Added linelocation to all errors

src/entry/unix/unix.rs

@@ -59,24 +59,24 @@ fn do_expression(
 	let Ok(g) = g else {panic!()};
 
 
-	// Display parsed string
-	write!(
-		stdout, " {}{}=>{}{} {}\r\n",
-		style::Bold, color::Fg(color::Magenta),
-		style::Reset, color::Fg(color::Reset),
-		g.to_string()
-	).unwrap();
-
 
 	// Evaluate expression
 	#[cfg(debug_assertions)]
 	RawTerminal::suspend_raw_mode(&stdout).unwrap();
-	let g = evaluate(&g, context);
+	let g_evaluated = evaluate(&g, context);
 	#[cfg(debug_assertions)]
 	RawTerminal::activate_raw_mode(&stdout).unwrap();
 
 	// Show output
-	if let Ok(q) = g {
+	if let Ok(q) = g_evaluated {
+		// Display parsed string
+		write!(
+			stdout, " {}{}=>{}{} {}\r\n",
+			style::Bold, color::Fg(color::Magenta),
+			style::Reset, color::Fg(color::Reset),
+			g.to_string()
+		).unwrap();
+
 		write!(
 			stdout, "\n  {}{}={} {}{}\r\n\n",
 			style::Bold,
@@ -88,12 +88,22 @@ fn do_expression(
 		return Ok(q);
 
 	} else {
-		match g {
+		match g_evaluated {
 			Ok(_) => unreachable!(),
 
-			Err(EvalError::TooBig) => {
+			Err((l, EvalError::TooBig)) => {
 				write!(
-					stdout, "\n  {}{}Mathematical Error: {}Number too big{}\r\n\n",
+					stdout, "{}{}{}{}{}{}\r\n",
+					color::Fg(color::Red),
+					style::Bold,
+					" ".repeat(l.pos + 4),
+					"^".repeat(l.len),
+					color::Fg(color::Reset),
+					style::Reset,
+				).unwrap();
+
+				write!(
+					stdout, "  {}{}Mathematical Error: {}Number too big{}\r\n\n",
 					style::Bold,
 					color::Fg(color::Red),
 					style::Reset,
@@ -101,9 +111,19 @@ fn do_expression(
 				).unwrap();
 			},
 
-			Err(EvalError::ZeroDivision) => {
+			Err((l, EvalError::ZeroDivision)) => {
 				write!(
-					stdout, "\n  {}{}Mathematical Error: {}Division by zero{}\r\n\n",
+					stdout, "{}{}{}{}{}{}\r\n",
+					color::Fg(color::Red),
+					style::Bold,
+					" ".repeat(l.pos + 4),
+					"^".repeat(l.len),
+					color::Fg(color::Reset),
+					style::Reset,
+				).unwrap();
+
+				write!(
+					stdout, "  {}{}Mathematical Error: {}Division by zero{}\r\n\n",
 					style::Bold,
 					color::Fg(color::Red),
 					style::Reset,
@@ -111,9 +131,19 @@ fn do_expression(
 				).unwrap();
 			},
 
-			Err(EvalError::BadMath) => {
+			Err((l, EvalError::BadMath)) => {
 				write!(
-					stdout, "\n  {}{}Mathematical Error: {}Failed to evaluate expression{}\r\n\n",
+					stdout, "{}{}{}{}{}{}\r\n",
+					color::Fg(color::Red),
+					style::Bold,
+					" ".repeat(l.pos + 4),
+					"^".repeat(l.len),
+					color::Fg(color::Reset),
+					style::Reset,
+				).unwrap();
+
+				write!(
+					stdout, "  {}{}Mathematical Error: {}Failed to evaluate expression{}\r\n\n",
 					style::Bold,
 					color::Fg(color::Red),
 					style::Reset,
@@ -121,9 +151,19 @@ fn do_expression(
 				).unwrap();
 			},
 
-			Err(EvalError::IncompatibleUnit) => {
+			Err((l, EvalError::IncompatibleUnit)) => {
 				write!(
-					stdout, "\n  {}{}Evaluation Error: {}Incompatible units{}\r\n\n",
+					stdout, "{}{}{}{}{}{}\r\n",
+					color::Fg(color::Red),
+					style::Bold,
+					" ".repeat(l.pos + 4),
+					"^".repeat(l.len),
+					color::Fg(color::Reset),
+					style::Reset,
+				).unwrap();
+
+				write!(
+					stdout, "  {}{}Evaluation Error: {}Incompatible units{}\r\n\n",
 					style::Bold,
 					color::Fg(color::Red),
 					style::Reset,
@@ -131,9 +171,19 @@ fn do_expression(
 				).unwrap();
 			},
 
