SqlFragment accumulator for buildSqlString, move FROM keyword into From::toSql()

Replace repetitive if-null-append pattern in Select/Update/Delete buildSqlString
with a fluent SqlFragment accumulator. Split From into toSql() (prepends FROM)
and renderTable() (bare table) so each SQL part is self-contained.

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

Author: simon-mundy

src/Sql/Delete.php

@@ -8,6 +8,7 @@
 use PhpDb\Adapter\Driver\DriverInterface;
 use PhpDb\Adapter\ParameterContainer;
 use PhpDb\Adapter\Platform\PlatformInterface;
+use PhpDb\Sql\Part\SqlFragment;
 use PhpDb\Sql\Part\SqlProcessor;
 use PhpDb\Sql\Part\From;
 use PhpDb\Sql\Part\Where as WherePart;
@@ -74,13 +75,9 @@ public function getRawState(?string $key = null): mixed
         return $key !== null && array_key_exists($key, $rawState) ? $rawState[$key] : $rawState;
     }
 
-    /**
-     * Get the statement keyword (e.g. "DELETE FROM").
-     * Override in subclasses for variants like "DELETE IGNORE FROM".
-     */
     protected function getStatementKeyword(): string
     {
-        return 'DELETE FROM';
+        return 'DELETE';
     }
 
     public function buildSqlString(
@@ -92,14 +89,9 @@ public function buildSqlString(
         $processor = new SqlProcessor($platform, $driver, $parameterContainer, $decorator);
         $processor->setParamPrefix($this->processInfo['paramPrefix']);
 
-        // Render inline: DELETE FROM table [WHERE ...]
-        $sql = $this->getStatementKeyword() . ' ' . $this->table->toSql($processor);
-
-        if (($partSql = $this->where?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        return $sql;
+        return (string) SqlFragment::of($this->getStatementKeyword())
+            ->part($this->table->toSql($processor))
+            ->part($this->where?->toSql($processor));
     }
 
     /**

src/Sql/Part/From.php

@@ -19,6 +19,12 @@ class From extends AbstractPart
     private ?string $resolvedTable = null;
 
     public function toSql(SqlProcessor $processor): ?string
+    {
+        $table = $this->renderTable($processor);
+        return $table !== null ? 'FROM ' . $table : null;
+    }
+
+    public function renderTable(SqlProcessor $processor): ?string
     {
         if ($this->ref === null) {
             return null;

src/Sql/Part/SqlFragment.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpDb\Sql\Part;
+
+use function implode;
+
+final class SqlFragment
+{
+    private array $parts = [];
+
+    public static function of(string $keyword): self
+    {
+        $f = new self();
+        $f->parts[] = $keyword;
+        return $f;
+    }
+
+    public function part(?string $part): self
+    {
+        if ($part !== null) {
+            $this->parts[] = $part;
+        }
+        return $this;
+    }
+
+    public function wrap(?string $suffix): self
+    {
+        if ($suffix !== null) {
+            $this->parts = ['( ' . implode(' ', $this->parts) . ' )', $suffix];
+        }
+        return $this;
+    }
+
+    public function __toString(): string
+    {
+        return implode(' ', $this->parts);
+    }
+}

src/Sql/Select.php

@@ -15,6 +15,7 @@
 use PhpDb\Sql\Part\Offset;
 use PhpDb\Sql\Part\OrderBy;
 use PhpDb\Sql\Part\Quantifier;
+use PhpDb\Sql\Part\SqlFragment;
 use PhpDb\Sql\Part\SqlProcessor;
 use PhpDb\Sql\Part\Table;
 use PhpDb\Sql\Part\Where as WherePart;
@@ -381,55 +382,18 @@ public function buildSqlString(
 
         $this->table->prepare($processor);
 
-        $sql = 'SELECT';
-
-        if (($partSql = $this->quantifier?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        $sql .= ' ' . $this->table->columns()->toSql($processor);
-
-        if (($tableSql = $this->table->from()->toSql($processor)) !== null) {
-            $sql .= ' FROM ' . $tableSql;
-        }
-
-        if (($partSql = $this->table->joins()?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        if (($partSql = $this->where?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        if (($partSql = $this->groupBy?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        if (($partSql = $this->having?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        if (($partSql = $this->orderBy?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        if (($partSql = $this->limit?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        if (($partSql = $this->offset?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        if ($this->combine !== null && ! $this->combine->isEmpty()) {
-            $sql     = '( ' . $sql . ' )';
-            $partSql = $this->combine->toSql($processor);
-            if ($partSql !== null) {
-                $sql .= ' ' . $partSql;
-            }
-        }
-
-        return $sql;
+        return (string) SqlFragment::of('SELECT')
+            ->part($this->quantifier?->toSql($processor))
+            ->part($this->table->columns()->toSql($processor))
+            ->part($this->table->from()->toSql($processor))
+            ->part($this->table->joins()?->toSql($processor))
+            ->part($this->where?->toSql($processor))
+            ->part($this->groupBy?->toSql($processor))
+            ->part($this->having?->toSql($processor))
+            ->part($this->orderBy?->toSql($processor))
+            ->part($this->limit?->toSql($processor))
+            ->part($this->offset?->toSql($processor))
+            ->wrap($this->combine?->toSql($processor));
     }
 
     /**

src/Sql/Update.php

@@ -10,6 +10,7 @@
 use PhpDb\Adapter\Platform\PlatformInterface;
 use PhpDb\Sql\Part\Joins as JoinsPart;
 use PhpDb\Sql\Part\Set as SetPart;
+use PhpDb\Sql\Part\SqlFragment;
 use PhpDb\Sql\Part\SqlProcessor;
 use PhpDb\Sql\Part\From;
 use PhpDb\Sql\Part\Where as WherePart;
@@ -134,20 +135,11 @@ public function buildSqlString(
         $processor = new SqlProcessor($platform, $driver, $parameterContainer, $decorator);
         $processor->setParamPrefix($this->processInfo['paramPrefix']);
 
-        // Render inline: UPDATE table [JOINS] SET ... [WHERE ...]
-        $sql = $this->getStatementKeyword() . ' ' . $this->table->toSql($processor);
-
-        if (($partSql = $this->joins?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-        if (($partSql = $this->set->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-        if (($partSql = $this->where?->toSql($processor)) !== null) {
-            $sql .= ' ' . $partSql;
-        }
-
-        return $sql;
+        return (string) SqlFragment::of($this->getStatementKeyword())
+            ->part($this->table->renderTable($processor))
+            ->part($this->joins?->toSql($processor))
+            ->part($this->set->toSql($processor))
+            ->part($this->where?->toSql($processor));
     }
 
     /**

test/unit/TestAsset/DeleteIgnore.php

@@ -10,6 +10,6 @@ class DeleteIgnore extends Delete
 {
     protected function getStatementKeyword(): string
     {
-        return 'DELETE IGNORE FROM';
+        return 'DELETE IGNORE';
     }
 }