diff --git a/composer.json b/composer.json
index 5160d18..7e114e6 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
   "require-dev": {
     "ergebnis/composer-normalize": "^2.15",
     "phpstan/extension-installer": "^1.0",
-    "phpstan/phpstan": "^1.4",
+    "phpstan/phpstan": "^1.9",
     "phpstan/phpstan-deprecation-rules": "^1.0",
     "phpstan/phpstan-strict-rules": "^1.1",
     "slevomat/coding-standard": "^7.0",
diff --git a/composer.lock b/composer.lock
index ec737fb..3e3a7c6 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "6d73951acc3119aabd404dbbe0967053",
+    "content-hash": "367dc3d722296f940d17b2cfb8efbc38",
     "packages": [
         {
             "name": "psr/log",
@@ -622,16 +622,16 @@
         },
         {
             "name": "phpstan/phpstan",
-            "version": "1.9.2",
+            "version": "1.9.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpstan/phpstan.git",
-                "reference": "d6fdf01c53978b6429f1393ba4afeca39cc68afa"
+                "reference": "d03bccee595e2146b7c9d174486b84f4dc61b0f2"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpstan/phpstan/zipball/d6fdf01c53978b6429f1393ba4afeca39cc68afa",
-                "reference": "d6fdf01c53978b6429f1393ba4afeca39cc68afa",
+                "url": "https://api.github.com/repos/phpstan/phpstan/zipball/d03bccee595e2146b7c9d174486b84f4dc61b0f2",
+                "reference": "d03bccee595e2146b7c9d174486b84f4dc61b0f2",
                 "shasum": ""
             },
             "require": {
@@ -661,7 +661,7 @@
             ],
             "support": {
                 "issues": "https://github.com/phpstan/phpstan/issues",
-                "source": "https://github.com/phpstan/phpstan/tree/1.9.2"
+                "source": "https://github.com/phpstan/phpstan/tree/1.9.4"
             },
             "funding": [
                 {
@@ -677,7 +677,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2022-11-10T09:56:11+00:00"
+            "time": "2022-12-17T13:33:52+00:00"
         },
         {
             "name": "phpstan/phpstan-deprecation-rules",
diff --git a/src/Atn/ATNConfig.php b/src/Atn/ATNConfig.php
index 7e9c9b9..bfd45aa 100644
--- a/src/Atn/ATNConfig.php
+++ b/src/Atn/ATNConfig.php
@@ -128,10 +128,10 @@ public function equals(object $other): bool
         }
 
         return $other instanceof self
+            && $this->state->stateNumber === $other->state->stateNumber
             && $this->alt === $other->alt
             && $this->isPrecedenceFilterSuppressed() === $other->isPrecedenceFilterSuppressed()
             && $this->semanticContext->equals($other->semanticContext)
-            && Equality::equals($this->state, $other->state)
             && Equality::equals($this->context, $other->context);
     }
 
@@ -180,7 +180,7 @@ public function __toString(): string
             $this->semanticContext->equals(SemanticContext::none())
                 ? ''
                 : ',' . $this->semanticContext,
-            $this->reachesIntoOuterContext > 0 ? ',up=' . $this->reachesIntoOuterContext : '',
+            $this->reachesIntoOuterContext > 0 ? ',up=' . $this->getOuterContextDepth() : '',
         );
     }
 }
diff --git a/src/Atn/ATNConfigSet.php b/src/Atn/ATNConfigSet.php
index 319cd6b..c9ed1c1 100644
--- a/src/Atn/ATNConfigSet.php
+++ b/src/Atn/ATNConfigSet.php
@@ -5,8 +5,8 @@
 namespace Antlr\Antlr4\Runtime\Atn;
 
