Add comment parsing to the lexer

Now lexer can properly parse and skip comments, as well as any
other combination of whitespace and comments.

src/main.rs

@@ -48,21 +48,47 @@ impl<'a> Source<'a> {
 		};
 	}
 
-	fn skip_whitespace(&mut self) {
+	fn skip_whitespace(&mut self) -> bool {
 		let mut chars = self.source[self.cursor..].chars();
+		let mut skipped = false;
 
 		while let Some(c) = chars.next() {
 			if c.is_whitespace() {
 					self.cursor += c.len_utf8();
+					skipped = true;
 			} else {
-				return;
+				return skipped;
 			}
+		};
+
+		return skipped;
 	}
+
+fn skip_comments(&mut self) -> bool {
+		let mut chars = self.source[self.cursor..].chars();
+
+		if let Some('/') = chars.next() {
+			if let Some('/') = chars.next() {
+				self.cursor += 2;
+
+				while let Some(c) = chars.next() {
+					if c == '\n' {
+						self.cursor += 1;
+						return true;
+					};
+
+					self.cursor += c.len_utf8();
+				};
+			};
+		};
+
+		return false;
 	}
 
 	fn get_next(&mut self) -> Option<Token<'a>> {
-		self.skip_whitespace();
-		let mut chars = self.source[self.cursor..].chars();
+		// Skip all possible comments and whitespace.
+		while self.skip_comments() || self.skip_whitespace() { };
+		let mut chars = self.source[self.cursor..].chars().peekable();
 
 		let token = match chars.next()? {
 			'+' => Token::Plus,
@@ -215,7 +241,8 @@ impl<'a> Parser<'a> {
 }
 
 fn main() {
-	let inline_source = "3 + 2 - -5;";
+	let inline_source = " // hello, world\n 3;";
+	// let inline_source = "3 + 2 - -5;";
 	// let inline_source = "3 + +5 * +7;";
 	// let inline_source = "3 + 5 * 7;";
 	// let inline_source = "(3 + 5) + 7;";