feat: add some trig functions

src/nodes/evaluate.rs

@@ -42,7 +42,13 @@ fn collapse_toplevel(nodes: &mut Vec<Node>, mut end: usize) {
         match &mut nodes[start..end][index + 1] {
             Node::Number(n) => match variant {
                 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(),
             },
             _ => panic!("function is missing an argument"),
         };

src/nodes/mod.rs

@@ -55,14 +55,26 @@ impl TryFrom<char> for Operator {
 #[derive(Clone, Debug, PartialEq)]
 enum Function {
     Sine,
+    ArcSine,
     Cosine,
+    ArcCosine,
+    Tangent,
+    ArcTangent,
+    Secant,
+    CoSecant,
 }
 impl FromStr for Function {
     type Err = ();
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         match s {
             "sin" => Ok(Self::Sine),
+            "asin" => Ok(Self::ArcSine),
             "cos" => Ok(Self::Cosine),
+            "acos" => Ok(Self::ArcCosine),
+            "tan" => Ok(Self::Tangent),
+            "atan" => Ok(Self::ArcTangent),
+            "sec" => Ok(Self::Secant),
+            "csc" => Ok(Self::CoSecant),
             _ => Err(()),
         }
     }