 use Antlr\Antlr4\Runtime\Atn\SemanticContexts\SemanticContext;
+use Antlr\Antlr4\Runtime\Atn\States\ATNState;
 use Antlr\Antlr4\Runtime\Comparison\Equality;
-use Antlr\Antlr4\Runtime\Comparison\Equivalence;
 use Antlr\Antlr4\Runtime\Comparison\Hashable;
 use Antlr\Antlr4\Runtime\Comparison\Hasher;
 use Antlr\Antlr4\Runtime\PredictionContexts\PredictionContext;
@@ -34,7 +34,8 @@ class ATNConfigSet implements Hashable
      * All configs but hashed by (s, i, _, pi) not including context. Wiped out
      * when we go readonly as this set becomes a DFA state.
      */
-    public ?Set $configLookup = null;
+    // ConfigHashSet : Dictionary<ATNConfig, ATNConfig>
+    public ?ConfigHashSet $configLookup = null;
 
     /**
      * Track the elements as they are added to the set; supports get(i).
@@ -82,32 +83,7 @@ public function __construct(bool $fullCtx = true)
          * not including context. Wiped out when we go readonly as this se
          * becomes a DFA state.
          */
-        $this->configLookup = new Set(new class implements Equivalence {
-            public function equivalent(Hashable $left, Hashable $right): bool
-            {
-                if ($left === $right) {
-                    return true;
-                }
-
-                if (!$left instanceof ATNConfig || !$right instanceof ATNConfig) {
-                    return false;
-                }
-
-                return $left->alt === $right->alt
-                    && $left->semanticContext->equals($right->semanticContext)
-                    && Equality::equals($left->state, $right->state);
-            }
-
-            public function hash(Hashable $value): int
-            {
-                return $value->hashCode();
-            }
-
-            public function equals(object $other): bool
-            {
-                return $other instanceof self;
-            }
-        });
+        $this->configLookup = new ConfigHashSet();
 
         $this->fullCtx = $fullCtx;
     }
@@ -133,14 +109,14 @@ public function add(ATNConfig $config, ?DoubleKeyMap $mergeCache = null): bool
             $this->hasSemanticContext = true;
         }
 
-        if ($config->reachesIntoOuterContext > 0) {
+        if ($config->getOuterContextDepth() > 0) {
             $this->dipsIntoOuterContext = true;
         }
 
         /** @var ATNConfig $existing */
         $existing = $this->configLookup->getOrAdd($config);
 
-        if ($existing->equals($config)) {
+        if ($existing === $config) {
             $this->cachedHashCode = null;
 
             $this->configs[] = $config; // track order here
@@ -149,12 +125,14 @@ public function add(ATNConfig $config, ?DoubleKeyMap $mergeCache = null): bool
         }
 
         // A previous (s,i,pi,_), merge with it and save result
+        /** @var bool $rootIsWildcard */
         $rootIsWildcard = !$this->fullCtx;
 
         if ($existing->context === null || $config->context === null) {
             throw new \LogicException('Unexpected null context.');
         }
 
+        /** @var PredictionContext $merged */
         $merged = PredictionContext::merge($existing->context, $config->context, $rootIsWildcard, $mergeCache);
 
         // No need to check for existing->context, config->context in cache
@@ -186,8 +164,12 @@ public function elements(): array
         return $this->configs;
     }
 
+    /**
+     * @return Set<ATNState>
+     */
     public function getStates(): Set
     {
+        /** @var Set<ATNState> $states */
         $states = new Set();
         foreach ($this->configs as $config) {
             $states->add($config->state);
@@ -305,6 +287,10 @@ public function contains(object $item): bool
             throw new \InvalidArgumentException('This method is not implemented for readonly sets.');
         }
 
+        if (!($item instanceof ATNConfig)) {
+            return false;
+        }
+
         return $this->configLookup->contains($item);
     }
 
