WIP pratt parsing

asklyphe-frontend/src/math.rs

@@ -31,6 +31,16 @@ enum Op {
 	Func(Func), // A function is an Op that takes whatever the next thing is and binds it, either the next number or whatever is in parens
 }
 
+impl Op {
+	fn get_lbp(&self) -> f64 {
+		todo!();
+	}
+
+	fn get_rbp(&self) -> f64 {
+		todo!();
+	}
+}
+
 #[derive(Debug)]
 enum BinOp {
 	Add,
@@ -71,7 +81,7 @@ enum Const {
 }
 
 #[derive(Debug)]
-enum LexErr {
+enum ParseErr {
 	Eof,
 	Invalid,
 }
@@ -89,7 +99,7 @@ impl Lexer<'_> {
 
 	fn new(data: &str) -> Lexer<'_> { Lexer {data, data_ptr: data, idx: 0} }
 	
-	fn next(&mut self) -> Result<Token, LexErr> {
+	fn next(&mut self) -> Result<Token, ParseErr> {
 		match self.data.chars().nth(self.idx) {
 			Some(val) => {
 				debug!("lexing char '{}' at idx {}", val, self.idx);
@@ -114,16 +124,16 @@ impl Lexer<'_> {
 
 						match self.data[start..self.idx].parse() {
 							Ok(val) => Ok(Token::Atom(Atom::Number(val))),
-							Err(e) => Err(LexErr::Invalid),
+							Err(e) => Err(ParseErr::Invalid),
 						}
 					},
 					_ => {
 						debug!("got invalid char '{}'", val);
-						Err(LexErr::Invalid)
+						Err(ParseErr::Invalid)
 					}
 				}
 			}
-			None => Err(LexErr::Eof),
+			None => Err(ParseErr::Eof),
 		}
 	}
 
@@ -132,8 +142,8 @@ impl Lexer<'_> {
 		let mut tokens: Vec<Token> = vec![];
 		loop {
 			match self.next() {
-				Err(LexErr::Eof) => return Some(tokens),
+				Err(ParseErr::Eof) => return Some(tokens),
-				Err(LexErr::Invalid) => return None,
+				Err(ParseErr::Invalid) => return None,
 				Ok(tok) => tokens.push(tok),
 			}
 			// debug!("tokens: {:?}", tokens);
@@ -145,14 +155,6 @@ struct Parser<'a> {
 	lex: Lexer<'a>,
 }
 
-#[derive(Debug)]
-enum ParseErr {
-	Eof,
-	Invalid,
-	// TODO, add more or maybe just use an option instead
-}
-
-
 impl Parser<'_> {
 	fn new(lex: Lexer) -> Parser { Parser {lex} }
 
@@ -161,11 +163,41 @@ impl Parser<'_> {
 	}
 
 	fn parse_expr(&mut self, min_bp: f64) -> Result<Expr, ParseErr> {
-		while let Ok(val) = self.lex.next() {debug!("token: {:?}", val)}
+		/*while let Ok(val) = self.lex.next() {debug!("token: {:?}", val)}
 		match self.lex.next().err() {
 			
 			_ => return Err(ParseErr::Invalid),
+		}*/
+		let mut lhs: Expr = match self.lex.next() {
+			Ok(val) => match val {
+				Token::Atom(val) => Ok(Expr::Atom(val)),
+				Token::Op(op) => match op {
+					Op::BinOp(BinOp::LParen) => self.parse_expr(op.get_lbp()),
+					_ => Err(ParseErr::Invalid),
+				},
+			},
+			Err(err) => Err(err),
+		}.map_err(|err| { debug!("Unexpected error at start of expr: {:?}", err); err })?;
+		loop {
+			let op: Op = match self.lex.next() {
+				Err(ParseErr::Eof) => break,
+				Err(e) => return Err(e),
+				Ok(tok) => match tok {
+					Token::Op(op) => match op {
+						Op::BinOp(op) => match op {
+							BinOp::RParen => break,
+							_ => Ok(Op::BinOp(op)),
+						},
+						Op::Func(f) => Ok(Op::Func(f)),
+					}
+					_ => Err(ParseErr::Invalid),
+				}
+			}.map_err(|err| { debug!("Unexpected error inside expr: {:?}", err); err })?;
+			if (op.get_lbp() < min_bp) { break; }
+			let rhs: Expr = self.parse_expr(op.get_rbp())?;
+			lhs = Expr::Node(op, vec![lhs, rhs]);
 		}
+		Ok(lhs)
 	}
 }
 
@@ -181,6 +213,6 @@ enum Op {
 // TODO: look at that parser video again
 #[derive(Debug)]
 enum Expr {
-	Atom(Token),
+	Atom(Atom),
 	Node(Op, Vec<Expr>),
 }