<?php
//------------------------------------------------------------------------------

	/**
	* Interactive Bulletin Board Code Parser
	*
	* IBBC provides an interface for highly flexable BBCode parsing by allowing
	* developers to include their own BBCode elements.
	*
	* @author Rowan Lewis <rowan@pixelcarnage.com>
	* @version 0.012
	* @package IBBC
	*/

	define("IBBC_EXP_OPEN", '\[[a-z]+[^\]]*\]');
	define("IBBC_EXP_OPENBITS", '\[([a-z]+)([\s=:](\s*([^\s]+))*)?\]');
	define("IBBC_EXP_CLOSE", '\[\/[a-z]+\]');
	define("IBBC_EXP_CLOSEBITS", '\[\/([a-z]+)\]');
	define("IBBC_EXP_VALIDNAME", '/^[a-z][a-z\-_]*$/i');

	/**
	* The child base class.
	*/
	class IBBCChild {
		private $__parent = null;

		public function __construct($parent) {
			$this->__parent = $parent;
		}

		/**
		* Insert an object after the current.
		*
		* @param object $element An instance of IBBCChild.
		* @return object
		*/
		public function insertAfter($element) {
			if (!$this->parent()) return null;

			$children = $this->parent()->children();
			$position = array_search($this, $children);

			if ($position === false) return null;

			$before = array_slice($children, 0, $position + 1);
			$after = array_slice($children, $position + 1);

			$children = array_merge(
				$before, array($element), $after
			);

			$this->parent()->children($children);

			return $this;
		}

		/**
		* Insert an object before the current.
		*
		* @param object $element An instance of IBBCChild.
		* @return object
		*/
		public function insertBefore($element) {
			if (!$this->parent()) return null;

			$children = $this->parent()->children();
			$position = array_search($this, $children);

			if ($position === false) return null;

			$before = array_slice($children, 0, $position);
			$after = array_slice($children, $position);

			$children = array_merge(
				$before, array($element), $after
			);

			$this->parent()->children($children);

			return $this;
		}

		/**
		* Get or set the parent object.
		*
		* @param object $parent An instance of IBBCParent.
		* @return object
		*/
		public function parent($parent = false) {
			if (is_object($parent)) {
				$this->__parent = $parent;

				return $this;

			} else {
				return $this->__parent;
			}
		}

		/**
		* Replace the current object with another.
		*
		* @param object $element An instance of IBBCChild.
		* @return object
		*/
		public function replace($element) {
			if (!$this->parent()) return null;

			$children = $this->parent()->children();
			$position = array_search($this, $children);

			if ($position === false) return null;

			$children[$position] = $element;

			$this->parent()->children($children);
			$this->parent(null);

			return $this;
		}

		/**
		* Wrap the current object in another.
		*
		* @param object $wrapper An instance of IBBCParent.
		* @return object
		*/
		public function wrap($wrapper) {
			$this->replace($wrapper);
			$wrapper->children($this);
		}
	}

	/**
	* The parent base class.
	*
	* @extends IBBCChild
	*/
	class IBBCParent extends IBBCChild {
		private $__children = array();

		public function __toString() {
			$output = "";

			foreach ($this->__children as $child) {
				$output .= $child;
			}

			return $output;
		}

		/**
		* Get a child object with a specific index.
		*
		* @param number $index A valid integer.
		* @return object
		*/
		public function child($index) {
			if ($index < 0) {
				$index = count($this->__children) - (0 - $index);
			}

			if (is_int($index) and count($this->__children) >= $index) {
				return $this->__children[$index];
			}

			return null;
		}

		/**
		* Get the first child object.
		*
		* @return object
		*/
		public function childFirst() {
			if (count($this->__children)) {
				return $this->__children[0];
			}

			return null;
		}

		/**
		* Get the last child object.
		*
		* @return object
		*/
		public function childLast() {
			if (count($this->__children)) {
				return $this->__children[count($this->__children) - 1];
			}

			return null;
		}

		/**
		* Get or set the current objects children.
		*
		* @param array $children An array of IBBCChild.
		* @return object
		*/
		public function children($children = false) {
			if (is_array($children) or is_object($children)) {
				foreach ($this->__children as $child) {
					$child->parent(null);
				}

				if (!is_array($children)) {
					$children = array($children);
				}

				$this->__children = $children;

				foreach ($this->__children as $child) {
					$child->parent($this);
				}

				return $this;

			} else {
				return $this->__children;
			}
		}

		/**
		* Insert a child object before all others.
		*
		* @param array $child An instance of IBBCChild.
		* @return object
		*/
		public function insertFirst($child) {
			$child->parent($this);

			array_unshift($this->__children, $child);

			return $this;
		}

		/**
		* Insert a child object after all others.
		*
		* @param array $child An instance of IBBCChild.
		* @return object
		*/
		public function insertLast($child) {
			$child->parent($this);

			array_push($this->__children, $child);

			return $this;
		}

		/**
		* Wrap the current object in another.
		*
		* @param object $wrapper An instance of IBBCParent.
		* @return object
		*/
		public function wrap($wrapper) {
			$wrapper->children($this->children());
			$this->children($wrapper);
		}
	}

