Rewrote parser

src/parser.rs

@@ -1,34 +1,37 @@
 mod tokenize;
-mod replace_pre;
-mod fold_operators;
-mod unwrap_groups;
+mod treeify;
 
 use crate::parser::tokenize::tokenize;
-use crate::parser::replace_pre::replace_pre;
-use crate::parser::fold_operators::fold_operators;
-use crate::parser::unwrap_groups::unwrap_groups;
+use crate::parser::treeify::treeify;
 
 use std::collections::VecDeque;
 
 
+/// Tokens represent logical objects in an expession.
+/// 
+/// Tokens starting with `Pre*` are intermediate tokens, and
+/// will never show up in a fully-parsed expression tree.
 #[derive(Debug)]
 pub enum Token {
 
-	// Used only while tokenizing.
-	// All of these are replaced with one of the tokens below.
-	//
-	// If parsing is successful,
-	//  - all PreGroups will vanish
-	//  - all PreOperators will become Operators
-	//  - all PreNumbers will become Numbers
-	PreGroup(LineLocation, VecDeque<Token>),
-	PreOperator(LineLocation, String),
+	/// Used only while tokenizing.
+	/// Will be replaced with a Number once we finish.
 	PreNumber(LineLocation, String),
+
+	/// Used only while tokenizing.
+	/// Will be replaced with one of the Tokens below once we finish.
 	PreWord(LineLocation, String),
 
-	Number(f64),
+	/// Used only until operators are parsed.
+	/// Each of these will become one of the operators below.
+	PreOperator(LineLocation, Operators),
 
-	// Operators
+	/// Used only until operators are parsed.
+	/// PreGroups aren't needed once we have a tree.
+	PreGroup(LineLocation, VecDeque<Token>),
+
+
+	Number(LineLocation, f64),
 	Multiply(VecDeque<Token>),
 	Divide(VecDeque<Token>),
 	Add(VecDeque<Token>),
@@ -39,6 +42,27 @@ pub enum Token {
 	Modulo(VecDeque<Token>),
 }
 
+
+/// Operator types, in order of increasing priority.
+/// The Null operator MUST be equal to zero.
+#[derive(Debug)]
+#[derive(Copy, Clone)]
+pub enum Operators {
+	Null = 0,
+	ModuloLong, // Mod invoked with "mod"
+	Subtract,
+	Add,
+	Divide,
+	Multiply,
+	ImplicitMultiply,
+	Modulo, // Mod invoked with %
+	Power,
+	Negative,
+	Factorial,
+}
+
+/// Specifies the location of a token in an input string.
+/// Used to locate ParserErrors.
 #[derive(Debug)]
 #[derive(Copy, Clone)]
 pub struct LineLocation {
@@ -46,22 +70,34 @@ pub struct LineLocation {
 	pub len: usize
 }
 
+/// Types of parser errors.
+/// If we cannot parse a string, one of these is returned.
 #[derive(Debug)]
 pub enum ParserError {
 	InvalidChar,
 	MissingCloseParen,
 	Syntax,
-	BadNumber  // Cannot parse a number
+	InvalidImplicitMultiply,
+	BadNumber 
 }
 
 
-
+/// Parse a user string. This is the only method that should be used
+/// outside this module.
+/// 
+/// # Arguments:
+/// `s`: the string to parse. Must be trimmed.
+/// 
+/// # Returns:
+/// - `Err(LineLocation, ParserError)` if we couldn't parse this string.
+/// `LineLocation` specifies *where* the error is, and `ParserError` specifies
+/// *what* the error is.
+/// 
+/// - `Ok(Token)` otherwise, where `Token` is the top of an expression tree.
 pub fn parse(s: &String) -> Result<Token, (LineLocation, ParserError)> {
 
 	let mut g: Token = tokenize(s)?;
-	replace_pre(&mut g)?;
-	fold_operators(&mut g)?;
-	unwrap_groups(&mut g)?;
+	treeify(&mut g)?;
 	
 	return Ok(g);
 }

src/parser/fold_operators.rs

@@ -1,4 +1,4 @@
-use std::collections::VecDeque;
+/*use std::collections::VecDeque;
 
 use crate::parser::Token;
 use crate::parser::LineLocation;
@@ -176,4 +176,4 @@ pub fn fold_operators(exp: &mut Token) -> Result<(), (LineLocation, ParserError)
 	)?;
 
