From 74b29455e5d511871cd46bdefd68726d076f2073 Mon Sep 17 00:00:00 2001
From: Book-reader <thevoid@outlook.co.nz>
Date: Fri, 5 Sep 2025 23:58:06 +1200
Subject: [PATCH] Constants work and *finally* fix the off-by-one in lexing

---
 asklyphe-frontend/src/math.rs | 40 +++++++++++++++++++++++++++++++----
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/asklyphe-frontend/src/math.rs b/asklyphe-frontend/src/math.rs
index 125061f..683530c 100644
--- a/asklyphe-frontend/src/math.rs
+++ b/asklyphe-frontend/src/math.rs
@@ -120,6 +120,8 @@ impl Atom {
 			Atom::Const(c) => match c {
 				Const::Pi => 3.141592653589793238462643383279,
 				Const::E => 2.718281828459045235360287471352,
+				Const::Inf => f64::INFINITY,
+				Const::Nan => f64::NAN,
 			}
 		}
 	}
@@ -167,8 +169,23 @@ impl Func {
 enum Const {
 	Pi,
 	E,
+	Inf,
+	Nan,
 }
 
+
+impl Const {
+	fn names() -> &'static [(Const, &'static [&'static str])] {
+		&[
+			(Const::Pi, &["pi", "PI", "π"]),
+			(Const::E, &["e", "euler"]),
+			(Const::Inf, &["inf", "infinity", "∞"]),
+			(Const::Nan, &["nan", "NaN"])
+		]
+	}
+}
+
+
 #[derive(Debug, Copy, Clone, PartialEq)]
 enum ParseErr {
 	Eof,
@@ -224,12 +241,22 @@ impl Lexer<'_> {
 						let len = self.data_ptr.chars().count();
 						for (f, names) in Func::names() {
 							for name in *names {
-								if self.data_ptr.starts_with(name) {
-									self.next_by = if self.data_ptr.len() > name.len() { name.chars().count() + 1} else { name.chars().count() };
+								let n_len = name.chars().count();
+								if self.data_ptr.starts_with(name) && (len == n_len || !self.data_ptr.chars().nth(n_len).unwrap().is_alphabetic()) {
+									self.next_by = name.chars().count();
 									return Ok(Token::Op(Op::Func(*f)));
 								}
 							}
 						}
+						for (f, names) in Const::names() {
+							for name in *names {
+								let n_len = name.chars().count();
+								if self.data_ptr.starts_with(name) && (len == n_len || !self.data_ptr.chars().nth(n_len).unwrap().is_alphabetic()) {
+									self.next_by = name.chars().count();
+									return Ok(Token::Atom(Atom::Const(*f)));
+								}
+							}
+						}
 						debug!("got invalid char '{}'", val);
 						Err(ParseErr::Invalid)
 					}
@@ -299,8 +326,13 @@ impl Parser<'_> {
 				Token::Op(op) => match op {
 					Op::LParen => {
 						let val = self.parse_expr(0.0);
-						assert_eq!(self.lex.next(), Ok(Token::Op(Op::RParen)));
-						val
+						if self.lex.next() != Ok(Token::Op(Op::RParen)) {
+							debug!("Unclosed parens");
+							Err(ParseErr::Invalid)
+						}
+						else {
+							val
+						}
 					},
 					// Op::Func(f) => Ok(Expr::Node(Op::Func(f), vec![self.parse_expr(op.get_lbp())?])),
 					_ => match op.bp_prefix() {