Make FileView more type-safe.

9 files changed, 132 insertions, 121 deletions

diff --git a/c/data.cpp b/c/data.cpp
index 60decc9..9dd6ef8 100644
--- a/c/data.cpp
+++ b/c/data.cpp
@@ -1,65 +1 @@
-#include <memory>
-#include <vector>
-
 #include "data.h"
-#include "win.h"
-
-template <typename T>
-inline unsigned char* ValToBuf(const T& val, unsigned char* const buf)
-{
-	memcpy(buf, &val, sizeof(val));
-	return buf+sizeof(val);
-}
-
-template <typename T>
-inline unsigned char* BufToVal(unsigned char* const buf, T& val)
-{
-	memcpy(&val, buf, sizeof(val));
-	return buf+sizeof(val);
-}
-
-FileView::FileView(const wchar_t* const filename, const size_t cb)
-{
-	hf = CreateFile(filename, GENERIC_READ|GENERIC_WRITE,
-	    0, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
-	if (hf == INVALID_HANDLE_VALUE) {
-		if (GetLastError() == ERROR_FILE_NOT_FOUND) {
-			hf = CreateFile(filename, GENERIC_READ|GENERIC_WRITE,
-			    0, nullptr, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, nullptr);
-			if (hf == INVALID_HANDLE_VALUE)
-				throw Win32Error{};
-		} else
-			throw Win32Error{};
-	}
-
-	LARGE_INTEGER cbMap;
-	cbMap.QuadPart = cb;
-	hm = CreateFileMapping(hf, nullptr, PAGE_READWRITE,
-	    cbMap.HighPart, cbMap.LowPart, nullptr);
-	if (!hm)
-		throw Win32Error{};
-
-	view = reinterpret_cast<unsigned char*>(MapViewOfFile(hm, FILE_MAP_ALL_ACCESS, 0, 0, 0));
-	if (!view)
-		throw Win32Error{};
-}
-
-FileView::~FileView()
-{
-	FlushViewOfFile(view, 0);
-	UnmapViewOfFile(view);
-	CloseHandle(hm);
-	CloseHandle(hf);
-}
-
-void Write(unsigned char* buf, const ElvDataA& e)
-{
-	memcpy(buf, reinterpret_cast<const unsigned char*>(&e), sizeof(e));
-}
-
-ElvDataA* Read(unsigned char* const buf)
-{
-	if (buf[0] != 'a')
-		return nullptr;
-	return reinterpret_cast<ElvDataA*>(buf);
-}
diff --git a/c/data.h b/c/data.h
index 2cc4c14..a93b256 100644
--- a/c/data.h
+++ b/c/data.h
@@ -1,15 +1,21 @@
 #ifndef DATA_H
 #define DATA_H
 
+#include <stdexcept>
+
 #include "pl.h"
 #include "util.h"
 #include "wcharptr.h"
+#include "win.h"
+
+/* The structs ending with A are written as-is to disk. As such, they
+ * should be regarded as immutable. If the format needs to be changed
+ * in the future, then new structs ending with B should be added. */
 
-/* ElvDataA and DlvDataA are written as-is to disk; note the careful
- * alignment. As such, they should be regarded as immutable. If the
- * format needs to be changed in the future, then new structs called
- * ElvDataB and DlvDataB should be added. */
+/* Note that unsigned chars are 1-byte-aligned, wchar_t are
+ * 2-byte-aligned and ints are 4-byte-aligned (on x86 Windows). */
 
+/* Basic episode data presented in episode list view. */
 struct ElvDataA
 {
 	unsigned char version = 'a';
@@ -21,6 +27,7 @@ struct ElvDataA
 	wchar_t title[128] = {0};
 };
 
+/* Extra episode data presented in data list view. */
 struct DlvDataA
 {
 	wchar_t date[32] = {0};
@@ -30,21 +37,86 @@ struct DlvDataA
 	wchar_t wiki[192] = {0};
 };
 
