Use paths to identify when a rule fails

When nested-structural validation fails, it's challenging to identify
which rule failed from the main exception message. A great example is
the `Issue796Test.php` file. The exception message says:

host must be a string

But you're left unsure whether it's the `host` key from the `mysql` key
or the `postgresql` key.

This commit changes that behaviour by introducing the concept of "Path."
The `path` represents the path that a rule has taken, and we can use it
in structural rules to identify the path of an array or object.

Here's what it looks like before and after:

```diff
-host must be a string
+`.mysql.host` must be a string
```

Because paths are a specific concept, I added a dot (`.`) at the
beginning of all paths when displaying them. I was inspired by the `jq`
syntax. I also added backticks around paths to distinguish them from any
other value.

I didn't manage to fix a test, and I skipped it instead of fixing it
because I want to make changes in how we display error messages as
arrays, and it will be easier to fix it then.

library/Message/Placeholder/Quoted.php

@@ -16,6 +16,11 @@ public function __construct(
     ) {
     }
 
+    public static function fromPath(int|string $path): self
+    {
+        return new self('.' . $path);
+    }
+
     public function getValue(): string
     {
         return $this->value;

library/Message/StandardFormatter.php

@@ -14,6 +14,7 @@
 
 use function array_filter;
 use function array_key_exists;
+use function array_map;
 use function array_reduce;
 use function array_values;
 use function count;
@@ -35,22 +36,22 @@ public function __construct(
     }
 
     /**
-     * @param array<string, mixed> $templates
+     * @param array<string|int, mixed> $templates
      */
     public function main(Result $result, array $templates, Translator $translator): string
     {
         $selectedTemplates = $this->selectTemplates($result, $templates);
         if (!$this->isFinalTemplate($result, $selectedTemplates)) {
             foreach ($this->extractDeduplicatedChildren($result) as $child) {
-                return $this->main($child, $selectedTemplates, $translator);
+                return $this->main($this->resultWithPath($result, $child), $selectedTemplates, $translator);
             }
         }
 
         return $this->renderer->render($this->getTemplated($result, $selectedTemplates), $translator);
     }
 
     /**
-     * @param array<string, mixed> $templates
+     * @param array<string|int, mixed> $templates
      */
     public function full(
         Result $result,
@@ -68,13 +69,19 @@ public function full(
             $rendered .= sprintf(
                 '%s- %s' . PHP_EOL,
                 $indentation,
-                $this->renderer->render($this->getTemplated($result, $selectedTemplates), $translator),
+                $this->renderer->render(
+                    $this->getTemplated($depth > 0 ? $result->withDeepestPath() : $result, $selectedTemplates),
+                    $translator
+                ),
             );
             $depth++;
         }
 
         if (!$isFinalTemplate) {
-            $results = $this->extractDeduplicatedChildren($result);
+            $results = array_map(
+                fn(Result $child) => $this->resultWithPath($result, $child),
+                $this->extractDeduplicatedChildren($result)
+            );
             foreach ($results as $child) {
                 $rendered .= $this->full(
                     $child,
@@ -91,37 +98,44 @@ public function full(
     }
 
     /**
-     * @param array<string, mixed> $templates
+     * @param array<string|int, mixed> $templates
      *
-     * @return array<string, mixed>
+     * @return array<string|int, mixed>
      */
     public function array(Result $result, array $templates, Translator $translator): array
     {
         $selectedTemplates = $this->selectTemplates($result, $templates);
         $deduplicatedChildren = $this->extractDeduplicatedChildren($result);
         if (count($deduplicatedChildren) === 0 || $this->isFinalTemplate($result, $selectedTemplates)) {
             return [
-                $result->id => $this->renderer->render($this->getTemplated($result, $selectedTemplates), $translator),
+                $result->getDeepestPath() ?? $result->id => $this->renderer->render(
+                    $this->getTemplated($result->withDeepestPath(), $selectedTemplates),
+                    $translator
+                ),
             ];
         }
 
         $messages = [];
         foreach ($deduplicatedChildren as $child) {
-            $messages[$child->id] = $this->array(
-                $child,
+            $key = $child->getDeepestPath() ?? $child->id;
+            $messages[$key] = $this->array(
+                $this->resultWithPath($result, $child),
                 $this->selectTemplates($child, $selectedTemplates),
                 $translator
             );
-            if (count($messages[$child->id]) !== 1) {
+            if (count($messages[$key]) !== 1) {
                 continue;
             }
 