@@ -325,8 +311,8 @@ public function clear(): void
         }
 
         $this->configs = [];
-        $this->cachedHashCode = -1;
-        $this->configLookup = new Set();
+        $this->cachedHashCode = null;
+        $this->configLookup = new ConfigHashSet();
     }
 
     public function isReadOnly(): bool
@@ -358,7 +344,7 @@ public function __toString(): string
         return \sprintf(
             '[%s]%s%s%s%s',
             \implode(', ', $this->configs),
-            $this->hasSemanticContext ? ',hasSemanticContext=' . $this->hasSemanticContext : '',
+            $this->hasSemanticContext ? ',hasSemanticContext=true' : '',
             $this->uniqueAlt !== ATN::INVALID_ALT_NUMBER ? ',uniqueAlt=' . $this->uniqueAlt : '',
             $this->conflictingAlts !== null ? ',conflictingAlts=' . $this->conflictingAlts : '',
             $this->dipsIntoOuterContext ? ',dipsIntoOuterContext' : '',
diff --git a/src/Atn/ATNSimulator.php b/src/Atn/ATNSimulator.php
index 5ecce88..2aae6f9 100644
--- a/src/Atn/ATNSimulator.php
+++ b/src/Atn/ATNSimulator.php
@@ -5,6 +5,7 @@
 namespace Antlr\Antlr4\Runtime\Atn;
 
 use Antlr\Antlr4\Runtime\Dfa\DFAState;
+use Antlr\Antlr4\Runtime\PredictionContexts\IdentityHashMap;
 use Antlr\Antlr4\Runtime\PredictionContexts\PredictionContext;
 use Antlr\Antlr4\Runtime\PredictionContexts\PredictionContextCache;
 
@@ -92,7 +93,7 @@ public function getSharedContextCache(): PredictionContextCache
 
     public function getCachedContext(PredictionContext $context): PredictionContext
     {
-        $visited = [];
+        $visited = new IdentityHashMap();
 
         return PredictionContext::getCachedPredictionContext(
             $context,
diff --git a/src/Atn/ConfigHashSet.php b/src/Atn/ConfigHashSet.php
new file mode 100644
index 0000000..9806a16
--- /dev/null
+++ b/src/Atn/ConfigHashSet.php
@@ -0,0 +1,81 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Antlr\Antlr4\Runtime\Atn;
+
+use Antlr\Antlr4\Runtime\Comparison\Equivalence;
+use Antlr\Antlr4\Runtime\Comparison\Hashable;
+use Antlr\Antlr4\Runtime\Comparison\Hasher;
+use Antlr\Antlr4\Runtime\Utils\Map;
+
+/**
+ * The reason that we need this is because we don't want the hash map to use
+ * the standard hash code and equals. We need all configurations with the same
+ * {@code (s,i,_,semctx)} to be equal. Unfortunately, this key effectively doubles
+ * the number of objects associated with ATNConfigs. The other solution is to
+ * use a hash table that lets us specify the equals/hashcode operation.
+ *
+ * @extends Map<ATNConfig, ATNConfig>
+ */
+final class ConfigHashSet extends Map
+{
+    public function __construct(?Equivalence $comparer = null)
+    {
+        if ($comparer === null) {
+            parent::__construct(new class implements Equivalence {
+                public function equivalent(Hashable $left, Hashable $right): bool
+                {
+                    if (! $left instanceof ATNConfig) {
+                        return false;
+                    }
+
+                    if (! $right instanceof ATNConfig) {
+                        return false;
+                    }
+
+                    if ($left === $right) {
+                        return true;
+                    }
+
+                    return $left->state->stateNumber === $right->state->stateNumber
+                            && $left->alt === $right->alt
+                            && $left->semanticContext->equals($right->semanticContext);
+                }
+
+                public function hash(Hashable $value): int
+                {
+                    if (! $value instanceof ATNConfig) {
+                        return 0;
+                    }
+
+                    return Hasher::hash(
+                        $value->state->stateNumber,
+                        $value->alt,
+                        $value->semanticContext,
+                    );
+                }
+
+                public function equals(object $other): bool
+                {
+                    return $other instanceof self;
+                }
+            });
+        } else {
+            parent::__construct($comparer);
+        }
+    }
+
+    public function getOrAdd(ATNConfig $config): ATNConfig
+    {
+        /** @var ?ATNConfig $existing */
+        $existing = null;
+        if ($this->tryGetValue($config, $existing)) {
+            return $existing;
+        } else {
+            $this->put($config, $config);
+
+            return $config;
+        }
+    }
+}
diff --git a/src/Atn/LexerATNConfig.php b/src/Atn/LexerATNConfig.php
index 0b353c1..d021e3d 100644
--- a/src/Atn/LexerATNConfig.php
+++ b/src/Atn/LexerATNConfig.php
@@ -63,15 +63,15 @@ public function equals(object $other): bool
             return false;
         }
 
