libfoundation: Use new narrowing casts

peter-b · peter-b · commit 8f1dedde3143 · 2017-04-01T12:14:29.000+01:00
Use the new `MCNarrowCast()` and `MCNarrow()` templates in some places
where explicit narrowing occurs.

Note that when using `MCNarrow()` it is no longer necessary to know
anything about the types involved.
diff --git a/libfoundation/include/foundation-unicode.h b/libfoundation/include/foundation-unicode.h
@@ -39,7 +39,7 @@ inline bool MCUnicodeCodepointToSurrogates(codepoint_t p_codepoint,
 {
     if (p_codepoint < 0x10000)
     {
-        r_leading = unichar_t(p_codepoint); /* safe narrowing */
+        r_leading = MCNarrowCast<unichar_t>(p_codepoint);
         r_trailing = 0;
         return false;
     }
diff --git a/libfoundation/src/foundation-stream.cpp b/libfoundation/src/foundation-stream.cpp
@@ -112,23 +112,14 @@ static bool __MCMemoryInputStreamTell(MCStreamRef p_stream, filepos_t& r_positio
 {
 	__MCMemoryInputStream *self;
 	self = (__MCMemoryInputStream *)MCStreamGetExtraBytesPtr(p_stream);
-	r_position = self -> pointer;
-	return true;
+    return MCNarrow(self->pointer, r_position);
 }
 
 static bool __MCMemoryInputStreamSeek(MCStreamRef p_stream, filepos_t p_position)
 {
-    /* This type is large enough to hold both the maximum value of
-     * filepos_t and the maximum value of a size_t. */
-    using file_size_t = decltype(filepos_t{} + size_t{});
-
 	__MCMemoryInputStream *self;
 	self = (__MCMemoryInputStream *)MCStreamGetExtraBytesPtr(p_stream);
-	if (p_position < 0
-        || /*NARROWING*/file_size_t(p_position) > self -> length)
-		return false;
-	self -> pointer = (size_t)p_position;
-	return true;
+    return MCNarrow(p_position, self->pointer);
 }
 
 static MCStreamCallbacks kMCMemoryInputStreamCallbacks =

Original file line number	Diff line number	Diff line change
`@@ -39,7 +39,7 @@ inline bool MCUnicodeCodepointToSurrogates(codepoint_t p_codepoint,`
`39`	`39`	`{`
`40`	`40`	`if (p_codepoint < 0x10000)`
`41`	`41`	`{`
`42`		`- r_leading = unichar_t(p_codepoint); /* safe narrowing */`
	`42`	`+ r_leading = MCNarrowCast<unichar_t>(p_codepoint);`
`43`	`43`	`r_trailing = 0;`
`44`	`44`	`return false;`
`45`	`45`	`}`
Original file line number	Diff line number	Diff line change
`@@ -112,23 +112,14 @@ static bool __MCMemoryInputStreamTell(MCStreamRef p_stream, filepos_t& r_positio`
`112`	`112`	`{`
`113`	`113`	`__MCMemoryInputStream *self;`
`114`	`114`	`self = (__MCMemoryInputStream *)MCStreamGetExtraBytesPtr(p_stream);`
`115`		`- r_position = self -> pointer;`
`116`		`- return true;`
	`115`	`+ return MCNarrow(self->pointer, r_position);`
`117`	`116`	`}`
`118`	`117`
`119`	`118`	`static bool __MCMemoryInputStreamSeek(MCStreamRef p_stream, filepos_t p_position)`
`120`	`119`	`{`
`121`		`- /* This type is large enough to hold both the maximum value of`
`122`		`- * filepos_t and the maximum value of a size_t. */`
`123`		`- using file_size_t = decltype(filepos_t{} + size_t{});`
`124`		`-`
`125`	`120`	`__MCMemoryInputStream *self;`
`126`	`121`	`self = (__MCMemoryInputStream *)MCStreamGetExtraBytesPtr(p_stream);`
`127`		`- if (p_position < 0`
`128`		`- \|\| /NARROWING/file_size_t(p_position) > self -> length)`
`129`		`- return false;`
`130`		`- self -> pointer = (size_t)p_position;`
`131`		`- return true;`
	`122`	`+ return MCNarrow(p_position, self->pointer);`
`132`	`123`	`}`
`133`	`124`
`134`	`125`	`static MCStreamCallbacks kMCMemoryInputStreamCallbacks =`