changes in Rcpp modules to allow declaration of the copy constructor of a class

with the `copy_constructor` declaration:

```
    #include <Rcpp.h>
    using namespace Rcpp ;

    class Foo{
      public:
        Foo( int x_ ) : x(x_){}
        int x ;
    } ;

    RCPP_MODULE(test){
      class_<Foo>("Foo")
        .constructor<int>()
        .copy_constructor()
        .field( "x", &Foo::x)
      ;
  }
```

This is associated with the `copy` R function :

```
f <- new( Foo, 1 )
g <- copy( f)
g$x
!identical( g$.pointer, f$.pointer )
```

Author: romainfrancois

DESCRIPTION

@@ -1,17 +1,17 @@
 Package: Rcpp
 Title: Seamless R and C++ Integration
-Version: 0.12.4.1
+Version: 0.12.4.2
 Date: 2016-03-26
-Author: Dirk Eddelbuettel, Romain Francois, JJ Allaire, Kevin Ushey, 
+Author: Dirk Eddelbuettel, Romain Francois, JJ Allaire, Kevin Ushey,
  Qiang Kou, Douglas Bates and John Chambers
 Maintainer: Dirk Eddelbuettel <edd@debian.org>
 Description: The 'Rcpp' package provides R functions as well as C++ classes which
  offer a seamless integration of R and C++. Many R data types and objects can be
  mapped back and forth to C++ equivalents which facilitates both writing of new
- code as well as easier integration of third-party libraries. Documentation 
- about 'Rcpp' is provided by several vignettes included in this package, via the 
- 'Rcpp Gallery' site at <http://gallery.rcpp.org>, the paper by Eddelbuettel and 
- Francois (2011, JSS), and the book by Eddelbuettel (2013, Springer); see 
+ code as well as easier integration of third-party libraries. Documentation
+ about 'Rcpp' is provided by several vignettes included in this package, via the
+ 'Rcpp Gallery' site at <http://gallery.rcpp.org>, the paper by Eddelbuettel and
+ Francois (2011, JSS), and the book by Eddelbuettel (2013, Springer); see
  'citation("Rcpp")' for details on these last two.
 Depends: R (>= 3.0.0)
 Imports: methods, utils

NAMESPACE

@@ -30,10 +30,9 @@ export(Module,
        demangle,
        sizeof,
        cpp_object_initializer,
-       cpp_object_dummy, 
-       Rcpp.plugin.maker
+       cpp_object_dummy,
+       Rcpp.plugin.maker,
+       copy
        )
 S3method( print, bytes )
 exportClass(RcppClass)
-
-

R/Module.R

@@ -1,4 +1,4 @@
-# Copyright (C) 2010 - 2014 John Chambers, Dirk Eddelbuettel and Romain Francois
+# Copyright (C) 2010 - 2016 John Chambers, Dirk Eddelbuettel and Romain Francois
 #
 # This file is part of Rcpp.
 #
@@ -128,7 +128,6 @@ new_CppObject_xp <- function(module, pointer, ...) {
 new_dummyObject <- function(...)
     .External( class__dummyInstance, ...)
 
-
 # class method for $initialize
 cpp_object_initializer <- function(.self, .refClassDef, ..., .object_pointer){
     selfEnv <- as.environment(.self)
@@ -438,3 +437,8 @@ cpp_fields <- function( CLASS, where){
 
 .CppClassName <- function(name)
     paste0("Rcpp_",name)
+
+copy <- function( obj ){
+		xp <- .Call(copy_constructor, obj$.cppclass, obj$.pointer )
+
+}

