xo-object2: add DString::from_cstr + utest

src/object2/DString.cpp

@@ -4,6 +4,7 @@
  **/
 
 #include "DString.hpp"
+#include <cstring>
 
 namespace xo {
     using xo::facet::typeseq;
@@ -31,6 +32,24 @@ namespace xo {
 
             return result;
         }
+
+        DString *
+        DString::from_cstr(obj<AAllocator> mm,
+                           const char * cstr)
+        {
+            size_type len = std::strlen(cstr);
+            size_type cap = len + 1;
+
+            void * mem = mm.alloc(typeseq::id<DString>(),
+                                  sizeof(DString) + cap);
+
+            DString * result = new (mem) DString();
+            result->capacity_ = cap;
+            result->size_ = len;
+            std::memcpy(result->chars_, cstr, cap);
+
+            return result;
+        }
     } /*namespace scm*/
 } /*namespace xo*/
 

utest/DString.test.cpp

@@ -6,6 +6,7 @@
 #include <xo/object2/DString.hpp>
 #include <xo/alloc2/arena/IAllocator_DArena.hpp>
 #include <catch2/catch.hpp>
+#include <cstring>
 
 namespace xo {
     using xo::scm::DString;
@@ -30,6 +31,22 @@ namespace xo {
             REQUIRE(s->size() == 0);
             REQUIRE(s->chars()[0] == '\0');
         }
+
+        TEST_CASE("DString-from_cstr", "[object2][DString]")
+        {
+            ArenaConfig cfg { .name_ = "testarena",
+                              .size_ = 4*1024 };
+            DArena arena = DArena::map(cfg);
+            auto alloc = with_facet<AAllocator>::mkobj(&arena);
+
+            const char * cstr = "hello world";
+            DString * s = DString::from_cstr(alloc, cstr);
+
+            REQUIRE(s != nullptr);
+            REQUIRE(s->capacity() == 12);
+            REQUIRE(s->size() == 11);
+            REQUIRE(std::strcmp(s->chars(), cstr) == 0);
+        }
     } /*namespace ut*/
 } /*namespace xo*/