fixes #488 - allow StructMeta copyFrom / deepcopyFrom / updateFrom to work on base types as well

Signed-off-by: Rob Ambalu <[email protected]>

Author: robambalu

cpp/csp/engine/Struct.cpp

@@ -201,6 +201,22 @@ bool StructMeta::isDerivedType( const StructMeta * derived, const StructMeta * b
     return b != nullptr;
 }
 
+const StructMeta * StructMeta::commonBase( const StructMeta * x, const StructMeta *  y )
+{
+    const StructMeta * m = x;
+    while( m && m != y )
+        m = m -> m_base.get();
+
+    if( !m )
+    {
+        m = y;
+        while( m && m != x )
+            m = m -> m_base.get();
+    }
+    return m;
+
+}
+
 void StructMeta::initialize( Struct * s ) const
 {
     //TODO optimize initialize to use default if availbel instead of constructing
@@ -231,25 +247,29 @@ void StructMeta::copyFrom( const Struct * src, Struct * dest )
     if( unlikely( src == dest ) )
         return;
 
-    if( dest -> meta() != src -> meta() && 
-        !StructMeta::isDerivedType( src -> meta(), dest -> meta() ) )
-            CSP_THROW( TypeError, "Attempting to copy from struct type '" << src -> meta() -> name() << "' to struct type '" << dest -> meta() -> name() 
-                       << "'. copy_from may only be used to copy from same type or derived types" );
+    const StructMeta * meta = commonBase( src -> meta(), dest -> meta() );
+    if( !meta )
+    {
+        CSP_THROW( TypeError, "Attempting to copy from struct type '" << src -> meta() -> name() << "' to struct type '" << dest -> meta() -> name() 
+                   << "'. copy_from may only be used to copy from struct with a common base type" );
+    }
 
-    dest -> meta() -> copyFromImpl( src, dest, false );
+    meta -> copyFromImpl( src, dest, false );
 }
 
 void StructMeta::deepcopyFrom( const Struct * src, Struct * dest )
 {
     if( unlikely( src == dest ) )
         return;
 
-    if( dest -> meta() != src -> meta() && 
-        !StructMeta::isDerivedType( src -> meta(), dest -> meta() ) )
-            CSP_THROW( TypeError, "Attempting to deepcopy from struct type '" << src -> meta() -> name() << "' to struct type '" << dest -> meta() -> name() 
-                       << "'. deepcopy_from may only be used to copy from same type or derived types" );
-
-    dest -> meta() -> copyFromImpl( src, dest, true );
+    const StructMeta * meta = commonBase( src -> meta(), dest -> meta() );
+    if( !meta )
+    {
+        CSP_THROW( TypeError, "Attempting to deepcopy from struct type '" << src -> meta() -> name() << "' to struct type '" << dest -> meta() -> name() 
+                   << "'. deepcopy_from may only be used to copy from struct with a common base type" );
+    }
+    
+    meta -> copyFromImpl( src, dest, true );
 }   
 
 void StructMeta::copyFromImpl( const Struct * src, Struct * dest, bool deepcopy ) const
@@ -291,12 +311,15 @@ void StructMeta::updateFrom( const Struct * src, Struct * dest )
     if( unlikely( src == dest ) )
         return;
 
-    if( dest -> meta() != src -> meta() && 
-        !StructMeta::isDerivedType( src -> meta(), dest -> meta() ) )
-            CSP_THROW( TypeError, "Attempting to update from struct type '" << src -> meta() -> name() << "' to struct type '" << dest -> meta() -> name() 
-                       << "'. update_from may only be used to update from same type or derived types" );
+    const StructMeta * meta = commonBase( src -> meta(), dest -> meta() );
+    
+    if( !meta )
+    {
+        CSP_THROW( TypeError, "Attempting to update from struct type '" << src -> meta() -> name() << "' to struct type '" << dest -> meta() -> name() 
+                   << "'. update_from may only be used to update from struct with a common base type" );
+    }
 
-    dest -> meta() -> updateFromImpl( src, dest );
+    meta -> updateFromImpl( src, dest );
 }    
 
 void StructMeta::updateFromImpl( const Struct * src, Struct * dest ) const

cpp/csp/engine/Struct.h

@@ -634,6 +634,7 @@ class StructMeta : public std::enable_shared_from_this<StructMeta>
 
     //returns true if derived == base or if derived is a derived type of base
     static bool isDerivedType( const StructMeta * derived, const StructMeta * base );
+    static const StructMeta * commonBase( const StructMeta * x, const StructMeta * y );
 
     template<typename T>
     std::shared_ptr<typename StructField::upcast<T>::type> getMetaField( const char * fieldname, const char * expectedtype );

csp/tests/impl/test_struct.py

@@ -692,6 +692,15 @@ def test_copy_from(self):
                     for key in blank.metadata().keys():
                         self.assertEqual(getattr(blank, key), getattr(source, key), (typ, typ2, key))
 
+                    # Test other direction ( derived copy from base )
+                    blank = typ2()
+                    source = typ()
+                    for key in typ.metadata().keys():
+                        setattr(source, key, values[key])
+                    blank.copy_from(source)
+                    for key in source.metadata().keys():
+                        self.assertEqual(getattr(blank, key), getattr(source, key), (typ, typ2, key))
+
     def test_copy_from_unsets(self):
         source = DerivedMixed(i=1, f=2.3, i2=4, s2="woodchuck")
         dest1 = DerivedMixed(i=5, b=True, l2=[1, 2, 3])
@@ -712,6 +721,14 @@ def test_copy_from_unsets(self):
         self.assertFalse(hasattr(dest2, "s"))  # unsets
         self.assertFalse(hasattr(dest2, "a1"))
 
+        # from base class -> derived
+        dest3 = DerivedMixed()
+        dest3.copy_from(dest2)
+        self.assertTrue(dest3.i == 1)  # overrides already set value
+        self.assertTrue(dest3.f == 2.3)  # adds
+        self.assertTrue(dest3.s == "banana")  # no unsets
+        self.assertTrue(dest3.a1 == [4, 5, 6])
+
     def test_deepcopy_from(self):
         source = StructWithLists(
             struct_list=[BaseNative(i=123)], fast_list=[BaseNative(i=123)], dialect_generic_list=[{"a": 1}]
@@ -751,6 +768,14 @@ def test_update_from(self):
         self.assertTrue(dest2.s == "banana")  # no unsets
         self.assertTrue(dest2.a1 == [4, 5, 6])
 
+        # update from base class
+        dest3 = DerivedMixed()
+        dest3.update_from(dest2)
+        self.assertTrue(dest3.i == 1)  # overrides already set value
+        self.assertTrue(dest3.f == 2.3)  # adds
+        self.assertTrue(dest3.s == "banana")  # no unsets
+        self.assertTrue(dest3.a1 == [4, 5, 6])
+
     def test_update(self):
         dest = DerivedMixed(i2=5, b=True, l2=[1, 2, 3], s="foo")
         dest.update(f2=5.5, s2="bar")