-            $messages[$child->id] = current($messages[$child->id]);
+            $messages[$key] = current($messages[$key]);
         }
 
         if (count($messages) > 1) {
             $self = [
-                '__root__' => $this->renderer->render($this->getTemplated($result, $selectedTemplates), $translator),
+                '__root__' => $this->renderer->render(
+                    $this->getTemplated($result->withDeepestPath(), $selectedTemplates),
+                    $translator
+                ),
             ];
 
             return $self + $messages;
@@ -130,6 +144,19 @@ public function array(Result $result, array $templates, Translator $translator):
         return $messages;
     }
 
+    public function resultWithPath(Result $parent, Result $child): Result
+    {
+        if ($parent->path !== null && $child->path !== null && $child->path !== $parent->path) {
+            return $child->withPath($parent->path);
+        }
+
+        if ($parent->path !== null && $child->path === null) {
+            return $child->withPath($parent->path);
+        }
+
+        return $child;
+    }
+
     private function isAlwaysVisible(Result $result, Result ...$siblings): bool
     {
         if ($result->isValid) {
@@ -165,56 +192,66 @@ private function isAlwaysVisible(Result $result, Result ...$siblings): bool
         );
     }
 
-    /** @param array<string, mixed> $templates */
+    /** @param array<string|int, mixed> $templates */
     private function getTemplated(Result $result, array $templates): Result
     {
         if ($result->hasCustomTemplate()) {
             return $result;
         }
 
-        if (!isset($templates[$result->id]) && isset($templates['__root__'])) {
-            return $result->withTemplate($templates['__root__']);
-        }
+        foreach ([$result->path, $result->name, $result->id, '__root__'] as $key) {
+            if (!isset($templates[$key])) {
+                continue;
+            }
 
-        if (!isset($templates[$result->id])) {
-            return $result;
-        }
+            if (is_string($templates[$key])) {
+                return $result->withTemplate($templates[$key]);
+            }
 
-        $template = $templates[$result->id];
-        if (is_string($template)) {
-            return $result->withTemplate($template);
+            throw new ComponentException(
+                sprintf('Template for "%s" must be a string, %s given', $key, stringify($templates[$key]))
+            );
         }
 
-        throw new ComponentException(
-            sprintf('Template for "%s" must be a string, %s given', $result->id, stringify($template))
-        );
+        return $result;
     }
 
     /**
-     * @param array<string, mixed> $templates
+     * @param array<string|int, mixed> $templates
      */
     private function isFinalTemplate(Result $result, array $templates): bool
     {
-        if (isset($templates[$result->id]) && is_string($templates[$result->id])) {
-            return true;
+        $keys = [$result->path, $result->name, $result->id];
+        foreach ($keys as $key) {
+            if (isset($templates[$key]) && is_string($templates[$key])) {
+                return true;
+            }
         }
 
         if (count($templates) !== 1) {
             return false;
         }
 
-        return isset($templates['__root__']) || isset($templates[$result->id]);
+        foreach ($keys as $key) {
+            if (isset($templates[$key])) {
+                return true;
+            }
+        }
+
+        return isset($templates['__root__']);
     }
 
     /**
-     * @param array<string, mixed> $templates
+     * @param array<string|int, mixed> $templates
      *
-     * @return array<string, mixed>
+     * @return array<string|int, mixed>
      */
-    private function selectTemplates(Result $message, array $templates): array
+    private function selectTemplates(Result $result, array $templates): array
     {
-        if (isset($templates[$message->id]) && is_array($templates[$message->id])) {
-            return $templates[$message->id];
+        foreach ([$result->path, $result->name, $result->id] as $key) {
+            if (isset($templates[$key]) && is_array($templates[$key])) {
+                return $templates[$key];
+            }
         }
 
         return $templates;
@@ -227,7 +264,7 @@ private function extractDeduplicatedChildren(Result $result): array
         $deduplicatedResults = [];
         $duplicateCounters = [];
         foreach ($result->children as $child) {
-            $id = $child->id;
+            $id = $child->getDeepestPath() ?? $child->id;
             if (isset($duplicateCounters[$id])) {
                 $id .= '.' . ++$duplicateCounters[$id];
             } elseif (array_key_exists($id, $deduplicatedResults)) {
@@ -236,7 +273,13 @@ private function extractDeduplicatedChildren(Result $result): array
                 $duplicateCounters[$id] = 2;
                 $id .= '.2';
             }
-            $deduplicatedResults[$id] = $child->isValid ? null : $child->withId($id);
+
+            if ($child->path === null) {
+                $deduplicatedResults[$id] = $child->isValid ? null : $child->withId($id);
+                continue;
+            }
+
+            $deduplicatedResults[$id] = $child->isValid ? null : $child;
         }
 
