perf: use bc-string

dub.sdl

@@ -12,6 +12,7 @@ importPaths "./src/native"
 dependency "automem" version="~>0.6.6"
 preGenerateCommands "git submodule update --init" # despacer download
 dependency "despacer" path="./src/native/despacer/bindings/d"
+dependency "bc-string" version="1.2.2"
 
 configuration "executable" {
   targetType "executable"

dub.selections.json

@@ -2,6 +2,7 @@
 	"fileVersion": 1,
 	"versions": {
 		"automem": "0.6.7",
+		"bc-string": "1.2.2",
 		"despacer": {"path":"src/native/despacer/bindings/d"},
 		"test_allocator": "0.3.3",
 		"unit-threaded": "2.0.3"

src/native/lib.d

@@ -1,6 +1,7 @@
 module minijson.lib;
 
 import std : ctRegex, matchAll, matchFirst;
+import bc.string: String;
 
 import despacer.simd_check : supports_sse4_1, supports_avx2;
 
@@ -22,7 +23,7 @@ string minifyString(in string jsonString, in bool hasComment = false) @trusted
   auto in_string = false;
   auto in_multiline_comment = false;
   auto in_singleline_comment = false;
-  string result;
+  String result;
   size_t from = 0;
   auto rightContext = "";
 
@@ -99,7 +100,7 @@ string minifyString(in string jsonString, in bool hasComment = false) @trusted
     match.popFront();
   }
   result ~= rightContext;
-  return result;
+  return cast (string) result;
 }
 
 private bool hasNoSlashOrEvenNumberOfSlashes(in string leftContextSubstr) @safe @nogc