Improve addition implementation

src/interface.rs

@@ -236,19 +236,11 @@ impl Operation {
     ) -> Result<Value> {
         let left = self.left.run(context, &mut cursor, source)?;
         let right = self.right.run(context, &mut cursor, source)?;
+        let result = match self.operator {
+            "+" => left + right,
+            _ => return Err(Error::CustomMessage("Operator not supported.".to_string())),
+        };
 
-        match self.operator {
+        Ok(result?)
-            "+" => {
-                let integer_result = left.as_int()? + right.as_int()?;
-
-                Ok(Value::Integer(integer_result))
-            }
-            "-" => {
-                let integer_result = left.as_int()? - right.as_int()?;
-
-                Ok(Value::Integer(integer_result))
-            }
-            _ => Ok(Value::Empty),
-        }
     }
 }

src/value/mod.rs

@@ -17,6 +17,7 @@ use std::{
     convert::TryFrom,
     fmt::{self, Display, Formatter},
     marker::PhantomData,
+    ops::Add,
 };
 
 pub mod function;
@@ -241,6 +242,51 @@ impl Value {
     }
 }
 
+impl Add for Value {
+    type Output = Result<Value>;
+
+    fn add(self, right: Self) -> Self::Output {
+        match (self, right) {
+            (Value::String(left), Value::String(right)) => {
+                let concatenated = left + &right;
+
+                Ok(Value::String(concatenated))
+            }
+            (Value::String(string), other) | (other, Value::String(string)) => {
+                Err(Error::ExpectedString { actual: other })
+            }
+            (Value::Float(left), Value::Float(right)) => {
+                let addition = left + right;
+
+                Ok(Value::Float(addition))
+            }
+            (Value::Float(_), other) | (other, Value::Float(_)) => {
+                Err(Error::ExpectedFloat { actual: other })
+            }
+            (Value::Integer(left), Value::Integer(right)) => Ok(Value::Integer(left + right)),
+            (Value::Integer(_), other) | (other, Value::Integer(_)) => {
+                Err(Error::ExpectedInt { actual: other })
+            }
+            (Value::Boolean(_), Value::Boolean(_)) => todo!(),
+            (Value::Boolean(_), other) | (other, Value::Boolean(_)) => {
+                Err(Error::ExpectedBoolean { actual: other })
+            }
+            (Value::List(_), Value::List(_)) => todo!(),
+            (Value::List(_), other) | (other, Value::List(_)) => {
+                Err(Error::ExpectedList { actual: other })
+            }
+            (Value::Map(_), Value::Map(_)) => todo!(),
+            (Value::Map(_), other) | (other, Value::Map(_)) => {
+                Err(Error::ExpectedMap { actual: other })
+            }
+            (Value::Empty, Value::Empty) => Ok(Value::Empty),
+            _ => Err(Error::CustomMessage(
+                "Cannot add the given types.".to_string(),
+            )),
+        }
+    }
+}
+
 impl Eq for Value {}
 
 impl PartialOrd for Value {