added log function

src/main.rs

@@ -43,6 +43,7 @@ enum FunctionType {
     Sine,
     Cosine,
     NaturalLog,
+    Log10,
     Max,
     Min,
     SquareRoot,
@@ -153,6 +154,7 @@ impl std::fmt::Display for Token {
                 FunctionType::Max => write!(f, "max"),
                 FunctionType::Min => write!(f, "min"),
                 FunctionType::SquareRoot => write!(f, "sqrt"),
+                FunctionType::Log10 => write!(f, "log"),
             },
         }
     }
@@ -223,6 +225,7 @@ fn parse_buffer(buf: &str) -> Result<Token, TokenizeError> {
         "sin" => Ok(Token::Function(FunctionType::Sine)),
         "cos" => Ok(Token::Function(FunctionType::Cosine)),
         "ln" => Ok(Token::Function(FunctionType::NaturalLog)),
+        "log" => Ok(Token::Function(FunctionType::Log10)),
         "max" => Ok(Token::Function(FunctionType::Max)),
         "min" => Ok(Token::Function(FunctionType::Min)),
         "sqrt" => Ok(Token::Function(FunctionType::SquareRoot)),
@@ -428,6 +431,7 @@ fn calculate(tokens: Vec<Token>) -> Result<f64, CalculateError> {
                     FunctionType::Sine => Some(n.sin()),
                     FunctionType::Cosine => Some(n.cos()),
                     FunctionType::NaturalLog => Some(n.ln()),
+                    FunctionType::Log10 => Some(n.log10()),
                     FunctionType::SquareRoot => Some(n.sqrt()),
                     _ => None,
                 };
@@ -501,6 +505,14 @@ mod tests {
             tokenize("sqrt"),
             Ok(vec![Token::Function(FunctionType::SquareRoot)])
         );
+        assert_eq!(
+            tokenize("ln"),
+            Ok(vec![Token::Function(FunctionType::Log10)])
+        );
+        assert_eq!(
+            tokenize("log"),
+            Ok(vec![Token::Function(FunctionType::Log10)])
+        );
         assert_eq!(
             tokenize("3.14159265358979323"),
             Ok(vec![Token::Number(3.14159265358979323)])