make StringProxy::operator== const to lift ambiguities. closes #854

Author: romainfrancois

inst/include/Rcpp/vector/string_proxy.h

@@ -187,31 +187,30 @@ namespace internal{
 			std::for_each( begin(), end(), op );
 		}
 
-		bool operator==( const char* other){
+		bool operator==( const char* other) const {
 			return strcmp( begin(), other ) == 0 ;
 		}
-		bool operator!=( const char* other){
+		bool operator!=( const char* other) const {
 			return strcmp( begin(), other ) != 0 ;
 		}
 
-		bool operator==( const string_proxy& other){
+		bool operator==( const string_proxy& other) const {
 			return strcmp( begin(), other.begin() ) == 0 ;
 		}
-		bool operator!=( const string_proxy& other){
+		bool operator!=( const string_proxy& other) const {
 			return strcmp( begin(), other.begin() ) != 0 ;
 		}
 
-                bool operator==( SEXP other ) const {
-                    return get() == other;
-                }
+        bool operator==( SEXP other ) const {
+            return get() == other;
+        }
 
-                bool operator!=( SEXP other ) const {
-                    return get() != other;
-                }
+        bool operator!=( SEXP other ) const {
+            return get() != other;
+        }
 
-
-		private:
-			static std::string buffer ;
+	private:
+		static std::string buffer ;
 
 	} ;
 

inst/unitTests/cpp/Vector.cpp

@@ -868,3 +868,12 @@ List ListNoProtect_crosspolicy(Vector<VECSXP, NoProtectStorage> data){
     data2[0] = data[0];
     return data2;
 }
+
+// [[Rcpp::export]]
+bool CharacterVector_test_equality(CharacterVector x, CharacterVector y) {
+    if (x.length() != y.length()) {
+        return false;
+    }
+
+    return std::equal(x.begin(), x.end(), y.begin());
+}

inst/unitTests/runit.Vector.R

@@ -772,4 +772,8 @@ if (.runThisTest) {
         data2 <- ListNoProtect_crosspolicy(data)
         checkEquals(data, data2)
     }
+
+    test.CharacterVector_test_equality <- function(){
+       checkTrue( !CharacterVector_test_equality("foo", "bar") )
+    }
 }