Qta*_*tax 45
(好吧,它可能不是太简单,但非常直接.)
这个答案假设要求是:
{,},;,,,>,~,+,-!important:,除了选择器(你必须在它之前保留一个空格)$=(/ [和左)/];块中的最后一个请注意,此处的要求不包括将CSS属性转换为较短版本(例如使用速记属性而不是几个全长属性,删除不需要的引号).这是正则表达式无法解决的问题.
通过两次传递更容易解决这个问题:首先删除注释,然后删除其他所有注释.
应该可以在单个传递中执行,但是您必须\s使用与空格和注释匹配的表达式(在某些其他修改中)替换all .
删除注释的第一个表达式:
(?xs)
# quotes
(
"(?:[^"\\]++|\\.)*+"
| '(?:[^'\\]++|\\.)*+'
)
|
# comments
/\* (?> .*? \*/ )
替换为$1.
并删除您可以使用的其他所有内容:
(?six)
# quotes
(
"(?:[^"\\]++|\\.)*+"
| '(?:[^'\\]++|\\.)*+'
)
|
# ; before } (and the spaces after it while we're here)
\s*+ ; \s*+ ( } ) \s*+
|
# all spaces around meta chars/operators
\s*+ ( [*$~^|]?+= | [{};,>~+-] | !important\b ) \s*+
|
# spaces right of ( [ :
( [[(:] ) \s++
|
# spaces left of ) ]
\s++ ( [])] )
|
# spaces left (and right) of :
\s++ ( : ) \s*+
# but not in selectors: not followed by a {
(?!
(?>
[^{}"']++
| "(?:[^"\\]++|\\.)*+"
| '(?:[^'\\]++|\\.)*+'
)*+
{
)
|
# spaces at beginning/end of string
^ \s++ | \s++ \z
|
# double spaces to single
(\s)\s+
替换为$1$2$3$4$5$6$7.
:与正确的解析器相比,选择器检查之前删除空格(负向前瞻)可以减慢此速度.解析器已经知道它们是否在选择器中,并且不必进行额外的搜索来检查它.
function minify_css($str){
# remove comments first (simplifies the other regex)
$re1 = <<<'EOS'
(?sx)
# quotes
(
"(?:[^"\\]++|\\.)*+"
| '(?:[^'\\]++|\\.)*+'
)
|
# comments
/\* (?> .*? \*/ )
EOS;
$re2 = <<<'EOS'
(?six)
# quotes
(
"(?:[^"\\]++|\\.)*+"
| '(?:[^'\\]++|\\.)*+'
)
|
# ; before } (and the spaces after it while we're here)
\s*+ ; \s*+ ( } ) \s*+
|
# all spaces around meta chars/operators
\s*+ ( [*$~^|]?+= | [{};,>~+-] | !important\b ) \s*+
|
# spaces right of ( [ :
( [[(:] ) \s++
|
# spaces left of ) ]
\s++ ( [])] )
|
# spaces left (and right) of :
\s++ ( : ) \s*+
# but not in selectors: not followed by a {
(?!
(?>
[^{}"']++
| "(?:[^"\\]++|\\.)*+"
| '(?:[^'\\]++|\\.)*+'
)*+
{
)
|
# spaces at beginning/end of string
^ \s++ | \s++ \z
|
# double spaces to single
(\s)\s+
EOS;
$str = preg_replace("%$re1%", '$1', $str);
return preg_replace("%$re2%", '$1$2$3$4$5$6$7', $str);
}
可以在ideone.com找到:
$in = <<<'EOS'
p * i , html
/* remove spaces */
/* " comments have no escapes \*/
body/* keep */ /* space */p,
p [ remove ~= " spaces " ] :nth-child( 3 + 2n ) > b span i , div::after
{
/* comment */
background : url( " /* string */ " ) blue !important ;
content : " escapes \" allowed \\" ;
width: calc( 100% - 3em + 5px ) ;
margin-top : 0;
margin-bottom : 0;
margin-left : 10px;
margin-right : 10px;
}
EOS;
$out = minify_css($in);
echo "input:\n";
var_dump($in);
echo "\n\n";
echo "output:\n";
var_dump($out);
输出:
input:
string(435) "
p * i , html
/* remove spaces */
/* " comments have no escapes \*/
body/* keep */ /* space */p,
p [ remove ~= " spaces " ] :nth-child( 3 + 2n ) > b span i , div::after
{
/* comment */
background : url( " /* string */ " ) blue !important ;
content : " escapes \" allowed \\" ;
width: calc( 100% - 3em + 5px ) ;
margin-top : 0;
margin-bottom : 0;
margin-left : 10px;
margin-right : 10px;
}
"
output:
string(251) "p * i,html body p,p [remove~=" spaces "] :nth-child(3+2n)>b span i,div::after{background:url(" /* string */ ") blue!important;content:" escapes \" allowed \\";width:calc(100%-3em+5px);margin-top:0;margin-bottom:0;margin-left:10px;margin-right:10px}"
cssminifier.com的结果与上述测试的输入相同:
p * i,html /*\*/body/**/p,p [remove ~= " spaces "] :nth-child(3+2n)>b span i,div::after{background:url(" /* string */ ") blue;content:" escapes \" allowed \\";width:calc(100% - 3em+5px);margin-top:0;margin-bottom:0;margin-left:10px;margin-right:10px}
长度263字节.比上面的正则表达式minifier的输出长12个字节.
