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tools/parser_sql/processors/UnionProcessor.php

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+<?php
+/**
+ * UnionProcessor.php
+ *
+ * This file implements the processor for the UNION statements.
+ *
+ * Copyright (c) 2010-2012, Justin Swanhart
+ * with contributions by André Rothe <arothe@phosco.info, phosco@gmx.de>
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+require_once(dirname(__FILE__) . '/AbstractProcessor.php');
+require_once(dirname(__FILE__) . '/SQLProcessor.php');
+require_once(dirname(__FILE__) . '/DefaultProcessor.php');
+require_once(dirname(__FILE__) . '/../utils/ExpressionType.php');
+
+/**
+ * 
+ * This class processes the UNION statements.
+ * 
+ * @author arothe
+ * 
+ */
+class UnionProcessor extends AbstractProcessor {
+
+    public function isUnion($queries) {
+        $unionTypes = array('UNION', 'UNION ALL');
+        foreach ($unionTypes as $unionType) {
+            if (!empty($queries[$unionType])) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * MySQL supports a special form of UNION:
+     * (select ...)
+     * union
+     * (select ...)
+     *
+     * This function handles this query syntax. Only one such subquery
+     * is supported in each UNION block. (select)(select)union(select) is not legal.
+     * The extra queries will be silently ignored.
+     */
+    protected function processMySQLUnion($queries) {
+        $unionTypes = array('UNION', 'UNION ALL');
+        foreach ($unionTypes as $unionType) {
+
+            if (empty($queries[$unionType])) {
+                continue;
+            }
+
+            foreach ($queries[$unionType] as $key => $tokenList) {
+                foreach ($tokenList as $z => $token) {
+                    $token = trim($token);
+                    if ($token === "") {
+                        continue;
+                    }
+
+                    // starts with "(select"
+                    if (preg_match("/^\\(\\s*select\\s*/i", $token)) {
+                        $processor = new DefaultProcessor();
+                        $queries[$unionType][$key] = $processor->process($this->removeParenthesisFromStart($token));
+                        break;
+                    }
+
+                    $processor = new SQLProcessor();
+                    $queries[$unionType][$key] = $processor->process($queries[$unionType][$key]);
+                    break;
+                }
+            }
+        }
+        // it can be parsed or not
+        return $queries;
+    }
+
+    public function process($inputArray) {
+        $outputArray = array();
+
+        // ometimes the parser needs to skip ahead until a particular
+        // oken is found
+        $skipUntilToken = false;
+
+        // his is the last type of union used (UNION or UNION ALL)
+        // ndicates a) presence of at least one union in this query
+        // b) the type of union if this is the first or last query
+        $unionType = false;
+
+        // ometimes a "query" consists of more than one query (like a UNION query)
+        // his array holds all the queries
+        $queries = array();
+
+        foreach ($inputArray as $key => $token) {
+            $trim = trim($token);
+
+            // overread all tokens till that given token
+            if ($skipUntilToken) {
+                if ($trim === "") {
+                    continue; // read the next token
+                }
+                if (strtoupper($trim) === $skipUntilToken) {
+                    $skipUntilToken = false;
+                    continue; // read the next token
+                }
+            }
+
+            if (strtoupper($trim) !== "UNION") {
+                $outputArray[] = $token; // here we get empty tokens, if we remove these, we get problems in parse_sql()
+                continue;
+            }
+
+            $unionType = "UNION";
+
+            // we are looking for an ALL token right after UNION
+            for ($i = $key + 1; $i < count($inputArray); ++$i) {
+                if (trim($inputArray[$i]) === "") {
+                    continue;
+                }
+                if (strtoupper($inputArray[$i]) !== "ALL") {
+                    break;
+                }
+                // the other for-loop should overread till "ALL"
+                $skipUntilToken = "ALL";
+                $unionType = "UNION ALL";
+            }
+
+            // store the tokens related to the unionType
+            $queries[$unionType][] = $outputArray;
+            $outputArray = array();
+        }
+
+        // the query tokens after the last UNION or UNION ALL
+        // or we don't have an UNION/UNION ALL
+        if (!empty($outputArray)) {
+            if ($unionType) {
+                $queries[$unionType][] = $outputArray;
+            } else {
+                $queries[] = $outputArray;
+            }
+        }
+
+        return $this->processMySQLUnion($queries);
+    }
+
+}
+?>