-			Err(EvalError::BadDefineName) => {
+			Err((l, EvalError::BadDefineName)) => {
 				write!(
-					stdout, "\n  {}{}Evaluation Error: {}Invalid variable name{}\r\n\n",
+					stdout, "{}{}{}{}{}{}\r\n",
+					color::Fg(color::Red),
+					style::Bold,
+					" ".repeat(l.pos + 4),
+					"^".repeat(l.len),
+					color::Fg(color::Reset),
+					style::Reset,
+				).unwrap();
+
+				write!(
+					stdout, "  {}{}Evaluation Error: {}Invalid variable name{}\r\n\n",
 					style::Bold,
 					color::Fg(color::Red),
 					style::Reset,

src/evaluate/evaluate.rs

@@ -1,13 +1,13 @@
 use crate::parser::Expression;
 use crate::parser::Operator;
 use crate::context::Context;
-
+use crate::parser::LineLocation;
 
 use super::operator::eval_operator;
 use super::function::eval_function;
 use super::EvalError;
 
-pub fn evaluate(t: &Expression, context: &mut Context) -> Result<Expression, EvalError> {
+pub fn evaluate(t: &Expression, context: &mut Context) -> Result<Expression, (LineLocation, EvalError)> {
 
 	// Keeps track of our position in the expression tree.
 	// For example, the coordinates [0, 2, 1] are interpreted as follows:
@@ -40,15 +40,23 @@ pub fn evaluate(t: &Expression, context: &mut Context) -> Result<Expression, Eva
 
 
 			let new = match g {
-				Expression::Quantity(_) => None,
+				Expression::Quantity(_, _) => None,
 
-				Expression::Constant(c) => { Some(evaluate(&c.value(), context).unwrap()) },
+				Expression::Constant(_, c) => { Some(evaluate(&c.value(), context).unwrap()) },
-				Expression::Variable(s) => { context.get_variable(&s) },
+				Expression::Variable(_, s) => { context.get_variable(&s) },
-				Expression::Operator(Operator::Function(f), v) => { Some(eval_function(&f, &v)?) },
+				Expression::Operator(_, Operator::Function(_), _) => { Some(eval_function(g)?) },
-				Expression::Operator(o, v) => { eval_operator(&o, &v, context)? },
+				Expression::Operator(_, _, _) => { eval_operator(g, context)? },
 			};
 
-			if new.is_some() { *g = new.unwrap()}
+			if let Some(mut new) = new {
+				if let Expression::Constant(_,_) = g {
+					// Fix constant line location.
+					// Constant expansion does not change the location of a value,
+					// but other operations might.
+					new.set_linelocation(&g.get_linelocation());
+				}
+				*g = new;
+			}
 
 
 			// Move up the tree
@@ -62,11 +70,11 @@ pub fn evaluate(t: &Expression, context: &mut Context) -> Result<Expression, Eva
 
 			// Don't evaluate the first argument of a define.
 			// This prevents variables from being expanded before a re-assignment.
-			if let Expression::Operator(Operator::Define, _) = g {
+			if let Expression::Operator(_, Operator::Define, _) = g {
-					*coords.last_mut().unwrap() += 1;
+				*coords.last_mut().unwrap() += 1;
 				coords.push(0);
 				continue;
-				}
+			}
 
 			coords.push(0);
 		}

src/evaluate/function.rs

@@ -1,56 +1,58 @@
-use std::collections::VecDeque;
-
 use crate::parser::Expression;
 use crate::parser::Function;
+use crate::parser::Operator;
+use crate::parser::LineLocation;
 use super::EvalError;
 
+pub fn eval_function(g: &Expression) -> Result<Expression, (LineLocation, EvalError)> {
+
+	let Expression::Operator(loc, Operator::Function(f), args) = g else {panic!()};
 
-pub fn eval_function(f: &Function, args: &VecDeque<Expression>) -> Result<Expression, EvalError> {
 	if args.len() != 1 {panic!()};
 	let a = &args[0];
-	let Expression::Quantity(q) = a else {panic!()};
+	let Expression::Quantity(l, q) = a else {panic!()};
 
 
 	match f {
-		Function::NoUnit => { return Ok(Expression::Quantity(q.without_unit())); }
+		Function::NoUnit => { return Ok(Expression::Quantity(*loc + *l, q.without_unit())); }
-		Function::ToBase => { return Ok(Expression::Quantity(q.convert_to_base())); }
+		Function::ToBase => { return Ok(Expression::Quantity(*loc + *l, q.convert_to_base())); }
 		_ => {}
 	}
 
 	if !q.unitless() {
-		return Err(EvalError::IncompatibleUnit);
+		return Err((*loc + *l, EvalError::IncompatibleUnit));
 	}
 
 	match f {
-		Function::Abs => { return Ok(Expression::Quantity(q.abs())); },
+		Function::Abs => { return Ok(Expression::Quantity(*loc + *l, q.abs())); },
-		Function::Floor => { return Ok(Expression::Quantity(q.floor())); },
+		Function::Floor => { return Ok(Expression::Quantity(*loc + *l, q.floor())); },
-		Function::Ceil => { return Ok(Expression::Quantity(q.ceil())); },
+		Function::Ceil => { return Ok(Expression::Quantity(*loc + *l, q.ceil())); },
-		Function::Round => { return Ok(Expression::Quantity(q.round())); },
+		Function::Round => { return Ok(Expression::Quantity(*loc + *l, q.round())); },
 
