add erase function (#218)

CMakeLists.txt

@@ -33,6 +33,8 @@ if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR
      -Wno-unneeded-member-function
      -Wno-unused-member-function
      -Wno-unsafe-buffer-usage
+     -Wno-deprecated-declarations
+     -Wno-ctad-maybe-unsupported
      -Werror
   )
 elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")

include/cista/containers/string.h

@@ -45,6 +45,12 @@ struct generic_string {
     set_non_owning(s, len);
   }
 
+  generic_string(generic_string&& o) { move_from(std::move(o)); }
+  generic_string(generic_string const& o) { copy_from(o); }
+
+  generic_string& operator=(generic_string&& o) { move_from(std::move(o)); }
+  generic_string& operator=(generic_string const& o) { copy_from(o); }
+
   char* begin() noexcept { return data(); }
   char* end() noexcept { return data() + size(); }
   char const* begin() const noexcept { return data(); }
@@ -311,6 +317,19 @@ struct generic_string {
     return h_.size_;
   }
 
+  generic_string& erase(msize_t const pos, msize_t const n) {
+    if (!is_short() && !h_.self_allocated_) {
+      set_owning(view());
+    }
+    auto const size_before = size();
+    std::memmove(data() + pos, data() + pos + n, size_before - (pos + n));
+    std::memset(data() + size_before - n, 0U, n);
+    if (!is_short()) {
+      h_.size_ = size_before - n;
+    }
+    return *this;
+  }
+
   struct heap {
     bool is_short_{false};
     bool self_allocated_{false};

test/string_test.cc

@@ -1,4 +1,5 @@
 #include <iostream>
+#include <vector>
 
 #include "doctest.h"
 
@@ -31,6 +32,26 @@ TEST_CASE("string long short corner 14") {
   CHECK(s.view() == CORNER_CASE_SHORT_14);
 }
 
+TEST_CASE("string erase") {
+  auto uut = std::vector<cista::generic_string<char const*>>{};
+  auto ref = std::vector<std::string>{};
+  for (auto const s :
+       {CORNER_CASE_SHORT_14, CORNER_CASE_SHORT_15, CORNER_CASE_LONG_16}) {
+    auto x = cista::generic_string{
+        s, cista::generic_string<char const*>::non_owning};
+    x.erase(3, 7);
+    uut.emplace_back(std::move(x));
+
+    auto y = std::string{s};
+    y.erase(3, 7);
+    ref.emplace_back(std::move(y));
+  }
+
+  for (auto i = 0U; i != ref.size(); ++i) {
+    CHECK(ref[i] == uut[i].view());
+  }
+}
+
 TEST_CASE("string long short corner 15") {
   auto s = string{CORNER_CASE_SHORT_15, string::owning};
   CHECK(s.is_short());