1 files changed, 61 insertions, 0 deletions
diff --git a/src/function.rs b/src/function.rs
new file mode 100644
index 0000000..bb6462d
--- /dev/null
+++ b/src/function.rs
@@ -0,0 +1,61 @@
+use crate::AngleMode;
+
+pub enum Function {
+    Sin,  // Sine
+    Cos,  // Cosine
+    Tan,  // Tangent
+    Asin, // Inverse sine
+    Acos, // Inverse cosine
+    Atan, // Inverse tangent
+    Deg,  // Convert from radians to degrees
+    Rad,  // Convert from degrees to radians
+}
+
+impl Function {
+    pub fn parse(s: &str) -> Result<Self, ParseFunctionError> {
+        match s {
+            "sin" => Ok(Self::Sin),
+            "cos" => Ok(Self::Cos),
+            "tan" => Ok(Self::Tan),
+            "asin" => Ok(Self::Asin),
+            "acos" => Ok(Self::Acos),
+            "atan" => Ok(Self::Atan),
+            "deg" => Ok(Self::Deg),
+            "rad" => Ok(Self::Rad),
+            _ => Err(ParseFunctionError(s.to_string())),
+        }
+    }
+
+    pub fn call(&self, val: f64, angle_mode: AngleMode) -> f64 {
+        match self {
+            Self::Sin => match angle_mode {
+                AngleMode::Degrees => val.to_radians().sin(),
+                AngleMode::Radians => val.sin(),
+            },
+            Self::Cos => match angle_mode {
+                AngleMode::Degrees => val.to_radians().cos(),
+                AngleMode::Radians => val.cos(),
+            },
+            Self::Tan => match angle_mode {
+                AngleMode::Degrees => val.to_radians().tan(),
+                AngleMode::Radians => val.tan(),
+            },
+            Self::Asin => match angle_mode {
+                AngleMode::Degrees => val.asin().to_degrees(),
+                AngleMode::Radians => val.asin(),
+            },
+            Self::Acos => match angle_mode {
+                AngleMode::Degrees => val.acos().to_degrees(),
+                AngleMode::Radians => val.acos(),
+            },
+            Self::Atan => match angle_mode {
+                AngleMode::Degrees => val.atan().to_degrees(),
+                AngleMode::Radians => val.atan(),
+            },
+            Self::Deg => val.to_degrees(),
+            Self::Rad => val.to_radians(),
+        }
+    }
+}
+
+pub struct ParseFunctionError(String);