-		Function::NaturalLog => { return Ok(Expression::Quantity(q.ln())); },
+		Function::NaturalLog => { return Ok(Expression::Quantity(*loc + *l, q.ln())); },
-		Function::TenLog => { return Ok(Expression::Quantity(q.log10())); },
+		Function::TenLog => { return Ok(Expression::Quantity(*loc + *l, q.log10())); },
 
-		Function::Sin => { return Ok(Expression::Quantity(q.sin())); },
+		Function::Sin => { return Ok(Expression::Quantity(*loc + *l, q.sin())); },
-		Function::Cos => { return Ok(Expression::Quantity(q.cos())); },
+		Function::Cos => { return Ok(Expression::Quantity(*loc + *l, q.cos())); },
-		Function::Tan => { return Ok(Expression::Quantity(q.tan())); },
+		Function::Tan => { return Ok(Expression::Quantity(*loc + *l, q.tan())); },
-		Function::Asin => { return Ok(Expression::Quantity(q.asin())); },
+		Function::Asin => { return Ok(Expression::Quantity(*loc + *l, q.asin())); },
-		Function::Acos => { return Ok(Expression::Quantity(q.acos())); },
+		Function::Acos => { return Ok(Expression::Quantity(*loc + *l, q.acos())); },
-		Function::Atan => { return Ok(Expression::Quantity(q.atan())); },
+		Function::Atan => { return Ok(Expression::Quantity(*loc + *l, q.atan())); },
 
-		Function::Csc => { return Ok(Expression::Quantity(q.csc())); },
+		Function::Csc => { return Ok(Expression::Quantity(*loc + *l, q.csc())); },
-		Function::Sec => { return Ok(Expression::Quantity(q.sec())); },
+		Function::Sec => { return Ok(Expression::Quantity(*loc + *l, q.sec())); },
-		Function::Cot => { return Ok(Expression::Quantity(q.cot())); },
+		Function::Cot => { return Ok(Expression::Quantity(*loc + *l, q.cot())); },
 
-		Function::Sinh => { return Ok(Expression::Quantity(q.sinh())); },
+		Function::Sinh => { return Ok(Expression::Quantity(*loc + *l, q.sinh())); },
-		Function::Cosh => { return Ok(Expression::Quantity(q.cosh())); },
+		Function::Cosh => { return Ok(Expression::Quantity(*loc + *l, q.cosh())); },
-		Function::Tanh => { return Ok(Expression::Quantity(q.tanh())); },
+		Function::Tanh => { return Ok(Expression::Quantity(*loc + *l, q.tanh())); },
-		Function::Asinh => { return Ok(Expression::Quantity(q.asinh())); },
+		Function::Asinh => { return Ok(Expression::Quantity(*loc + *l, q.asinh())); },
-		Function::Acosh => { return Ok(Expression::Quantity(q.acosh())); },
+		Function::Acosh => { return Ok(Expression::Quantity(*loc + *l, q.acosh())); },
-		Function::Atanh => { return Ok(Expression::Quantity(q.atanh())); },
+		Function::Atanh => { return Ok(Expression::Quantity(*loc + *l, q.atanh())); },
 
-		Function::Csch => { return Ok(Expression::Quantity(q.csch())); },
+		Function::Csch => { return Ok(Expression::Quantity(*loc + *l, q.csch())); },
-		Function::Sech => { return Ok(Expression::Quantity(q.sech())); },
+		Function::Sech => { return Ok(Expression::Quantity(*loc + *l, q.sech())); },
-		Function::Coth => { return Ok(Expression::Quantity(q.coth())); },
+		Function::Coth => { return Ok(Expression::Quantity(*loc + *l, q.coth())); },
 
 		Function::ToBase
 		| Function::NoUnit

src/evaluate/operator.rs

@@ -1,12 +1,15 @@
-use std::collections::VecDeque;
+use crate::parser::LineLocation;
-
 use crate::quantity::Quantity;
 use crate::parser::Operator;
 use crate::parser::Expression;
 use super::EvalError;
 use crate::context::Context;
 
-pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut Context) -> Result<Option<Expression>, EvalError> {
+
+pub fn eval_operator(g: &Expression, context: &mut Context) -> Result<Option<Expression>, (LineLocation, EvalError)> {
+
+	let Expression::Operator(op_loc, op, args) = g else {panic!()};
+
 	match op {
 		Operator::Function(_) => unreachable!("Functions are handled seperately."),
 
@@ -14,42 +17,61 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			if args.len() != 2 { panic!() };
 			let b = &args[1];
 
-			if let Expression::Variable(s) = &args[0] {
+			if let Expression::Variable(l, s) = &args[0] {
 				let r = context.push_var(s.clone(), b.clone());
-				if r.is_err() { return Err(EvalError::BadDefineName); }
+				if r.is_err() { return Err((*l, EvalError::BadDefineName)); }
 				return Ok(Some(b.clone()));
-			} else { return Err(EvalError::BadDefineName); }
+			} else { return Err((args[0].get_linelocation(), EvalError::BadDefineName)); }
 		},
 
 		Operator::Negative => {
 			if args.len() != 1 { panic!() };
 			let args = &args[0];
 
