add multiple functions to canvas

1 files changed, 15 insertions, 11 deletions

diff --git a/src/math/expression_function.rs b/src/math/expression_function.rs
index 44f83d1..b9a480f 100644
--- a/src/math/expression_function.rs
+++ b/src/math/expression_function.rs
@@ -17,19 +17,23 @@ pub struct ExpressionFunction {
 }
 
 impl ExpressionFunction {
-    pub fn from_string(str: String, operations: &Vec<Operation>) -> Self {
+    pub fn from_string(str: String, operations: &Vec<Operation>) -> Result<Self, ()> {
         let str = str.replace(' ', "");
-        let (lhs, expr) = str.split_once('=').unwrap();
-        let (name, a) = lhs.split_once('(').unwrap();
-        let args: Vec<String> = a[0..a.len() - 1]
-            .split(',')
-            .map(|s| s.to_string())
-            .collect();
-        Self {
-            expr: Expression::from_string(expr, operations),
-            name: name.to_string(),
-            args,
+        if let Some((lhs, expr)) = str.split_once('=') {
+            if let Some((name, a)) = lhs.split_once('(') {
+                let args: Vec<String> = a[0..a.len() - 1]
+                    .split(',')
+                    .map(|s| s.to_string())
+                    .collect();
+
+                return Ok(Self {
+                    expr: Expression::from_string(expr, operations),
+                    name: name.to_string(),
+                    args,
+                })
+            }
         }
+        Err(())
     }
 
     pub fn name(&self) -> &str {