Fix code to use getreg() instead

I just missed the fact that getreg() also works and I don't need to hack
to use clip_convert_selection() and the mod on it. This is kind of...
odd, because clip_convert_selection() is essentially doing the same
thing as getreg() with *very* minor differences. You would hope that
would be consolidated and refactored into a single function, but of
course not.

Also cleaned up some comments to make it clear that evaluateExpression
probably would have worked except for the autocmd blocking part.

src/MacVim/MMBackend.m

@@ -1357,10 +1357,10 @@ - (NSString *)evaluateExpression:(in bycopy NSString *)expr
     return eval;
 }
 
-/// Extracts the text currently selected in visual mode, and return them in str/len.
+/// Extracts the text currently selected in visual mode, and returns it.
 ///
-/// @return the motion type (e.g. blockwise), or -1 for failure.
-static int extractSelectedText(char_u **str, long_u *len)
+/// @return the string representing the selected text, or NULL if failure.
+static char_u *extractSelectedText()
 {
     // Note: Most of the functionality in Vim that allows for extracting useful
     // text from a selection are in the register & clipboard utility functions.
@@ -1372,7 +1372,7 @@ static int extractSelectedText(char_u **str, long_u *len)
 
     if (!(VIsual_active && (State & MODE_NORMAL))) {
         // This only works when we are in visual mode and have stuff to select.
-        return -1;
+        return NULL;
     }    
 
     // Step 1: Find a register to yank the selection to. If we don't do this we
@@ -1423,9 +1423,8 @@ static int extractSelectedText(char_u **str, long_u *len)
     ca.retval = CA_NO_ADJ_OP_END;
     do_pending_operator(&ca, 0, TRUE);
 
-    // Step 3: Convert the yank register to a single piece of useful text. This
-    // will handle all the edge cases of different modes (e.g. blockwise, etc).
-    const int convert_result = clip_convert_selection(str, len, NULL);
+    // Step 3: Extract the text from the yank ('0') register.
+    char_u *str = get_reg_contents(0, 0);
 
     // Step 4: Clean up the yank register, and restore it back.
     set_y_current(target_reg); // should not be necessary as it's done in do_pending_operator above (since regname was set to 0), but just to be safe and verbose in intention.
@@ -1447,7 +1446,7 @@ static int extractSelectedText(char_u **str, long_u *len)
 
     unblock_autocmds();
 
-    return convert_result;
+    return str;
 }
 
 /// Extract the currently selected text (in visual mode) and send that to the
@@ -1460,23 +1459,19 @@ - (BOOL)selectedTextToPasteboard:(byref NSPasteboard *)pboard
         if (!pboard)
             return YES;
 
-        long_u llen = 0; char_u *str = 0;
-        int type = extractSelectedText(&str, &llen);
-        if (type < 0)
+        char_u *str = extractSelectedText();
+        if (!str)
             return NO;
 
-        // TODO: Avoid overflow.
-        int len = (int)llen;
         if (output_conv.vc_type != CONV_NONE) {
-            char_u *conv_str = string_convert(&output_conv, str, &len);
+            char_u *conv_str = string_convert(&output_conv, str, NULL);
             if (conv_str) {
                 vim_free(str);
                 str = conv_str;
             }
         }
 
-        NSString *string = [[NSString alloc]
-            initWithBytes:str length:len encoding:NSUTF8StringEncoding];
+        NSString *string = [[NSString alloc] initWithUTF8String:str];
 
         NSArray *types = [NSArray arrayWithObject:NSStringPboardType];
         [pboard declareTypes:types owner:nil];

src/MacVim/MMWindowController.m

@@ -1685,13 +1685,11 @@ - (NSTabViewItem *)addNewTabViewItem
 /// Ask Vim to fill in the pasteboard with the currently selected text in visual mode.
 - (BOOL)askBackendForSelectedText:(NSPasteboard *)pb
 {
-    // We use a dedicated API for this instead of just using something like
-    // evaluateExpression because there's a fair bit of logic in Vim that
-    // figures out how to convert from a visual selection to an externally
-    // presentable text in the clipboard code. Part of the complexity has to do
-    // with the three modes (character/blockwise/linewise) that visual mode can
-    // be in. We would like to reuse that code, instead of hacking it via some
-    // expression evaluation results.
+    // This could potentially be done via evaluateExpression by yanking the
+    // selection, then returning the results via getreg('@') and restoring the
+    // register. Using a dedicated API is probably a little safer (e.g. it
+    // prevents TextYankPost autocmd's from triggering) and efficient
+    // and hence this is what we use for now.
     BOOL reply = NO;
     id backendProxy = [vimController backendProxy];
 

src/clipboard.c

@@ -2114,19 +2114,7 @@ clip_convert_selection(char_u **str, long_u *len, Clipboard_T *cbd)
     int_u	eolsize;
     yankreg_T	*y_ptr;
 
-    if (!cbd)
-    {
-	// MacVim extension: This makes this function much more useful as we
-	// can now extract usable texts from any registers for use instead of
-	// being forced to go through the system clipboard. This is useful for
-	// features that expose selected texts (e.g. system services) without
-	// polluting the system clipboard. 
-	int unname_register = get_unname_register();
-	if (unname_register < 0)
-	    return -1;
-	y_ptr = get_y_register(unname_register);
-    }
-    else if (cbd == &clip_plus)
+    if (cbd == &clip_plus)
 	y_ptr = get_y_register(PLUS_REGISTER);
     else
 	y_ptr = get_y_register(STAR_REGISTER);