Implement joining iterator ranges into a string

g2o/stuff/string_tools.h

@@ -27,6 +27,8 @@
 #ifndef G2O_STRING_TOOLS_H
 #define G2O_STRING_TOOLS_H
 
+#include <algorithm>
+#include <iterator>
 #include <sstream>
 #include <string>
 #include <vector>
@@ -115,6 +117,30 @@ G2O_STUFF_API std::string strExpandFilename(const std::string& filename);
 G2O_STUFF_API std::vector<std::string> strSplit(const std::string& s,
                                                 const std::string& delim);
 
+/**
+ * @brief Join into a string using a delimeter
+ *
+ * @tparam Iterator
+ * @tparam std::iterator_traits<Iterator>::value_type
+ * @param b begin of the range for output
+ * @param e end of the range for output
+ * @param delimiter will be inserted in between elements
+ * @return std::string joined string
+ */
+template <typename Iterator,
+          typename Value = typename std::iterator_traits<Iterator>::value_type>
+std::string strJoin(Iterator b, Iterator e, const std::string& delimiter = "") {
+  if (b == e) return "";
+  std::ostringstream os;
+  std::copy(b, std::prev(e),
+            std::ostream_iterator<Value>(os, delimiter.c_str()));
+  b = std::prev(e);
+  if (b != e) {
+    os << *b;
+  }
+  return os.str();
+}
+
 /**
  * read a line from is into currentLine.
  * @return the number of characters read into currentLine (excluding newline),

unit_test/stuff/string_tools_tests.cpp

@@ -79,6 +79,14 @@ TEST(Stuff, StrSplit) {
     ASSERT_EQ(std::to_string(i + 1), tokens[i]);
 }
 
+TEST(Stuff, StrJoin) {
+  std::vector<int> int_data = {1, 2, 3};
+  EXPECT_EQ("123", g2o::strJoin(int_data.begin(), int_data.end()));
+  EXPECT_EQ("1", g2o::strJoin(int_data.begin(), std::next(int_data.begin())));
+  EXPECT_EQ("", g2o::strJoin(int_data.begin(), int_data.begin()));
+  EXPECT_EQ("1, 2, 3", g2o::strJoin(int_data.begin(), int_data.end(), ", "));
+}
+
 TEST(Stuff, StrStartsWith) {
   ASSERT_FALSE(g2o::strStartsWith("Hello World!", "World!"));
   ASSERT_TRUE(g2o::strStartsWith("Hello World!", "Hello"));