-			if let Expression::Quantity(v) = args {
+			if let Expression::Quantity(l, v) = args {
-				return Ok(Some(Expression::Quantity(-v.clone())));
+				return Ok(Some(Expression::Quantity(*l, -v.clone())));
 			} else { return Ok(None); }
 		},
 
 		Operator::Add => {
 			let mut sum: Quantity;
-			if let Expression::Quantity(s) = &args[0] {
+			let mut loc: LineLocation;
+			if let Expression::Quantity(l, s) = &args[0] {
 				sum = s.clone();
+				loc = l.clone();
 			} else { return Ok(None); };
 
+
+			// Flag that is set to true if we find incompatible units.
+			// We don't stop right away because we need to add all linelocations
+			// to show a pretty error.
+			let mut incompatible_units = false;
+
 			let mut i: usize = 1;
 			while i < args.len() {
 				let j = &args[i];
-				if let Expression::Quantity(v) = j {
+				if let Expression::Quantity(l, v) = j {
 
 					if !sum.unit.compatible_with(&v.unit) {
-						return Err(EvalError::IncompatibleUnit);
+						incompatible_units = true;
 					}
 
-					sum += v.clone();
+					if !incompatible_units { sum += v.clone(); }
-				} else { return Ok(None); }
+					loc += *l;
+				} else {
+					if incompatible_units {
+						return Err((loc + *op_loc, EvalError::IncompatibleUnit));
+					}
+					return Ok(None);
+				}
 				i += 1;
 			}
-			return Ok(Some(Expression::Quantity(sum)));
+
+			if incompatible_units {
+				return Err((loc + *op_loc, EvalError::IncompatibleUnit));
+			}
+
+			return Ok(Some(Expression::Quantity(loc + *op_loc, sum)));
 		},
 
 		Operator::Subtract => {
@@ -57,9 +79,9 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			let a = &args[0];
 			let b = &args[1];
 
-			if let Expression::Quantity(a) = a {
+			if let Expression::Quantity(la, a) = a {
-				if let Expression::Quantity(b) = b {
+				if let Expression::Quantity(lb, b) = b {
-					return Ok(Some(Expression::Quantity(a.clone() - b.clone())));
+					return Ok(Some(Expression::Quantity(*la + *lb, a.clone() - b.clone())));
 				}
 			}
 
@@ -73,10 +95,10 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			let a = &args[0];
 			let b = &args[1];
 
-			if let Expression::Quantity(a) = a {
+			if let Expression::Quantity(la, a) = a {
-				if let Expression::Quantity(b) = b {
+				if let Expression::Quantity(lb, b) = b {
-					if b.is_zero() { return Err(EvalError::ZeroDivision); }
+					if b.is_zero() { return Err((*la + *lb, EvalError::ZeroDivision)); }
-					return Ok(Some(Expression::Quantity(a.clone() / b.clone())));
+					return Ok(Some(Expression::Quantity(*la + *lb, a.clone() / b.clone())));
 				}
 			}
 
@@ -85,14 +107,23 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 
 		Operator::ImplicitMultiply |
 		Operator::Multiply => {
-			let mut prod = Quantity::new_rational(1f64).unwrap();
+			let mut prod: Quantity;
-			for i in args.iter() {
+			let mut loc: LineLocation;
-				let j = i;
+			if let Expression::Quantity(l, s) = &args[0] {
-				if let Expression::Quantity(v) = j {
+				prod = s.clone();
+				loc = l.clone();
+			} else { return Ok(None); };
+
+			let mut i: usize = 1;
+			while i < args.len() {
+				let j = &args[i];
+				if let Expression::Quantity(l, v) = j {
 					prod *= v.clone();
+					loc += *l;
 				} else { return Ok(None); }
+				i += 1;
 			}
-			return Ok(Some(Expression::Quantity(prod)));
+			return Ok(Some(Expression::Quantity(loc + *op_loc, prod)));
 		},
 
 		Operator::ModuloLong
@@ -101,18 +132,18 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			let a = &args[0];
 			let b = &args[1];
 
-			if let Expression::Quantity(va) = a {
+			if let Expression::Quantity(la, va) = a {
-				if let Expression::Quantity(vb) = b {
+				if let Expression::Quantity(lb, vb) = b {
 
 					if !(va.unitless() && vb.unitless()) {
-						return Err(EvalError::IncompatibleUnit);
+						return Err((*la + *lb + *op_loc, EvalError::IncompatibleUnit));
 					}
 
-					if vb <= &Quantity::new_rational(1f64).unwrap() { return Err(EvalError::BadMath); }
+					if vb <= &Quantity::new_rational(1f64).unwrap() { return Err((*la + *lb + *op_loc, EvalError::BadMath)); }
-					if va.fract() != Quantity::new_rational(0f64).unwrap() { return Err(EvalError::BadMath); }
+					if va.fract() != Quantity::new_rational(0f64).unwrap() { return Err((*la + *lb + *op_loc, EvalError::BadMath)); }
-					if vb.fract() != Quantity::new_rational(0f64).unwrap() { return Err(EvalError::BadMath); }
+					if vb.fract() != Quantity::new_rational(0f64).unwrap() { return Err((*la + *lb + *op_loc, EvalError::BadMath)); }
 
