From b5fb64a6bf6896e75cf2c77dcfc8ccfe7986851b Mon Sep 17 00:00:00 2001
From: John Koster <john@stillat.com>
Date: Sat, 8 Feb 2025 15:04:08 -0600
Subject: [PATCH] Improves compilation of custom functions declared within a
 component's template

---
 CHANGELOG.md                                  |  4 ++
 src/Compiler/ComponentCompiler.php            |  2 +
 .../ComponentStages/RewriteFunctions.php      | 27 +++++++
 src/Parser/Visitors/FindFunctionsVisitor.php  | 25 +++++++
 src/Parser/Visitors/RenameFunctionVisitor.php | 70 +++++++++++++++++++
 tests/Compiler/CustomFunctionsTest.php        | 22 ++++++
 .../components/functions/declared.blade.php   |  9 +++
 7 files changed, 159 insertions(+)
 create mode 100644 src/Compiler/ComponentStages/RewriteFunctions.php
 create mode 100644 src/Parser/Visitors/FindFunctionsVisitor.php
 create mode 100644 src/Parser/Visitors/RenameFunctionVisitor.php
 create mode 100644 tests/Compiler/CustomFunctionsTest.php
 create mode 100644 tests/resources/components/functions/declared.blade.php

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 09b2e4a..6116e4d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- Improves compilation of custom functions declared within a component's template
+
 ## [v1.0.6](https://github.com/Stillat/dagger/compare/v1.0.5...v1.0.6) - 2025-01-31
 
 - Corrects an issue where Blade stack compilation results in array index errors
diff --git a/src/Compiler/ComponentCompiler.php b/src/Compiler/ComponentCompiler.php
index 5417ff8..e19e984 100644
--- a/src/Compiler/ComponentCompiler.php
+++ b/src/Compiler/ComponentCompiler.php
@@ -8,6 +8,7 @@
 use Stillat\Dagger\Compiler\ComponentStages\ExtractsRenderCalls;
 use Stillat\Dagger\Compiler\ComponentStages\RemoveUseStatements;
 use Stillat\Dagger\Compiler\ComponentStages\ResolveNamespaces;
+use Stillat\Dagger\Compiler\ComponentStages\RewriteFunctions;
 use Stillat\Dagger\Compiler\Concerns\CompilesPhp;
 use Stillat\Dagger\Parser\PhpParser;
 
@@ -42,6 +43,7 @@ public function compile(string $component): string
                 ResolveNamespaces::class,
                 RemoveUseStatements::class,
                 new ExtractsRenderCalls($this),
+                RewriteFunctions::class,
             ])
             ->thenReturn();
 
