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/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\VarDumper\Cloner;

/**
 * @author Nicolas Grekas &lt;p@tchwork.com&gt;
 */
class VarCloner extends AbstractCloner
{
    private static $gid;
    private static $arrayCache = [];

    /**
     * {@inheritdoc}
     */
    protected function doClone($var)
    {
        $len = 1;                       // Length of $queue
        $pos = 0;                       // Number of cloned items past the minimum depth
        $refsCounter = 0;               // Hard references counter
        $queue = [[$var]];              // This breadth-first queue is the return value
        $hardRefs = [];                 // Map of original zval ids to stub objects
        $objRefs = [];                  // Map of original object handles to their stub object counterpart
        $objects = [];                  // Keep a ref to objects to ensure their handle cannot be reused while cloning
        $resRefs = [];                  // Map of original resource handles to their stub object counterpart
        $values = [];                   // Map of stub objects' ids to original values
        $maxItems = $this-&gt;maxItems;
        $maxString = $this-&gt;maxString;
        $minDepth = $this-&gt;minDepth;
        $currentDepth = 0;              // Current tree depth
        $currentDepthFinalIndex = 0;    // Final $queue index for current tree depth
        $minimumDepthReached = 0 === $minDepth; // Becomes true when minimum tree depth has been reached
        $cookie = (object) [];          // Unique object used to detect hard references
        $a = null;                      // Array cast for nested structures
        $stub = null;                   // Stub capturing the main properties of an original item value
                                        // or null if the original value is used directly

        if (!$gid = self::$gid) {
            $gid = self::$gid = md5(random_bytes(6)); // Unique string used to detect the special $GLOBALS variable
        }
        $arrayStub = new Stub();
        $arrayStub-&gt;type = Stub::TYPE_ARRAY;
        $fromObjCast = false;

        for ($i = 0; $i &lt; $len; ++$i) {
            // Detect when we move on to the next tree depth
            if ($i &gt; $currentDepthFinalIndex) {
                ++$currentDepth;
                $currentDepthFinalIndex = $len - 1;
                if ($currentDepth &gt;= $minDepth) {
                    $minimumDepthReached = true;
                }
            }

            $refs = $vals = $queue[$i];
            foreach ($vals as $k =&gt; $v) {
                // $v is the original value or a stub object in case of hard references

                if (\PHP_VERSION_ID &gt;= 70400) {
                    $zvalRef = ($r = \ReflectionReference::fromArrayElement($vals, $k)) ? $r-&gt;getId() : null;
                } else {
                    $refs[$k] = $cookie;
                    $zvalRef = $vals[$k] === $cookie;
                }

                if ($zvalRef) {
                    $vals[$k] = &amp;$stub;         // Break hard references to make $queue completely
                    unset($stub);               // independent from the original structure
                    if (\PHP_VERSION_ID &gt;= 70400 ? null !== $vals[$k] = $hardRefs[$zvalRef] ?? null : $v instanceof Stub &amp;&amp; isset($hardRefs[spl_object_id($v)])) {
                        if (\PHP_VERSION_ID &gt;= 70400) {
                            $v = $vals[$k];
                        } else {
                            $refs[$k] = $vals[$k] = $v;
                        }
                        if ($v-&gt;value instanceof Stub &amp;&amp; (Stub::TYPE_OBJECT === $v-&gt;value-&gt;type || Stub::TYPE_RESOURCE === $v-&gt;value-&gt;type)) {
                            ++$v-&gt;value-&gt;refCount;
                        }
                        ++$v-&gt;refCount;
                        continue;
                    }
                    $vals[$k] = new Stub();
                    $vals[$k]-&gt;value = $v;
                    $vals[$k]-&gt;handle = ++$refsCounter;