-					return Ok(Some(Expression::Quantity(va.clone() % vb.clone())));
+					return Ok(Some(Expression::Quantity(*la + *lb + *op_loc, va.clone() % vb.clone())));
 				} else { return Ok(None); }
 			} else { return Ok(None); }
 		},
@@ -122,13 +153,13 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			let a = &args[0];
 			let b = &args[1];
 
-			if let Expression::Quantity(va) = a {
+			if let Expression::Quantity(la, va) = a {
-				if let Expression::Quantity(vb) = b {
+				if let Expression::Quantity(lb, vb) = b {
 					let n = va.clone().convert_to(vb.clone());
 					if n.is_none() {
-						return Err(EvalError::IncompatibleUnit);
+						return Err((*la + *lb + *op_loc, EvalError::IncompatibleUnit));
 					}
-					return Ok(Some(Expression::Quantity(n.unwrap())));
+					return Ok(Some(Expression::Quantity(*la + *lb, n.unwrap())));
 				} else { return Ok(None); }
 			} else { return Ok(None); }
 		},
@@ -138,11 +169,11 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			if args.len() != 1 { panic!() }
 			let a = &args[0];
 
-			if let Expression::Quantity(va) = a {
+			if let Expression::Quantity(l, v) = a {
-				if va.is_negative() { return Err(EvalError::BadMath); }
+				if v.is_negative() { return Err((*l + *op_loc, EvalError::BadMath)); }
-				let p = va.pow(Quantity::new_rational_from_string("0.5").unwrap());
+				let p = v.pow(Quantity::new_rational_from_string("0.5").unwrap());
-				if p.is_nan() {return Err(EvalError::BadMath);}
+				if p.is_nan() {return Err((*l + *op_loc, EvalError::BadMath));}
-				return Ok(Some(Expression::Quantity(p)));
+				return Ok(Some(Expression::Quantity(*l, p)));
 			} else { return Ok(None); }
 		},
 
@@ -151,20 +182,20 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			let a = &args[0];
 			let b = &args[1];
 
-			if let Expression::Quantity(va) = a {
+			if let Expression::Quantity(la, va) = a {
-				if let Expression::Quantity(vb) = b {
+				if let Expression::Quantity(lb, vb) = b {
 
 					if !vb.unitless() {
-						return Err(EvalError::IncompatibleUnit);
+						return Err((*lb, EvalError::IncompatibleUnit));
 					}
 
 					if va.is_zero() && vb.is_negative() {
-						return Err(EvalError::ZeroDivision);
+						return Err((*la + *lb + *op_loc, EvalError::ZeroDivision));
 					}
 
 					let p = va.pow(vb.clone());
-					if p.is_nan() {return Err(EvalError::BadMath);}
+					if p.is_nan() {return Err((*la + *lb + *op_loc, EvalError::BadMath));}
-					return Ok(Some(Expression::Quantity(p)));
+					return Ok(Some(Expression::Quantity(*la + *lb + *op_loc, p)));
 				} else { return Ok(None); }
 			} else { return Ok(None); }
 		},
@@ -173,14 +204,14 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 			if args.len() != 1 {panic!()};
 			let args = &args[0];
 
-			if let Expression::Quantity(v) = args {
+			if let Expression::Quantity(l, v) = args {
 
 				if !v.unitless() {
-					return Err(EvalError::IncompatibleUnit);
+					return Err((*l + *op_loc, EvalError::IncompatibleUnit));
 				}
 
-				if !v.fract().is_zero() { return Err(EvalError::BadMath); }
+				if !v.fract().is_zero() { return Err((*l + *op_loc, EvalError::BadMath)); }
-				if v > &Quantity::new_rational(50_000f64).unwrap() { return Err(EvalError::TooBig); }
+				if v > &Quantity::new_rational(50_000f64).unwrap() { return Err((*l + *op_loc, EvalError::TooBig)); }
 
 				let mut prod = Quantity::new_rational(1f64).unwrap();
 				let mut u = v.clone();
@@ -189,7 +220,7 @@ pub fn eval_operator(op: &Operator, args: &VecDeque<Expression>, context: &mut C
 					u = u - Quantity::new_rational(1f64).unwrap();
 				}
 
-				return Ok(Some(Expression::Quantity(prod)));
+				return Ok(Some(Expression::Quantity(*l + *op_loc, prod)));
 			} else { return Ok(None); }
 		}
 	};

src/parser/expression/expression.rs

@@ -3,24 +3,26 @@ use crate::quantity::Quantity;
 
 use super::Operator;
 use super::Constant;
+use super::super::LineLocation;
+
 
 /// Expressions represent logical objects in an expession.
 #[derive(Debug)]
 #[derive(Clone)]
 pub enum Expression {
-	Variable(String),
+	Variable(LineLocation, String),
-	Quantity(Quantity),
+	Quantity(LineLocation, Quantity),
-	Constant(Constant),
+	Constant(LineLocation, Constant),
-	Operator(Operator, VecDeque<Expression>),
+	Operator(LineLocation, Operator, VecDeque<Expression>),
 }
 