diff --git a/src/Compiler/ComponentStages/RewriteFunctions.php b/src/Compiler/ComponentStages/RewriteFunctions.php
new file mode 100644
index 0000000..a168e38
--- /dev/null
+++ b/src/Compiler/ComponentStages/RewriteFunctions.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Stillat\Dagger\Compiler\ComponentStages;
+
+use Closure;
+use PhpParser\NodeTraverser;
+use Stillat\Dagger\Parser\Visitors\FindFunctionsVisitor;
+use Stillat\Dagger\Parser\Visitors\RenameFunctionVisitor;
+
+class RewriteFunctions extends AbstractStage
+{
+    public function handle($ast, Closure $next)
+    {
+        $traverser = new NodeTraverser;
+
+        $finder = new FindFunctionsVisitor;
+        $traverser->addVisitor($finder);
+        $traverser->traverse($ast);
+
+        $traverser->removeVisitor($finder);
+
+        $modifyFunctionsVisitor = new RenameFunctionVisitor($finder->getFunctionNames());
+        $traverser->addVisitor($modifyFunctionsVisitor);
+
+        return $next($traverser->traverse($ast));
+    }
+}
diff --git a/src/Parser/Visitors/FindFunctionsVisitor.php b/src/Parser/Visitors/FindFunctionsVisitor.php
new file mode 100644
index 0000000..65ac01b
--- /dev/null
+++ b/src/Parser/Visitors/FindFunctionsVisitor.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace Stillat\Dagger\Parser\Visitors;
+
+use PhpParser\Node;
+use PhpParser\NodeVisitorAbstract;
+
+class FindFunctionsVisitor extends NodeVisitorAbstract
+{
+    protected array $functionNames = [];
+
+    public function enterNode(Node $node)
+    {
+        if (! $node instanceof Node\Stmt\Function_) {
+            return;
+        }
+
+        $this->functionNames[] = $node->name->toString();
+    }
+
+    public function getFunctionNames(): array
+    {
+        return $this->functionNames;
+    }
+}
diff --git a/src/Parser/Visitors/RenameFunctionVisitor.php b/src/Parser/Visitors/RenameFunctionVisitor.php
new file mode 100644
index 0000000..de494af
--- /dev/null
+++ b/src/Parser/Visitors/RenameFunctionVisitor.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Stillat\Dagger\Parser\Visitors;
+
+use PhpParser\Node;
+use PhpParser\NodeVisitorAbstract;
+use Stillat\Dagger\Support\Utils;
+
+class RenameFunctionVisitor extends NodeVisitorAbstract
+{
+    protected array $functionNames = [];
+
+    public function __construct(array $functionNames)
+    {
+        $this->functionNames = $this->buildFunctionNameMap($functionNames);
+    }
+
+    protected function buildFunctionNameMap(array $functionNames): array
+    {
+        return collect($functionNames)
+            ->mapWithKeys(function ($name) {
+                return [$name => $name.'_'.Utils::makeRandomString()];
+            })
+            ->all();
+    }
+
+    public function enterNode(Node $node)
+    {
+        if (! $node instanceof Node\Expr\FuncCall || ! $node->name instanceof Node\Name) {
+            return;
+        }
+
+        $functionName = $node->name->toString();
+
+        if (! isset($this->functionNames[$functionName])) {
+            return;
+        }
+
+        $node->name = new Node\Name($this->functionNames[$functionName]);
+    }
+
+    public function leaveNode(Node $node)
+    {
+        if (! $node instanceof Node\Stmt\Function_) {
+            return null;
+        }
+
+        $functionName = $node->name->toString();
+
+        if (! isset($this->functionNames[$functionName])) {
+            return null;
+        }
+
+        $newFunctionName = $this->functionNames[$functionName];
+
+        $node->name = new Node\Identifier($newFunctionName);
+
+        return new Node\Stmt\If_(
+            new Node\Expr\BooleanNot(
+                new Node\Expr\FuncCall(
+                    new Node\Name('function_exists'),
+                    [new Node\Arg(new Node\Scalar\String_($newFunctionName))]
+                )
+            ),
+            [
+                'stmts' => [$node],
+            ]
+        );
+    }
+}
diff --git a/tests/Compiler/CustomFunctionsTest.php b/tests/Compiler/CustomFunctionsTest.php
new file mode 100644
index 0000000..6bbf743
--- /dev/null
+++ b/tests/Compiler/CustomFunctionsTest.php
@@ -0,0 +1,22 @@
+<?php
+
+use Stillat\Dagger\Tests\CompilerTestCase;
+
+uses(CompilerTestCase::class);
+
+test('custom functions in a component are compiled', function () {
+    $template = <<<'BLADE'
+@for ($i = 0; $i < 5; $i++)
+<c-functions.declared title="The Title: {{ $i }}" />
+@endfor
+BLADE;
+
+    $expected = <<<'EXPECTED'
+THE TITLE: 0THE TITLE: 1THE TITLE: 2THE TITLE: 3THE TITLE: 4
+EXPECTED;
+
+    $this->assertSame(
+        $expected,
+        $this->render($template)
+    );
+});
diff --git a/tests/resources/components/functions/declared.blade.php b/tests/resources/components/functions/declared.blade.php
new file mode 100644
index 0000000..1935017
--- /dev/null
+++ b/tests/resources/components/functions/declared.blade.php
@@ -0,0 +1,9 @@
+<?php
+\Stillat\Dagger\component()->props(['title'])->trimOutput();
+
+function toUpper($value) {
+  return mb_strtoupper($value);
+}
+?>
+
+{{ toUpper($title) }}