fix: constant implicit mult

before, "pi 2" caused a panic while "2 pi" worked just fine.
now both directions work :)

src/formatting.rs

@@ -3,7 +3,7 @@ use rug::Float;
 use crate::nodes::{self, Error};
 
 pub fn pretty_eval(input: &str, max_digits: usize) -> Result<String, Error> {
-    let (prefix, deliminator, input) = input.rsplit_once_last(&["= ", "& ", "plus.minus "]);
+    let (prefix, deliminator, input) = input.rsplit_once_any(&["plus.minus ", "& ", "= "]);
 
     // no need to remove the character here,
     // as we ignore it in all other logic already
@@ -32,16 +32,22 @@ pub fn pretty_eval(input: &str, max_digits: usize) -> Result<String, Error> {
 }
 
 trait StrExt {
-    fn rsplit_once_last<'a, 'b>(&'a self, delimiters: &[&'b str]) -> (&'a str, &'b str, &'a str);
+    fn rsplit_once_any<'a>(
+        &'a self,
+        delimiters: &[&'static str],
+    ) -> (&'a str, &'static str, &'a str);
 }
 impl StrExt for str {
-    fn rsplit_once_last<'a, 'b>(&'a self, delimiters: &[&'b str]) -> (&'a str, &'b str, &'a str) {
+    fn rsplit_once_any<'a>(
-        delimiters
+        &'a self,
-            .iter()
+        delimiters: &[&'static str],
-            .filter_map(|delimiter| self.rfind(delimiter).map(|i| (delimiter, i)))
+    ) -> (&'a str, &'static str, &'a str) {
-            .max_by_key(|(_, i)| *i)
+        for delimiter in delimiters {
-            .map(|(delimiter, i)| (&self[..i], *delimiter, &self[i + delimiter.len()..]))
+            if let Some((prefix, suffix)) = self.rsplit_once(delimiter) {
-            .unwrap_or(("", "", self))
+                return (prefix, delimiter, suffix);
+            }
+        }
+        return ("", "", self);
     }
 }
 
@@ -118,14 +124,6 @@ mod tests {
         assert_eq!(pretty_eval("-11", MAX_DIGITS).unwrap(), "-11");
     }
 
-    #[test]
-    fn complex_prefix() {
-        assert_eq!(
-            pretty_eval("plus.minus 5 & = 5", MAX_DIGITS).unwrap(),
-            "plus.minus 5 & = 5"
-        );
-    }
-
     #[test]
     fn basic_get_significant_digits() {
         let many_zeros = eval("14.00643 + 1.00784 * 4 + 35.446 + 15.9994 * 4");

src/nodes/parse.rs

@@ -127,7 +127,7 @@ impl FromStr for Nodes {
                         && !(c == '-' && filtered_string.chars().nth(i - 1).is_some_and(|c| c == 'e'))
                     {
                         // likely a constant before this number
-                        // no need to check for parenthesis here though (why?)
+                        // no need to check for parenthesis though (why?)
                         if matches!(nodes.last(), Some(Node::Number(_))) {
                             nodes.push(Node::Operator(Default::default()));
                         }