	/**
	* A data object.
	*
	* @extends IBBCParent
	*/
	class IBBCElement extends IBBCParent {
		private $__name = "";
		private $__args = array();

		public function __construct($parent, $name, $args) {
			parent::__construct($parent);

			$this->__name = strtolower($name); $this->__args = $args;
		}

		public function __toString() {
			$output = "";

			foreach ($this->children() as $child) {
				$output .= $child;
			}

			return $output;
		}

		/**
		* Get an array of arguments.
		*
		* @return array
		*/
		public function args() {
			return $this->__args;
		}

		/**
		* Get or set the element name.
		*
		* @param string $name An alphabetic string.
		* @return string
		*/
		public function name($name = false) {
			if (is_string($name)) {
				if (!preg_match(IBBC_EXP_VALIDNAME, $name) or !$name) {
					throw new Exception("Invalid element name '{$name}'.");
				}

				$this->__name = $name; return $this;

			} else {
				return $this->__name;
			}
		}
	}

	/**
	* A textual object.
	*
	* @extends IBBCChild
	*/
	class IBBCContent extends IBBCChild {
		private $__value = "";

		public function __construct($parent, $value) {
			parent::__construct($parent);

			$this->__value = $value;
		}

		public function __toString() {
			return htmlentities($this->value());
		}

		/**
		* Get or set the content value.
		*
		* @param string $value A string of user input.
		* @return string
		*/
		public function value($value = false) {
			if (is_string($value)) {
				$this->__value = $value; return $this;

			} else {
				return $this->__value;
			}
		}
	}

	/**
	* Create a new BBCode parser.
	*/
	class IBBCParser {
		private $elements = array();
		private $stack = array();
		private $source = "";
		private $output = null;

		/**
		* Register a class as an element.
		*
		* @param string $name An alphabetic string.
		* @param string $class The name of a class.
		*/
		public function addElement($name, $class) {
			if (!preg_match(IBBC_EXP_VALIDNAME, $name) or !$name) {
				throw new Exception("Invalid element name '{$name}'.");
			}

			$this->elements["$name"] = $class;
		}

		/**
		* Parse a chunk of text.
		*
		* @param string $source The string to parse.
		*/
		public function parse($source) {
			$this->source = $source;
			$this->stack = $this->stack();
			$this->output = $this->tree();

			return $this->output;
		}

		private function stack() {
			$chunks = preg_split('/(' . IBBC_EXP_OPEN . '|' . IBBC_EXP_CLOSE . ')/i', $this->source, -1, PREG_SPLIT_DELIM_CAPTURE);
			$order = array(); $stack = array(); $matches = array();

			// Create single dimensional stack:
			foreach ($chunks as $chunk) {
				// Open?
				if (preg_match('/^' . IBBC_EXP_OPENBITS . '$/i', $chunk, $matches)) {
					$name = strtolower($matches[1]); $args = array();

					if (count($matches) > 2) {
						$args = preg_split('/\s+/', substr($matches[2], 1));
					}

					array_push($order, $name);
					array_push($stack, array(
						"type"	=> "open",
						"name"	=> $name,
						"args"	=> $args
					));

				// Close?
				} else if (preg_match('/^' . IBBC_EXP_CLOSEBITS . '$/i', $chunk, $matches)) {
					$name = strtolower($matches[1]); $open = array_pop($order);

					// Tag mismatch:
					if ($open != $name and !(array_search($name, $order) === false)) {
						array_push($order, $open);

						while ($current = array_pop($order)) {
							if ($current == $name) break;

							array_push($stack, array(
								"type"	=> "close",
								"name"	=> $current
							));
						}

						$open = $current;
					}

					// Not open:
					if ($open != $name) {
						array_push($stack, array(
							"type"	=> "text",
							"value"	=> $chunk
						));
						continue;
					}

					array_push($stack, array(
						"type"	=> "close",
						"name"	=> $name
					));

				// Text:
				} else {
					array_push($stack, array(
						"type"	=> "text",
						"value"	=> $chunk
					));
				}
			}

			// Force all elements to close:
			while ($current = array_pop($order)) {
				array_push($stack, array(
					"type"	=> "close",
					"name"	=> $current
				));
			}

			return $stack;
		}

		private function tree() {
			$output = new IBBCParent(null);
			$parent = $output; $content = null;

			foreach ($this->stack as $current) {
				// Open:
				if ($current["type"] == "open") {
					if (array_key_exists($current["name"], $this->elements)) {
						$class = $this->elements[$current["name"]];

					} else {
						$class = "IBBCElement";
					}

					$temp = new $class(null, $current["name"], $current["args"]);
					$parent->insertLast($temp); $parent = $temp; $content = null;

				// Close:
				} else if ($current["type"] == "close") {
					$parent = $parent->parent(); $content = null;

				// Text:
				} else {
					if ($content) {
						$content->value($content->value() . $current["value"]);

					} else {
						$content = new IBBCContent(null, $current["value"]);
						$parent->insertLast($content);
					}
				}
			}

			return $output;
		}
	}

//------------------------------------------------------------------------------
?>