                    if (\PHP_VERSION_ID &gt;= 70400) {
                        $hardRefs[$zvalRef] = $vals[$k];
                    } else {
                        $refs[$k] = $vals[$k];
                        $h = spl_object_id($refs[$k]);
                        $hardRefs[$h] = &amp;$refs[$k];
                        $values[$h] = $v;
                    }
                }
                // Create $stub when the original value $v cannot be used directly
                // If $v is a nested structure, put that structure in array $a
                switch (true) {
                    case null === $v:
                    case \is_bool($v):
                    case \is_int($v):
                    case \is_float($v):
                        continue 2;
                    case \is_string($v):
                        if ('' === $v) {
                            continue 2;
                        }
                        if (!preg_match('//u', $v)) {
                            $stub = new Stub();
                            $stub-&gt;type = Stub::TYPE_STRING;
                            $stub-&gt;class = Stub::STRING_BINARY;
                            if (0 &lt;= $maxString &amp;&amp; 0 &lt; $cut = \strlen($v) - $maxString) {
                                $stub-&gt;cut = $cut;
                                $stub-&gt;value = substr($v, 0, -$cut);
                            } else {
                                $stub-&gt;value = $v;
                            }
                        } elseif (0 &lt;= $maxString &amp;&amp; isset($v[1 + ($maxString &gt;&gt; 2)]) &amp;&amp; 0 &lt; $cut = mb_strlen($v, 'UTF-8') - $maxString) {
                            $stub = new Stub();
                            $stub-&gt;type = Stub::TYPE_STRING;
                            $stub-&gt;class = Stub::STRING_UTF8;
                            $stub-&gt;cut = $cut;
                            $stub-&gt;value = mb_substr($v, 0, $maxString, 'UTF-8');
                        } else {
                            continue 2;
                        }
                        $a = null;
                        break;

                    case \is_array($v):
                        if (!$v) {
                            continue 2;
                        }
                        $stub = $arrayStub;

                        if (\PHP_VERSION_ID &gt;= 80100) {
                            $stub-&gt;class = array_is_list($v) ? Stub::ARRAY_INDEXED : Stub::ARRAY_ASSOC;
                            $a = $v;
                            break;
                        }

                        $stub-&gt;class = Stub::ARRAY_INDEXED;

                        $j = -1;
                        foreach ($v as $gk =&gt; $gv) {
                            if ($gk !== ++$j) {
                                $stub-&gt;class = Stub::ARRAY_ASSOC;
                                $a = $v;
                                $a[$gid] = true;
                                break;
                            }
                        }

                        // Copies of $GLOBALS have very strange behavior,
                        // let's detect them with some black magic
                        if (isset($v[$gid])) {
                            unset($v[$gid]);
                            $a = [];
                            foreach ($v as $gk =&gt; &amp;$gv) {
                                if ($v === $gv &amp;&amp; (\PHP_VERSION_ID &lt; 70400 || !isset($hardRefs[\ReflectionReference::fromArrayElement($v, $gk)-&gt;getId()]))) {
                                    unset($v);
                                    $v = new Stub();
                                    $v-&gt;value = [$v-&gt;cut = \count($gv), Stub::TYPE_ARRAY =&gt; 0];
                                    $v-&gt;handle = -1;
                                    if (\PHP_VERSION_ID &gt;= 70400) {
                                        $gv = &amp;$a[$gk];
                                        $hardRefs[\ReflectionReference::fromArrayElement($a, $gk)-&gt;getId()] = &amp;$gv;
                                    } else {
                                        $gv = &amp;$hardRefs[spl_object_id($v)];
                                    }
                                    $gv = $v;
                                }

                                $a[$gk] = &amp;$gv;
                            }
                            unset($gv);
                        } else {
                            $a = $v;
                        }
                        break;

                    case \is_object($v):
                        if (empty($objRefs[$h = spl_object_id($v)])) {
                            $stub = new Stub();
                            $stub-&gt;type = Stub::TYPE_OBJECT;
                            $stub-&gt;class = \get_class($v);
                            $stub-&gt;value = $v;
                            $stub-&gt;handle = $h;
                            $a = $this-&gt;castObject($stub, 0 &lt; $i);
                            if ($v !== $stub-&gt;value) {
                                if (Stub::TYPE_OBJECT !== $stub-&gt;type || null === $stub-&gt;value) {
                                    break;
                                }
                                $stub-&gt;handle = $h = spl_object_id($stub-&gt;value);
                            }
                            $stub-&gt;value = null;
                            if (0 &lt;= $maxItems &amp;&amp; $maxItems &lt;= $pos &amp;&amp; $minimumDepthReached) {
                                $stub-&gt;cut = \count($a);
                                $a = null;
                            }
                        }
                        if (empty($objRefs[$h])) {
                            $objRefs[$h] = $stub;
                            $objects[] = $v;
                        } else {
                            $stub = $objRefs[$h];
                            ++$stub-&gt;refCount;
                            $a = null;
                        }
                        break;

