From de52f18788809614dd2db56fa777ad1491072b8d Mon Sep 17 00:00:00 2001
From: Ben Ruijl <benruyl@gmail.com>
Date: Fri, 7 Jun 2024 12:05:42 +0200
Subject: [PATCH] Support parsing floats in scientific notation

---
 src/coefficient.rs |  2 +-
 src/parser.rs      | 74 +++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 68 insertions(+), 8 deletions(-)

diff --git a/src/coefficient.rs b/src/coefficient.rs
index 69533687..7a95c6ab 100644
--- a/src/coefficient.rs
+++ b/src/coefficient.rs
@@ -1353,7 +1353,7 @@ mod test {
         );
         assert_eq!(
             r,
-            "1.5707963267948966192313216916397514420985846996875529104874722*x+21.472450319416851"
+            "1.5707963267948966192313216916397514420985846996875529104874722*x+21.472450421034925"
         );
     }
 
diff --git a/src/parser.rs b/src/parser.rs
index 28b3a774..5ee38801 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -650,7 +650,7 @@ impl Token {
 
         let ops = ['\0', '^', '+', '*', '-', '(', ')', '/', ',', '[', ']'];
         let whitespace = [' ', '\t', '\n', '\r', '\\'];
-        let forbidden = [';', ':', '&', '!', '%'];
+        let forbidden = [';', ':', '&', '!', '%', '.'];
 
         let mut char_iter = input.chars();
         let mut c = char_iter.next().unwrap_or('\0'); // add EOF as a token
@@ -680,12 +680,55 @@ impl Token {
                     }
                 }
                 ParseState::Number => {
-                    if c != '_' && c != ' ' && c != '.' && !c.is_ascii_digit() {
+                    let mut last_digit_is_exp = false;
+                    loop {
+                        if c.is_ascii_digit() {
+                            id_buffer.push(c);
+                            c = char_iter.next().unwrap_or('\0');
+                            last_digit_is_exp = false;
+                            continue;
+                        }
+
+                        if last_digit_is_exp && c != '-' && c != '+' {
+                            // input cannot be a floating point number
+                            // add a multiplication operator, e.g 2.2ex => 2.2*ex
+
+                            let e = id_buffer.pop().unwrap();
+                            state = ParseState::Any;
+                            stack.push(Token::Number(id_buffer.as_str().into()));
+                            id_buffer.clear();
+
+                            extra_ops.push(e);
+                            extra_ops.push(c);
+                            c = '*';
+
+                            break;
+                        }
+
+                        if c == '\0' {
+                            last_digit_is_exp = false;
+                            break;
+                        }
+
+                        let digit_is_exp = c == 'e' || c == 'E';
+
+                        if c != '_' && c != ' ' {
+                            if !digit_is_exp && !last_digit_is_exp && c != '.' {
+                                break;
+                            }
+
+                            id_buffer.push(c);
+                        }
+
+                        last_digit_is_exp = digit_is_exp;
+
+                        c = char_iter.next().unwrap_or('\0');
+                    }
+
+                    if !last_digit_is_exp {
                         state = ParseState::Any;
                         stack.push(Token::Number(id_buffer.as_str().into()));
                         id_buffer.clear();
-                    } else if c != '_' && c != ' ' {
-                        id_buffer.push(c);
                     }
                 }
                 ParseState::RationalPolynomial => {
@@ -1247,7 +1290,13 @@ impl Token {
 mod test {
     use std::sync::Arc;
 
-    use crate::{atom::Atom, domains::integer::Z, parser::Token, state::State};
+    use crate::{
+        atom::Atom,
+        domains::integer::Z,
+        parser::Token,
+        printer::{AtomPrinter, PrintOptions},
+        state::State,
+    };
 
     #[test]
     fn pow() {
@@ -1271,13 +1320,24 @@ mod test {
     fn liberal() {
         let input = Atom::parse(
             "89233_21837281 x   
-            ^2 / y + 5",
+            ^2 / y + 5 + 5x",
         )
         .unwrap();
-        let res = Atom::parse("8923321837281*x^2*y^-1+5").unwrap();
+        let res = Atom::parse("8923321837281*x^2*y^-1+5+5x").unwrap();
         assert_eq!(input, res);
     }
 
+    #[test]
+    fn float() {
+        let input = Atom::parse("1.2x+1e-5+1e+5 1.1234e23 +2exp(5)").unwrap();
+
+        let r = format!(
+            "{}",
+            AtomPrinter::new_with_options(input.as_view(), PrintOptions::file())
+        );
+        assert_eq!(r, "1.2000000000000000*x+2*exp(5)+1.1234000000000000e28");
+    }
+
     #[test]
     fn square_bracket_function() {
         let input = Atom::parse("v1  [v1, v2]+5 + v1[]").unwrap();