From 32266d07f61b6888d439de6b2c7d9a5a617c49f2 Mon Sep 17 00:00:00 2001
From: Nick Krichevsky <nick@ollien.com>
Date: Fri, 24 May 2024 10:42:23 -0400
Subject: [PATCH] Allow eq eq comparison between strings

---
 src/eval.rs | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/eval.rs b/src/eval.rs
index 6ec7c59..a39bfec 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -1,4 +1,7 @@
-use std::fmt::{self, Display, Formatter};
+use std::{
+    fmt::{self, Display, Formatter},
+    rc::Rc,
+};
 
 use crate::{
     ast::{Expr, ExprVisitor, LiteralValue, Stmt, StmtVisitor},
@@ -120,7 +123,12 @@ impl ExprVisitor<Result<EvaluatedValue, ScriptError>> for InterpreterRunner<'_>
             // Finish the short circuit; if we get to this point the result will always be right.
             TokenKind::Or | TokenKind::And => Ok(right_operand),
 
-            TokenKind::Plus => evaluate_addition((left_operand, right_operand), operator),
+            TokenKind::Plus => evaluate_arithmetic_or_string_operation(
+                (left_operand, right_operand),
+                operator,
+                |left, right| EvaluatedValue::Number(left + right),
+                |left, right| EvaluatedValue::String((left.to_string() + right.as_ref()).into()),
+            ),
 
             TokenKind::Minus => evaluate_binary_arithmetic(
                 (left_operand, right_operand),
@@ -164,16 +172,18 @@ impl ExprVisitor<Result<EvaluatedValue, ScriptError>> for InterpreterRunner<'_>
                 |left_value, right_value| EvaluatedValue::Boolean(left_value <= right_value),
             ),
 
-            TokenKind::EqualEqual => evaluate_binary_arithmetic(
+            TokenKind::EqualEqual => evaluate_arithmetic_or_string_operation(
                 (left_operand, right_operand),
                 operator,
                 |left_value, right_value| EvaluatedValue::Boolean(left_value == right_value),
+                |left_value, right_value| EvaluatedValue::Boolean(left_value == right_value),
             ),
 
-            TokenKind::BangEqual => evaluate_binary_arithmetic(
+            TokenKind::BangEqual => evaluate_arithmetic_or_string_operation(
                 (left_operand, right_operand),
                 operator,
                 |left_value, right_value| EvaluatedValue::Boolean(left_value != right_value),
+                |left_value, right_value| EvaluatedValue::Boolean(left_value != right_value),
             ),
 
             _ => unreachable!(
@@ -287,18 +297,22 @@ fn convert_arithmetic_operands(
     }
 }
 
-fn evaluate_addition(
+fn evaluate_arithmetic_or_string_operation<
+    F: FnOnce(f64, f64) -> EvaluatedValue,
+    G: FnOnce(Rc<str>, Rc<str>) -> EvaluatedValue,
+>(
     (left, right): (EvaluatedValue, EvaluatedValue),
     operator: &Token,
+    make_number_output: F,
+    make_string_output: G,
 ) -> Result<EvaluatedValue, ScriptError> {
     match (left, right) {
         (EvaluatedValue::Number(left_value), EvaluatedValue::Number(right_value)) => {
-            Ok(EvaluatedValue::Number(left_value + right_value))
+            Ok(make_number_output(left_value, right_value))
         }
 
         (EvaluatedValue::String(left_value), EvaluatedValue::String(right_value)) => {
-            let concatted = left_value.to_string() + right_value.as_ref();
-            Ok(EvaluatedValue::String(concatted.into()))
+            Ok(make_string_output(left_value, right_value))
         }
 
         // TODO: we could improve this error (and others) to include the types