[tracker: 1/6] tracker-turtle-reader.c: track current line and column numbers

[Sam Thursfield <sthursfield src gnome org>]

commit 0989ac8383f8fca70d7651f55ebfacf2b0de8e54
Author: Abanoub Ghadban <abanoub gdb gmail com>
Date:   Tue Jun 29 17:26:13 2021 +0200

    tracker-turtle-reader.c: track current line and column numbers
    
    Add the functionality of tracking the current line and column numbers of the turtle file being parsed.
    These numbers will be used to specify the location of the parsing warning or error when happen.
    The seek_input() function is added, so it can be used to advance in the ontology file.
    Each time a token is parsed, the seek_input() function is called to skip the parsed token.
    It counts the number of characters and new lines in the parsed token and it update the current line and 
column numbers according to them.

 src/libtracker-data/tracker-turtle-reader.c | 63 +++++++++++++++++++++++++----
 1 file changed, 55 insertions(+), 8 deletions(-)
---
diff --git a/src/libtracker-data/tracker-turtle-reader.c b/src/libtracker-data/tracker-turtle-reader.c
index b5eb4247e..7853582e3 100644
--- a/src/libtracker-data/tracker-turtle-reader.c
+++ b/src/libtracker-data/tracker-turtle-reader.c
@@ -58,6 +58,8 @@ struct _TrackerTurtleReader {
        gchar *object_lang;
        gboolean object_is_uri;
        ParserState state;
+       goffset line_no;
+       goffset column_no;
 };
 
 enum {
@@ -100,6 +102,8 @@ tracker_turtle_reader_constructed (GObject *object)
 
        reader->buffered_stream =
                G_BUFFERED_INPUT_STREAM (g_buffered_input_stream_new (reader->stream));
+       reader->line_no = 1;
+       reader->column_no = 1;
 
        G_OBJECT_CLASS (tracker_turtle_reader_parent_class)->constructed (object);
 }
@@ -246,6 +250,53 @@ pop_stack (TrackerTurtleReader *reader)
        g_array_remove_index (reader->parser_state, reader->parser_state->len - 1);
 }
 
+static void
+calculate_num_lines_and_columns (const gchar     *start,
+                                 gsize            count,
+                                 goffset         *num_lines,
+                                 goffset         *num_columns)
+{
+       *num_lines = 0;
+       *num_columns = 0;
+
+       for (size_t i = 0; i < count; i++)
+       {
+               if (*(start + i) == '\n') {
+                       *num_lines += 1;
+                       *num_columns = 1;
+               } else {
+                       *num_columns += 1;
+               }
+       }
+}
+
+static gsize
+seek_input (TrackerTurtleReader *reader,
+            gsize                count)
+{
+       const gchar *buffer;
+       gsize size;
+       goffset num_lines;
+       goffset num_columns;
+
+       buffer = g_buffered_input_stream_peek_buffer (reader->buffered_stream,
+                                                     &size);
+       count = MIN (count, size);
+       if (!count)
+               return 0;
+
+       calculate_num_lines_and_columns (buffer, count, &num_lines, &num_columns);
+
+       reader->line_no += num_lines;
+       if (num_lines > 0) {
+               reader->column_no = num_columns;
+       } else {
+               reader->column_no += num_columns;
+       }
+       return g_input_stream_skip (G_INPUT_STREAM (reader->buffered_stream),
+                                   count, NULL, NULL);
+}
+
 static gboolean
 parse_token (TrackerTurtleReader *reader,
              const gchar         *token)
@@ -260,8 +311,7 @@ parse_token (TrackerTurtleReader *reader,
                return FALSE;
        if (strncasecmp (buffer, token, len) != 0)
                return FALSE;
-       if (!g_input_stream_skip (G_INPUT_STREAM (reader->buffered_stream),
-                                 len, NULL, NULL))
+       if (!seek_input (reader, len))
                return FALSE;
 
        return TRUE;
@@ -290,8 +340,7 @@ parse_terminal (TrackerTurtleReader  *reader,
 
        str = g_strndup (&buffer[padding], end - buffer - (2 * padding));
 
-       if (!g_input_stream_skip (G_INPUT_STREAM (reader->buffered_stream),
-                                 end - buffer, NULL, NULL)) {
+       if (!seek_input (reader, end - buffer)) {
                g_free (str);
                return FALSE;
        }
@@ -376,8 +425,7 @@ advance_whitespace (TrackerTurtleReader *reader)
                if (!(WS))
                        break;
 
-               if (!g_input_stream_skip (G_INPUT_STREAM (reader->buffered_stream),
-                                         1, NULL, NULL))
+               if (!seek_input (reader, 1))
                        break;
        }
 }
@@ -478,8 +526,7 @@ advance_whitespace_and_comments (TrackerTurtleReader *reader)
                if (!str)
                        break;
 
-               if (!g_input_stream_skip (G_INPUT_STREAM (reader->buffered_stream),
-                                         str + 1 - buffer, NULL, NULL))
+               if (!seek_input (reader, str + 1 - buffer))
                        break;
        }
 }