From 8756ace462ab94e540d53c633b7e76c21b7a6bcd Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Mon, 13 Mar 2023 21:32:05 -0230
Subject: inverse trig functions

---
 src/function.rs | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/input.rs    |  4 +++-
 src/lib.rs      | 59 ++++---------------------------------------------------
 3 files changed, 68 insertions(+), 56 deletions(-)
 create mode 100644 src/function.rs

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);
diff --git a/src/input.rs b/src/input.rs
index dbfe763..4de615f 100644
--- a/src/input.rs
+++ b/src/input.rs
@@ -32,7 +32,9 @@ impl Calculator {
                 }
                 KeyCode::Enter => {
                     if let Ok(func) = Function::parse(&self.input_buffer) {
-                        self.call_function(func);
+                        if let Some(val) = self.stack.pop() {
+                            self.stack.push(func.call(val, self.angle_mode));
+                        }
                     } else if let Ok(c) = Constant::parse(&self.input_buffer) {
                         self.stack.push(c.value());
                     } else if let Ok(bu) = self.input_buffer.parse::<f64>() {
diff --git a/src/lib.rs b/src/lib.rs
index 039258c..db316f0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,9 +3,12 @@ use std::{
     fmt::{self, Display, Formatter},
 };
 
+mod function;
 mod input;
 pub mod ui;
 
+pub use function::Function;
+
 #[derive(Default)]
 pub struct Calculator {
     stack: Vec<f64>,
@@ -35,41 +38,10 @@ impl Calculator {
             Operator::Exp => lhs.powf(rhs),
         });
     }
-
-    fn call_function(&mut self, func: Function) {
-        let mut val = match self.stack.pop() {
-            Some(v) => v,
-            None => {
-                return;
-            }
-        };
-        self.stack.push(match func {
-            Function::Sin => {
-                if self.angle_mode == AngleMode::Degrees {
-                    val = val.to_radians();
-                }
-                val.sin()
-            }
-            Function::Cos => {
-                if self.angle_mode == AngleMode::Degrees {
-                    val = val.to_radians();
-                }
-                val.cos()
-            }
-            Function::Tan => {
-                if self.angle_mode == AngleMode::Degrees {
-                    val = val.to_radians();
-                }
-                val.tan()
-            }
-            Function::Deg => val.to_degrees(),
-            Function::Rad => val.to_radians(),
-        });
-    }
 }
 
 #[derive(Default, Copy, Clone, PartialEq)]
-enum AngleMode {
+pub enum AngleMode {
     #[default]
     Degrees,
     Radians,
@@ -120,29 +92,6 @@ impl Operator {
 
 struct ParseOperatorError(char);
 
-enum Function {
-    Sin, // Sine
-    Cos, // Cosine
-    Tan, // Tangent
-    Deg, // Convert from radians to degrees
-    Rad, // Convert from degrees to radians
-}
-
-impl Function {
-    fn parse(s: &str) -> Result<Self, ParseFunctionError> {
-        match s {
-            "sin" => Ok(Self::Sin),
-            "cos" => Ok(Self::Cos),
-            "tan" => Ok(Self::Tan),
-            "deg" => Ok(Self::Deg),
-            "rad" => Ok(Self::Rad),
-            _ => Err(ParseFunctionError(s.to_string())),
-        }
-    }
-}
-
-struct ParseFunctionError(String);
-
 enum Constant {
     Pi, // Archimedes’ constant (π)
     E,  // Euler's number (e)
-- 
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