From ba0750ff48bcf97ef99602fe27322fa706a93b6b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Mon, 22 Aug 2022 01:05:05 +0200
Subject: Add Buf class.

---
 c/util.h | 45 +++++++++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 16 deletions(-)

(limited to 'c/util.h')

diff --git a/c/util.h b/c/util.h
index 1d8d222..698ce10 100644
--- a/c/util.h
+++ b/c/util.h
@@ -4,42 +4,51 @@
 #include <algorithm>
 #include <cstring>
 #include <memory>
+#include <string>
 #include <SWI-Prolog.h>
 #include <windows.h>
 
-#define CAT(a, b) a##b
-#define APPLY(a, ...) a(__VA_ARGS__)
-#define UNUSED APPLY(CAT, unused_, __COUNTER__)
+/* Buf is a span-like structure of a buffer and its size. */
+template <typename T>
+struct Buf
+{
+	T* data;
+	size_t size;
+	Buf(T* data, size_t size) : data(data), size(size) {}
+	Buf(std::basic_string<T>& s) : data(s.data()), size(s.capacity()) {}
+	template <size_t N> Buf(T (&data)[N]) : data(data), size(N) {}
+	operator T*() { return data; }
+	T& operator *() { return *data; }
+	T& operator [](size_t i) { return data[i]; }
+};
 
-/* Format static wide string. */
-template<size_t N, typename... T>
-inline int Swprintf(wchar_t (&buf)[N], const wchar_t* const fmt, T... xs)
+/* Format wide string. */
+template<typename... T>
+inline int Swprintf(Buf<wchar_t> buf, const wchar_t* const fmt, T... xs)
 {
-	return _snwprintf_s(buf, N, _TRUNCATE, fmt, xs...);
+	return _snwprintf_s(buf, buf.size, _TRUNCATE, fmt, xs...);
 }
 
 /* Format static narrow string. */
-template<size_t N, typename... T>
-inline int Sprintf(char (&buf)[N], const char* const fmt, T... xs)
+template<typename... T>
+inline int Sprintf(Buf<char> buf, const char* const fmt, T... xs)
 {
-	return _snprintf_s(buf, N, _TRUNCATE, fmt, xs...);
+	return _snprintf_s(buf, buf.size, _TRUNCATE, fmt, xs...);
 }
 
 /* Copy to static wide string buffer. */
-template <size_t N>
-inline wchar_t* Wcscpy(wchar_t (&dst)[N], const wchar_t* const src)
+inline wchar_t* Wcscpy(Buf<wchar_t> dst, const wchar_t* const src)
 {
-	const size_t len = std::min(N, wcslen(src)+1);
+	const size_t len = std::min(dst.size, wcslen(src)+1);
 	memcpy(dst, src, len*sizeof(wchar_t));
 	dst[len-1] = 0;
 	return dst;
 }
 
 /* Copy to static narrow string buffer. */
-template <size_t N>
-inline char* Strcpy(char (&dst)[N], const char* const src)
+inline char* Strcpy(Buf<char> dst, const char* const src)
 {
-	const size_t len = std::min(N, strlen(src)+1);
+	const size_t len = std::min(dst.size, strlen(src)+1);
 	memcpy(dst, src, len);
 	dst[len-1] = 0;
 	return dst;
@@ -52,4 +61,8 @@ inline int Cmp(const int a, const int b)
 	return -1;
 }
 
+#define CAT(a, b) a##b
+#define APPLY(a, ...) a(__VA_ARGS__)
+#define UNUSED APPLY(CAT, unused_, __COUNTER__)
+
 #endif
-- 
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