Renamed token and pretoken

src/parser/expression/expression.rs

@@ -0,0 +1,86 @@
+use std::collections::VecDeque;
+use crate::quantity::Quantity;
+
+use super::Operator;
+use super::Constant;
+
+/// Expressions represent logical objects in an expession.
+#[derive(Debug)]
+#[derive(Clone)]
+pub enum Expression {
+	Variable(String),
+	Quantity(Quantity),
+	Constant(Constant),
+	Operator(Operator, VecDeque<Expression>),
+}
+
+impl ToString for Expression {
+	fn to_string(&self) -> String {
+		match self {
+			Expression::Quantity(v) => v.to_string(),
+			Expression::Constant(c) => c.to_string(),
+			Expression::Variable(s) => s.clone(),
+			Expression::Operator(o,a) => o.print(a)
+		}
+	}
+}
+
+impl Expression {
+	// This is called only when this is the outermost 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::Constant(c) => c.to_string(),
+			Expression::Variable(s) => s.clone(),
+			Expression::Operator(o,a) => o.print(a)
+		}
+	}
+
+	pub fn is_quantity(&self) -> bool {
+		match self {
+			Expression::Quantity(_) => true,
+			_ => false
+		}
+	}
+
+	#[inline(always)]
+	pub fn get_args_mut(&mut self) -> Option<&mut VecDeque<Expression>> {
+		match self {
+			Expression::Operator(_, ref mut a) => Some(a),
+			_ => None
+		}
+	}
+
+	#[inline(always)]
+	pub fn get_args(&self) -> Option<&VecDeque<Expression>> {
+		match self {
+			Expression::Operator(_, ref a) => Some(a),
+			_ => None
+		}
+	}
+
+	#[inline(always)]
+	pub fn get_at_coords<'a, 'b, I>(&'a self, coords: I) -> Option<&'a Expression>
+	where I: IntoIterator<Item = &'b usize> + Sized {
+		let mut g = self;
+		for t in coords.into_iter() {
+			let args = g.get_args();
+			let Some(args) = args else { return None; };
+			g = &args[*t];
+		}
+		return Some(g);
+	}
+
+	#[inline(always)]
+	pub fn get_at_coords_mut<'a, 'b, I>(&'a mut self, coords: I) -> Option<&'a mut Expression>
+	where I: IntoIterator<Item = &'b usize> + Sized {
+		let mut g = self;
+		for t in coords.into_iter() {
+			let args = g.get_args_mut();
+			let Some(args) = args else { return None; };
+			g = &mut args[*t];
+		}
+		return Some(g);
+	}
+}