 impl ToString for Expression {
 	fn to_string(&self) -> String {
 		match self {
-			Expression::Quantity(v) => v.to_string(),
+			Expression::Quantity(_, v) => v.to_string(),
-			Expression::Constant(c) => c.to_string(),
+			Expression::Constant(_, c) => c.to_string(),
-			Expression::Variable(s) => s.clone(),
+			Expression::Variable(_, s) => s.clone(),
-			Expression::Operator(o,a) => o.print(a)
+			Expression::Operator(_, o,a) => o.print(a)
 		}
 	}
 }
@@ -30,16 +32,16 @@ impl Expression {
 	// This sometimes leads to different--usually more verbose--behavior.
 	pub fn to_string_outer(&self) -> String {
 		match self {
-			Expression::Quantity(v) => v.to_string_outer(),
+			Expression::Quantity(_, v) => v.to_string_outer(),
-			Expression::Constant(c) => c.to_string(),
+			Expression::Constant(_, c) => c.to_string(),
-			Expression::Variable(s) => s.clone(),
+			Expression::Variable(_, s) => s.clone(),
-			Expression::Operator(o,a) => o.print(a)
+			Expression::Operator(_, o,a) => o.print(a)
 		}
 	}
 
 	pub fn is_quantity(&self) -> bool {
 		match self {
-			Expression::Quantity(_) => true,
+			Expression::Quantity(_,_) => true,
 			_ => false
 		}
 	}
@@ -47,7 +49,7 @@ impl Expression {
 	#[inline(always)]
 	pub fn get_args_mut(&mut self) -> Option<&mut VecDeque<Expression>> {
 		match self {
-			Expression::Operator(_, ref mut a) => Some(a),
+			Expression::Operator(_, _, ref mut a) => Some(a),
 			_ => None
 		}
 	}
@@ -55,7 +57,7 @@ impl Expression {
 	#[inline(always)]
 	pub fn get_args(&self) -> Option<&VecDeque<Expression>> {
 		match self {
-			Expression::Operator(_, ref a) => Some(a),
+			Expression::Operator(_, _, ref a) => Some(a),
 			_ => None
 		}
 	}
@@ -83,4 +85,23 @@ impl Expression {
 		}
 		return Some(g);
 	}
+
+	pub fn get_linelocation(&self) -> LineLocation {
+		match self {
+			Expression::Quantity(l, _)
+			| Expression::Constant(l, _)
+			| Expression::Variable(l, _)
+			| Expression::Operator(l, _,_)
+			=> { l.clone() }
+		}
+	}
+
+	pub fn set_linelocation(&mut self, loc: &LineLocation) {
+		match self {
+			Expression::Quantity(l, _) => { *l = *loc },
+			Expression::Constant(l, _) => { *l = *loc },
+			Expression::Variable(l, _) => { *l = *loc },
+			Expression::Operator(l, _,_) => { *l = *loc },
+		}
+	}
 }

src/parser/expression/operator.rs

@@ -110,7 +110,7 @@ impl Operator {
 	#[inline(always)]
 	fn add_parens_to_arg(&self, arg: &Expression) -> String {
 		let mut astr: String = arg.to_string();
-		if let Expression::Operator(o,_) = arg {
+		if let Expression::Operator(_, o,_) = arg {
 			if o < self {
 				astr = format!("({})", astr);
 			}
@@ -121,7 +121,7 @@ impl Operator {
 	#[inline(always)]
 	fn add_parens_to_arg_strict(&self, arg: &Expression) -> String {
 		let mut astr: String = arg.to_string();
-		if let Expression::Operator(o,_) = arg {
+		if let Expression::Operator(_, o,_) = arg {
 			if o <= self {
 				astr = format!("({})", astr);
 			}
@@ -220,15 +220,15 @@ impl Operator {
 				// multiplied by a unit (like 10 m)
 				// Times sign should stay in all other cases.
 				let no_times = {
-					if let Expression::Quantity(p) = a {
+					if let Expression::Quantity(_, p) = a {
-						if let Expression::Quantity(q) = b {
+						if let Expression::Quantity(_, q) = b {
 							p.unitless() && !q.unitless()
 						} else {false}
 					} else {false}
 				};
 
 				if no_times {
-					let Expression::Quantity(u) = b else {panic!()};
+					let Expression::Quantity(_, u) = b else {panic!()};
 					if u.unit.no_space() {
 						return format!("{}{}",
 							self.add_parens_to_arg_strict(a),
@@ -252,7 +252,7 @@ impl Operator {
 				let a = &args[0];
 				let b = &args[1];
 
