Fix the order of clauses in SELECT statements involing UNIONs.

Author: udan11

src/Parser.php

@@ -151,7 +151,7 @@ class Parser
         'FROM'                  => array(
             'class'             => 'SqlParser\\Components\\ExpressionArray',
             'field'             => 'from',
-            'options'           => array('skipColumn' => true),
+            'options'           => array('skipColumn' => true, 'noBrackets' => true),
         ),
         'GROUP BY'              => array(
             'class'             => 'SqlParser\\Components\\OrderKeyword',
@@ -297,6 +297,13 @@ class Parser
      */
     public $statements = array();
 
+    /**
+     * The number of opened brackets.
+     *
+     * @var int
+     */
+    public $brackets = 0;
+
     /**
      * Constructor.
      *
@@ -381,6 +388,12 @@ public function parse()
                 continue;
             }
 
+            // Counting the brackets around statements.
+            if ($token->value === '(') {
+                ++$this->brackets;
+                continue;
+            }
+
             // Statements can start with keywords only.
             // Comments, whitespaces, etc. are ignored.
             if ($token->type !== Token::TYPE_KEYWORD) {

src/Statement.php

@@ -122,7 +122,14 @@ public function build()
          */
         $built = array();
 
-        foreach (static::$CLAUSES as $clause) {
+        /**
+         * Statement's clauses.
+         *
+         * @var array
+         */
+        $clauses = $this->getClauses();
+
+        foreach ($clauses as $clause) {
             /**
              * The name of the clause.
              *
@@ -224,6 +231,13 @@ public function parse(Parser $parser, TokensList $list)
                 break;
             }
 
+            // Checking if this closing bracket is the pair for a bracket
+            // outside the statement.
+            if (($token->value === ')') && ($parser->brackets > 0)) {
+                --$parser->brackets;
+                continue;
+            }
+
             // Only keywords are relevant here. Other parts of the query are
             // processed in the functions below.
             if ($token->type !== Token::TYPE_KEYWORD) {
@@ -363,6 +377,16 @@ public function after(Parser $parser, TokensList $list, Token $token)
 
     }
 
+    /**
+     * Gets the clauses of this statement.
+     *
+     * @return array
+     */
+    public function getClauses()
+    {
+        return static::$CLAUSES;
+    }
+
     /**
      * Builds the string representation of this statement.
      *

src/Statements/SelectStatement.php

@@ -195,4 +195,25 @@ class SelectStatement extends Statement
      * @var SelectStatement[]
      */
     public $union = array();
+
+    /**
+     * Gets the clauses of this statement.
+     *
+     * @return array
+     */
+    public function getClauses()
+    {
+        // This is a cheap fix for `SELECT` statements that contain `UNION`.
+        // The `ORDER BY` and `LIMIT` clauses should be at the end of the
+        // statement.
+        if (!empty($this->union)) {
+            $clauses = static::$CLAUSES;
+            unset($clauses['ORDER BY']);
+            unset($clauses['LIMIT']);
+            $clauses['ORDER BY'] = array('ORDER BY', 3);
+            $clauses['LIMIT'] = array('LIMIT', 3);
+            return $clauses;
+        }
+        return static::$CLAUSES;
+    }
 }

src/Utils/Query.php

@@ -546,15 +546,7 @@ public static function getClause($statement, $list, $clause, $type = 0, $skipFir
          *
          * @var array $clauses
          */
-        $clauses = array_flip(array_keys($statement::$CLAUSES));
-
-        // This is a cheap fix for `SELECT` statements that contain `UNION`.
-        // Replacing the `ORDER BY` or `LIMIT` clauses should replace the last
-        // clause.
-        if (($statement instanceof SelectStatement) && (!empty($statement->union))) {
-            $clauses['ORDER BY'] = count($clauses) + 1;
-            $clauses['LIMIT'] = count($clauses) + 2;
-        }
+        $clauses = array_flip(array_keys($statement->getClauses()));
 
         /**
          * Lexer used for lexing the clause.