From c23733d2882f8d0b47e3685b2ccdf899397511d8 Mon Sep 17 00:00:00 2001
From: Federico Igne <undyamon@disroot.org>
Date: Fri, 15 Dec 2023 18:21:49 +0100
Subject: feat(cpp): add 'accumulate' and 'trim' util functions

---
 2023/include/util.h | 52 ++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 42 insertions(+), 10 deletions(-)

diff --git a/2023/include/util.h b/2023/include/util.h
index 1b5f1c5..e396e3c 100644
--- a/2023/include/util.h
+++ b/2023/include/util.h
@@ -5,35 +5,67 @@
 #include <cstring>
 #include <stdexcept>
 #include <string>
+#include <string_view>
 
 namespace util
 {
 
-/* TODO */
+namespace separators
+{
+
 constexpr char SPACE[] = " ";
 constexpr char COLON[] = ":";
 constexpr char SEMICOLON[] = ";";
+constexpr char COMMA[] = ",";
 
-inline void trim(std::string& str)
+}
+
+/** @brief Trims a string view.
+ *
+ * @param the string view.
+ */
+inline void trim(std::string_view& view)
 {
-    str.erase(str.begin(), std::find_if_not(str.cbegin(), str.cend(), ::isspace));
-    str.erase(std::find_if_not(str.crbegin(), str.crend(), ::isspace).base(), str.end());
+    std::string_view spaces{ " \f\r\n\t\v" };
+    if (auto n = view.find_first_not_of(spaces); n != view.npos)
+    {
+        view.remove_prefix(n);
+    }
+    if (auto n = view.find_last_not_of(spaces); n != view.npos)
+    {
+        view.remove_suffix(view.size() - n - 1);
+    }
 }
 
+/** @brief Split a string view according to a delimiter.
+ *
+ * This function applies a custom callable to all substring of a string
+ * view generated by splitting it according to a delimiter.
+ *
+ * @tparam delim the delimiter to split the string view.
+ * @tparam Accumulate a callable to call on each substring.
+ * @param view the string view.
+ * @param the callable object.
+ */
 template<const char* delim, typename Accumulate>
-void accumulate(const std::string& str, Accumulate acc)
+void accumulate(std::string_view& view, Accumulate acc)
 {
-    size_t pos{};
+    size_t from{}, to;
     std::string elem;
 
-    while ((pos = str.find(delim)) != std::string::npos) {
-        auto sub = str.substr(0, pos);
+    while ((to = view.find(delim, from)) != std::string_view::npos) {
+        auto sub = view.substr(from, to - from);
+        trim(sub);
+        acc(sub);
+        from = to + std::strlen(delim);
+    }
+    auto sub = view.substr(from);
+    if (not sub.empty())
+    {
         trim(sub);
         acc(sub);
-        pos += std::strlen(delim);
     }
 }
-/* ---- */
 
 /** @brief Discard element from stream by type.
  *
-- 
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