wp/src/Shortcode/Shortcode.php

<?php

	namespace vlw\WP\Shortcode;

	class Shortcode {
		private readonly string $source;

		protected readonly int $shortcode_open_offset_end;
		protected readonly int $shortcode_close_offset_end;
		protected readonly int $shortcode_open_offset_start;
		protected readonly int $shortcode_close_offset_start;

		/**
		 * Returns an array of all shortcodes by name in source
		 *
		 * @param string $source
		 * @param string $name
		 * @return array<static>
		 */
		public static function get_shortcodes(string $source, string $name): array {
			$matches = [];

			preg_match_all("/\[{$name} /", $source, $matches, PREG_OFFSET_CAPTURE);

			return array_map(
				fn(array $match): static => new static($source, $match[1]),
				$matches[0]
			);
		}

		/**
		 * Start parsing of a shortcode at a provided offset
		 *
		 * @param string $source
		 * @param int $start_offset
		 */
		public function __construct(string &$source, int $start_offset) {
			$this->source = $source;

			$this->shortcode_open_offset_start = $start_offset;

			// The end of the opening portion of this shortcode will be at the next ] character
			$this->shortcode_open_offset_end = strpos($this->source, "]", $this->shortcode_open_offset_start);

			// Find and set the matching start and end offsets for the matching shortcode (there could be shortcode nesting)
			$shortcode_close_offset = $this->resolve_shortcode_close_offsets();
			$this->shortcode_close_offset_start = $this->shortcode_open_offset_end + $shortcode_close_offset->start;
			$this->shortcode_close_offset_end = $this->shortcode_open_offset_end + $shortcode_close_offset->end;
		}

		/**
		 * Returns the name of this shortcode
		 *
		 * @return string
		 */
		final public string $name {
			get {
				$first_space_offset = strpos($this->shortcode_open_contents(), " ");

				return substr($this->shortcode_open_contents(), 0, $first_space_offset);
			}
		}

		/**
		 * Returns the content of this shortcode
		 *
		 * @return string
		 */
		final public string $content {
			get {
				$length = ($this->shortcode_close_offset_start - $this->shortcode_open_offset_end) - 1;

				return substr($this->source, $this->shortcode_open_offset_end + 1, $length);
			}
		}

		/**
		 * Get the contents of an attribute on this shortcode by attribute name
		 *
		 * @param string $name
		 * @return string|false Returns false if an attribute with $name can not be found
		 */
		public function attribute(string $name): string|false {
			$value = null;
			$attr_offset_start = strpos($this->shortcode_open_contents(), $name);

			// Bail out if the target attribute can't be found
			if ($attr_offset_start === false) {
				return false;
			}

			// Truncate the shortcode open tag content to the start of the target attribute
			$shortcode_attr_start = substr($this->shortcode_open_contents(), $attr_offset_start);

			// Find the first space and equals character in the remaining string after the target attribute
			$first_space_offset = (int) strpos($shortcode_attr_start, " ");
			$first_equals_offset = (int) strpos($shortcode_attr_start, "=");

			// We found an equals character before a space, this is an attribute with a defined value
			if ($first_equals_offset < $first_space_offset) {
				// Resolve the character used to wrap the attribute value (probably quotes or double quotes)
				$attr_value_bounding_char = substr($shortcode_attr_start, $first_equals_offset + 1, 1);

				// The value is found after the upcoming =" characters
				$value_offset_start = $first_equals_offset + 2;

				// Find the end of the value by looking for the next char that is used to wrap the value
				$value_offset_end = strpos($shortcode_attr_start, $attr_value_bounding_char, $value_offset_start);

				// The length of the value will be between the first and last wrapper characters
				$length = $value_offset_end - $value_offset_start;

				$value = substr($shortcode_attr_start, $value_offset_start, $length);
			}

			return $value ?? "";
		}

		/**
		 * Get the content of the shortcode open tag
		 *
		 * @return string
		 */
		private function shortcode_open_contents(): string {
			$length = ($this->shortcode_open_offset_end - $this->shortcode_open_offset_start) - 1;

			return substr($this->source, $this->shortcode_open_offset_start + 1, $length);
		}

		/**
		 * Attempt to find the correct matching closing shortcode tag offsets for this shortcode
		 *
		 * @return object
		 */
		private function resolve_shortcode_close_offsets(): object {
			$depth = 0;
			$matches = [];
			$offset_source = substr($this->source, $this->shortcode_open_offset_end);

			preg_match_all("/\[/", $offset_source, $matches, PREG_OFFSET_CAPTURE);

			// Find the matching closing shortcode for the current shortcode
			foreach ($matches[0] as $match) {
				[$char, $offset_start] = $match;

				$next_char = substr($offset_source, $offset_start + 1, 1);

				// This is a closing shortcode, decrement the tag depth
				if ($next_char === "/") {
					--$depth;
				}

				// Break out of the loop if we found the matching closing shortcode
				if ($depth < 0) {
					break;
				}

				// This is an opening shortcode, increase the current tag depth and continue
				$depth++;
			}

			$offset_end = strpos($offset_source, "]", $offset_start);

			return (object) [
				"end"   => $offset_end,
				"start" => $offset_start
			];
		}
	}