Implement join().

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

CMakeLists.txt

@@ -33,6 +33,8 @@ if(BUILD_TESTING)
 
   ament_add_gtest(test_basic test/test_basic.cpp)
 
+  ament_add_gtest(test_join test/test_join.cpp)
+
   ament_add_gtest(test_split test/test_split.cpp)
 
   ament_add_gtest(test_filesystem_helper test/test_filesystem_helper.cpp)

include/rcpputils/join.hpp

@@ -0,0 +1,71 @@
+// Copyright (c) 2019, Open Source Robotics Foundation, Inc.
+// All rights reserved.
+//
+// Software License Agreement (BSD License 2.0)
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+//  * Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+//  * Redistributions in binary form must reproduce the above
+//    copyright notice, this list of conditions and the following
+//    disclaimer in the documentation and/or other materials provided
+//    with the distribution.
+//  * Neither the name of the copyright holders nor the names of its
+//    contributors may be used to endorse or promote products derived
+//    from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef RCPPUTILS__JOIN_HPP_
+#define RCPPUTILS__JOIN_HPP_
+
+#include <algorithm>
+#include <iterator>
+#include <sstream>
+#include <string>
+
+namespace rcpputils
+{
+
+/// Join values in a container turned into strings by a given delimiter
+/**
+ * \param[in] container is a collection of values to be turned into string and joined.
+ * \param[in] delim is a delimiter to join values turned into strings.
+ * \tparam CharT is the string character type.
+ * \tparam ValueT is the container value type.
+ * \tparam AllocatorT is the container allocator type.
+ * \tparam ContainerT is the container template type.
+ * \return joined string
+ */
+template<
+  typename CharT, typename ValueT, typename AllocatorT,
+  template<typename T, class A> class ContainerT>
+std::basic_string<CharT>
+join(const ContainerT<ValueT, AllocatorT> & container, const CharT * delim)
+{
+  std::basic_ostringstream<CharT> s;
+  std::copy(container.begin(), container.end(), std::ostream_iterator<ValueT, CharT>(s, delim));
+  std::basic_string<CharT> result = s.str();
+  if (delim) {
+    result = result.substr(0, result.length() - strlen(delim));
+  }
+  return result;
+}
+
+}  // namespace rcpputils
+
+#endif  // RCPPUTILS__JOIN_HPP_

test/test_join.cpp

@@ -0,0 +1,94 @@
+// Copyright 2019 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <gtest/gtest.h>
+
+#include <list>
+#include <string>
+#include <vector>
+
+#include "rcpputils/join.hpp"
+
+
+TEST(test_join, join_strings_vector) {
+  {
+    const std::vector<std::string> zero_elements;
+    EXPECT_EQ("", rcpputils::join(zero_elements, ""));
+    EXPECT_EQ("", rcpputils::join(zero_elements, ", "));
+  }
+  {
+    const std::vector<std::string> one_element{"foo"};
+    EXPECT_EQ("foo", rcpputils::join(one_element, ""));
+    EXPECT_EQ("foo", rcpputils::join(one_element, ", "));
+  }
+  {
+    const std::vector<std::string> many_elements{"foo", "bar", "baz"};
+    EXPECT_EQ("foobarbaz", rcpputils::join(many_elements, ""));
+    EXPECT_EQ("foo, bar, baz", rcpputils::join(many_elements, ", "));
+  }
+}
+
+TEST(test_join, join_strings_list) {
+  {
+    const std::list<std::string> zero_elements;
+    EXPECT_EQ("", rcpputils::join(zero_elements, ""));
+    EXPECT_EQ("", rcpputils::join(zero_elements, ", "));
+  }
+  {
+    const std::list<std::string> one_element{"foo"};
+    EXPECT_EQ("foo", rcpputils::join(one_element, ""));
+    EXPECT_EQ("foo", rcpputils::join(one_element, ", "));
+  }
+  {
+    const std::list<std::string> many_elements{"foo", "bar", "baz"};
+    EXPECT_EQ("foobarbaz", rcpputils::join(many_elements, ""));
+    EXPECT_EQ("foo, bar, baz", rcpputils::join(many_elements, ", "));
+  }
+}
+
+TEST(test_join, join_ints_vector) {
+  {
+    const std::vector<int> zero_elements;
+    EXPECT_EQ("", rcpputils::join(zero_elements, ""));
+    EXPECT_EQ("", rcpputils::join(zero_elements, ", "));
+  }
+  {
+    const std::vector<int> one_element{1};
+    EXPECT_EQ("1", rcpputils::join(one_element, ""));
+    EXPECT_EQ("1", rcpputils::join(one_element, ", "));
+  }
+  {
+    const std::vector<int> many_elements{1, 2, 3};
+    EXPECT_EQ("123", rcpputils::join(many_elements, ""));
+    EXPECT_EQ("1, 2, 3", rcpputils::join(many_elements, ", "));
+  }
+}
+
+TEST(test_join, join_ints_list) {
+  {
+    const std::list<int> zero_elements;
+    EXPECT_EQ("", rcpputils::join(zero_elements, ""));
+    EXPECT_EQ("", rcpputils::join(zero_elements, ", "));
+  }
+  {
+    const std::list<int> one_element{1};
+    EXPECT_EQ("1", rcpputils::join(one_element, ""));
+    EXPECT_EQ("1", rcpputils::join(one_element, ", "));
+  }
+  {
+    const std::list<int> many_elements{1, 2, 3};
+    EXPECT_EQ("123", rcpputils::join(many_elements, ""));
+    EXPECT_EQ("1, 2, 3", rcpputils::join(many_elements, ", "));
+  }
+}