 	return Ok(());
-}
+}*/

src/parser/replace_pre.rs

@@ -1,33 +0,0 @@
-use crate::parser::Token;
-use crate::parser::LineLocation;
-use crate::parser::ParserError;
-
-
-pub fn replace_pre(g: &mut Token) -> Result<(), (LineLocation, ParserError)> {
-
-	match g {
-		Token::PreGroup(_, ref mut vec) => {
-			for i in vec.iter_mut() {
-				replace_pre(i)?;
-			}
-		},
-		Token::PreNumber(l, s) => {
-			let n = match s.parse() {
-				Ok(n) => n,
-				Err(_) => return Err((*l, ParserError::BadNumber))
-			};
-			*g = Token::Number(n);
-		}
-		Token::PreWord(l, ref s) => {
-			if s == "mod" {
-				*g = Token::PreOperator(*l, String::from("mod"));
-			} else {
-				return Err((*l, ParserError::Syntax));
-			}
-		},
-		Token::PreOperator(_, _) => {},
-		_ => { panic!(); }
-	};
-
-	return Ok(());
-}

src/parser/tokenize.rs

@@ -3,7 +3,10 @@ use std::collections::VecDeque;
 use crate::parser::Token;
 use crate::parser::LineLocation;
 use crate::parser::ParserError;
+use crate::parser::Operators;
 
+/// Updates the length of a Token's LineLocation.
+/// Run whenever a token is finished.
 #[inline(always)]
 fn update_line_location(mut t: Token, stop_i: usize) -> Token {
 	match t {
@@ -24,7 +27,93 @@ fn update_line_location(mut t: Token, stop_i: usize) -> Token {
 }
 
 
+/// Look at the last two elements of `g`:
+/// - if one is an operator, do nothing.
+/// - if they are a valid implicit multiplication pair, add an ImplicitMultiply between them
+/// - if they aren't, throw an error.
+#[inline(always)]
+fn insert_implicit(
+	g: &mut VecDeque<Token>
+) -> Result<(), (LineLocation, ParserError)> {
+	if g.len() >= 2 {
+		let b: Token = g.pop_back().unwrap();
+		let a: &Token = g.back().unwrap();
 
+		match (a, &b) {
+
+			// Not implicit multiplication, ignore
+			(Token::PreOperator(_,_), _) |
+			(_, Token::PreOperator(_,_))
+			=> { g.push_back(b); },
+
+			// Valid implicit multiplications
+			(Token::PreGroup(_,_), Token::PreGroup(ref l,_)) |
+			(Token::PreGroup(_,_), Token::Number(ref l,_)) |
+			(Token::Number(_,_), Token::PreGroup(ref l,_))
+			=> {
+				let LineLocation { pos: i, .. } = l;
+				g.push_back(Token::PreOperator(
+					LineLocation{pos: i-1, len: 0},
+					Operators::ImplicitMultiply
+				));
+				g.push_back(b);
+			},
+
+			// Invalid implicit multiplications
+			(Token::Number(_,_), Token::Number(l,_))
+			=> {
+				let LineLocation { pos: i, .. } = l;
+				return Err((
+					LineLocation{pos: i-1, len: 2},
+					ParserError::InvalidImplicitMultiply
+				));
+			},
+
+			_ => panic!()
+		}
+	};
+	return Ok(());
+}
+
+
+
+/// Pushes (and potentially processes) a token we just read to a vector.
+/// - Converts all `PreNumbers` to `Numbers`, returning a BadNumber error if necessary
+/// - Converts all `PreWords` to other tokens.
+fn push_token(
+	g_now: &mut VecDeque<Token>,
+	i: usize,
+	t: Option<Token>
+) -> Result<(), (LineLocation, ParserError)>{
+	if t.is_none() {
+		return Ok(());
+	} else {
+		let t: Token = update_line_location(t.unwrap(), i);
+		g_now.push_back(match t {
+			Token::PreNumber(l, s) => {
+				let n = match s.parse() {
+					Ok(n) => n,
+					Err(_) => return Err((l, ParserError::BadNumber))
+				};
+				Token::Number(l, n)
+			},
+			Token::PreWord(l, s) => {
+				if s == "mod" {
+					Token::PreOperator(l, Operators::ModuloLong)
+				} else {
+					return Err((l, ParserError::Syntax));
+				}
+			},
+			Token::PreOperator(_, _) => t,
+			_ => panic!()
+		});
+		insert_implicit(g_now)?;
+	}
+	return Ok(());
+}
+
+
+/// Turns a string into Tokens. First stage of parsing.
 pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 	let mut t: Option<Token> = None; // The current token we're reading
 	let mut g: Vec<Token> = Vec::with_capacity(8); // Vector of "grouping levels"
@@ -45,15 +134,15 @@ pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 				g_now.push_back(
 					Token::PreOperator(
 						LineLocation{pos: i, len: 1},
-						String::from("!")
+						Operators::Factorial
 					)
 				);
 			},
 
