From d47bf05034e9e4699321bee6fb36764e2e7cf115 Mon Sep 17 00:00:00 2001
From: Yihong Yu <hazelyumyk@gmail.com>
Date: Wed, 25 Sep 2024 14:42:33 -0700
Subject: [PATCH] add special case for tables

---
 core/rule_generator.py       | 17 +++++++++++++----
 tests/test_rule_generator.py |  2 +-
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/core/rule_generator.py b/core/rule_generator.py
index d8c3f1e..d27163f 100644
--- a/core/rule_generator.py
+++ b/core/rule_generator.py
@@ -839,17 +839,17 @@ def tables(pattern_json: str, rewrite_json: str) -> list:
         rewriteSet = defaultdict(list)
 
         for table in patternTables:
-            if type(table['value']) is str and type(table['name']) is str:
+            if type(table['value']) is str and type(table['name']) is str and table['name'] not in patternSet[table['value']]:
                 patternSet[table['value']].append(table['name'])
 
         for table in rewriteTables:
-            if type(table['value']) is str and type(table['name']) is str:
-                rewriteSet[table['value']].append(table['name'])
+            if type(table['value']) is str and type(table['name']) is str and table['name'] not in rewriteSet[table['value']]:
+                rewriteSet[table['value']].append(table['name'])      
 
         superSet = []
         for patternValue, patternNames in patternSet.items():
             rewriteNames = rewriteSet.get(patternValue, [])
-            # special case: 
+            # special case 1: 
             #   if the patternTable ONLY has {'value': 'employee', 'name': 'employee'}
             #   and the rewriteTable ONLY has {'value': 'employee', 'name': 'e1'},
             #   we replace 'employee' with 'e1' as table alias  
@@ -861,6 +861,15 @@ def tables(pattern_json: str, rewrite_json: str) -> list:
             #
             if len(patternNames) == 1 and len(rewriteNames) == 1 and patternNames[0] == patternValue:
                 patternNames = rewriteNames
+            # special case 2:
+            #   if the patternTable ONLY has {'value': 'employee', 'name': 'employee'}
+            #   and the rewriteTable has multiple alias to the same table, e.g., {'value': 'employee', 'name': 'e1'}, {'value': 'employee', 'name': 'e2'}
+            #   we directly append 'e1' and 'e2' as table alias to the superSet as IN MOST CASES patternTable's name should be included in rewriteTable's alias name
+            #   the purpose is for the next step when we replace tables with variables
+            #
+            elif len(patternNames) == 1 and len(rewriteNames) != 0 and patternNames[0] == patternValue:
+                superSet += [{'value': patternValue, 'name': name} for name in rewriteNames]
+                continue
             else:
                 patternNames += [name for name in rewriteNames if name not in patternNames]
             superSet += [{'value': patternValue, 'name': name} for name in patternNames]
diff --git a/tests/test_rule_generator.py b/tests/test_rule_generator.py
index 3a203cb..010ef35 100644
--- a/tests/test_rule_generator.py
+++ b/tests/test_rule_generator.py
@@ -2162,7 +2162,7 @@ def test_generate_general_rule_16():
 
     q0_rule, q1_rule = unify_variable_names(rule['pattern'], rule['rewrite'])
     assert q0_rule== "SELECT <x1>, <x2>, <x3>, <x4>, <x5>, <x6> FROM <x7> WHERE <x2> IN (SELECT <x2> FROM <x7> WHERE <x6> = <x8> AND <x3> = <x9>) ORDER BY <x2>, <x3>"
-    assert q1_rule == "SELECT <x10>.<x1>, <x10>.<x2>, <x10>.<x3>, <x10>.<x4>, <x10>.<x5>, <x10>.<x6> FROM <x10> JOIN <x11> ON <x11>.<x2> = <x10>.<x2> WHERE <x11>.<x6> = <x8> AND <x11>.<x3> = <x9> ORDER BY <x10>.<x2>, <x10>.<x3>"
+    assert q1_rule == "SELECT <x7>.<x1>, <x7>.<x2>, <x7>.<x3>, <x7>.<x4>, <x7>.<x5>, <x7>.<x6> FROM <x7> JOIN <x10> ON <x10>.<x2> = <x7>.<x2> WHERE <x10>.<x6> = <x8> AND <x10>.<x3> = <x9> ORDER BY <x7>.<x2>, <x7>.<x3>"
 
 
 def test_generate_general_rule_17():