support casting ranked to unranked (forward_)tree

alib2std/src/extensions/forward_tree.hpp

@@ -34,6 +34,20 @@ class forward_tree {
 		tree_node ( T && data, std::vector < tree_node > && children ) : data ( std::move ( data ) ), children ( std::move ( children ) ) {
 		}
+		template < class AnotherArityChecker >
+		tree_node ( const typename forward_tree < T, AnotherArityChecker >::tree_node & node, const AnotherArityChecker & arityChecker ) : data ( node.data ), children ( ) {
+			// INFO: The AnotherArityChecker parameter is there only to deduce the template parameter, it cannot be used to check that resulting tree_node comply with the arity checker of the resulting tree because it is different
+			for ( const typename forward_tree < T, AnotherArityChecker >::tree_node & child : node.children )
+				children.push_back ( tree_node ( child, arityChecker ) );
+		}
+
+		template < class AnotherArityChecker >
+		tree_node ( typename forward_tree < T, AnotherArityChecker >::tree_node && node, const AnotherArityChecker & arityChecker ) : data ( std::move ( node.data ) ), children ( ) {
+			// INFO: The AnotherArityChecker parameter is there only to deduce the template parameter, it cannot be used to check that resulting tree_node comply with the arity checker of the resulting tree because it is different
+			for ( typename forward_tree < T, AnotherArityChecker >::tree_node & child : node.children )
+				children.push_back ( tree_node ( std::move ( child ), arityChecker ) );
+		}
+
 		~tree_node ( ) noexcept {
 		}
@@ -454,6 +468,20 @@ public:
 		friend class forward_tree;
 	};
+// ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+
+	void checkArities ( const tree_node & node ) const {
+		if ( !arityChecker ( node.getData ( ), node.getChildren ( ).size ( ) ) )
+			throw std::length_error ( "Invalid number of children" );
+
+		for ( const tree_node & child : node.getChildren ( ) )
+			checkArities ( child );
+	}
+
+	void checkArities ( ) const {
+		return checkArities ( root );
+	}
+
 // ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 private:
@@ -537,6 +565,16 @@ public:
 		insert_helper ( begin ( ), begin ( ).end ( ), begin, end );
 	}
+	template < class AnotherArityChecker = AnyArity < T > >
+	forward_tree ( const forward_tree < T, AnotherArityChecker > & other, ArityChecker arityChecker = ArityChecker ( ) ) : arityChecker ( arityChecker ), root ( other.root, AnotherArityChecker ( ) ) {
+		checkArities ( );
+	}
+
+	template < class AnotherArityChecker = AnyArity < T > >
+	forward_tree ( forward_tree < T, AnotherArityChecker > && other, ArityChecker arityChecker = ArityChecker ( ) ) : arityChecker ( arityChecker ), root ( std::move ( other.root ), AnotherArityChecker ( ) ) {
+		checkArities ( );
+	}
+
 // ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 	const_children_iterator begin ( ) const {
@@ -744,6 +782,9 @@ public:
 		return os;
 	}
+	template < class R, class AnotherArityChecker >
+	friend class forward_tree;
+
 };
 template < class T, class ... Ts >

