From e61485012ecfaf8145668790ec3fb17ff2307862 Mon Sep 17 00:00:00 2001
From: Tangent Wantwight <tangent128@gmail.com>
Date: Sat, 29 Jul 2023 14:50:49 -0400
Subject: [PATCH] Make thunk used for recursive braces more understandable

---
 notcl.js | 19 ++++++++-----------
 peg.js   | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/notcl.js b/notcl.js
index 05478f3..be89430 100644
--- a/notcl.js
+++ b/notcl.js
@@ -6,7 +6,7 @@
  */
 
 var Notcl = (() => {
-  const { AtLeast, Choose, End, Map, Regex, Sequence } = Peg;
+  const { AtLeast, Choose, End, Map, Regex, Sequence, Use } = Peg;
 
   const InterCommandWhitespace = Regex(/\s+/y);
 
@@ -23,13 +23,17 @@ var Notcl = (() => {
   // WIP, need to be able to escape braces correctly
   // WIP, error if anything after closing brace
 
-  const BracePattern = Map(
+  /** @type {Peg.Pattern<string>} */
+  const Brace = Map(
     Sequence(
       Regex(/\{/y),
       AtLeast(
         0,
         Choose(
-          Map(Brace, (text) => `{${text}}`),
+          Map(
+            Use(() => Brace),
+            (text) => `{${text}}`
+          ),
           Map(Regex(/[^{}]+/y), ([text]) => text)
         )
       ),
@@ -37,19 +41,12 @@ var Notcl = (() => {
     ),
     ([_left, fragments, _right]) => fragments.join("")
   );
-  /**
-   * @type {Peg.Pattern<string>}
-   */
-  function Brace(source, index) {
-    // Thunk to allow Brace to recurse
-    return BracePattern(source, index);
-  }
 
   const Word = Map(
     Sequence(
       PreWordWhitespace,
       Choose(
-        Map(BracePattern, (text) => ({
+        Map(Brace, (text) => ({
           text,
         })),
         BasicWord
diff --git a/peg.js b/peg.js
index 5f2c76b..2c81c0e 100644
--- a/peg.js
+++ b/peg.js
@@ -21,6 +21,21 @@ Peg.WrapPattern = function (pattern) {
   return /** @type {Peg.Pattern<T>} */ (pattern);
 };
 
+/**
+ * Proxies to a pattern retrieved from an accessor function.
+ *
+ * Allows using a pattern recursively in its own definition, by returning the value of the const assigned to.
+ *
+ * @template T
+ * @param {() => Peg.Pattern<T>} getPattern
+ * @returns {Peg.Pattern<T>}
+ */
+Peg.Use = function (getPattern) {
+  return Peg.WrapPattern(function (source, index) {
+    return getPattern()(source, index);
+  });
+};
+
 /**
  * Creates a pattern that wraps another pattern, transforming the returned value on a match
  * @template T, U