-			// Minus sign can be both a Negative and an Operator.
+			// The minus sign can be both a Negative and an Operator.
 			// Needs special treatment.
 			'-' => {
-				if t.is_some() { g_now.push_back(update_line_location(t.unwrap(), i)); t = None; }
+				push_token(g_now, i, t)?; t = None;
 				match g_now.back() {
 					// If previous token was any of the following,
 					// this is the "minus" operator
@@ -63,7 +152,7 @@ pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 						g_now.push_back(
 							Token::PreOperator(
 								LineLocation{pos: i, len: 1},
-								String::from(c)
+								Operators::Subtract
 							)
 						);
 					},
@@ -73,7 +162,7 @@ pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 						g_now.push_back(
 							Token::PreOperator(
 								LineLocation{pos: i, len: 1},
-								String::from("neg")
+								Operators::Negative
 							)
 						);
 					}
@@ -93,7 +182,7 @@ pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 					// If we're not building a number, finalize
 					// previous token and start one.
 					_ => {
-						if t.is_some() { g_now.push_back(update_line_location(t.unwrap(), i)); }
+						push_token(g_now, i, t)?;
 						t = Some(Token::PreNumber(LineLocation{pos: i, len: 0}, String::from(c)));
 					}
 				};
@@ -118,27 +207,33 @@ pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 				};
 			},
 
-
-			// Operation
+			// Operator
 			// Always one character
-			'+' |
-			'*' |
-			'/' |
-			'^' |
-			'%' => {
+			'+' | '*' | '/' | '^' | '%' => {
 				// Finalize previous token
-				if t.is_some() { g_now.push_back(update_line_location(t.unwrap(), i)); t = None; }
-				g_now.push_back(Token::PreOperator(LineLocation{pos: i, len: 1}, String::from(c)));
+				push_token(g_now, i, t)?; t = None;
+				g_now.push_back(
+					Token::PreOperator(
+						LineLocation{pos: i, len: 1},
+						match c {
+							'^' => Operators::Power,
+							'%' => Operators::Modulo,
+							'*' => Operators::Multiply,
+							'/' => Operators::Divide,
+							'+' => Operators::Add,
+							_ => panic!()
+						}
+					)
+				);
 			}
 			
-			// Groups
-			// Always one character
+			// Group
 			'(' => {
-				if t.is_some() { g_now.push_back(update_line_location(t.unwrap(), i)); t = None; }
+				push_token(g_now, i, t)?; t = None;
 				g.push(Token::PreGroup(LineLocation{pos: i, len: 0}, VecDeque::with_capacity(8)));
 			},
 			')' => {
-				if t.is_some() { g_now.push_back(update_line_location(t.unwrap(), i)); t = None; }
+				push_token(g_now, i, t)?; t = None;
 				let new_group: Token = g.pop().unwrap();
 
 				let g_now: &mut VecDeque<Token> = match g.last_mut().unwrap() {
@@ -151,10 +246,10 @@ pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 
 			// Space. Basic seperator.
 			' ' => {
-				if t.is_some() { g_now.push_back(update_line_location(t.unwrap(), i)); t = None; }
+				push_token(g_now, i, t)?; t = None;
 			}
 