alib2std/src/extensions/tree.hpp

@@ -39,6 +39,24 @@ class tree {
 				child.parent = this;
 		}
+		template < class AnotherArityChecker >
+		tree_node ( const typename tree < T, AnotherArityChecker >::tree_node & node, const AnotherArityChecker & arityChecker ) : data ( node.data ), parent ( nullptr ), children ( ) {
+			// INFO: The AnotherArityChecker parameter is there only to deduce the template parameter, it cannot be used to check that resulting tree_node comply with the arity checker of the resulting tree because it is different
+			for ( const typename tree < T, AnotherArityChecker >::tree_node & child : node.children ) {
+				children.push_back ( tree_node ( child, arityChecker ) );
+				children [ children.size ( ) - 1 ].parent = this;
+			}
+		}
+
+		template < class AnotherArityChecker >
+		tree_node ( typename tree < T, AnotherArityChecker >::tree_node && node, const AnotherArityChecker & arityChecker ) : data ( std::move ( node.data ) ), parent ( nullptr ), children ( ) {
+			// INFO: The AnotherArityChecker parameter is there only to deduce the template parameter, it cannot be used to check that resulting tree_node comply with the arity checker of the resulting tree because it is different
+			for ( typename tree < T, AnotherArityChecker >::tree_node & child : node.children ) {
+				children.push_back ( tree_node ( std::move ( child ), arityChecker ) );
+				children [ children.size ( ) - 1 ].parent = this;
+			}
+		}
+
 		~tree_node ( ) noexcept {
 		}
@@ -473,6 +491,20 @@ public:
 		friend class tree;
 	};
+// ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+
+	void checkArities ( const tree_node & node ) const {
+		if ( !arityChecker ( node.getData ( ), node.getChildren ( ).size ( ) ) )
+			throw std::length_error ( "Invalid number of children" );
+
+		for ( const tree_node & child : node.getChildren ( ) )
+			checkArities ( child );
+	}
+
+	void checkArities ( ) const {
+		return checkArities ( root );
+	}
+
 // ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 private:
@@ -562,6 +594,16 @@ public:
 		insert_helper ( begin ( ), begin ( ).end ( ), begin, end );
 	}
+	template < class AnotherArityChecker = AnyArity < T > >
+	tree ( const tree < T, AnotherArityChecker > & other, ArityChecker arityChecker = ArityChecker ( ) ) : arityChecker ( arityChecker ), root ( other.root, AnotherArityChecker ( ) ) {
+		checkArities ( );
+	}
+
+	template < class AnotherArityChecker = AnyArity < T > >
+	tree ( tree < T, AnotherArityChecker > && other, ArityChecker arityChecker = ArityChecker ( ) ) : arityChecker ( arityChecker ), root ( std::move ( other.root ), AnotherArityChecker ( ) ) {
+		checkArities ( );
+	}
+
 // ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 	const_children_iterator begin ( ) const {
@@ -786,6 +828,9 @@ public:
 		return os;
 	}
+	template < class R, class AnotherArityChecker >
+	friend class tree;
+
 };
 template < class T, class ... Ts >

alib2std/test-src/extensions/ForwardTreeTest.cpp

@@ -113,6 +113,17 @@ void ForwardTreeTest::testTreeStdStructure ( ) {
 	std::forward_tree < char, RankedArityChecker > rt2 ( 'c' );
 	swap ( rt, rt2 );
+	std::forward_tree < char > rt2unranked ( rt2 );
+
+	std::forward_tree < char, RankedArityChecker > rt3 ( rt2unranked );
+
+	CPPUNIT_ASSERT ( rt2 == rt3 );
+
+	rt2unranked.push_back ( rt2unranked.begin ( ), 'f' );
+
+	typedef std::forward_tree < char, RankedArityChecker > rankedforwardtree;
+	CPPUNIT_ASSERT_THROW ( ( void ) rankedforwardtree ( rt2unranked ), std::length_error);
+
 	std::cout << rt << std::endl;
 	std::stringstream ss3;
 	ss3 << rt;

alib2std/test-src/extensions/TreeTest.cpp

@@ -124,6 +124,17 @@ void TreeTest::testTreeStdStructure ( ) {
 	std::tree < char, RankedArityChecker > rt2 ( 'c' );
 	swap ( rt, rt2 );
+	std::tree < char > rt2unranked ( rt2 );
+
+	std::tree < char, RankedArityChecker > rt3 ( rt2unranked );
+
+	CPPUNIT_ASSERT ( rt2 == rt3 );
+
+	rt2unranked.push_back ( rt2unranked.begin ( ), 'f' );
+
+	typedef std::tree < char, RankedArityChecker > rankedforwardtree;
+	CPPUNIT_ASSERT_THROW ( ( void ) rankedforwardtree ( rt2unranked ), std::length_error);
+
 	CPPUNIT_ASSERT ( rt.checkStructure ( ) );
 	std::cout << rt << std::endl;
 	std::stringstream ss3;