begin to beeing able to use function in rust code

Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+meval = "0.2.0"

src/main.rs

@@ -1,4 +1,5 @@
 use std::env;
+use meval::tokenizer::tokenize;
 
 fn main() {
     let args: Vec<String> = env::args().skip(1).take(3).collect();
@@ -18,13 +19,30 @@ fn main() {
             println!("Usage: $0 -1:1 3:-5 10:1.5")
         }
     }
+
+    #[cfg(debug_assertions)]
+    default_points(&mut points);
+
+
     group_by_x(&mut points);
 
     let m1 = (points[0][1] - points[1][1]) / (points[0][0] - points[1][0]);
-    if m1 == (points[1][1] - points[2][1]) / (points[1][0] - points[2][0]) {
+    let function = if m1 == (points[1][1] - points[2][1]) / (points[1][0] - points[2][0]) {
-        println!("{}", straight_string(m1, &points));
+        straight_string(m1, &points)
     } else {
-        println!("{}", square_string(&points));
+        square_string(&points)
+    };
+
+    if function.contains("NaN") {
+        panic!("Contains NaN, this is probably the result of bad math");
+    }
+    let expr2 = tokenize(function.as_str()).unwrap();
+    println!("{:?}", expr2);
+}
+
+fn default_points(points: &mut [[f64;2];3]) {
+    if points.iter().all(|row| row.iter().all(|&x| x == 0.0)) {
+        *points = [[-1.0,1.0], [2.0,4.0], [3.0,9.0]];
     }
 }
 
@@ -111,7 +129,7 @@ fn square_string(points: &[[f64;2];3]) -> String {
         if a == -1.0 {
             "-".to_string()
         } else if a != 1.0 {
-            a.to_string()
+            format!("{}{}", a, " * ")
         } else {
             "".to_string()
         },
@@ -124,7 +142,7 @@ fn square_string(points: &[[f64;2];3]) -> String {
                     " + ".to_string()
                 },
                 if b != 1.0 {
-                    format!("{}x", b.abs())
+                    format!("{} * x", b.abs())
                 } else {
                     "x".to_string()
                 }