util: Add Join helper to join a list of strings

2 files changed, 40 insertions, 0 deletions

diff --git a/src/util/string.cpp b/src/util/string.cpp
new file mode 100644
index 0000000000..8ea3a1afc6
--- /dev/null
+++ b/src/util/string.cpp
@@ -0,0 +1,5 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/string.h>
diff --git a/src/util/string.h b/src/util/string.h
new file mode 100644
index 0000000000..dec0c19b08
--- /dev/null
+++ b/src/util/string.h
@@ -0,0 +1,35 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTIL_STRING_H
+#define BITCOIN_UTIL_STRING_H
+
+#include <functional>
+#include <string>
+#include <vector>
+
+/**
+ * Join a list of items
+ *
+ * @param list       The list to join
+ * @param separator  The separator
+ * @param unary_op   Apply this operator to each item in the list
+ */
+template <typename T, typename UnaryOp>
+std::string Join(const std::vector<T>& list, const std::string& separator, UnaryOp unary_op)
+{
+    std::string ret;
+    for (size_t i = 0; i < list.size(); ++i) {
+        if (i > 0) ret += separator;
+        ret += unary_op(list.at(i));
+    }
+    return ret;
+}
+
+inline std::string Join(const std::vector<std::string>& list, const std::string& separator)
+{
+    return Join(list, separator, [](const std::string& i) { return i; });
+}
+
+#endif // BITCOIN_UTIL_STRENCODINGS_H