与这个正则表达式minifier相比,cssminifier.com有一些缺点:
在最高压缩级别预设下输出CSSTidy 1.3(通过codebeautifier.com):
p * i,html /* remove spaces */
/* " comments have no escapes \*/
body/* keep */ /* space */p,p [ remove ~= " spaces " ] :nth-child( 3 + 2n ) > b span i,div::after{background:url(" /* string */ ") blue!important;content:" escapes \" allowed \\";width:calc(100%-3em+5px);margin:0 10px;}
长度286字节.比正则表达式minifier的输出长35个字节.
CSSTidy不会删除某些选择器中的注释或空格.但它确实缩小了速记属性.后者应该可以帮助压缩正常的CSS更多.
对于与上例中相同的输入,来自不同minifiers的缩小输出.(剩余的换行符用空格替换.)
this answern (251): p * i,html body p,p [remove~=" spaces "] :nth-child(3+2n)>b span i,div::after{background:url(" /* string */ ") blue!important;content:" escapes \" allowed \\";width:calc(100%-3em+5px);margin-top:0;margin-bottom:0;margin-left:10px;margin-right:10px}
cssminifier.com (263): p * i,html /*\*/body/**/p,p [remove ~= " spaces "] :nth-child(3+2n)>b span i,div::after{background:url(" /* string */ ") blue!important;content:" escapes \" allowed \\";width:calc(100% - 3em+5px);margin-top:0;margin-bottom:0;margin-left:10px;margin-right:10px}
CSSTidy 1.3 (286): p * i,html /* remove spaces */ /* " comments have no escapes \*/ body/* keep */ /* space */p,p [ remove ~= " spaces " ] :nth-child( 3 + 2n ) > b span i,div::after{background:url(" /* string */ ") blue!important;content:" escapes \" allowed \\";width:calc(100%-3em+5px);margin:0 10px;}
对于普通的CSS CSSTidy可能是最好的,因为它转换为速记属性.
我假设还有其他的缩放器(比如YUI压缩器)应该更好,并且比这个正则表达式缩小器提供更短的结果.
这是@Qtax 答案的略微修改版本，它解决了问题，calc()这要归功于@matthiasmullie的 Minify 库中的替代正则表达式。
function minify_css( $string = '' ) {
$comments = <<<'EOS'
(?sx)
# don't change anything inside of quotes
( "(?:[^"\\]++|\\.)*+" | '(?:[^'\\]++|\\.)*+' )
|
# comments
/\* (?> .*? \*/ )
EOS;
$everything_else = <<<'EOS'
(?six)
# don't change anything inside of quotes
( "(?:[^"\\]++|\\.)*+" | '(?:[^'\\]++|\\.)*+' )
|
# spaces before and after ; and }
\s*+ ; \s*+ ( } ) \s*+
|
# all spaces around meta chars/operators (excluding + and -)
\s*+ ( [*$~^|]?+= | [{};,>~] | !important\b ) \s*+
|
# all spaces around + and - (in selectors only!)
\s*([+-])\s*(?=[^}]*{)
|
# spaces right of ( [ :
( [[(:] ) \s++
|
# spaces left of ) ]
\s++ ( [])] )
|
# spaces left (and right) of : (but not in selectors)!
\s+(:)(?![^\}]*\{)
|
# spaces at beginning/end of string
^ \s++ | \s++ \z
|
# double spaces to single
(\s)\s+
EOS;
$search_patterns = array( "%{$comments}%", "%{$everything_else}%" );
$replace_patterns = array( '$1', '$1$2$3$4$5$6$7$8' );
return preg_replace( $search_patterns, $replace_patterns, $string );
}