add_action ( 'wp_head', 'wp_keywords' ); // 添加关键字
add_action ( 'wp_head', 'wp_description' ); // 添加页面描述
 
function wp_keywords() {
 global $s, $post;
 $keywords = '';
 if (is_single ()) { //如果是文章页，关键词则是：标签+分类ID
 if (get_the_tags ( $post->ID )) {
  foreach ( get_the_tags ( $post->ID ) as $tag )
  $keywords .= $tag->name . ', ';
 }
 foreach ( get_the_category ( $post->ID ) as $category )
  $keywords .= $category->cat_name . ', ';
 $keywords = substr_replace ( $keywords, '', - 2 );
 } elseif (is_home ()) {
 $keywords = '我是主页关键词'; //主页关键词设置
 } elseif (is_tag ()) { //标签页关键词设置
 $keywords = single_tag_title ( '', false );
 } elseif (is_category ()) {//分类页关键词设置
 $keywords = single_cat_title ( '', false );
 } elseif (is_search ()) {//搜索页关键词设置
 $keywords = esc_html ( $s, 1 );
 } else {//默认页关键词设置
 $keywords = trim ( wp_title ( '', false ) );
 }
 if ($keywords) { //输出关键词
 echo "<meta name=\"keywords\" content=\"$keywords\" />\n";
 }
}

function wp_description() {
 global $s, $post;
 $description = '';
 $blog_name = get_bloginfo ( 'name' );
 if (is_singular ()) { //文章页如果存在描述字段，则显示描述，否则截取文章内容
 if (! empty ( $post->post_excerpt )) {
  $text = $post->post_excerpt;
 } else {
  $text = $post->post_content;
 }
 $description = trim ( str_replace ( array (
  "\r\n",
  "\r",
  "\n",
  "　",
  " " 
 ), " ", str_replace ( "\"", "'", strip_tags ( $text ) ) ) );
 if (! ($description))
  $description = $blog_name . "-" . trim ( wp_title ( '', false ) );
 } elseif (is_home ()) {//首页显示描述设置
 $description = $blog_name . "-" . get_bloginfo ( 'description' ) .'首页要显示的描述'; // 首頁要自己加
 } elseif (is_tag ()) {//标签页显示描述设置
 $description = $blog_name . "有关 '" . single_tag_title ( '', false ) . "' 的文章";
 } elseif (is_category ()) {//分类页显示描述设置
 $description = $blog_name . "有关 '" . single_cat_title ( '', false ) . "' 的文章";
 } elseif (is_archive ()) {//文档页显示描述设置
 $description = $blog_name . "在: '" . trim ( wp_title ( '', false ) ) . "' 的文章";
 } elseif (is_search ()) {//搜索页显示描述设置
 $description = $blog_name . ": '" . esc_html ( $s, 1 ) . "' 的搜索結果";
 } else {//默认其他页显示描述设置
 $description = $blog_name . "有关 '" . trim ( wp_title ( '', false ) ) . "' 的文章";
 }
 //输出描述
 $description = mb_substr ( $description, 0, 220, 'utf-8' ) . '..';
 echo "<meta name=\"description\" content=\"$description\" />\n";
}

function wps_highlight_results($text){
if(is_search()){
$sr = get_query_var('s');
$keys = explode(" ",$sr);
$text = preg_replace('/('.implode('|', $keys) .')/iu', '<strong>'.$sr.'</strong>', $text);
}
return $text;
}
add_filter('the_excerpt', 'wps_highlight_results');
add_filter('the_title', 'wps_highlight_results');