Move /src to /subprojects

This will facilitate breaking up Nix into multiple packages for each
component with Meson.

subprojects/libutil/strings-inline.hh

@@ -0,0 +1,106 @@
+#pragma once
+
+#include "strings.hh"
+
+namespace nix {
+
+template<class C, class CharT>
+C basicTokenizeString(std::basic_string_view<CharT> s, std::basic_string_view<CharT> separators)
+{
+    C result;
+    auto pos = s.find_first_not_of(separators, 0);
+    while (pos != s.npos) {
+        auto end = s.find_first_of(separators, pos + 1);
+        if (end == s.npos)
+            end = s.size();
+        result.insert(result.end(), std::basic_string<CharT>(s, pos, end - pos));
+        pos = s.find_first_not_of(separators, end);
+    }
+    return result;
+}
+
+template<class C>
+C tokenizeString(std::string_view s, std::string_view separators)
+{
+    return basicTokenizeString<C, char>(s, separators);
+}
+
+template<class C, class CharT>
+C basicSplitString(std::basic_string_view<CharT> s, std::basic_string_view<CharT> separators)
+{
+    C result;
+    size_t pos = 0;
+    while (pos <= s.size()) {
+        auto end = s.find_first_of(separators, pos);
+        if (end == s.npos)
+            end = s.size();
+        result.insert(result.end(), std::basic_string<CharT>(s, pos, end - pos));
+        pos = end + 1;
+    }
+
+    return result;
+}
+
+template<class C>
+C splitString(std::string_view s, std::string_view separators)
+{
+    return basicSplitString<C, char>(s, separators);
+}
+
+template<class CharT, class C>
+std::basic_string<CharT> basicConcatStringsSep(const std::basic_string_view<CharT> sep, const C & ss)
+{
+    size_t size = 0;
+    bool tail = false;
+    // need a cast to string_view since this is also called with Symbols
+    for (const auto & s : ss) {
+        if (tail)
+            size += sep.size();
+        size += std::basic_string_view<CharT>{s}.size();
+        tail = true;
+    }
+    std::basic_string<CharT> s;
+    s.reserve(size);
+    tail = false;
+    for (auto & i : ss) {
+        if (tail)
+            s += sep;
+        s += i;
+        tail = true;
+    }
+    return s;
+}
+
+template<class C>
+std::string concatStringsSep(const std::string_view sep, const C & ss)
+{
+    return basicConcatStringsSep<char, C>(sep, ss);
+}
+
+template<class C>
+std::string dropEmptyInitThenConcatStringsSep(const std::string_view sep, const C & ss)
+{
+    size_t size = 0;
+
+    // TODO? remove to make sure we don't rely on the empty item ignoring behavior,
+    //       or just get rid of this function by understanding the remaining calls.
+    // for (auto & i : ss) {
+    //     // Make sure we don't rely on the empty item ignoring behavior
+    //     assert(!i.empty());
+    //     break;
+    // }
+
+    // need a cast to string_view since this is also called with Symbols
+    for (const auto & s : ss)
+        size += sep.size() + std::string_view(s).size();
+    std::string s;
+    s.reserve(size);
+    for (auto & i : ss) {
+        if (s.size() != 0)
+            s += sep;
+        s += i;
+    }
+    return s;
+}
+
+} // namespace nix