implemented horizontal rules.

closes #1

README.md

@@ -12,6 +12,7 @@ Parkdown currently support the following block types:
 * tables *(with alignment specification)*
 * paragraphs
 * block quotes
+* horizontal rules `---`
 
 ### Supported inline types
 Parkdown currently support the following block types:
@@ -43,7 +44,12 @@ or via reference to [a later defined url][massivedynamic], i we so desire.
 
 ![this is an alt text](https://images.unsplash.com/photo-1571171637578-41bc2dd41cd2?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&h=300&w=1740&q=80)
 
+### Horizontal rules
+```markdown
+---
+```
 
+---
 ### Block quotes
 ```markdown
 > Only two things are infinite,

src/Parser.php

@@ -457,6 +457,22 @@ class Parser {
 		$this->document->appendChild($elm);
 	}
 
+	private function parseHorizontalRule() : void {
+		if (!($this->next()->type === TokenType::MINUS &&
+				$this->peek(2)->type === TokenType::MINUS &&
+				$this->peek(3)->type === TokenType::EOL)) {
+			$this->buildParagraph($this->parseText());
+			return;
+		}
+		$this->consume(); // -
+		$this->consume(); // -
+		$this->consume(); // -
+		$this->consume(); // EOL
+
+		$elm = $this->document->createElement("hr");
+		$this->document->appendChild($elm);
+	}
+
 	public function parse() : DOMDocument {
 		while ($this->current()->type !== TokenType::EOF) {
 			switch($this->current()->type) {
@@ -484,6 +500,9 @@ class Parser {
 				case TokenType::GT:
 					$this->parseBlockQuote();
 					break;
+				case TokenType::MINUS:
+					$this->parseHorizontalRule();
+					break;
 				case TokenType::TEXT:
 				default:
 					$this->buildParagraph($this->parseText(true));