-				if let Expression::Quantity(q) = a {
+				if let Expression::Quantity(_, q) = a {
 					if q.is_one() {
 						return format!("{}⁻¹",
 							self.add_parens_to_arg_strict(b)

src/parser/linelocation.rs

@@ -0,0 +1,59 @@
+use std::cmp;
+use std::ops::Add;
+use std::ops::AddAssign;
+use std::cmp::Ordering;
+
+/// Specifies the location of a token in an input string.
+#[derive(Debug)]
+#[derive(Copy, Clone)]
+pub struct LineLocation {
+	pub pos: usize,
+	pub len: usize
+}
+
+impl LineLocation {
+	pub fn zero(&self) -> bool {
+		return self.pos == 0 && self.len == 0
+	}
+}
+
+impl PartialEq for LineLocation {
+	fn eq(&self, other: &Self) -> bool {
+		self.pos == other.pos &&
+		self.len ==other.len
+	}
+}
+
+impl PartialOrd for LineLocation {
+	fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+		return self.pos.partial_cmp(&other.pos);
+	}
+}
+
+impl Add for LineLocation {
+	type Output = Self;
+
+	fn add(self, other: Self) -> Self::Output {
+		if self.zero() { return other; }
+		if other.zero() { return self; }
+
+		let start = cmp::min(self.pos, other.pos);
+		let end = cmp::max(self.pos+self.len-1, other.pos+other.len-1);
+		return LineLocation{
+			pos: start,
+			len: end - start+1
+		};
+	}
+}
+
+impl AddAssign for LineLocation where {
+	fn add_assign(&mut self, other: Self) {
+		if self.zero() {*self = other}
+		if other.zero() { return }
+
+		let start = cmp::min(self.pos, other.pos);
+		let end = cmp::max(self.pos+self.len-1, other.pos+other.len-1);
+		self.pos = start;
+		self.len = end - start + 1;
+	}
+}

src/parser/mod.rs

@@ -3,11 +3,11 @@ mod stage;
 mod token;
 mod parsererror;
 mod expression;
+mod linelocation;
 
 use self::{
 	token::Token,
 	parsererror::ParserError,
-	parsererror::LineLocation
 };
 
 pub use self::{
@@ -15,6 +15,7 @@ pub use self::{
 	expression::Constant,
 	expression::Operator,
 	expression::Function,
+	linelocation::LineLocation,
 };
 
 use crate::context::Context;
@@ -27,7 +28,6 @@ pub fn parse(
 	let expressions = stage::tokenize(s);
 	let (_, expressions) = stage::find_subs(expressions);
 	let g = stage::groupify(expressions)?;
-
 	let g = stage::treeify(g, context)?;
 
 	return Ok(g);
@@ -50,11 +50,12 @@ pub fn substitute(
 
 	let l = s.chars().count();
 	let expressions = stage::tokenize(s);
-	let (subs, _) = stage::find_subs(expressions);
+	let (mut subs, _) = stage::find_subs(expressions);
 	let mut new_c = l - c;
 
-	for r in subs.iter() {
+	while subs.len() > 0 {
-		// find_subs gives substitutions in reverse order.
+		let r = subs.pop_back().unwrap();
+		// Apply substitutions in reverse order
 
 		if { // Don't substitute if our cursor is inside the substitution
 			c >= r.0.pos &&

src/parser/parsererror.rs

@@ -1,11 +1,3 @@
-/// Specifies the location of a token in an input string.
-#[derive(Debug)]
-#[derive(Copy, Clone)]
-pub struct LineLocation {
-	pub pos: usize,
-	pub len: usize
-}
-
 /// Types of parser errors.
 /// If we cannot parse a string, one of these is returned.
 #[derive(Debug)]

src/parser/stage/groupify.rs

@@ -194,9 +194,12 @@ pub fn groupify(
 	Token,
 	(LineLocation, ParserError)
 > {
+
+	let last_linelocation = g.back().unwrap().get_line_location().clone();
+
 	// Vector of grouping levels
 	let mut levels: Vec<(LineLocation, VecDeque<Token>)> = Vec::with_capacity(8);
-	levels.push((LineLocation{pos: 0, len: 0}, VecDeque::with_capacity(8)));
+	levels.push((LineLocation{pos: 0, len: last_linelocation.pos + last_linelocation.len}, VecDeque::with_capacity(8)));
 
 	// Makes sure parenthesis are matched
 	let mut i_level = 0;
@@ -212,10 +215,7 @@ pub fn groupify(
 			},
 
 			Token::GroupEnd(l) => {
-				let l = LineLocation {
+				let l = *l_now + l;
-					pos: l_now.pos,
-					len: l.len + l.pos - l_now.pos
-				};
 
 				if i_level == 0 { return Err((l, ParserError::ExtraCloseParen)) }
 				if v_now.len() == 0 { return Err((l, ParserError::EmptyGroup)) }
@@ -259,5 +259,5 @@ pub fn groupify(
 	let (_, mut v) = levels.pop().unwrap();
 	lookback(&mut v)?;
 
-	return Ok(Token::Group(LineLocation{pos:0, len:0}, v));
+	return Ok(Token::Group(LineLocation{pos:0, len:last_linelocation.pos + last_linelocation.len}, v));
 }

src/parser/stage/treeify.rs

@@ -85,11 +85,8 @@ fn treeify_binary(
 		} {
 			return Ok(false);
 		} else {
-			let tl = *this.get_line_location();
+			let tl = *this.get_line_location() + *l;
-			return Err((
+			return Err((tl, ParserError::Syntax));
-				LineLocation{pos: tl.pos, len: l.pos - tl.pos + l.len},
-				ParserError::Syntax
-			));
 		}
 	}
 
