Reworked lookback

src/parser/groupify.rs

@@ -10,21 +10,27 @@ use crate::tokens::Operator;
 fn lookback(
 	g: &mut VecDeque<PreToken>
 ) -> Result<(), (LineLocation, ParserError)> {
-	if g.len() == 1 {
-		let a: PreToken = g.pop_back().unwrap();
+
+	for i in 0..g.len() {
+
+		println!("{i} {:?}", g);
+		
+		if i < 1 {
+			let a: PreToken = g.remove(i).unwrap();
+
 			match &a {
 				PreToken::PreOperator(l,o)
 				=> {
 					if o == "-" {
-					g.push_back(PreToken::PreOperator(*l, String::from("neg")));
-				} else { g.push_back(a); }
+						g.insert(i, PreToken::PreOperator(*l, String::from("neg")));
+					} else { g.insert(i, a); }
 				},
-			_ => { g.push_back(a); }
+				_ => { g.insert(i, a); }
 			};
 	
 		} else {
-		let b: PreToken = g.pop_back().unwrap();
-		let a: PreToken = g.pop_back().unwrap();
+			let a: PreToken = g.remove(i-1).unwrap();
+			let b: PreToken = g.remove(i-1).unwrap();
 	
 			match (&a, &b) {
 				// Insert ImplicitMultiply
@@ -37,12 +43,14 @@ fn lookback(
 				| (PreToken::PreWord(_,_), PreToken::PreNumber(l,_))
 				| (PreToken::PreWord(_,_), PreToken::PreWord(l,_))
 				=> {
-				g.push_back(a);
-				g.push_back(PreToken::PreOperator(
-					LineLocation{pos: l.pos-1, len: 0},
+					let loc = LineLocation{pos: l.pos-1, len: 0};
+
+					g.insert(i-1, b);
+					g.insert(i-1, PreToken::PreOperator(
+						loc,
 						String::from("i*")
 					));
-				g.push_back(b);
+					g.insert(i-1, a);
 				},
 	
 				// The following are syntax errors
@@ -65,46 +73,56 @@ fn lookback(
 							!o.as_ref().unwrap().is_left_associative()
 						)
 					} {
-					g.push_back(a);
-					g.push_back(PreToken::PreOperator(*l, String::from("neg")));
-				} else { g.push_back(a); g.push_back(b); }
+						g.insert(i-1, PreToken::PreOperator(*l, String::from("neg")));
+						g.insert(i-1, a);
+					} else { g.insert(i-1, b); g.insert(i-1, a); }
 				}
 	
-			// Insert implicit multiplications for unary operators
+				// Insert implicit multiplications for right-unary operators
 				(PreToken::PreNumber(_,_), PreToken::PreOperator(l,s))
 				| (PreToken::PreGroup(_,_), PreToken::PreOperator(l,s))
 				| (PreToken::PreWord(_,_), PreToken::PreOperator(l,s))
 				=> {
 					let o = Operator::from_string(s);
-				g.push_back(a);
+					let loc = LineLocation{pos: l.pos-1, len: 0};
+
+					g.insert(i-1, b);
 					if o.is_some() {
 						let o = o.unwrap();
 						if (!o.is_binary()) && (!o.is_left_associative()) {
-						g.push_back(PreToken::PreOperator(
-							LineLocation{pos: l.pos-1, len: 0},
+							g.insert(i-1, PreToken::PreOperator(
+								loc,
+								String::from("i*")
+							));
+						} else if (!o.is_binary()) && o.is_left_associative() {
+							g.insert(i-1, PreToken::PreOperator(
+								loc,
 								String::from("i*")
 							));
 						}
 					}
-				g.push_back(b);
+					g.insert(i-1, a);
 				},
 	
+				// Insert implicit multiplications for left-unary operators.
 				(PreToken::PreOperator(_,s), PreToken::PreNumber(l,_))
 				| (PreToken::PreOperator(_,s), PreToken::PreGroup(l,_))
 				| (PreToken::PreOperator(_,s), PreToken::PreWord(l,_))
 				=> {
 					let o = Operator::from_string(s);
-				g.push_back(a);
+					let loc = LineLocation{pos: l.pos-1, len: 0};
+
+					g.insert(i-1, b);
 					if o.is_some() {
 						let o = o.unwrap();
 						if (!o.is_binary()) && o.is_left_associative() {
-						g.push_back(PreToken::PreOperator(
-							LineLocation{pos: l.pos-1, len: 0},
+							g.insert(i-1, PreToken::PreOperator(
+								loc,
 								String::from("i*")
 							));
 						}
 					}
-				g.push_back(b);
+					g.insert(i-1, a);
 				},
 	
 				// This shouldn't ever happen.
@@ -117,6 +135,10 @@ fn lookback(
 				=> panic!()
 			}
 		};
+	}
+
+	println!("{:?}", g);
+	
 	return Ok(());
 }
 
@@ -155,16 +177,15 @@ pub(in crate::parser) fn groupify(
 
 				i_level -= 1;
 
-				let (_, v) = levels.pop().unwrap();
+				let (_, mut v) = levels.pop().unwrap();
 				let (_, v_now) = levels.last_mut().unwrap();
+				lookback(&mut v)?;
 
 				v_now.push_back(PreToken::PreGroup(l, v));
-				lookback(v_now)?;
 			},
 
 			_ => {
 				v_now.push_back(t);
-				lookback(v_now)?;
 			}
 		}
 
@@ -180,16 +201,18 @@ pub(in crate::parser) fn groupify(
 
 	// Auto-close parenthesis
 	while levels.len() != 1 {
-		let (l, v) = levels.pop().unwrap();
+		let (l, mut v) = levels.pop().unwrap();
 		let (_, v_now) = levels.last_mut().unwrap();
 
 		if v.len() == 0 { return Err((l, ParserError::EmptyGroup)) }
+		lookback(&mut v)?;
 
 		v_now.push_back(PreToken::PreGroup(l, v));
-		lookback(v_now)?;
 	}
 
 
-	let (_, v) = levels.pop().unwrap();
+	let (_, mut v) = levels.pop().unwrap();
+	lookback(&mut v)?;
+
 	return Ok(PreToken::PreGroup(LineLocation{pos:0, len:0}, v));
 }