Merge pull request sass#2543 from mgreter/bugfix/unicode-aware-error-…

…indicator

Make error indicator Unicode aware

src/parser.cpp

@@ -99,6 +99,15 @@ namespace Sass {
     // consume unicode BOM
     read_bom();
 
+    // scan the input to find invalid utf8 sequences
+    const char* it = utf8::find_invalid(position, end);
+
+    // report invalid utf8
+    if (it != end) {
+      pstate += Offset::init(position, it);
+      throw Exception::InvalidSass(pstate, "Invalid UTF-8 sequence");
+    }
+
     // create a block AST node to hold children
     Block_Obj root = SASS_MEMORY_NEW(Block, pstate, 0, true);
 

src/sass_context.cpp

@@ -72,24 +72,35 @@ namespace Sass {
 
       // now create the code trace (ToDo: maybe have util functions?)
       if (e.pstate.line != std::string::npos && e.pstate.column != std::string::npos) {
-        size_t line = e.pstate.line;
+        size_t lines = e.pstate.line;
         const char* line_beg = e.pstate.src;
-        while (line_beg && *line_beg && line) {
-          if (*line_beg == '\n') --line;
-          ++line_beg;
+        // scan through src until target line
+        // move line_beg pointer to line start
+        while (line_beg && *line_beg && lines != 0) {
+          if (*line_beg == '\n') --lines;
+          utf8::unchecked::next(line_beg); 
         }
         const char* line_end = line_beg;
+        // move line_end before next newline character
         while (line_end && *line_end && *line_end != '\n') {
           if (*line_end == '\n') break;
           if (*line_end == '\r') break;
-          line_end++;
+          utf8::unchecked::next(line_end); 
         }
-        size_t max_left = 42; size_t max_right = 78;
-        size_t move_in = e.pstate.column > max_left ? e.pstate.column - max_left : 0;
-        size_t shorten = (line_end - line_beg) - move_in > max_right ?
-          (line_end - line_beg) - move_in - max_right : 0;
-        msg_stream << ">> " << std::string(line_beg + move_in, line_end - shorten) << "\n";
-        msg_stream << "   " << std::string(e.pstate.column - move_in, '-') << "^\n";
+        if (line_end && *line_end != 0) ++ line_end;
+        size_t line_len = line_end - line_beg;
+        size_t move_in = 0; size_t shorten = 0;
+        size_t left_chars = 42; size_t max_chars = 76;
+        // reported excerpt should not exceed `max_chars` chars
+        if (e.pstate.column > line_len) left_chars = e.pstate.column;
+        if (e.pstate.column > left_chars) move_in = e.pstate.column - left_chars;
+        if (line_len > max_chars + move_in) shorten = line_len - move_in - max_chars;
+        utf8::advance(line_beg, move_in, line_end);
+        utf8::retreat(line_end, shorten, line_beg);
+        std::string sanitized; std::string marker(e.pstate.column - move_in, '-');
+        utf8::replace_invalid(line_beg, line_end, std::back_inserter(sanitized));
+        msg_stream << ">> " << sanitized << "\n";
+        msg_stream << "   " << marker << "^\n";
       }
 
       JsonNode* json_err = json_mkobject();

src/utf8/checked.h

@@ -193,6 +193,13 @@ namespace utf8
             utf8::next(it, end);
     }
 
+    template <typename octet_iterator, typename distance_type>
+    void retreat (octet_iterator& it, distance_type n, octet_iterator start)
+    {
+        for (distance_type i = 0; i < n; ++i)
+            utf8::prior(it, start);
+    }
+
     template <typename octet_iterator>
     typename std::iterator_traits<octet_iterator>::difference_type
     distance (octet_iterator first, octet_iterator last)

src/utf8/unchecked.h

@@ -116,6 +116,13 @@ namespace utf8
                 utf8::unchecked::next(it);
         }
 
+        template <typename octet_iterator, typename distance_type>
+        void retreat (octet_iterator& it, distance_type n)
+        {
+            for (distance_type i = 0; i < n; ++i)
+                utf8::unchecked::prior(it);
+        }
+
         template <typename octet_iterator>
         typename std::iterator_traits<octet_iterator>::difference_type
         distance (octet_iterator first, octet_iterator last)