inst/NEWS.Rd

@@ -14,9 +14,16 @@
     \itemize{
       R 3.3.0 Windows with Rtools 3.3 is now supported (Qin Wenfeng in PR \ghpr{451}).
     }
+    \item Changes in Rcpp Modules:
+    \itemize{
+      \item New function \code{copy} to invoke the copy constructor of a
+      C++ class that has been exposed by modules. \code{copy} only
+      works if the copy constructor has been declared by the
+      \code{copy\_constructor} module declaration.
+    }
   }
 }
-      
+
 \section{Changes in Rcpp version 0.12.4 (2016-03-22)}{
   \itemize{
     \item Changes in Rcpp API:
@@ -65,13 +72,13 @@
       \ghpr{406} by Qiang fixing \ghit{365}).
       \item A missing \code{std::hash} function interface for
       \code{Rcpp::String} has been addded (PR \ghpr{408} by Qiang fixing
-      \ghit{84}). 
+      \ghit{84}).
     }
     \item Changes in Rcpp Attributes:
     \itemize{
       \item Avoid invalid function names when generating C++ interfaces (PR
       \ghpr{403} by JJ fixing \ghit{402}).
-      \item Insert additional space around \code{&} in function interface (PR 
+      \item Insert additional space around \code{&} in function interface (PR
       \ghpr{400} by Kazuki Fukui fixing \ghit{278}).
     }
     \item Changes in Rcpp Modules:
@@ -95,7 +102,7 @@
       by Florian)
       \item Before creating a single String object from a \code{SEXP}, ensure
       that it is from a vector of length one (PR \ghpr{376} by Dirk, fixing
-      \ghit{375}). 
+      \ghit{375}).
       \item No longer use \code{STRING_ELT} as a left-hand side, thanks to a
       heads-up by Luke Tierney (PR \ghpr{378} by Dirk, fixing \ghit{377}).
       \item Rcpp Module objects are now checked more carefully (PR \ghpr{381}
@@ -107,7 +114,7 @@
       \item \code{operator<<()} now always shows decimal points (PR \ghpr{396}
       by Dan)
       \item Matrix classes now have a \code{transpose()} function (PR \ghpr{397}
-      by Dirk fixing \ghit{383}) 
+      by Dirk fixing \ghit{383})
       \item \code{operator<<()} for complex types was added (PRs \ghpr{398} by
       Qiang and \ghpr{399} by Dirk, fixing \ghit{187})
     }
@@ -125,20 +132,20 @@
     \item Changes in Rcpp Documentation:
     \itemize{
       \item The \code{NEWS} file now links to GitHub issue tickets and pull
-      requests. 
+      requests.
       \item The \code{Rcpp.bib} file with bibliographic references was updated.
     }
   }
 }
-      
+
 \section{Changes in Rcpp version 0.12.1 (2015-09-10)}{
   \itemize{
     \item Changes in Rcpp API:
     \itemize{
-      \item Correct use of WIN32 instead of _WIN32 to please Windows 10 
+      \item Correct use of WIN32 instead of _WIN32 to please Windows 10
       \item Add an assignment operator to \code{DimNameProxy} (PR \ghpr{339} by Florian)
       \item Add vector and matrix accessors \code{.at()} with bounds checking
-      (PR \ghpr{342} by Florian) 
+      (PR \ghpr{342} by Florian)
       \item Correct character vector conversion from single char (PR \ghpr{344} by
       Florian fixing issue \ghit{343})
       \item Correct on use of \code{R_xlen_t} back to \code{size_t} (PR \ghpr{348} by
@@ -186,13 +193,13 @@
       R expressions; this should resolve errors where calling handlers (e.g.
       through \code{suppressMessages()}) were not properly respected.
       \item All internal length variables have been changed from \code{R_len_t}
-      to \code{R_xlen_t} to support vectors longer than 2^31-1 elements (via 
+      to \code{R_xlen_t} to support vectors longer than 2^31-1 elements (via
       PR \ghpr{303} by Qiang Kou).
       \item The sugar function \code{sapply} now supports lambda functions
       (addressing \ghit{213} thanks to Matt Dziubinski)
       \item The \code{var} sugar function now uses a more robust two-pass
       method, supports complex numbers, with new unit tests added (via PR
-      \ghpr{320} by Matt Dziubinski) 
+      \ghpr{320} by Matt Dziubinski)
       \item \code{String} constructors now allow encodings (via PR \ghpr{310}
       by Qiang Kou)
       \item \code{String} objects are preserving the underlying \code{SEXP}
@@ -201,7 +208,7 @@
       \item DataFrame constructors are now a little more careful (via PR
       \ghpr{301} by Romain Francois)
       \item For R 3.2.0 or newer, \code{Rf_installChar()} is used instead of
-      \code{Rf_install(CHAR())} (via PR \ghpr{332}). 
+      \code{Rf_install(CHAR())} (via PR \ghpr{332}).
     }
     \item Changes in Rcpp Attributes:
     \itemize{
@@ -233,7 +240,7 @@
       matrices (via a pull request by Dmitrii Meleshko).
       \item A new \code{empty()} string constructor was added (via another pull
       request).
-      \item Better support for Vectors with a storage policy different from the 
+      \item Better support for Vectors with a storage policy different from the
       default, i.e. \code{NoProtectStorage}, was added.
     }
     \item Changes in Rcpp Attributes:
@@ -258,16 +265,16 @@
       \item The \code{Rcpp::Environment} constructor can now use a supplied
       parent environment.
       \item The \code{Rcpp::Function} constructor can now use a supplied
-      environment or namespace. 
+      environment or namespace.
       \item The \code{attributes_hidden} macro from R is used to shield internal
       functions; the \code{R_ext/Visibility.h} header is now included as well.
-      \item A \code{Rcpp::print} function was added as a wrapper around \code{Rf_PrintValue}. 
+      \item A \code{Rcpp::print} function was added as a wrapper around \code{Rf_PrintValue}.
     }
     \item Changes in Rcpp Attributes:
     \itemize{
       \item The \code{pkg_types.h} file is now included in \code{RcppExports.cpp}
-      if it is present in either the \code{inst/include} or \code{src}. 
-      \item \code{sourceCpp} was modified to allow includes of local files 
+      if it is present in either the \code{inst/include} or \code{src}.
+      \item \code{sourceCpp} was modified to allow includes of local files
       (e.g. \code{#include "foo.hpp"}). Implementation files (*.cc; *.cpp) corresponding
       to local includes are also automatically built if they exist.
       \item The generated attributes code was simplified with respect to

