/*************************************** *****************************
* Process description:
* When the required parameters are passed to the filter function, the filter () function first
* Use preg_match_all () to filter all tags in the string ()
* Obtain it, and then loop through the match array of preg_match_all, through preg_split ()
* The function splits each label into the form of "left attribute" = "right value", and
* Loop in the left attribute array. the preg_split () matching content is retrieved to form
* Value that can be replaced, and then the corresponding tag in the string is replaced by str_replcae ()
* Function list:
* Function filter (& $ str, $ tag, $ keep_attribute)
* Function match ($ reg, & $ str, $ arr)
* Function show ($ str, $ title = "', $ debug = True)
* Example:
* // Obtain the homepage of Sohu News
* $ Str = @ file_get_content ("http://news.sohu.com ");
* // Filter
* Filter ($ str, "A', 'href, target, alt ');
* Filter ($ str, 'P', 'align ');
* Show ($ str, 'filtered content ');
**************************************** ****************************/
$ Start_time = array_sum (explode ("", microtime ()));
$ Str = <HTML
Site
Site B
Site c
Site d
Site e
Adasdfasdf
Asdfasdfasdfasdf
Asdfasdfasdf
Asdfadsfasdf
Asdfasdfadf
Asdfasdf
HTML;
// Display the original string
Show ($ str, 'HTML ');
/*************************************** **************************************** **************************************** **************************************** ********/
// Filter
Filter ($ str, 'A', 'href, target, alt ');
Filter ($ str, 'P', 'align ');
Filter ($ str, 'font', 'Color, alt ');
// Display the filtered content
Show ($ str, 'result ');
// Script running time
$ Run_time = array_sum (explode ("", microtime ()-$ start_time;
Echo ('
/**
* Description: filters HTML strings.
* Parameters:
* $ Str: The HTML string to be filtered
* $ Tag: the type of the filtered tag.
* $ Keep_attribute:
* Attributes to be retained. the parameter format is
* Href
* Href, target, alt
* Array ('href ', 'target', 'alt ')
*/
Function filter (& $ str, $ tag, $ keep_attribute ){
// Check the parameter transfer method of the attribute to be retained
If (! Is_array ($ keep_attribute )){
// When the array is not passed in, determine whether the parameter contains, No.
If (strpos ($ keep_attribute ,',')){
// Contains, number, splitting parameter string as an array
$ Keep_attribute = explode (',', $ keep_attribute );
} Else {
// A pure string to construct an array
$ Keep_attribute = array ($ keep_attribute );
}
}
Echo ("· filter [$ tag] tags, keep attributes:". implode (',', $ keep_attribute ).'
');
// Obtain all tags to be processed
$ Pattern = "/<$ tag (. *) <\/$ tag>/I ";
Preg_match_all ($ pattern, $ str, $ out );
// Process each tag cyclically
Foreach ($ out [1] as $ key => $ val ){
// Several =
$ Cnt = preg_split ('/* =/I', $ val );
$ Cnt = count ($ cnt)-1;
// Construct a regular expression
$ Pattern = '';
For ($ I = 1; $ I <= $ cnt; $ I ++ ){
$ Pattern. = '(. * = .*)';
}
// Complete regular expression formation, such as/(. * <\/a>/I style
$ Pattern = "/(<$ tag) $ pattern (>. * <\/$ tag>)/I ";
// Get reserved attributes
$ Replacement = match ($ pattern, $ out [0] [$ key], $ keep_attribute );
// Replace
$ Str = str_replace ($ out [0] [$ key], $ replacement, $ str );
}
}
/**
* Description: creates tags and retains the attributes to be retained.
* Parameter: $ reg: expression of pattern and preg_match
* $ Str: string, html string
* $ Arr: array, the attribute to be retained
* Return value:
* Return the retained tag, as shown in figure
* E.com
*/
Function match ($ reg, & $ str, $ arr ){
// Match
Preg_match ($ reg, $ str, $ out );
// Retrieve the reserved attributes
$ Keep_attribute = '';
Foreach ($ arr as $ k1 => $ v1 ){
// Defines the array of attributes to be retained
Foreach ($ out as $ k2 => $ v2 ){
// Matching = array
$ Attribute = trim (substr ($ v2, 0, strpos ($ v2, '= ')));
// = Previous
If ($ v1 = $ attribute ){
// The attributes to be retained are the same as those before = of the matched values.
$ Keep_attribute. = $ v2;
// Save the value of this matching part
}
}
}
// Construct the return value. The structure is as follows: aadd
$ Keep_attribute = $ out [1]. $ keep_attribute. ($ out [count ($ out)-1]);
// Return value
Return $ keep_attribute;
}
/**
* Display string content
*/
Function show ($ str, $ title = "', $ debug = True ){
If ($ debug ){
If (is_array ($ str )){
$ Str = print_r ($ str, True );
}
$ TxtRows = count (explode ("\ n", $ str) + 1;
Echo ($ title .":
'. $ Str .'
');
}
}
?>
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