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    <h3>Editing: UseStatementPass.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

/*
 * This file is part of Psy Shell.
 *
 * (c) 2012-2023 Justin Hileman
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Psy\CodeCleaner;

use PhpParser\Node;
use PhpParser\Node\Name;
use PhpParser\Node\Name\FullyQualified as FullyQualifiedName;
use PhpParser\Node\Stmt\GroupUse;
use PhpParser\Node\Stmt\Namespace_;
use PhpParser\Node\Stmt\Use_;
use PhpParser\Node\Stmt\UseItem;
use PhpParser\Node\Stmt\UseUse;
use PhpParser\NodeTraverser;

/**
 * Provide implicit use statements for subsequent execution.
 *
 * The use statement pass remembers the last use statement line encountered:
 *
 *     use Foo\Bar as Baz;
 *
 * ... which it then applies implicitly to all future evaluated code, until the
 * current namespace is replaced by another namespace.
 */
class UseStatementPass extends CodeCleanerPass
{
    private $aliases = [];
    private $lastAliases = [];
    private $lastNamespace = null;

    /**
     * Re-load the last set of use statements on re-entering a namespace.
     *
     * This isn't how namespaces normally work, but because PsySH has to spin
     * up a new namespace for every line of code, we do this to make things
     * work like you'd expect.
     *
     * @param Node $node
     *
     * @return int|Node|null Replacement node (or special return value)
     */
    public function enterNode(Node $node)
    {
        if ($node instanceof Namespace_) {
            // If this is the same namespace as last namespace, let's do ourselves
            // a favor and reload all the aliases...
            if (\strtolower($node-&gt;name ?: '') === \strtolower($this-&gt;lastNamespace ?: '')) {
                $this-&gt;aliases = $this-&gt;lastAliases;
            }
        }
    }

    /**
     * If this statement is a namespace, forget all the aliases we had.
     *
     * If it's a use statement, remember the alias for later. Otherwise, apply
     * remembered aliases to the code.
     *
     * @param Node $node
     *
     * @return int|Node|Node[]|null Replacement node (or special return value)
     */
    public function leaveNode(Node $node)
    {
        // Store a reference to every &quot;use&quot; statement, because we'll need them in a bit.
        if ($node instanceof Use_) {
            foreach ($node-&gt;uses as $useItem) {
                $this-&gt;aliases[\strtolower($useItem-&gt;getAlias())] = $useItem-&gt;name;
            }

            // @todo Rename to Node_Visitor::REMOVE_NODE once we drop support for PHP-Parser 4.x
            return NodeTraverser::REMOVE_NODE;
        }

        // Expand every &quot;use&quot; statement in the group into a full, standalone &quot;use&quot; and store 'em with the others.
        if ($node instanceof GroupUse) {
            foreach ($node-&gt;uses as $useItem) {
                $this-&gt;aliases[\strtolower($useItem-&gt;getAlias())] = Name::concat($node-&gt;prefix, $useItem-&gt;name, [
                    'startLine' =&gt; $node-&gt;prefix-&gt;getAttribute('startLine'),
                    'endLine'   =&gt; $useItem-&gt;name-&gt;getAttribute('endLine'),
                ]);
            }

            // @todo Rename to Node_Visitor::REMOVE_NODE once we drop support for PHP-Parser 4.x
            return NodeTraverser::REMOVE_NODE;
        }

        // Start fresh, since we're done with this namespace.
        if ($node instanceof Namespace_) {
            $this-&gt;lastNamespace = $node-&gt;name;
            $this-&gt;lastAliases = $this-&gt;aliases;
            $this-&gt;aliases = [];

            return;
        }

        // Do nothing with UseItem; this an entry in the list of uses in the use statement.
        // @todo Remove UseUse once we drop support for PHP-Parser 4.x
        if ($node instanceof UseUse || $node instanceof UseItem) {
            return;
        }

        // For everything else, we'll implicitly thunk all aliases into fully-qualified names.
        foreach ($node as $name =&gt; $subNode) {
            if ($subNode instanceof Name) {
                if ($replacement = $this-&gt;findAlias($subNode)) {
                    $node-&gt;$name = $replacement;
                }
            }
        }

        return $node;
    }

    /**
     * Find class/namespace aliases.
     *
     * @param Name $name
     *
     * @return FullyQualifiedName|null
     */
    private function findAlias(Name $name)
    {
        $that = \strtolower($name);
        foreach ($this-&gt;aliases as $alias =&gt; $prefix) {
            if ($that === $alias) {
                return new FullyQualifiedName($prefix-&gt;toString());
            } elseif (\substr($that, 0, \strlen($alias) + 1) === $alias.'\\') {
                return new FullyQualifiedName($prefix-&gt;toString().\substr($name, \strlen($alias)));
            }
        }
    }
}
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