Add dchar constructor

source/tanya/container/string.d

@@ -12,6 +12,7 @@
  */  
 module tanya.container.string;
 
+import core.checkedint;
 import core.exception;
 import core.stdc.string;
 import std.algorithm.comparison;
@@ -58,6 +59,49 @@ struct String
     {
         this(allocator);
 
+        bool overflow;
+        auto size = mulu(str.length, 4, overflow);
+        assert(!overflow);
+
+        reserve(size);
+
+        auto s = data;
+        foreach (c; str)
+        {
+            if (c < 0x80)
+            {
+                *s++ = c & 0x7f;
+                length_ += 1;
+            }
+            else if (c < 0x800)
+            {
+                *s++ = 0xc0 | (c >> 6) & 0xff;
+                *s++ = 0x80 | (c & 0x3f);
+                length_ += 2;
+            }
+            else if (c < 0xd800 || c - 0xe000 < 0x2000)
+            {
+                *s++ = 0xe0 | (c >> 12) & 0xff;
+                *s++ = 0x80 | ((c >> 6) & 0x3f);
+                *s++ = 0x80 | (c & 0x3f);
+                length_ += 3;
+            }
+            else if (c - 0x10000 < 0x100000)
+            {
+                *s++ = 0xf0 | (c >> 18);
+                *s++ = 0x80 | ((c >> 12) & 0x3f);
+                *s++ = 0x80 | ((c >> 6) & 0x3f);
+                *s++ = 0x80 | (c & 0x3f);
+                length_ += 4;
+            }
+        }
+    }
+
+    ///
+    @nogc @safe unittest
+    {
+        auto s = String("Отказаться от вина - в этом страшная вина."d);
+        assert("Отказаться от вина - в этом страшная вина." == s.get);
     }
 
     /// Ditto.
@@ -175,5 +219,17 @@ struct String
         assert(s.capacity == 38);
     }
 
+	/**
+	 * Returns an array used internally by the string.
+	 * The length of the returned array may be smaller than the size of the
+     * reserved memory for the string.
+	 *
+	 * Returns: The array representing the string.
+	 */
+    inout(char[]) get() inout pure nothrow @trusted @nogc
+    {
+        return data[0 .. length_];
+    }
+
     mixin DefaultAllocator;
 }