refactor: factor out function aquisition

src/nodes/eval.rs

@@ -41,7 +41,7 @@ fn collapse_toplevel(nodes: &mut Vec<Node>, mut end: usize) -> Result<(), Error>
         .rposition(|n| *n == Node::ParenthesisStart)
         .unwrap_or(0);
 
-    while let Some((index, variant)) = nodes[start..end]
+    while let Some((index, function)) = nodes[start..end]
         .iter()
         .enumerate()
         .filter_map(|(i, n)| match n {
@@ -58,20 +58,7 @@ fn collapse_toplevel(nodes: &mut Vec<Node>, mut end: usize) -> Result<(), Error>
             return Err(Error::MissingArgument(node.clone()));
         };
 
-        match variant {
+        function.for_float()(n);
-            Function::Sqrt => n.sqrt_mut(),
-
-            Function::Ln => n.ln_mut(),
-
-            Function::Sine => n.sin_mut(),
-            Function::ArcSine => n.asin_mut(),
-            Function::Cosine => n.cos_mut(),
-            Function::ArcCosine => n.acos_mut(),
-            Function::Tangent => n.tan_mut(),
-            Function::ArcTangent => n.atan_mut(),
-            Function::Secant => n.sec_mut(),
-            Function::CoSecant => n.csc_mut(),
-        };
 
         nodes.remove(start + index);
         end -= 1;
@@ -185,6 +172,25 @@ fn collapse_toplevel(nodes: &mut Vec<Node>, mut end: usize) -> Result<(), Error>
     Ok(())
 }
 
+impl Function {
+    fn for_float(&self) -> impl FnMut(&mut Float) {
+        match self {
+            Function::Sqrt => Float::sqrt_mut,
+
+            Function::Ln => Float::ln_mut,
+
+            Function::Sine => Float::sin_mut,
+            Function::ArcSine => Float::asin_mut,
+            Function::Cosine => Float::cos_mut,
+            Function::ArcCosine => Float::acos_mut,
+            Function::Tangent => Float::tan_mut,
+            Function::ArcTangent => Float::atan_mut,
+            Function::Secant => Float::sec_mut,
+            Function::CoSecant => Float::csc_mut,
+        }
+    }
+}
+
 #[cfg(test)]
 use super::PREC;