         return array_values(array_filter($deduplicatedResults));

library/Message/StandardRenderer.php

@@ -37,9 +37,12 @@ public function __construct(
     public function render(Result $result, Translator $translator, ?string $template = null): string
     {
         $parameters = $result->parameters;
-        $parameters['name'] ??= $result->name ?? $this->placeholder('input', $result->input, $translator);
+        $parameters['path'] = $result->path !== null ? Quoted::fromPath($result->path) : null;
         $parameters['input'] = $result->input;
 
+        $builtName = $result->name ?? $parameters['path'] ?? $this->placeholder('input', $result->input, $translator);
+        $parameters['name'] ??= $builtName;
+
         $rendered = (string) preg_replace_callback(
             '/{{(\w+)(\|([^}]+))?}}/',
             function (array $matches) use ($parameters, $translator) {

library/Result.php

@@ -10,11 +10,12 @@
 namespace Respect\Validation;
 
 use Respect\Validation\Rules\Core\Nameable;
-use Respect\Validation\Rules\Core\Renameable;
 
 use function array_filter;
 use function array_map;
 use function count;
+use function end;
+use function explode;
 use function lcfirst;
 use function preg_match;
 use function strrchr;
@@ -39,7 +40,7 @@ public function __construct(
         public readonly ?string $name = null,
         ?string $id = null,
         public readonly ?Result $adjacent = null,
-        public readonly bool $unchangeableId = false,
+        public readonly string|int|null $path = null,
         Result ...$children,
     ) {
         $this->id = $id ?? lcfirst(substr((string) strrchr($rule::class, '\\'), 1));
@@ -102,10 +103,6 @@ public function withExtraParameters(array $parameters): self
 
     public function withId(string $id): self
     {
-        if ($this->unchangeableId) {
-            return $this;
-        }
-
         return $this->clone(id: $id);
     }
 
@@ -114,14 +111,44 @@ public function withIdFrom(Rule $rule): self
         return $this->clone(id: lcfirst(substr((string) strrchr($rule::class, '\\'), 1)));
     }
 
-    public function withUnchangeableId(string $id): self
+    public function withPath(string|int $path): self
+    {
+        return $this->clone(
+            adjacent: $this->adjacent?->withPath($path),
+            path: $this->path === null ? $path : $path . '.' . $this->path,
+        );
+    }
+
+    public function withDeepestPath(): self
+    {
+        $path = $this->getDeepestPath();
+        if ($path === null || $path === (string) $this->path) {
+            return $this;
+        }
+
+        return $this->clone(
+            adjacent: $this->adjacent?->withPath($path),
+            path: $path,
+        );
+    }
+
+    public function getDeepestPath(): ?string
     {
-        return $this->clone(id: $id, unchangeableId: true);
+        if ($this->path === null) {
+            return null;
+        }
+
+        $paths = explode('.', (string) $this->path);
+        if (count($paths) === 1) {
+            return (string) $this->path;
+        }
+
+        return end($paths);
     }
 
     public function withPrefix(string $prefix): self
     {
-        if ($this->id === $this->name || $this->unchangeableId) {
+        if ($this->id === $this->name || $this->path !== null) {
             return $this;
         }
 
@@ -136,10 +163,10 @@ public function withChildren(Result ...$children): self
     public function withName(string $name): self
     {
         return $this->clone(
-            name: $this->rule instanceof Renameable ? $name : ($this->name ?? $name),
+            name: $this->name ?? $name,
             adjacent: $this->adjacent?->withName($name),
             children: array_map(
-                static fn (Result $child) => $child->withName($child->name ?? $name),
+                static fn (Result $child) => $child->path === null ? $child->withName($child->name ?? $name) : $child,
                 $this->children
             ),
         );
@@ -223,7 +250,7 @@ private function clone(
         ?string $name = null,
         ?string $id = null,
         ?Result $adjacent = null,
-        ?bool $unchangeableId = null,
+        string|int|null $path = null,
         ?array $children = null
     ): self {
         return new self(
@@ -236,7 +263,7 @@ private function clone(
             $name ?? $this->name,
             $id ?? $this->id,
             $adjacent ?? $this->adjacent,
-            $unchangeableId ?? $this->unchangeableId,
+            $path ?? $this->path,
             ...($children ?? $this->children)
         );
     }