From 5a34b0f6f7b5a0b6a9a77a8166cb3a3752499b0d Mon Sep 17 00:00:00 2001
From: Tangent Wantwight <tangent128@gmail.com>
Date: Sat, 18 May 2024 21:33:17 -0400
Subject: [PATCH] Factor out common infix op logic

---
 src/lib/expr.ts | 46 ++++++++++++++--------------------------------
 1 file changed, 14 insertions(+), 32 deletions(-)

diff --git a/src/lib/expr.ts b/src/lib/expr.ts
index c0d1e96..4af04a1 100644
--- a/src/lib/expr.ts
+++ b/src/lib/expr.ts
@@ -58,44 +58,26 @@ function map(
   }
 }
 
+function makeInfixOp(token:RegExp, leftBindingPower: number,rightBindingPower: number, op: (left: number, right: number) => Value | ErrorResult):TokenHandler {
+  return {
+    leftBindingPower,
+    token,
+    parse: ({ value: left }, matched, parser) =>
+      map(parser.parseSubExpression(rightBindingPower), (right) => op(left, right)),
+  }
+}
+
 const Operators: TokenHandler[] = [
   {
     leftBindingPower: -1,
     token: NUMBER_TOKEN,
     parse: (left, matched) => ({ value: Number(matched) }),
   },
-  {
-    leftBindingPower: 10,
-    token: PLUS_TOKEN,
-    parse: ({ value: left }, matched, parser) =>
-      map(parser.parseSubExpression(11), (right) => ({ value: left + right })),
-  },
-  {
-    leftBindingPower: 10,
-    token: MINUS_TOKEN,
-    parse: ({ value: left }, matched, parser) =>
-      map(parser.parseSubExpression(11), (right) => ({ value: left - right })),
-  },
-  {
-    leftBindingPower: 20,
-    token: TIMES_TOKEN,
-    parse: ({ value: left }, matched, parser) =>
-      map(parser.parseSubExpression(21), (right) => ({ value: left * right })),
-  },
-  {
-    leftBindingPower: 20,
-    token: FLOOR_TOKEN,
-    parse: ({ value: left }, matched, parser) =>
-      map(parser.parseSubExpression(21), (right) => ({
-        value: Math.floor(left / right),
-      })),
-  },
-  {
-    leftBindingPower: 20,
-    token: DIV_TOKEN,
-    parse: ({ value: left }, matched, parser) =>
-      map(parser.parseSubExpression(21), (right) => ({ value: left / right })),
-  },
+  makeInfixOp(PLUS_TOKEN, 10, 11, (left, right) => ({ value: left + right })),
+  makeInfixOp(MINUS_TOKEN, 10, 11, (left, right) => ({ value: left - right })),
+  makeInfixOp(TIMES_TOKEN, 10, 11, (left, right) => ({ value: left * right })),
+  makeInfixOp(FLOOR_TOKEN, 10, 11, (left, right) => ({ value: Math.floor(left / right) })),
+  makeInfixOp(DIV_TOKEN, 10, 11, (left, right) => ({ value: left / right })),
 ];
 
 const ZERO = { value: 0 };