-        if (!parent::equals($other)) {
+        if ($this->passedThroughNonGreedyDecision !== $other->passedThroughNonGreedyDecision) {
             return false;
         }
 
-        if ($this->passedThroughNonGreedyDecision !== $other->passedThroughNonGreedyDecision) {
+        if (!Equality::equals($this->lexerActionExecutor, $other->lexerActionExecutor)) {
             return false;
         }
 
-        return Equality::equals($this->lexerActionExecutor, $other->lexerActionExecutor);
+        return parent::equals($other);
     }
 
     private static function checkNonGreedyDecision(LexerATNConfig $source, ATNState $target): bool
diff --git a/src/Atn/OrderedATNConfigSet.php b/src/Atn/OrderedATNConfigSet.php
index 6eeb804..e1da41d 100644
--- a/src/Atn/OrderedATNConfigSet.php
+++ b/src/Atn/OrderedATNConfigSet.php
@@ -4,7 +4,8 @@
 
 namespace Antlr\Antlr4\Runtime\Atn;
 
-use Antlr\Antlr4\Runtime\Utils\Set;
+use Antlr\Antlr4\Runtime\Comparison\Equivalence;
+use Antlr\Antlr4\Runtime\Comparison\Hashable;
 
 final class OrderedATNConfigSet extends ATNConfigSet
 {
@@ -12,6 +13,35 @@ public function __construct()
     {
         parent::__construct();
 
-        $this->configLookup = new Set();
+        $this->configLookup = new ConfigHashSet(new class implements Equivalence {
+            public function equivalent(Hashable $left, Hashable $right): bool
+            {
+                if ($left === $right) {
+                    return true;
+                }
+
+                /** @phpstan-ignore-next-line */
+                if ($left === null) {
+                    return false;
+                }
+
+                /** @phpstan-ignore-next-line */
+                if ($right === null) {
+                    return false;
+                }
+
+                return $left->equals($right);
+            }
+
+            public function hash(Hashable $value): int
+            {
+                return $value->hashCode();
+            }
+
+            public function equals(object $other): bool
+            {
+                return $other instanceof self;
+            }
+        });
     }
 }
diff --git a/src/Atn/States/ATNState.php b/src/Atn/States/ATNState.php
index 8a9d51e..3261754 100644
--- a/src/Atn/States/ATNState.php
+++ b/src/Atn/States/ATNState.php
@@ -152,7 +152,7 @@ public function __toString(): string
 
     public function hashCode(): int
     {
-        return $this->getStateType();
+        return $this->stateNumber;
     }
 
     abstract public function getStateType(): int;
diff --git a/src/ParserTraceListener.php b/src/ParserTraceListener.php
index d194b11..4e2e24c 100644
--- a/src/ParserTraceListener.php
+++ b/src/ParserTraceListener.php
@@ -27,6 +27,7 @@ public function enterEveryRule(ParserRuleContext $context): void
             $this->parser->getRuleNames()[$context->getRuleIndex()],
             $token === null? '' : $token->getText() ?? '',
         );
+        echo \PHP_EOL;
     }
 
     public function visitTerminal(TerminalNode $node): void
@@ -36,6 +37,7 @@ public function visitTerminal(TerminalNode $node): void
             $node->getSymbol(),
             $this->parser->getCurrentRuleName(),
         );
+        echo \PHP_EOL;
     }
 
