Improve escaped sequence parsing

src/prelexer.cpp

@@ -70,7 +70,15 @@ namespace Sass {
     {
       return sequence<
         exactly<'\\'>,
-        any_char
+        alternatives <
+          minmax_range<
+            3, 3, xdigit
+          >,
+          any_char
+        >,
+        optional <
+          exactly <' '>
+        >
       >(src);
     }
 
@@ -960,5 +968,19 @@ namespace Sass {
       return got ? pos : 0;
     }
 
+    template <size_t min, size_t max, prelexer mx>
+    const char* minmax_range(const char* src)
+    {
+      size_t got = 0;
+      const char* pos = src;
+      while (got < max) {
+        if (!mx(pos)) break;
+        ++ pos; ++ got;
+      }
+      if (got < min) return 0;
+      if (got > min) return 0;
+      return pos;
+    }
+
   }
 }

src/prelexer.hpp

@@ -393,6 +393,9 @@ namespace Sass {
     template <size_t size, prelexer mx, prelexer pad>
     const char* padded_token(const char* src);
 
+    template <size_t min, size_t max, prelexer mx>
+    const char* minmax_range(const char* src);
+
   }
 }
 

src/util.cpp

@@ -363,6 +363,8 @@ namespace Sass {
           // ToDo: Maybe we could do this without creating a substring
           uint32_t cp = strtol(s.substr (i + 1, len - 1).c_str(), nullptr, 16);
 
+          if (s[i + len] == ' ') ++ len;
+
           // assert invalid code points
           if (cp == 0) cp = 0xFFFD;
           // replace bell character