+/* Variable template for obtaining the version of a given struct. */
+template <typename T>
+constexpr inline unsigned char Version = T{}.version;
+
+template <typename T, typename = void>
+constexpr inline bool HasVersion = false;
+
+template <typename T>
+constexpr inline bool HasVersion<T, std::void_t<typename T::version>> = true;
+
+/* FileView objects manage a memory-mapped file. The view buffer may
+ * be treated as an array of a given type T. Note that reading and
+ * writing a view can throw structured exceptions. We ignore these. */
+template <typename T>
 struct FileView
 {
-	FileView(const wchar_t* filename, size_t cb);
-	~FileView();
-	inline operator unsigned char*() { return view; }
-	inline operator ElvDataA*() { return reinterpret_cast<ElvDataA*>(view); }
+	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);
+		if (hf == INVALID_HANDLE_VALUE) {
+			if (GetLastError() == ERROR_FILE_NOT_FOUND) {
+				hf = CreateFile(filename, GENERIC_READ|GENERIC_WRITE,
+				    0, nullptr, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, nullptr);
+				if (hf == INVALID_HANDLE_VALUE)
+					throw Win32Error{};
+			} else
+				throw Win32Error{};
+		}
+
+		LARGE_INTEGER cbMap;
+		cbMap.QuadPart = c*sizeof(T);
+		hm = CreateFileMapping(hf, nullptr, PAGE_READWRITE,
+		    cbMap.HighPart, cbMap.LowPart, nullptr);
+		if (!hm)
+			throw Win32Error{};
+
+		view = reinterpret_cast<T*>(MapViewOfFile(hm, FILE_MAP_ALL_ACCESS, 0, 0, 0));
+		if (!view)
+			throw Win32Error{};
+	}
+
+	~FileView()
+	{
+		FlushViewOfFile(view, 0);
+		UnmapViewOfFile(view);
+		CloseHandle(hm);
+		CloseHandle(hf);
+	}
+
+	/* Access element by index, performing bounds check and, if
+	 * applicable for T, version validation. */
+	T& At(size_t i)
+	{
+		if (i >= c)
+			throw std::out_of_range("index larger than buffer");
+
+		T& t = view[i];
+
+		if constexpr (HasVersion<T>)
+			if (t.version != Version<T>)
+				throw std::runtime_error("invalid struct version");
+
+		/* TODO: Use a custom exception type that informs the
+		 * user of possible data corruption. */
+
+		return t;
+	}
+
+	inline operator T*() noexcept
+	{
+		return view;
+	}
+
 	HANDLE hf;
 	HANDLE hm;
-	unsigned char* view;
-	/* TODO: Handle exceptions on read and write... */
+	T* view;
+	size_t c;
 };
-
-void Write(unsigned char* buf, const ElvDataA& e);
-ElvDataA* Read(unsigned char* buf);
-
+	
 inline int FromWeb(const int iEp, ElvDataA& e, DlvDataA& d) noexcept
 {
 	WcharPtr title, wiki, date, source, hint;
diff --git a/c/debug.cpp b/c/debug.cpp
index 6b5baff..b23df37 100644
--- a/c/debug.cpp
+++ b/c/debug.cpp
@@ -19,13 +19,13 @@ Benchmark::Benchmark(const char* const name, const int id, const int avgmax)
 	if (!freq) {
 		static LARGE_INTEGER liFreq;
 		if (!QueryPerformanceFrequency(&liFreq))
-			throw Win32Error();
+			throw Win32Error{};
 		freq = liFreq.QuadPart;
 	}
 
 	LARGE_INTEGER liTicks;
 	if (!QueryPerformanceCounter(&liTicks))
-		throw Win32Error();
+		throw Win32Error{};
 	ticks = liTicks.QuadPart;
 }
 
diff --git a/c/episodelistview.cpp b/c/episodelistview.cpp
index 0451132..be753a6 100644
--- a/c/episodelistview.cpp
+++ b/c/episodelistview.cpp
@@ -12,9 +12,11 @@
 #include "util.h"
 #include "win.h"
 
+constexpr size_t MAX_EPISODES = 8192;
+
 EpisodeListView::EpisodeListView(const HWND hWndParent)
 	: ListView(hWndParent, reinterpret_cast<HMENU>(IDC_EPISODELISTVIEW), 0),
-	  m_fv(L"elvdata.dat", sizeof(ElvDataA)*8192)
+	  m_fv(L"elvdata.dat", MAX_EPISODES)
 {
 	LVCOLUMN lvc;
 
@@ -55,7 +57,7 @@ void EpisodeListView::HandleContextMenu(const WORD command)
 
 	LVITEM lvi = {LVIF_PARAM, -1};
 	while (FindNextItem(&lvi, LVNI_SELECTED)) {
-		ElvDataA& e = static_cast<ElvDataA*>(m_fv)[lvi.lParam-1];
+		ElvDataA& e = m_fv.At(lvi.lParam-1);
 