     public function exitEveryRule(ParserRuleContext $context): void
@@ -48,6 +50,7 @@ public function exitEveryRule(ParserRuleContext $context): void
             $this->parser->getRuleNames()[$context->getRuleIndex()],
             $token === null? '' : $token->getText() ?? '',
         );
+        echo \PHP_EOL;
     }
 
     public function visitErrorNode(ErrorNode $node): void
diff --git a/src/PredictionContexts/ArrayPredictionContext.php b/src/PredictionContexts/ArrayPredictionContext.php
index a174752..e96646a 100644
--- a/src/PredictionContexts/ArrayPredictionContext.php
+++ b/src/PredictionContexts/ArrayPredictionContext.php
@@ -86,7 +86,7 @@ public function equals(object $other): bool
             return false;
         }
 
-        if ($this->returnStates === $other->returnStates) {
+        if (!($this->returnStates === $other->returnStates)) {
             return false;
         }
 
diff --git a/src/PredictionContexts/IdentityHashMap.php b/src/PredictionContexts/IdentityHashMap.php
new file mode 100644
index 0000000..e3be649
--- /dev/null
+++ b/src/PredictionContexts/IdentityHashMap.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Antlr\Antlr4\Runtime\PredictionContexts;
+
+use Antlr\Antlr4\Runtime\Comparison\Equivalence;
+use Antlr\Antlr4\Runtime\Comparison\Hashable;
+use Antlr\Antlr4\Runtime\Utils\Map;
+
+/**
+ * @extends Map<PredictionContext,PredictionContext>
+ */
+class IdentityHashMap extends Map
+{
+    public function __construct()
+    {
+        parent::__construct(new class implements Equivalence {
+            public function equivalent(Hashable $left, Hashable $right): bool
+            {
+                if (! $left instanceof PredictionContext) {
+                    return false;
+                }
+
+                if (! $right instanceof PredictionContext) {
+                    return false;
+                }
+
+                return $left === $right;
+            }
+
+            public function hash(Hashable $value): int
+            {
+                if (! $value instanceof PredictionContext) {
+                    return 0;
+                }
+
+                return $value->hashCode();
+            }
+
+            public function equals(object $other): bool
+            {
+                return $other instanceof self;
+            }
+        });
+    }
+}
diff --git a/src/PredictionContexts/PredictionContext.php b/src/PredictionContexts/PredictionContext.php
index 5e2c97c..e19a400 100644
--- a/src/PredictionContexts/PredictionContext.php
+++ b/src/PredictionContexts/PredictionContext.php
@@ -11,6 +11,7 @@
 use Antlr\Antlr4\Runtime\LoggerProvider;
 use Antlr\Antlr4\Runtime\RuleContext;
 use Antlr\Antlr4\Runtime\Utils\DoubleKeyMap;
+use Antlr\Antlr4\Runtime\Utils\Map;
 
 abstract class PredictionContext implements Hashable
 {
@@ -293,6 +294,10 @@ public static function mergeSingletons(
                 $payloads[0] = $b->returnState;
                 $payloads[1] = $a->returnState;
                 $parents = [$b->parent, $a->parent];
+            } else {
+                $payloads[0] = $a->returnState;
+                $payloads[1] = $b->returnState;
+                $parents = [$a->parent, $b->parent];
             }
 
             $a_ = new ArrayPredictionContext($parents, $payloads);
@@ -421,12 +426,22 @@ public static function mergeArrays(
         }
 
         // merge sorted payloads a + b => M
+        /** @var int $i */
         $i = 0;// walks a
+        /** @var int $j */
         $j = 0;// walks b
+        /** @var int $k */
         $k = 0;// walks target M array
 
+        /** @var array<int> $mergedReturnStates */
         $mergedReturnStates = [];
+        for ($ini = 0; $ini < \count($a->returnStates) + \count($b->returnStates); $ini++) {
+                $mergedReturnStates[$ini] = 0;
+        }
         $mergedParents = [];
+        for ($ini = 0; $ini < \count($a->returnStates) + \count($b->returnStates); $ini++) {
+                $mergedParents[$ini] = null;
+        }
 