inst/include/Rcpp/config.h

@@ -30,7 +30,6 @@
 #define RCPP_VERSION Rcpp_Version(0,12,4)
 
 // the current source snapshot
-#define RCPP_DEV_VERSION RcppDevVersion(0,12,4,1)
+#define RCPP_DEV_VERSION RcppDevVersion(0,12,4,2)
 
 #endif
-

inst/include/Rcpp/module/class.h

@@ -2,7 +2,7 @@
 //
 // class.h: Rcpp R/C++ interface class library -- Rcpp modules
 //
-// Copyright (C) 2012 - 2013 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2012 - 2016 Dirk Eddelbuettel and Romain Francois
 //
 // This file is part of Rcpp.
 //
@@ -60,7 +60,8 @@
             constructors(),
             factories(),
             class_pointer(0),
-            typeinfo_name("")
+            typeinfo_name(""),
+            has_copy_constructor(false)
         {
             class_pointer = get_instance() ;
         }
@@ -111,6 +112,11 @@
             return constructor( docstring, valid ) ;
         }
 
+        self& copy_constructor(){
+            class_pointer->has_copy_constructor = true ;
+            return *this ;
+        }
+
 #include <Rcpp/module/Module_generated_class_constructor.h>
 #include <Rcpp/module/Module_generated_class_factory.h>
 
