Make sourcemaps fully unicode aware

src/emitter.cpp

@@ -103,7 +103,10 @@ namespace Sass {
   // prepend some text or token to the buffer
   void Emitter::prepend_string(const std::string& text)
   {
-    wbuf.smap.prepend(Offset(text));
+    // do not adjust mappings for utf8 bom
+    if (text.compare("\xEF\xBB\xBF") != 0) {
+      wbuf.smap.prepend(Offset(text));
+    }
     wbuf.buffer = text + wbuf.buffer;
   }
 

src/position.cpp

@@ -1,5 +1,6 @@
 #include "sass.hpp"
 #include "position.hpp"
+#include <bitset>
 
 namespace Sass {
 
@@ -47,9 +48,20 @@ namespace Sass {
         // start new line
         column = 0;
       } else {
-        ++ column;
+        std::bitset<8> chr(*begin);
+        // skip over 10xxxxxx
+        // continuation bytes
+        if (chr[7] == 1) {
+          if (chr[6] != 0) {
+            column += 1;
+          }
+        }
+        // ascii char
+        else {
+          column += 1;
+        }
       }
-      ++begin;
+      ++ begin;
     }
     return *this;
   }

src/source_map.cpp

@@ -136,7 +136,7 @@ namespace Sass {
         }
       }
     }
-    // will adjust the offset
+    // adjust the buffer offset
     prepend(Offset(out.buffer));
     // now add the new mappings
     VECTOR_UNSHIFT(mappings, out.smap.mappings);