Allow tables to be used as table columns

This fix is specifically for WIENER-CRATE-MIB, which uses a "SEQUENCE"
declaration that includes a table object symbol. As a result, the
corresponding object type is considered to be a table column, resulting
in generated Python code that cannot be loaded.

This commit adds an extra restriction for object types to be considered
table columns, namely that they must not have a "SEQUENCE OF" type
syntax. In other words, object types that are tables are no longer ever
considered to be table columns. That restriction allows WIENER-CRATE-MIB
to be loaded properly.

The commit also adds a test case, which consists of a simplified version
of the construction found in WIENER-CRATE-MIB.

pysmi/codegen/intermediate.py

@@ -478,11 +478,13 @@ def genObjectType(self, data):
 
         if syntax[0]:
             nodetype = syntax[0] == "Bits" and "scalar" or syntax[0]  # Bits hack
-            nodetype = (
+            # If this object type is used as a column, but it also has a
+            # "SEQUENCE OF" syntax, then it is really a table and not a column.
+            isColumn = (
                 pysmiName in self.symbolTable[self.moduleName[0]]["_symtable_cols"]
-                and "column"
-                or nodetype
+                and syntax[1]
             )
+            nodetype = isColumn and "column" or nodetype
             outDict["nodetype"] = nodetype
 
         outDict["class"] = "objecttype"

tests/test_objecttype_smiv2_pysnmp.py

@@ -1097,6 +1097,69 @@ def testObjectTypeTableRowIndex(self):
         )
 
 
+class ObjectTypeMibTableAndColumnTestCase(unittest.TestCase):
+    """
+    TEST-MIB DEFINITIONS ::= BEGIN
+    IMPORTS
+      OBJECT-TYPE
+        FROM SNMPv2-SMI;
+
+      Overview ::= SEQUENCE {
+            testTable   TestEntry
+      }
+
+      testTable OBJECT-TYPE
+        SYNTAX          SEQUENCE OF TestEntry
+        MAX-ACCESS      not-accessible
+        STATUS          current
+        DESCRIPTION     "Test table"
+      ::= { 1 3 }
+
+      testEntry OBJECT-TYPE
+        SYNTAX          TestEntry
+        MAX-ACCESS      not-accessible
+        STATUS          current
+        DESCRIPTION     "Test row"
+        INDEX           { testIndex }
+      ::= { testTable 1 }
+
+      TestEntry ::= SEQUENCE {
+            testIndex   INTEGER
+      }
+
+      testIndex OBJECT-TYPE
+        SYNTAX          INTEGER
+        MAX-ACCESS      read-create
+        STATUS          current
+        DESCRIPTION     "Test column"
+      ::= { testEntry 1 }
+
+    END
+    """
+
+    def setUp(self):
+        ast = parserFactory()().parse(self.__class__.__doc__)[0]
+        mibInfo, symtable = SymtableCodeGen().genCode(ast, {})
+        self.mibInfo, pycode = PySnmpCodeGen().genCode(ast, {mibInfo.name: symtable})
+        codeobj = compile(pycode, "test", "exec")
+
+        self.ctx = {"mibBuilder": MibBuilder()}
+
+        exec(codeobj, self.ctx, self.ctx)
+
+    def testObjectTypeTableClass(self):
+        self.assertEqual(
+            self.ctx["testTable"].__class__.__name__, "MibTable", "bad table class"
+        )
+
+    def testObjectTypeTableRowClass(self):
+        self.assertEqual(
+            self.ctx["testEntry"].__class__.__name__,
+            "MibTableRow",
+            "bad table row class",
+        )
+
+
 suite = unittest.TestLoader().loadTestsFromModule(sys.modules[__name__])
 
 if __name__ == "__main__":