 		if (ID_SUBGROUP(command) == IDG_CTX_RATE) {
 			/* Process rate commands. */
@@ -117,7 +119,7 @@ LRESULT EpisodeListView::HandleNotify(const LPARAM lParam)
 	case LVN_GETDISPINFO:	/* Display item. */
 	    {
 		NMLVDISPINFO* const nm = reinterpret_cast<NMLVDISPINFO*>(lParam);
-		ElvDataA& e = reinterpret_cast<ElvDataA*>(m_fv.view)[nm->item.lParam-1];
+		ElvDataA& e = m_fv.At(nm->item.lParam-1);
 		wchar_t* vs[] = {e.siEp, e.title, e.sRating}; /* ELVSIEPISODE, ELVSITITLE, ELVSIRATING */
 		nm->item.pszText = vs[nm->item.iSubItem];
 		return 0;
@@ -166,7 +168,7 @@ LRESULT EpisodeListView::HandleNotify(const LPARAM lParam)
 			break;
 		case CDDS_ITEMPREPAINT:
 		    {
-			const ElvDataA& e = static_cast<ElvDataA*>(m_fv)[nm->nmcd.lItemlParam-1];
+			const ElvDataA& e = m_fv.At(nm->nmcd.lItemlParam-1);
 			if (!e.bWatched) {
 				extern HFONT g_hfBold;
 				Require(SelectObject(nm->nmcd.hdc, g_hfBold));
@@ -329,8 +331,8 @@ int CALLBACK EpisodeListView::SortProc(const LPARAM iItem1, const LPARAM iItem2,
 	 * If m_iSortCol is negative, the order is descending. */
 	const int order = Cmp(elv->m_iSortCol, 0);
 
-	const ElvDataA& e1 = static_cast<ElvDataA*>(elv->m_fv)[lvi1.lParam-1];
-	const ElvDataA& e2 = static_cast<ElvDataA*>(elv->m_fv)[lvi2.lParam-1];
+	const ElvDataA& e1 = elv->m_fv[lvi1.lParam-1];
+	const ElvDataA& e2 = elv->m_fv.At(lvi2.lParam-1);
 
 	switch (abs(elv->m_iSortCol)-1) {
 	case ELVSIEPISODE:
@@ -398,7 +400,7 @@ void EpisodeListView::Update()
 		SendMessage(hWnd, WM_SETREDRAW, FALSE, 0);
 		ListView_DeleteAllItems(hWnd);
 		for (int iEp = 1; iEp <= cEp; iEp++) {
-			ElvDataA e = static_cast<ElvDataA*>(m_fv)[iEp-1];
+			ElvDataA e = m_fv.At(iEp-1);
 
 			if (!e.siEp[0])
 				continue;
diff --git a/c/episodelistview.h b/c/episodelistview.h
index 0604d15..f58f3ca 100644
--- a/c/episodelistview.h
+++ b/c/episodelistview.h
@@ -33,7 +33,7 @@ struct EpisodeListView : public ListView
 private:
 	int m_iSortCol;
 	static int CALLBACK SortProc(LPARAM lParam1, LPARAM lParam2, LPARAM extra);
-	FileView m_fv;
+	FileView<ElvDataA> m_fv;
 };
 
 #endif
diff --git a/c/test.cpp b/c/test.cpp
index cecc408..84e0631 100644
--- a/c/test.cpp
+++ b/c/test.cpp
@@ -54,40 +54,42 @@ TESTS
 		FromProlog(6, e1_0);
 		FromProlog(10, e2_0);
 		{
-			FileView fv{L"tmp.dat", sizeof(ElvDataA)*2};
-			Write(fv, e1_0);
-			Write(reinterpret_cast<unsigned char*>(static_cast<ElvDataA*>(fv)+1), e2_0);
+			FileView<ElvDataA> fv{L"tmp.dat", 2};
+			memcpy(fv+0, &e1_0, sizeof(e1_0));
+			memcpy(fv+1, &e2_0, sizeof(e2_0));
 		}
 		{
-			FileView fv{L"tmp.dat", sizeof(ElvDataA)};
-			ElvDataA* e1 = Read(fv);
-			if (e1_0.rating != e1->rating)
-				FAIL("rating is different (%d/%d)", e1_0.rating, e1->rating);
-			if (e1_0.bWatched != e1->bWatched)
+			FileView<ElvDataA> fv{L"tmp.dat", 2};
+			const ElvDataA& e1 = *fv;
+			if (e1.version != 'a')
+				FAIL("version is different");
+			if (e1_0.rating != e1.rating)
+				FAIL("rating is different (%d/%d)", e1_0.rating, e1.rating);
+			if (e1_0.bWatched != e1.bWatched)
 				FAIL("bWatched is different");
-			if (e1_0.bTVOriginal != e1->bTVOriginal)
+			if (e1_0.bTVOriginal != e1.bTVOriginal)
 				FAIL("bTVOriginal is different");
-			if (wcscmp(e1_0.sRating, e1->sRating) != 0)
+			if (wcscmp(e1_0.sRating, e1.sRating) != 0)
 				FAIL("sRating is different");
-			if (wcscmp(e1_0.siEp, e1->siEp) != 0)
+			if (wcscmp(e1_0.siEp, e1.siEp) != 0)
 				FAIL("siEp is different");
-			if (wcscmp(e1_0.title, e1->title) != 0)
+			if (wcscmp(e1_0.title, e1.title) != 0)
 				FAIL("title is different");
 		}
 		{
-			FileView fv{L"tmp.dat", sizeof(ElvDataA)*2};
-			ElvDataA* e2 = Read(reinterpret_cast<unsigned char*>(static_cast<ElvDataA*>(fv)+1));
-			if (e2_0.rating != e2->rating)
-				FAIL("rating is different (%d/%d)", e2_0.rating, e2->rating);
-			if (e2_0.bWatched != e2->bWatched)
+			FileView<unsigned char> fv{L"tmp.dat", 2*sizeof(ElvDataA)};
+			ElvDataA& e2 = *reinterpret_cast<ElvDataA*>(&fv.At(sizeof(ElvDataA)));
+			if (e2_0.rating != e2.rating)
+				FAIL("rating is different (%d/%d)", e2_0.rating, e2.rating);
+			if (e2_0.bWatched != e2.bWatched)
 				FAIL("bWatched is different");
-			if (e2_0.bTVOriginal != e2->bTVOriginal)
+			if (e2_0.bTVOriginal != e2.bTVOriginal)
 				FAIL("bTVOriginal is different");
-			if (wcscmp(e2_0.sRating, e2->sRating) != 0)
+			if (wcscmp(e2_0.sRating, e2.sRating) != 0)
 				FAIL("sRating is different");
-			if (wcscmp(e2_0.siEp, e2->siEp) != 0)
+			if (wcscmp(e2_0.siEp, e2.siEp) != 0)
 				FAIL("siEp is different");
-			if (wcscmp(e2_0.title, e2->title) != 0)
+			if (wcscmp(e2_0.title, e2.title) != 0)
 				FAIL("title is different");
 		}
 		//DeleteFile(L"tmp.dat");
@@ -100,20 +102,19 @@ TESTS
 			return;
 