@@ -126,22 +123,33 @@ fn treeify_binary(
 		let left_pre = g_inner.remove(i-1).unwrap();
 		let this_pre = g_inner.remove(i-1).unwrap();
 		let right_pre = g_inner.remove(i-1).unwrap();
-		let left: Expression; let right: Expression;
+		let mut left: Expression; let mut right: Expression;
-		if let Token::Group(_, _) = right_pre { right = treeify(right_pre, context)?; } else {right = right_pre.to_expression(context)?;}
+		if let Token::Group(l, _) = right_pre {
-		if let Token::Group(_, _) = left_pre { left = treeify(left_pre, context)?; } else {left = left_pre.to_expression(context)?;}
+			right = treeify(right_pre, context)?;
+			right.set_linelocation(&(right.get_linelocation() + l));
+		} else {
+			right = right_pre.to_expression(context)?;
+		}
 
-		let o = {
+		if let Token::Group(l, _) = left_pre {
-			let Token::Operator(_, s) = this_pre else {panic!()};
+			left = treeify(left_pre, context)?;
+			left.set_linelocation(&(left.get_linelocation() + l));
+		} else {
+			left = left_pre.to_expression(context)?;
+		}
+
+		let (l, o) = {
+			let Token::Operator(l, s) = this_pre else {panic!()};
 			let o = Operator::from_string(&s);
 			if o.is_none() { panic!() }
-			o.unwrap()
+			(l, o.unwrap())
 		};
 
 		let mut new_token_args: VecDeque<Expression> = VecDeque::with_capacity(2);
 		new_token_args.push_back(left);
 		new_token_args.push_back(right);
 
-		g_inner.insert(i-1, Token::Container(Expression::Operator(o, new_token_args)));
+		g_inner.insert(i-1, Token::Container(Expression::Operator(l, o, new_token_args)));
 
 		return Ok(true);
 	} else {
@@ -204,12 +212,8 @@ fn treeify_unary(
 	}
 
 	if let Token::Operator(l, _) = next {
-		let tl = *this.get_line_location();
+		let tl = *this.get_line_location() + *l;
-		return Err((
+		return Err((tl, ParserError::Syntax));
-			LineLocation{pos: tl.pos, len: l.pos - tl.pos + l.len},
-			ParserError::Syntax
-		));
-
 	} else {
 
 		// This operator
@@ -239,28 +243,34 @@ fn treeify_unary(
 
 		if next_op.is_none() || this_op > next_op.unwrap() {
 			let this_pre = g_inner.remove(i).unwrap();
-			let next_pre: Token; let next: Expression;
+			let next_pre: Token; let mut next: Expression;
 			if left_associative {
 				next_pre = g_inner.remove(i-1).unwrap();
 			} else {
 				next_pre = g_inner.remove(i).unwrap();
 			}
-			if let Token::Group(_, _) = next_pre { next = treeify(next_pre, context)?; } else { next = next_pre.to_expression(context)? }
+			if let Token::Group(l, _) = next_pre {
+				next = treeify(next_pre, context)?;
+				next.set_linelocation(&(next.get_linelocation() + l));
+			} else {
+				next = next_pre.to_expression(context)?;
+			}
 
-			let o = {
+
-				let Token::Operator(_, s) = this_pre else {panic!()};
+			let (l, o) = {
+				let Token::Operator(l, s) = this_pre else {panic!()};
 				let o = Operator::from_string(&s);
 				if o.is_none() { panic!() }
-				o.unwrap()
+				(l, o.unwrap())
 			};
 
 			let mut new_token_args: VecDeque<Expression> = VecDeque::with_capacity(3);
 			new_token_args.push_back(next);
 
 			if left_associative {
-				g_inner.insert(i-1, Token::Container(Expression::Operator(o, new_token_args)));
+				g_inner.insert(i-1, Token::Container(Expression::Operator(l, o, new_token_args)));
 			} else {
-				g_inner.insert(i, Token::Container(Expression::Operator(o, new_token_args)));
+				g_inner.insert(i, Token::Container(Expression::Operator(l, o, new_token_args)));
 			}
 
 			return Ok(true);

src/parser/token.rs

@@ -74,20 +74,20 @@ impl Token {
 					return Err((l, ParserError::BadNumber))
 				}
 
-				return Ok(Expression::Quantity(r.unwrap()));
+				return Ok(Expression::Quantity(l, r.unwrap()));
 			},
 
-			Token::Word(_l, s) => {
+			Token::Word(l, s) => {
 
 				let c = Constant::from_string(&s);
-				if c.is_some() { return Ok(Expression::Constant(c.unwrap())); }
+				if c.is_some() { return Ok(Expression::Constant(l, c.unwrap())); }
 
 				let c = Unit::from_string(&s);
-				if c.is_some() { return Ok(Expression::Quantity(c.unwrap())); }
+				if c.is_some() { return Ok(Expression::Quantity(l, c.unwrap())); }
 
 				let c = context.get_variable(&s);
-				if c.is_some() { return Ok(Expression::Variable(s)); }
+				if c.is_some() { return Ok(Expression::Variable(l, s)); }
-				return Ok(Expression::Variable(s));
+				return Ok(Expression::Variable(l, s));
 			}
 
 			Token::Container(v) => { return Ok(v); }