Validate order of clauses in the parsing of statements

Fix #22

Signed-off-by: Deven Bansod <devenbansod.bits@gmail.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/src/Utils/Query.php b/src/Utils/Query.php
index 2e0982a..c3167ff 100644
--- a/src/Utils/Query.php
+++ b/src/Utils/Query.php
@@ -783,4 +783,66 @@ class Query
 
         return array(trim($statement), $query, $delimiter);
     }
+
+    /**
+     * Gets a starting offset of a specific clause.
+     *
+     * @param Statement  $statement The parsed query that has to be modified.
+     * @param TokensList $list      The list of tokens.
+     * @param string     $clause    The clause to be returned.
+     *
+     * @return int
+     */
+    public static function getClauseStartOffset($statement, $list, $clause)
+    {
+
+        /**
+         * The index of the current clause.
+         *
+         * @var int $currIdx
+         */
+        $currIdx = 0;
+
+        /**
+         * The count of brackets.
+         * We keep track of them so we won't insert the clause in a subquery.
+         *
+         * @var int $brackets
+         */
+        $brackets = 0;
+
+        /**
+         * The clauses of this type of statement and their index.
+         *
+         * @var array $clauses
+         */
+        $clauses = array_flip(array_keys($statement->getClauses()));
+
+        for ($i = $statement->first; $i <= $statement->last; ++$i) {
+            $token = $list->tokens[$i];
+
+            if ($token->type === Token::TYPE_COMMENT) {
+                continue;
+            }
+
+            if ($token->type === Token::TYPE_OPERATOR) {
+                if ($token->value === '(') {
+                    ++$brackets;
+                } elseif ($token->value === ')') {
+                    --$brackets;
+                }
+            }
+
+            if ($brackets == 0) {
+                if (($token->type === Token::TYPE_KEYWORD)
+                    && (isset($clauses[$token->value]))
+                    && ($clause === $token->value)
+                ) {
+                    return $i;
+                }
+            }
+        }
+
+        return -1;
+    }
 }