-			// Invalid token
+			// Invalid character
 			_ => { return Err((LineLocation{pos: i, len: 1}, ParserError::InvalidChar)); }
 		};
 	}
@@ -164,7 +259,7 @@ pub fn tokenize(input: &String) -> Result<Token, (LineLocation, ParserError)> {
 		Token::PreGroup(_, ref mut x) => x,
 		_ => panic!()
 	};
-	if t.is_some() { g_now.push_back(update_line_location(t.unwrap(), input.len())); }
+	push_token(g_now, input.len(), t)?;
 
 	if g.len() != 1 {
 		let q: LineLocation = match g.last_mut().unwrap() {

src/parser/treeify.rs

@@ -0,0 +1,90 @@
+use std::collections::VecDeque;
+
+use crate::parser::Token;
+use crate::parser::LineLocation;
+use crate::parser::ParserError;
+use crate::parser::Operators;
+
+
+pub fn treeify(
+	g: &mut Token,
+) -> Result<(), (LineLocation, ParserError)> {
+
+	let g_inner: &mut VecDeque<Token> = match g {
+		Token::PreGroup(_, ref mut x) => x,
+		_ => panic!()
+	};
+	let mut new: VecDeque<Token> = VecDeque::with_capacity(8);
+
+	let mut i = 1;
+	while g_inner.len() > 1 {
+
+		let a: isize;
+		if i == 1 {
+			a = Operators::Null as isize;
+		} else {
+			let q: Operators = match g_inner[i-2] {
+				Token::PreOperator(_, x) => x,
+				_ => panic!()
+			};
+			a = q as isize;
+		}
+
+		let b: isize = match g_inner[i] {
+			Token::PreOperator(_, x) => x,
+			_ => panic!()
+		} as isize;
+
+		let c: isize;
+		if i >= g_inner.len()-2 {
+			c = Operators::Null as isize;
+		} else {
+			let q: Operators = match g_inner[i+2] {
+				Token::PreOperator(_, x) => x,
+				_ => panic!()
+			};
+			c = q as isize;
+		}
+
+		println!("{}, {:?}", i, g_inner);
+		if b >= a && b >= c {
+			// This operator owns both its arguments.
+			let left = g_inner.remove(i-1).unwrap();
+			let this = g_inner.remove(i-1).unwrap();
+			let right = g_inner.remove(i-1).unwrap();
+
+			let (l, k) = match this {
+				Token::PreOperator(l, k) => (l, k),
+				_ => panic!()
+			};
+
+			let mut new_token_args: VecDeque<Token> = VecDeque::with_capacity(3);
+			new_token_args.push_back(left);
+			new_token_args.push_back(right);
+
+			g_inner.insert(
+				i-1,
+				match k {
+					Operators::Subtract => Token::Subtract(new_token_args),
+					Operators::Add => Token::Add(new_token_args),
+					Operators::Divide => Token::Divide(new_token_args),
+					Operators::Multiply => Token::Multiply(new_token_args),
+					Operators::ImplicitMultiply => Token::Multiply(new_token_args),
+					Operators::Modulo => Token::Modulo(new_token_args),
+					Operators::Power => Token::Power(new_token_args),
+					Operators::ModuloLong => Token::Modulo(new_token_args),
+					Operators::Negative => panic!(),
+					Operators::Factorial => panic!(),
+					Operators::Null => panic!()
+				}
+			);
+			if i >= 3 { i -= 2; }
+		} else {
+			// This operator has lower precedence than another.
+			// skip it for now.
+			i += 2;
+		}
+		println!("{}", i);
+	}
+	return Ok(());
+}

src/parser/unwrap_groups.rs

@@ -1,38 +0,0 @@
-use crate::parser::Token;
-use crate::parser::ParserError;
-use crate::parser::LineLocation;
-
-pub fn unwrap_groups(g: &mut Token) -> Result<(), (LineLocation, ParserError)> {
-
-	match g {
-		// If g is a PreGroup, unwrap it
-		Token::PreGroup(l, ref mut vec) => {
-			if vec.len() != 1 {
-				return Err((*l, ParserError::Syntax));
-			}
-			
-			let mut i = vec.pop_front().unwrap();
-			unwrap_groups(&mut i)?;
-			*g = i;
-		},
-
-		// If g has sub-elements, recursive call
-		Token::Multiply(ref mut vec) |
-		Token::Divide(ref mut vec) |
-		Token::Add(ref mut vec) |
-		Token::Subtract(ref mut vec) |
-		Token::Factorial(ref mut vec) |
-		Token::Negative(ref mut vec) |
-		Token::Power(ref mut vec) |
-		Token::Modulo(ref mut vec) => {
-			for i in vec.iter_mut() {
-				unwrap_groups(i)?;
-			}
-		},
-
-		// Otherwise, skip g.
-		_ => {}
-	};
-
-	return Ok(());
-}