From 1c8c5b619bc65de69df9502d51cbdfb4ca70a242 Mon Sep 17 00:00:00 2001
From: Steven Levithan <steves_list@hotmail.com>
Date: Wed, 13 Nov 2024 12:43:48 +0100
Subject: [PATCH] Remove \G handling case that adds complexity and trades
 against other supported cases

---
 spec/match-search-start.spec.js | 54 +--------------------------------
 src/transform.js                | 22 +-------------
 2 files changed, 2 insertions(+), 74 deletions(-)

diff --git a/spec/match-search-start.spec.js b/spec/match-search-start.spec.js
index 6a97a63..bb85b13 100644
--- a/spec/match-search-start.spec.js
+++ b/spec/match-search-start.spec.js
@@ -82,59 +82,7 @@ describe('Assertion: Search start', () => {
       expect(() => toDetails(r`(\Ga)+\G`)).toThrow();
     });
 
-    it('should allow if leading in a leading positive lookahead', () => {
-      expect('a').toExactlyMatch(r`(?=\G)a`);
-      expect('a').toExactlyMatch(r`(?=\Ga)a`);
-      expect('aaba'.match(toRegExp(r`(?=\Ga)a`, {global: true}))).toEqual(['a', 'a']);
-      expect(['a', 'b']).toExactlyMatch(r`(?=\G)a|\Gb`);
-      expect('a').toExactlyMatch(r`((?=\G)a)`);
-      expect(['a', 'A']).toExactlyMatch({
-        pattern: r`(?i)(?=\G)a`,
-        maxTestTarget: maxTestTargetForPatternMods,
-      });
-      // Similar but not covered
-      [ r`(?=\G|)a`,
-        r`(?:(?=\G))?a`,
-        r`(?=\G)a|b`,
-      ].forEach(pattern => {
-        expect(() => toDetails(pattern, {avoidSubclass: true})).toThrow();
-      });
-    });
-
-    it('should allow if trailing in a leading positive lookbehind', () => {
-      expect('a').toExactlyMatch(r`(?<=\G)a`);
-      expect(['aa', 'abaa']).not.toFindMatch(r`(?<=a\G)a`);
-      let re = toRegExp(r`(?<=a\G)a`);
-      re.lastIndex = 3;
-      expect(re.exec('abaa')?.index).toBe(3);
-      expect(['a', 'b']).toExactlyMatch(r`(?<=\G)a|\Gb`);
-      expect('a').toExactlyMatch(r`((?<=\G)a)`);
-      expect(['a', 'A']).toExactlyMatch({
-        pattern: r`(?i)(?<=\G)a`,
-        maxTestTarget: maxTestTargetForPatternMods,
-      });
-      // Similar but not covered
-      [ r`(?<=\G|)a`,
-        r`(?:(?<=\G))?a`,
-        r`(?<=\G)a|b`,
-      ].forEach(pattern => {
-        expect(() => toDetails(pattern, {avoidSubclass: true})).toThrow();
-      });
-    });
-
-    it('should throw if leading in a leading positive lookbehind', () => {
-      // [Oniguruma] Matches at index 3 within `abc`, but doesn't match within `aabc`
-      // [TODO] Emulatable by replacing `\G` with `^`, slicing the string to `lastIndex`, and doing
-      // a non-sticky search
-      expect(() => toDetails(r`(?<=\Gabc)`)).toThrow();
-    });
-
-    it('should throw if leading in a leading negative lookaround', () => {
-      expect(() => toDetails(r`(?!\G)a`, {avoidSubclass: true})).toThrow();
-      expect(() => toDetails(r`(?<!\G)a`, {avoidSubclass: true})).toThrow();
-    });
-
-    // Just documenting current behavior
+    // Documenting current behavior
     it('should throw for redundant but otherwise supportable assertions', () => {
       expect(() => toDetails(r`\G\Ga`)).toThrow();
       expect(() => toDetails(r`\Ga|\G\Gb`)).toThrow();
diff --git a/src/transform.js b/src/transform.js
index 22913c3..8586feb 100644
--- a/src/transform.js
+++ b/src/transform.js
@@ -705,27 +705,7 @@ function getKids(node) {
 }
 
 function getLeadingG(els) {
-  let firstToConsider = els.find(el => el.type !== AstTypes.Directive);
-  if (!firstToConsider) {
-    return null;
-  }
-  // Special case for leading positive lookaround with leading `\G`; else all leading assertions
-  // are ignored when looking for `\G`; can be nested within a wrapper group via subsequent
-  // recursion into groups
-  if (
-    isLookaround(firstToConsider) &&
-    !firstToConsider.negate &&
-    firstToConsider.alternatives.length === 1 &&
-    firstToConsider.alternatives[0].elements.length
-  ) {
-    const els = firstToConsider.alternatives[0].elements;
-    const index = firstToConsider.kind === AstAssertionKinds.lookahead ? 0 : els.length - 1;
-    // `\G` is first in lookahead or last in lookbehind
-    if (els[index].kind === AstAssertionKinds.search_start) {
-      return els[index];
-    }
-  }
-  firstToConsider = els.find(el => {
+  const firstToConsider = els.find(el => {
     return el.kind === AstAssertionKinds.search_start ?
       true :
       ( el.type !== AstTypes.Assertion &&