From ecb7eb0cb4d84f4a6297a194b9e40484aa0c9982 Mon Sep 17 00:00:00 2001
From: Steven Levithan <steves_list@hotmail.com>
Date: Fri, 25 Oct 2024 12:47:43 +0200
Subject: [PATCH] Demo: printAst

---
 README.md       |  6 +++---
 demo/index.html | 33 ++++++++++++++++++++++++++++++++-
 src/generate.js |  2 +-
 3 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 1c39ec3..2b30baa 100644
--- a/README.md
+++ b/README.md
@@ -59,16 +59,16 @@ Sets the JavaScript language version for generated patterns and flags. Later tar
 
 *Default: `'ES2024'`.*
 
-## Unicode, mixed case sensitivity
+## Unicode, mixed case-sensitivity
 
-Oniguruma-To-ES fully supports mixed case sensitivity (and handles the Unicode edge cases) regardless of JavaScript [target](#target). It also restricts Unicode properties to those supported by Oniguruma and the target JavaScript version.
+Oniguruma-To-ES fully supports mixed case-sensitivity (and handles the Unicode edge cases) regardless of JavaScript [target](#target). It also restricts Unicode properties to those supported by Oniguruma and the target JavaScript version.
 
 Oniguruma-To-ES focuses on being lightweight to make it better for use in browsers. This is partly achieved by not including heavyweight Unicode character data, which imposes a couple of minor/rare restrictions:
 
 - Character class intersection and nested negated classes are unsupported with target `ES2018`. Use target `ES2024` or later if you need support for these Oniguruma features.
 - A handful of Unicode properties that target a specific character case (ex: `\p{Lower}`) can't be used case-insensitively in patterns that contain other characters with a specific case that are used case-sensitively.
   - In other words, almost every usage is fine, inluding `A\p{Lower}`, `(?i:A\p{Lower})`, `(?i:A)\p{Lower}`, `(?i:A(?-i:\p{Lower}))`, and `\w(?i:\p{Lower})`, but not `A(?i:\p{Lower})`.
-  - Using these properties case-insensitively is basically never done intentionally, so you're unlikely to encounter this error unless it's actually catching a mistake.
+  - Using these properties case-insensitively is basically never done intentionally, so you're unlikely to encounter this error unless it's catching a mistake.
 
 ## Similar projects
 
diff --git a/demo/index.html b/demo/index.html
index fa66ad8..1e292c5 100644
--- a/demo/index.html
+++ b/demo/index.html
@@ -59,12 +59,43 @@ <h2>Try it</h2>
       </p>
     </details>
     <pre id="output"></pre>
-    <p><small>The output shows the result of calling <code>toRegExp</code>. Oniguruma-To-ES includes functions to generate additional formats: <code>compile</code> (returns an object with <code>pattern</code> and <code>flags</code> strings), <code>toOnigurumaAst</code>, and <code>toRegexAst</code> (for an AST based on <a href="https://github.com/slevithan/regex"><code>regex</code></a>). You can run all of these from the console on this page. <code>compile</code> and <code>toRegExp</code> accept pattern and flags strings and an options object. <code>toOnigurumaAst</code> and <code>toRegexAst</code> accept a pattern and flags.</small></p>
+    <p><small>The output shows the result of calling <code>toRegExp</code>. Oniguruma-To-ES includes functions to generate additional formats: <code>compile</code> (returns an object with <code>pattern</code> and <code>flags</code> strings), <code>toOnigurumaAst</code>, and <code>toRegexAst</code> (for an AST based on <a href="https://github.com/slevithan/regex"><code>regex</code></a>). You can run all of these from the console on this page. <code>compile</code> and <code>toRegExp</code> accept pattern and flags strings and an options object. <code>toOnigurumaAst</code> and <code>toRegexAst</code> accept a pattern and flags. You can also pass ASTs to <code>printAst</code>.</small></p>
   </main>
 
   <script src="../dist/index.min.js"></script>
   <script>
     Object.assign(globalThis, OnigurumaToES);
+
+    function printAst(ast) {
+      if (ast?.type !== 'Regex') {
+        throw new Error('Oniguruma or `regex` AST expected');
+      }
+      const isObject = value => ({}).toString.call(value) === '[object Object]';
+      const nodeIds = new Map();
+      let counter = 0;
+      console.log(JSON.stringify(ast, function (key, value) {
+        if (isObject(this) && !nodeIds.get(this) && key !== '') {
+          nodeIds.set(this, ++counter);
+        }
+        if (key === 'type') {
+          return `${value} [${nodeIds.get(this)}]`;
+        }
+        if (key === 'parent') {
+          let parentId = null;
+          if (isObject(value)) {
+            if (!nodeIds.has(value)) {
+              nodeIds.set(value, ++counter);
+            }
+            parentId = nodeIds.get(value);
+          }
+          return value ? `[${value.type}:${parentId}]` : value;
+        }
+        if (key === 'max' && value === Infinity) {
+          return '[Infinity]';
+        }
+        return value;
+      }, '│ '));
+    }
   </script>
   <script src="./demo.js"></script>
 </body>
diff --git a/src/generate.js b/src/generate.js
index 1246ef4..d4ba7d8 100644
--- a/src/generate.js
+++ b/src/generate.js
@@ -124,8 +124,8 @@ function generate(ast, options) {
   }
 
   const result = gen(ast);
-  // By default, `regex` implicitly chooses flag u or v; control it instead
   if (!minTargetEs2024) {
+    // Switch from flag v to u. By default, `regex` implicitly chooses; control it instead
     delete result.options.force.v;
     result.options.disable.v = true;
     result.options.unicodeSetsPlugin = null;