Add FileView::Initialized constructor.

1 files changed, 17 insertions, 1 deletions

diff --git a/c/data.h b/c/data.h
index c799e52..6b9a986 100644
--- a/c/data.h
+++ b/c/data.h
@@ -70,7 +70,23 @@ constexpr inline bool HasVersion<T, std::void_t<typename T::version>> = true;
 template <typename T>
 struct FileView
 {
-	FileView(const wchar_t* filename, size_t c_) : c(c_)
+	static FileView Initialized(const wchar_t* filename, size_t c, size_t cInit = 0)
+	{
+		bool bExisting = GetFileAttributes(filename) != INVALID_FILE_ATTRIBUTES;
+		FileView fv{filename, c};
+
+		/* If file didn't exist, initialize it with defaults. */
+		if (!bExisting) {
+			T t;
+			cInit = cInit? cInit: c;
+			for (size_t i = 0; i < cInit; i++)
+				memcpy(fv+i, &t, sizeof(T));
+		}
+
+		return fv;
+	}
+
+	FileView(const wchar_t* filename, size_t c) : c(c)
 	{
 		hf = CreateFile(filename, GENERIC_READ|GENERIC_WRITE,
 		    0, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);