         // walk and merge to yield mergedParents, mergedReturnStates
         while ($i < \count($a->returnStates) && $j < \count($b->returnStates)) {
@@ -476,13 +491,17 @@ public static function mergeArrays(
 
         // copy over any payloads remaining in either array
         if ($i < \count($a->returnStates)) {
-            for ($p = $i, $count = \count($a->returnStates); $p < $count; $p++) {
+            /** @var int $p */
+            $p = $i;
+            for (; $p < \count($a->returnStates); $p++) {
                 $mergedParents[$k] = $a->parents[$p];
                 $mergedReturnStates[$k] = $a->returnStates[$p];
                 $k++;
             }
         } else {
-            for ($p = $j, $count = \count($b->returnStates); $p < $count; $p++) {
+            /** @var int $p */
+            $p = $j;
+            for (; $p < \count($b->returnStates); $p++) {
                 $mergedParents[$k] = $b->parents[$p];
                 $mergedReturnStates[$k] = $b->returnStates[$p];
                 $k++;
@@ -503,17 +522,17 @@ public static function mergeArrays(
                 return $a_;
             }
 
+            // mergedParents = Arrays.CopyOf(mergedParents, k);
             $mergedParents = \array_slice($mergedParents, 0, $k);
+            // mergedReturnStates = Arrays.CopyOf(mergedReturnStates, k);
             $mergedReturnStates = \array_slice($mergedReturnStates, 0, $k);
         }
 
-        self::combineCommonParents($mergedParents);
-
         $M = new ArrayPredictionContext($mergedParents, $mergedReturnStates);
 
         // if we created same array as a or b, return that instead
         // TODO: track whether this is possible above during merge sort for speed
-        if ($M === $a) {
+        if ($M->equals($a)) {
             if ($mergeCache !== null) {
                 $mergeCache->set($a, $b, $a);
             }
@@ -529,7 +548,7 @@ public static function mergeArrays(
             return $a;
         }
 
-        if ($M === $b) {
+        if ($M->equals($b)) {
             if ($mergeCache !== null) {
                 $mergeCache->set($a, $b, $b);
             }
@@ -545,53 +564,57 @@ public static function mergeArrays(
             return $b;
         }
 
-        if ($mergeCache !== null) {
-            $mergeCache->set($a, $b, $M);
-        }
+        self::combineCommonParents($mergedParents);
 
         if (ParserATNSimulator::$traceAtnSimulation) {
             LoggerProvider::getLogger()
-                ->debug('mergeArrays a={a},b={b} -> M', [
+                ->debug('mergeArrays a={a},b={b} -> {M}', [
                     'a' => $a->__toString(),
                     'b' => $b->__toString(),
                     'M' => $M->__toString(),
                 ]);
         }
 
+        if ($mergeCache !== null) {
+            $mergeCache->set($a, $b, $M);
+        }
+
         return $M;
     }
 
     /**
-     * @param array<PredictionContext> $parents
+     * @param array<PredictionContext|null> $parents
      */
     protected static function combineCommonParents(array &$parents): void
     {
-        $uniqueParents = new \SplObjectStorage();
+        /** @var Map<PredictionContext, PredictionContext> $uniqueParents */
+        $uniqueParents = new Map();
 
+        /** @var PredictionContext|null $parent */
         foreach ($parents as $parent) {
-            if (!$uniqueParents->contains($parent)) {
-                $uniqueParents[$parent] = $parent;
+            if ($parent !== null && !$uniqueParents->contains($parent)) {
+                // don't replace.
+                $uniqueParents->put($parent, $parent);
             }
         }
 
         foreach ($parents as $i => $parent) {
-            $parents[$i] = $uniqueParents[$parent];
+            if ($parent !== null) {
+                $parents[$i] = $uniqueParents->get($parent);
+            }
         }
     }
 
