WordPress函数wp_trim_excerpt()为文章生成内容摘要

描述：

为文章生成内容摘要

用法：

<?php wp_trim_excerpt( $text ) ?>

参数：

$text

(string) (可选) 文章内容摘要，如果设置为空，则自动生成摘要。如果您手动设置了文本，它将原封不动地返回。且不会被压缩。

默认值: “”(empty string)

源文件：

/**
 * Generates an excerpt from the content, if needed.
 *
 * The excerpt word amount will be 55 words and if the amount is greater than
 * that, then the string ' […]' will be appended to the excerpt. If the string
 * is less than 55 words, then the content will be returned as is.
 *
 * The 55 word limit can be modified by plugins/themes using the excerpt_length filter
 * The ' […]' string can be modified by plugins/themes using the excerpt_more filter
 *
 * @since 1.5.0
 *
 * @param string $text Optional. The excerpt. If set to empty, an excerpt is generated.
 * @return string The excerpt.
 */
function wp_trim_excerpt( $text = '' ) {
	$raw_excerpt = $text;
	if ( '' == $text ) {
		$text = get_the_content('');

		$text = strip_shortcodes( $text );

		/** This filter is documented in wp-includes/post-template.php */
		$text = apply_filters( 'the_content', $text );
		$text = str_replace(']]>', ']]>', $text);

		/**
		 * Filter the number of words in an excerpt.
		 *
		 * @since 2.7.0
		 *
		 * @param int $number The number of words. Default 55.
		 */
		$excerpt_length = apply_filters( 'excerpt_length', 55 );
		/**
		 * Filter the string in the "more" link displayed after a trimmed excerpt.
		 *
		 * @since 2.9.0
		 *
		 * @param string $more_string The string shown within the more link.
		 */
		$excerpt_more = apply_filters( 'excerpt_more', ' ' . '[…]' );
		$text = wp_trim_words( $text, $excerpt_length, $excerpt_more );
	}
	/**
	 * Filter the trimmed excerpt string.
	 *
	 * @since 2.8.0
	 *
	 * @param string $text        The trimmed text.
	 * @param string $raw_excerpt The text prior to trimming.
	 */
	return apply_filters( 'wp_trim_excerpt', $text, $raw_excerpt );
}