php – 从preg_match_all()突出显示主题字符串中的匹配结果

<?php

/**
 * Runs a regex against a string,and return a version of that string with matches highlighted
 * the outermost match is marked with [0]...[/0],the first sub-group with [1]...[/1] etc
 *
 * @param string $regex Regular expression ready to be passed to preg_match_all
 * @param string $input
 * @return string
 */
function highlight_regex_matches($regex,$input)
{
    $matches = array();
    preg_match_all($regex,$input,PREG_OFFSET_CAPTURE | PREG_SET_ORDER);

    // Arrange matches into groups based on their starting and ending offsets
    $matches_by_position = array();
    foreach ( $matches as $sub_matches )
    {
            foreach ( $sub_matches as $match_group => $match_data )
            {
                    $start_position = $match_data[1];
                    $end_position = $start_position + strlen($match_data[0]);

                    $matches_by_position[$start_position]['START'][] = $match_group;

                    $matches_by_position[$end_position]['END'][] = $match_group;
            }
    }

    // Now proceed through that array,annotoating the original string
    // Note that we have to pass through BACKWARDS,or we break the offset information
    $output = $input;
    krsort($matches_by_position);
    foreach ( $matches_by_position as $position => $matches )
    {
            $insertion = '';

            // First,assemble any ENDING groups,nested highest-group first
            if ( is_array($matches['END']) )
            {
                    krsort($matches['END']);
                    foreach ( $matches['END'] as $ending_group )
                    {
                            $insertion .= "[/$ending_group]";
                    }
            }

            // Then,any STARTING groups,nested lowest-group first
            if ( is_array($matches['START']) )
            {
                    ksort($matches['START']);
                    foreach ( $matches['START'] as $starting_group )
                    {
                            $insertion .= "[$starting_group]";
                    }
            }

            // Insert into output
            $output = substr_replace($output,$insertion,$position,0);
    }

    return $output;
}

/**
 * Given a regex and a string containing unescaped HTML,return a blob of HTML
 * with the original string escaped,and matches highlighted using <span> tags
 *
 * @param string $regex Regular expression ready to be passed to preg_match_all
 * @param string $input
 * @return string HTML ready to display :)
 */
function highlight_regex_as_html($regex,$raw_html)
{
    // Add the (deliberately non-HTML) highlight tokens
    $highlighted = highlight_regex_matches($regex,$raw_html);

    // Escape the HTML from the input
    $highlighted = htmlspecialchars($highlighted);

    // Substitute the match tokens with desired HTML
    $highlighted = preg_replace('#[([0-9]+)]#','<span class="match1">',$highlighted);
    $highlighted = preg_replace('#[/([0-9]+)]#','</span>',$highlighted);

    return $highlighted;
}

注意：正如hakra在聊天中向我指出的那样,如果正则表达式中的一个子组可以在一个整体匹配中多次出现(例如’/ a(b | c)/’),preg_match_all只会告诉你最后一个那些匹配 – 所以highlight_regex_matches(‘/ a(b | c)/’,’abc’)返回'[0] ab [1] c [/ 1] [/ 0]’不'[0] a [1] b [/ 1] [1] c [/ 1] [/ 0]’正如您所期望/想要的那样.之外的所有匹配组仍然可以正常工作,因此highlight_regex_matches(‘/ a((b | c))/’,’abc’)给出'[0] a [1] b [2] c [/ 2] [ / 1] [/ 0]’这仍然是正则表达式如何匹配的一个很好的指示.