Cache Joins/Table rendering, match dot-qualified identifiers in ON tokenizer

- JoinSpec regex now captures dot-qualified identifiers as single tokens
  (film.film_id → 1 Identifier instead of 3 tokens)
- Joins::toSql caches full result when parameterContainer is null,
  tracked by platform identity via spl_object_id
- Table::prepare short-circuits on repeated renders for the same platform
- renderIdentifierFragment uses instanceof instead of getType() dispatch

Signed-off-by: Simon Mundy <simon.mundy@peptolab.com>

Author: simon-mundy

src/Sql/Part/JoinSpec.php

@@ -31,7 +31,7 @@
  */
 final readonly class JoinSpec
 {
-    private const IDENTIFIER_PATTERN = '/\b(?!(?:AS|AND|OR|BETWEEN)\b)([a-zA-Z_]\w*+)(?!\s*\()/i';
+    private const IDENTIFIER_PATTERN = '/\b(?!(?:AS|AND|OR|BETWEEN)\b)([a-zA-Z_]\w*+(?:\.[a-zA-Z_]\w*+)*)(?!\s*\()/i';
 
     public string|TableIdentifier|Select|ExpressionInterface $table;
     public JoinTableType $tableType;

src/Sql/Part/Joins.php

@@ -11,6 +11,7 @@
 
 use function count;
 use function implode;
+use function spl_object_id;
 
 /**
  * Wraps a Join model and renders all JOIN clauses.
@@ -26,12 +27,23 @@ class Joins extends AbstractPart
     /** @var JoinSpec[] Normalized join specifications, built at join() time */
     private array $specs = [];
 
+    private ?string $sqlCache = null;
+    private ?int $sqlCachePlatformId = null;
+
     public function toSql(SqlProcessor $processor): ?string
     {
         if ($this->specs === []) {
             return null;
         }
 
+        $canCache = $processor->parameterContainer === null;
+        if ($canCache) {
+            $platformId = spl_object_id($processor->platform);
+            if ($this->sqlCachePlatformId === $platformId) {
+                return $this->sqlCache;
+            }
+        }
+
         $joinSqlParts = [];
 
         foreach ($this->specs as $j => $spec) {
@@ -59,7 +71,14 @@ public function toSql(SqlProcessor $processor): ?string
             $joinSqlParts[] = "{$spec->type} JOIN {$renderedTable} ON {$onClause}";
         }
 
-        return implode(' ', $joinSqlParts);
+        $result = implode(' ', $joinSqlParts);
+
+        if ($canCache) {
+            $this->sqlCache = $result;
+            $this->sqlCachePlatformId = $platformId;
+        }
+
+        return $result;
     }
 
     public function isEmpty(): bool
@@ -88,13 +107,16 @@ public function join(
         // Normalize eagerly — the last join added is the one we just created
         $rawJoins      = $this->model->getJoins();
         $this->specs[] = new JoinSpec($rawJoins[count($rawJoins) - 1]);
+        $this->sqlCache = null;
         return $this;
     }
 
     public function reset(): static
     {
         $this->model = null;
         $this->specs = [];
+        $this->sqlCache = null;
+        $this->sqlCachePlatformId = null;
         return $this;
     }
 
@@ -103,5 +125,7 @@ public function __clone()
         if ($this->model !== null) {
             $this->model = clone $this->model;
         }
+        $this->sqlCache = null;
+        $this->sqlCachePlatformId = null;
     }
 }

src/Sql/Part/SqlProcessor.php

@@ -195,7 +195,7 @@ public function renderIdentifierFragment(array $tokens): string
     {
         $sql = '';
         foreach ($tokens as $token) {
-            $sql .= $token->getType() === ArgumentType::Identifier
+            $sql .= $token instanceof Identifier
                 ? $this->renderIdentifierArgument($token)
                 : $token->getValue();
         }

src/Sql/Part/Table.php

@@ -9,6 +9,8 @@
 use PhpDb\Sql\Select;
 use PhpDb\Sql\TableIdentifier;
 
+use function spl_object_id;
+
 /**
  * Unified container for FROM, Columns, and Joins.
  *
@@ -21,6 +23,7 @@ class Table
     private From $from;
     private Columns $columns;
     private ?Joins $joins = null;
+    private ?int $preparedPlatformId = null;
 
     /** Backward-compat model exposed via getRawState / __get */
     public ?Join $joinModel = null;
@@ -36,6 +39,7 @@ public function __construct()
     public function setFrom(string|array|TableIdentifier|Select|null $table): static
     {
         $this->from->set($table);
+        $this->preparedPlatformId = null;
         return $this;
     }
 
@@ -52,6 +56,7 @@ public function hasFrom(): bool
     public function resetFrom(): static
     {
         $this->from->set(null);
+        $this->preparedPlatformId = null;
         return $this;
     }
 
@@ -71,6 +76,7 @@ public function getColumns(): array
     public function setPrefixColumnsWithTable(bool $prefix): static
     {
         $this->columns->setPrefixColumnsWithTable($prefix);
+        $this->preparedPlatformId = null;
         return $this;
     }
 
@@ -94,6 +100,7 @@ public function join(
         string $type = Join::JOIN_INNER,
     ): static {
         ($this->joins ??= new Joins())->join($name, $on, $columns, $type);
+        $this->preparedPlatformId = null;
         return $this;
     }
 
@@ -105,19 +112,26 @@ public function hasJoins(): bool
     public function resetJoins(): static
     {
         $this->joins = null;
+        $this->preparedPlatformId = null;
         return $this;
     }
 
     // --- Prepare (wire parts before render) ---
 
     public function prepare(SqlProcessor $processor): void
     {
+        $platformId = spl_object_id($processor->platform);
+        if ($this->preparedPlatformId === $platformId) {
+            return;
+        }
+
         if ($this->columns->getPrefixColumnsWithTable() && !$this->from->isEmpty()) {
             $this->columns->setFromTablePrefix($this->from->getQuotedPrefix($processor));
         } else {
             $this->columns->setFromTablePrefix('');
         }
         $this->columns->setJoinSpecs($this->joins !== null ? $this->joins->getSpecs() : []);
+        $this->preparedPlatformId = $platformId;
     }
 
     // --- PartInterface accessors ---
@@ -146,5 +160,6 @@ public function __clone()
         if ($this->joins !== null) {
             $this->joins = clone $this->joins;
         }
+        $this->preparedPlatformId = null;
     }
 }