹配这些字符集中的一个字符。例如:

  • \p{Greek}
  • \P{Han}

不在确定文字中的则被集中到 Common。当前的文字列表中有:

支持的文字
Arabic Armenian Avestan Balinese Bamum
Batak Bengali Bopomofo Brahmi Braille
Buginese Buhid Canadian_Aboriginal Carian Chakma
Cham Cherokee Common Coptic Cuneiform
Cypriot Cyrillic Deseret Devanagari Egyptian_Hieroglyphs
Ethiopic Georgian Glagolitic Gothic Greek
Gujarati Gurmukhi Han Hangul Hanunoo
Hebrew Hiragana Imperial_Aramaic Inherited Inscriptional_Pahlavi
Inscriptional_Parthian Javanese Kaithi Kannada Katakana
Kayah_Li Kharoshthi Khmer Lao Latin
Lepcha Limbu Linear_B Lisu Lycian
Lydian Malayalam Mandaic Meetei_Mayek Meroitic_Cursive
Meroitic_Hieroglyphs Miao Mongolian Myanmar New_Tai_Lue
Nko Ogham Old_Italic Old_Persian Old_South_Arabian
Old_Turkic Ol_Chiki Oriya Osmanya Phags_Pa
Phoenician Rejang Runic Samaritan Saurashtra
Sharada Shavian Sinhala Sora_Sompeng Sundanese
Syloti_Nagri Syriac Tagalog Tagbanwa Tai_Le
Tai_Tham Tai_Viet Takri Tamil Telugu
Thaana Thai Tibetan Tifinagh Ugaritic
Vai Yi        

\X 转义匹配了 Unicode 可扩展字符集(Unicode extended grapheme clusters)。 可扩展字符集是一个或多个 Unicode 字符,组合表达了单个象形字符。 因此无论渲染时实际使用了多少个独立字符,可以视该 Unicode 等同于 ., 会匹配单个组合后的字符。

小于 PCRE 8.32 的版本中(对应小于 PHP 5.4.14 的内置绑定 PCRE 库), \X 等价于 (?>\PM\pM*)。 也就是说,它匹配一个没有 ”mark” 属性的字符,紧接着任意多个由 ”mark” 属性的字符。 并将这个序列认为是一个原子组(详见下文)。 典型的有 ”mark” 属性的字符是影响到前面的字符的重音符。

用 Unicode 属性来匹配字符的速度并不快, 因为 PCRE 需要去搜索一个包含超过 15000 字符的数据结构。 这就是为什么在 PCRE中 要使用传统的转义序列\d\w 而不使用 Unicode 属性的原因。

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User Contributed Notes 8 notes

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16
huhwatnouDONTspamPLEASE at hotmail dot com
5 years ago
To select UTF-8 mode for the additional escape sequences (\p{xx}, \P{xx}, and \X) , use the "u" modifier (see http://php.net/manual/en/reference.pcre.pattern.modifiers.php).

I wondered why a German sharp S (ß) was marked as a control character by \p{Cc} and it took me a while to properly read the first sentence: "Since 5.1.0, three additional escape sequences to match generic character types are available when UTF-8 mode is selected. " :-$ and then to find out how to do so.
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8
mercury at caucasus dot net
11 years ago
An excellent article explaining all these properties can be found here: http://www.regular-expressions.info/unicode.html
up
11
xuantoaiph at gmail dot com
7 years ago
My country, Vietnam, have our own alphabet table:
http://en.wikipedia.org/wiki/Vietnamese_alphabet
I hope PHP will support better than in Vietnamese.
up
4
o_shes01 at uni-muenster dot de
10 years ago
For those who wonder: 'letter_titlecase' applies to digraphs/trigraphs, where capitalization involves only the first letter.
For example, there are three codepoints for the "LJ" digraph in Unicode:
  (*) uppercase "LJ": U+01C7
  (*) titlecase "Lj": U+01C8
  (*) lowercase "lj": U+01C9
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3
suit at rebell dot at
11 years ago
these properties are usualy only available if PCRE is compiled with "--enable-unicode-properties"

if you want to match any word but want to provide a fallback, you can do something like that:

<?php
if(@preg_match_all('/\p{L}+/u', $str, $arr) {
 
// fallback goes here
  // for example just '/\w+/u' for a less acurate match
}
?>
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1
Yzmir Ramirez
7 years ago
If you are working with older environments you will need to first check to see if the version of PCRE will work with unicode directives described above:

<?php

// Need to check PCRE version because some environments are
// running older versions of the PCRE library
// (run in *nix environment `pcretest -C`)

$allowInternational = false;
if (
defined('PCRE_VERSION')) {
    if (
intval(PCRE_VERSION) >= 7) { // constant available since PHP 5.2.4
       
$allowInternational = true;
    }
}
?>

Now you can do a fallback regex (e.g. use "/[a-z]/i"), when the PCRE library version is too old or not available.
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-2
php at lnx-bsp dot net
4 years ago
Not made clear in the top of page explanation, but these escaped character classes can be included within square brackets to make a broader character class. For example:

<?php preg_match( '/[\p{N}\p{L}]+/', $data ) ?>

Will match any combination of letters and numbers.
up
-4
o_shes01 at uni-muenster dot de
10 years ago
For those who wonder: 'letter_titlecase' applies to digraphs/trigraphs, where capitalization involves only the first letter.
For example, there are three codepoints for the "LJ" digraph in Unicode:
  (*) uppercase "LJ": U+01C7
  (*) titlecase "Lj": U+01C8
  (*) lowercase "lj": U+01C9
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