-    /**
-     * @param array<PredictionContext|null> $visited
-     */
     public static function getCachedPredictionContext(
         PredictionContext $context,
         PredictionContextCache $contextCache,
-        array &$visited,
+        IdentityHashMap &$visited,
     ): self {
         if ($context->isEmpty()) {
             return $context;
         }
 
-        $existing = $visited[\spl_object_id($context)] ?? null;
+        $existing = $visited->get($context);
 
         if ($existing !== null) {
             return $existing;
@@ -600,7 +623,7 @@ public static function getCachedPredictionContext(
         $existing = $contextCache->get($context);
 
         if ($existing !== null) {
-            $visited[\spl_object_id($context)] = $existing;
+            $visited->put($context, $existing);
 
             return $existing;
         }
@@ -634,7 +657,7 @@ public static function getCachedPredictionContext(
         if (!$changed) {
             $contextCache->add($context);
 
-            $visited[\spl_object_id($context)] = $context;
+            $visited->put($context, $context);
 
             return $context;
         }
@@ -654,8 +677,8 @@ public static function getCachedPredictionContext(
         }
 
         $contextCache->add($updated);
-        $visited[\spl_object_id($updated)] = $updated;
-        $visited[\spl_object_id($context)] = $updated;
+        $visited->put($updated, $updated);
+        $visited->put($context, $updated);
 
         return $updated;
     }
diff --git a/src/Utils/Map.php b/src/Utils/Map.php
index 5bab247..f89afec 100644
--- a/src/Utils/Map.php
+++ b/src/Utils/Map.php
@@ -13,7 +13,7 @@
  * @template K of Hashable
  * @template V
  */
-final class Map implements Equatable, \Countable, \IteratorAggregate
+class Map implements Equatable, \Countable, \IteratorAggregate
 {
     /** @var array<int, array<array{K, V}>> */
     private array $table = [];
@@ -28,6 +28,11 @@ public function __construct(?Equivalence $equivalence = null)
         $this->equivalence = $equivalence ?? new DefaultEquivalence();
     }
 
+    public function isEmpty(): bool
+    {
+        return $this->count() === 0;
+    }
+
     public function count(): int
     {
         return $this->size;
@@ -132,34 +137,7 @@ public function remove(Hashable $key): void
 
     public function equals(object $other): bool
     {
-        if ($this === $other) {
-            return true;
-        }
-
-        if (!$other instanceof self
-            || $this->size !== $other->size
-            || !$this->equivalence->equals($other->equivalence)) {
-            return false;
-        }
-
-        foreach ($this->table as $hash => $bucket) {
-            if (!isset($other->table[$hash]) || \count($bucket) !== \count($other->table[$hash])) {
-                return false;
-            }
-
-            $otherBucket = $other->table[$hash];
-
-            foreach ($bucket as $index => [$key, $value]) {
-                [$otherKey, $otherValue] = $otherBucket[$index];
-
-                if (!$this->equivalence->equivalent($key, $otherKey)
-                    || !self::isEqual($value, $otherValue)) {
-                    return false;
-                }
-            }
-        }
-
-        return true;
+        return false;
     }
 
     /**
@@ -212,4 +190,27 @@ private static function isEqual(mixed $left, mixed $right): bool
 
         return $left === $right;
     }
+
+    /**
+     * @param K $key
+     * @param V $value
+     */
+    public function tryGetValue(Hashable $key, mixed &$value): bool
+    {
+        $hash = $this->equivalence->hash($key);
+
+        if (!isset($this->table[$hash])) {
+            $this->table[$hash] = [];
+        }
+
+        foreach ($this->table[$hash] as $index => [$entryKey, $entryValue]) {
+            if ($this->equivalence->equivalent($key, $entryKey)) {
+                $value = $entryValue;
+
+                return true;
+            }
+        }
+
+        return false;
+    }
 }