@@ -146,7 +152,18 @@
 
             throw std::range_error( "no valid constructor available for the argument list" ) ;
             END_RCPP
-                }
+        }
+
+        SEXP invoke_copy_constructor( SEXP object ){
+            BEGIN_RCPP
+
+            if( !has_copy_constructor )
+                stop("copy constructor not exposed") ;
+
+            XP xp(object) ;
+            return internal::make_new_object<Class>( new Class(*xp) ) ;
+            END_RCPP
+        }
 
         bool has_default_constructor(){
             int n = constructors.size() ;
@@ -476,7 +493,7 @@
         vec_signed_factory factories ;
         self* class_pointer ;
         std::string typeinfo_name ;
-
+        bool has_copy_constructor ;
 
         class_( ) : class_Base(), vec_methods(), properties(), specials(0), constructors(), factories() {};
 

inst/include/Rcpp/module/class_Base.h

@@ -2,7 +2,7 @@
 //
 // class_Base.h: Rcpp R/C++ interface class library -- Rcpp modules
 //
-// Copyright (C) 2012 - 2013 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2012 - 2016 Dirk Eddelbuettel and Romain Francois
 //
 // This file is part of Rcpp.
 //
@@ -37,6 +37,7 @@ class class_Base {
 
     virtual void run_finalizer(SEXP){ }
 
+    virtual SEXP invoke_copy_constructor(SEXP) = 0 ;
     virtual bool has_default_constructor(){ return false ; }
     virtual bool has_method( const std::string& ){
         return false ;
@@ -80,7 +81,7 @@ class class_Base {
     }
     void add_enum( const std::string& enum_name, const std::map<std::string, int>& value ){
 	    enums.insert( ENUM_MAP_PAIR( enum_name, value ) ) ;
-	}
+	  }
 
     std::string name ;
     std::string docstring ;

inst/unitTests/cpp/Module.cpp

@@ -111,6 +111,13 @@ class ModuleRandomizer {
     double min, max;
 };
 
+class ModuleCopyConstructor {
+public:
+  ModuleCopyConstructor(int x_) : x(x_){}
+
+  int x ;
+} ;
+
 RCPP_EXPOSED_CLASS(ModuleTest)
 class ModuleTest {
 public:
@@ -194,6 +201,12 @@ RCPP_MODULE(demoModule) {
 
         .method("get" , &ModuleRandomizer::get)
         ;
+
+    class_<ModuleCopyConstructor>( "ModuleCopyConstructor")
+        .constructor<int>
+        .copy_constructor()
+        .field( "x", &ModuleCopyConstructor::x)
+    ;
 }
 
 // [[Rcpp::export]]
@@ -215,4 +228,3 @@ double attr_Test_get_x_const_pointer(const ModuleTest* x) {
 double attr_Test_get_x_pointer(ModuleTest* x) {
     return x->value;
 }
-

inst/unitTests/runit.Module.R

@@ -27,12 +27,12 @@ if( .runThisTest && Rcpp:::capabilities()[["Rcpp modules"]] ) {
     }
 
     .setUp <- Rcpp:::unitTestSetup("Module.cpp")
-    
+
     test.Module <- function(){
         checkEquals( bar( 2L ), 4L )
         checkEquals( foo( 2L, 10.0 ), 20.0 )
         checkEquals( hello(), "hello" )
-        
+
         w <- new( ModuleWorld )
         checkEquals( w$greet(), "hello" )
         w$set( "hello world" )
@@ -51,7 +51,7 @@ if( .runThisTest && Rcpp:::capabilities()[["Rcpp modules"]] ) {
         checkEquals( Test_get_x_const_pointer(test), 3.0 )
         checkEquals( Test_get_x_ref(test), 3.0 )
         checkEquals( Test_get_x_pointer(test), 3.0 )
-        
+
         checkEquals( attr_Test_get_x_const_ref(test), 3.0 )
         checkEquals( attr_Test_get_x_const_pointer(test), 3.0 )
         checkEquals( attr_Test_get_x_ref(test), 3.0 )
@@ -94,4 +94,14 @@ if( .runThisTest && Rcpp:::capabilities()[["Rcpp modules"]] ) {
         checkEquals( test_const( seq(0,10) ), 11L )
     }
 
+    test.Module.copy.constructor <- function(){
+        f <- new( ModuleCopyConstructor, 2L)
+        g <- copy(f)
+        checkEquals( f$x, g$x )
+        checkTrue( !identical(f$.pointer, g$.pointer) )
+        g$x <- 4L
+        checkEquals( f$x, 2L)
+        checkEquals( g$x, 4L)
+    }
+
 }