                    default: // resource
                        if (empty($resRefs[$h = (int) $v])) {
                            $stub = new Stub();
                            $stub-&gt;type = Stub::TYPE_RESOURCE;
                            if ('Unknown' === $stub-&gt;class = @get_resource_type($v)) {
                                $stub-&gt;class = 'Closed';
                            }
                            $stub-&gt;value = $v;
                            $stub-&gt;handle = $h;
                            $a = $this-&gt;castResource($stub, 0 &lt; $i);
                            $stub-&gt;value = null;
                            if (0 &lt;= $maxItems &amp;&amp; $maxItems &lt;= $pos &amp;&amp; $minimumDepthReached) {
                                $stub-&gt;cut = \count($a);
                                $a = null;
                            }
                        }
                        if (empty($resRefs[$h])) {
                            $resRefs[$h] = $stub;
                        } else {
                            $stub = $resRefs[$h];
                            ++$stub-&gt;refCount;
                            $a = null;
                        }
                        break;
                }

                if ($a) {
                    if (!$minimumDepthReached || 0 &gt; $maxItems) {
                        $queue[$len] = $a;
                        $stub-&gt;position = $len++;
                    } elseif ($pos &lt; $maxItems) {
                        if ($maxItems &lt; $pos += \count($a)) {
                            $a = \array_slice($a, 0, $maxItems - $pos, true);
                            if ($stub-&gt;cut &gt;= 0) {
                                $stub-&gt;cut += $pos - $maxItems;
                            }
                        }
                        $queue[$len] = $a;
                        $stub-&gt;position = $len++;
                    } elseif ($stub-&gt;cut &gt;= 0) {
                        $stub-&gt;cut += \count($a);
                        $stub-&gt;position = 0;
                    }
                }

                if ($arrayStub === $stub) {
                    if ($arrayStub-&gt;cut) {
                        $stub = [$arrayStub-&gt;cut, $arrayStub-&gt;class =&gt; $arrayStub-&gt;position];
                        $arrayStub-&gt;cut = 0;
                    } elseif (isset(self::$arrayCache[$arrayStub-&gt;class][$arrayStub-&gt;position])) {
                        $stub = self::$arrayCache[$arrayStub-&gt;class][$arrayStub-&gt;position];
                    } else {
                        self::$arrayCache[$arrayStub-&gt;class][$arrayStub-&gt;position] = $stub = [$arrayStub-&gt;class =&gt; $arrayStub-&gt;position];
                    }
                }

                if (!$zvalRef) {
                    $vals[$k] = $stub;
                } elseif (\PHP_VERSION_ID &gt;= 70400) {
                    $hardRefs[$zvalRef]-&gt;value = $stub;
                } else {
                    $refs[$k]-&gt;value = $stub;
                }
            }

            if ($fromObjCast) {
                $fromObjCast = false;
                $refs = $vals;
                $vals = [];
                $j = -1;
                foreach ($queue[$i] as $k =&gt; $v) {
                    foreach ([$k =&gt; true] as $gk =&gt; $gv) {
                    }
                    if ($gk !== $k) {
                        $vals = (object) $vals;
                        $vals-&gt;{$k} = $refs[++$j];
                        $vals = (array) $vals;
                    } else {
                        $vals[$k] = $refs[++$j];
                    }
                }
            }

            $queue[$i] = $vals;
        }

        foreach ($values as $h =&gt; $v) {
            $hardRefs[$h] = $v;
        }

        return $queue;
    }
}
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