Modifying emitter to take brackets into account.

First, instead of directly writting the left or right parenthesis
characters, now functions are called for left or right delimiters
and change in case of parenthesis or brackets.

Second, in case of bracketed list, always add the brackets. Also add
comma in case it is a one-item comma-separate list. Otherwise it would
become a one-item space-separated list.

Third, libsass prevent from emitting invisible items. Thus, an empty
space / comma separated list won't be printed at all but bracketed
list are never invisible, event the empty ones.

Author: delapuente

src/inspect.cpp

@@ -360,10 +360,19 @@ namespace Sass {
     append_string(")");
   }
 
+  std::string Inspect::lbracket(List_Ptr list) {
+    return list->is_bracketed() ? "[" : "(";
+  }
+
+  std::string Inspect::rbracket(List_Ptr list) {
+    return list->is_bracketed() ? "]" : ")";
+  }
+
   void Inspect::operator()(List_Ptr list)
   {
-    if (output_style() == TO_SASS && list->empty()) {
-      append_string("()");
+    if (list->empty() && (output_style() == TO_SASS || list->is_bracketed())) {
+      append_string(lbracket(list));
+      append_string(rbracket(list));
       return;
     }
     std::string sep(list->separator() == SASS_SPACE ? " " : ",");
@@ -374,19 +383,24 @@ namespace Sass {
 
     bool was_space_array = in_space_array;
     bool was_comma_array = in_comma_array;
+    // if the list is bracketed, always include the left bracket
+    if (list->is_bracketed()) {
+      append_string(lbracket(list));
+    }
     // probably ruby sass eqivalent of element_needs_parens
-    if (output_style() == TO_SASS &&
+    else if (output_style() == TO_SASS &&
         list->length() == 1 &&
         !list->from_selector() &&
         !SASS_MEMORY_CAST(List, list->at(0)) &&
-        !SASS_MEMORY_CAST(Selector_List, list->at(0))) {
-      append_string("(");
+        !SASS_MEMORY_CAST(Selector_List, list->at(0))
+    ) {
+      append_string(lbracket(list));
     }
     else if (!in_declaration && (list->separator() == SASS_HASH ||
         (list->separator() == SASS_SPACE && in_space_array) ||
         (list->separator() == SASS_COMMA && in_comma_array)
     )) {
-      append_string("(");
+      append_string(lbracket(list));
     }
 
     if (list->separator() == SASS_SPACE) in_space_array = true;
@@ -415,19 +429,29 @@ namespace Sass {
 
     in_comma_array = was_comma_array;
     in_space_array = was_space_array;
+
+    // if the list is bracketed, always include the right bracket
+    if (list->is_bracketed()) {
+      if (list->separator() == SASS_COMMA && list->size() == 1) {
+        append_string(",");
+      }
+      append_string(rbracket(list));
+    }
     // probably ruby sass eqivalent of element_needs_parens
-    if (output_style() == TO_SASS &&
+    else if (output_style() == TO_SASS &&
         list->length() == 1 &&
         !list->from_selector() &&
         !SASS_MEMORY_CAST(List, list->at(0)) &&
-        !SASS_MEMORY_CAST(Selector_List, list->at(0))) {
-      append_string(",)");
+        !SASS_MEMORY_CAST(Selector_List, list->at(0))
+    ) {
+      append_string(",");
+      append_string(rbracket(list));
     }
     else if (!in_declaration && (list->separator() == SASS_HASH ||
         (list->separator() == SASS_SPACE && in_space_array) ||
         (list->separator() == SASS_COMMA && in_comma_array)
     )) {
-      append_string(")");
+      append_string(rbracket(list));
     }
 
   }

src/inspect.hpp

@@ -92,6 +92,9 @@ namespace Sass {
     virtual void operator()(Complex_Selector_Ptr);
     virtual void operator()(Selector_List_Ptr);
 
+    virtual std::string lbracket(List_Ptr);
+    virtual std::string rbracket(List_Ptr);
+
     // template <typename U>
     // void fallback(U x) { fallback_impl(reinterpret_cast<AST_Node_Ptr>(x)); }
   };

src/output.cpp

@@ -155,7 +155,7 @@ namespace Sass {
             Expression_Ptr item = &list->at(list_i);
             if (!item->is_invisible()) all_invisible = false;
           }
-          if (all_invisible) bPrintExpression = false;
+          if (all_invisible && !list->is_bracketed()) bPrintExpression = false;
         }
       }
       // Print if OK