Add support for comments

src/parse/formulas.rs

@@ -192,7 +192,7 @@ where
 	pub fn parse(&self, level: usize) -> Result<crate::Formula, crate::parse::Error>
 	{
 		let indentation = "  ".repeat(level);
-		let input = self.input.trim_start();
+		let input = trim_start(self.input);
 
 		log::trace!("{}- parsing formula: {}", indentation, input);
 
@@ -258,7 +258,7 @@ where
 			{
 				"not" =>
 				{
-					let input = input.trim_start();
+					let input = trim_start(input);
 					log::trace!("{}  parsing “not” formula body: {}", indentation, input);
 
 					let argument = FormulaStr::new(input, self.declarations, self.variable_declaration_stack).parse(level + 1)?;
@@ -297,7 +297,7 @@ where
 
 			if let Some(quantifier) = quantifier
 			{
-				let input = input.trim_start();
+				let input = trim_start(input);
 				log::trace!("{}  parsing “{:?}” formula body: {}", indentation, quantifier, input);
 
 				return self.quantified_formula(input, quantifier, level + 1);
@@ -347,7 +347,7 @@ where
 		{
 			log::trace!("{}  parsing predicate {}", indentation, predicate_name);
 
-			let input = input.trim_start();
+			let input = trim_start(input);
 
 			// Parse arguments if there are any
 			let (arguments, input) = match parenthesized_expression(input)?

src/parse/terms.rs

@@ -104,7 +104,7 @@ pub(crate) fn variable_declarations(input: &str)
 
 	loop
 	{
-		input = input.trim_start();
+		input = trim_start(input);
 
 		input = match symbol(input)
 		{
@@ -113,7 +113,7 @@ pub(crate) fn variable_declarations(input: &str)
 			_ => return Ok(Some((variable_declarations, input))),
 		};
 
-		input = input.trim_start();
+		input = trim_start(input);
 
 		let (variable_declaration, remaining_input) = match variable_declaration(input)
 		{
@@ -304,7 +304,7 @@ where
 		let indentation = "  ".repeat(level);
 		log::trace!("{}- parsing term: {}", indentation, self.input);
 
-		let input = self.input.trim_start();
+		let input = trim_start(self.input);
 
 		match input.chars().next()
 		{
@@ -442,7 +442,7 @@ where
 					let function_name = identifier;
 					log::trace!("{}  parsing function {}", indentation, function_name);
 
-					let input = input.trim_start();
+					let input = trim_start(input);
 
 					// Parse arguments if there are any
 					let (arguments, input) = match parenthesized_expression(input)?

src/parse/tokens.rs

@@ -3,6 +3,42 @@ fn substring_offset(substring: &str, string: &str) -> usize
 	substring.as_ptr() as usize - string.as_ptr() as usize
 }
 
+pub fn trim_start(mut input: &str) -> &str
+{
+	loop
+	{
+		let original_input = input;
+
+		input = input.trim_start();
+
+		let mut input_characters = input.chars();
+
+		if let Some('#') = input_characters.next()
+		{
+			input = input_characters.as_str();
+
+			match (input.find('\n'), input.find('\r'))
+			{
+				(Some(newline_index), Some(carriage_return_index)) =>
+				{
+					let split_index = std::cmp::min(newline_index, carriage_return_index);
+					input = input.split_at(split_index).1;
+				},
+				(Some(split_index), _)
+				| (_, Some(split_index)) => input = input.split_at(split_index).1,
+				_ => input = &input[..input.len()],
+			}
+		}
+
+		if input.is_empty() || input == original_input
+		{
+			break;
+		}
+	}
+
+	input
+}
+
 #[derive(Clone, Copy, Eq, PartialEq)]
 pub(crate) enum Keyword
 {
@@ -366,7 +402,7 @@ impl<'i, F> Tokens<'i, F>
 
 	fn next_token(&mut self) -> Option<Result<(usize, usize, Token<'i>), crate::parse::Error>>
 	{
-		self.input = self.input.trim_start();
+		self.input = trim_start(self.input);
 		let index_left = substring_offset(self.input, self.original_input);
 
 		let first_character = match self.input.chars().next()