 		{
-			FileView fv{L"tmp.dat", sizeof(ElvDataA)*8192};
-			unsigned char* p = fv;
+			FileView<ElvDataA> fv{L"tmp.dat", 8192};
+			ElvDataA* p = fv;
 
 			for (int iEp = 1; iEp <= cEp; iEp++) {
 				ElvDataA e;
 				FromProlog(iEp, e);
-				Write(p, e);
-				p += sizeof(e);
+				memcpy(p, &e, sizeof(e));
+				p++;
 			}
 		}
 		{
-			FileView fv{L"tmp.dat", sizeof(ElvDataA)*8192};
-			ElvDataA* ve = reinterpret_cast<ElvDataA*>(fv.view);
-			ElvDataA& e = ve[9];
+			FileView<ElvDataA> fv{L"tmp.dat", 8192};
+			ElvDataA& e = fv.At(9);
 			if (wcscmp(e.title, L"Pro Soccer Player Blackmail Case") != 0)
 				FAIL("title is not correct");
 		}
@@ -128,7 +129,7 @@ int RunTests()
 		//EpisodeDataFromWeb{},
 		EpisodeDataFromProlog{},
 		IO{},
-		MigrateElvDataFromPrologToDisk{},
+		//MigrateElvDataFromPrologToDisk{},
 	};
 
 	printf("Results (%llu tests):\n", sizeof(tests)/sizeof(*tests));
diff --git a/c/wcharptr.cpp b/c/wcharptr.cpp
index f659767..f7cb948 100644
--- a/c/wcharptr.cpp
+++ b/c/wcharptr.cpp
@@ -11,7 +11,7 @@ WcharPtr WcharPtr::FromNarrow(const char* const src, const int cp)
 	wchar_t* dst = new wchar_t[cchWide];
 	if (!MultiByteToWideChar(cp, 0, src, cchNarrow, dst, cchWide)) {
 		delete dst;
-		throw Win32Error();
+		throw Win32Error{};
 	}
 	return dst;
 }
diff --git a/c/win.cpp b/c/win.cpp
index 95ec9a7..28dba27 100644
--- a/c/win.cpp
+++ b/c/win.cpp
@@ -145,7 +145,7 @@ Library::Library(const wchar_t* const lib)
 {
 	m_hModule = LoadLibrary(lib);
 	if (!m_hModule)
-		throw Win32Error();
+		throw Win32Error{};
 }
 
 Library::~Library()
diff --git a/c/win.h b/c/win.h
index e9a6839..a77362f 100644
--- a/c/win.h
+++ b/c/win.h
@@ -53,7 +53,7 @@ T* Library::GetProcAddress(const char* const szProc) noexcept
 template <typename T>
 inline T Require(const T x)
 {
-	if (!x) throw Win32Error();
+	if (!x) throw Win32Error{};
 	return x;
 }
 
@@ -62,7 +62,7 @@ template <typename T>
 inline T Prefer(const T x)
 {
 	if (!x) {
-		EBMessageBox(Win32Error().What(), L"System Error", MB_ICONWARNING);
+		EBMessageBox(Win32Error{}.What(), L"System Error", MB_ICONWARNING);
 		return (T)0;
 	}
 	return x;