Rework word completion: 3 new parser functions

plugins/word-completion/completion-provider.vala

@@ -52,11 +52,9 @@ public class Scratch.Plugins.CompletionProvider : Gtk.SourceCompletionProvider,
     }
 
     public bool match (Gtk.SourceCompletionContext context) {
-        Gtk.TextIter start, end;
-        buffer.get_iter_at_offset (out end, buffer.cursor_position);
-        start = end.copy ();
-        Euclide.Completion.Parser.back_to_word_start (ref start);
-        string text = buffer.get_text (start, end, true);
+        Gtk.TextIter iter;
+        buffer.get_iter_at_offset (out iter, buffer.cursor_position);
+        string text = parser.get_word_immediately_before (iter);
 
         return parser.match (text);
     }
@@ -94,21 +92,10 @@ public class Scratch.Plugins.CompletionProvider : Gtk.SourceCompletionProvider,
         return 0;
     }
 
-    public bool get_start_iter (Gtk.SourceCompletionContext context,
-                                Gtk.SourceCompletionProposal proposal,
-                                out Gtk.TextIter iter) {
-        var mark = buffer.get_insert ();
-        Gtk.TextIter cursor_iter;
-        buffer.get_iter_at_mark (out cursor_iter, mark);
-
-        iter = cursor_iter;
-        Euclide.Completion.Parser.back_to_word_start (ref iter);
-        return true;
-    }
-
-
     private bool get_proposals (out GLib.List<Gtk.SourceCompletionItem>? props, bool no_minimum) {
         string to_find = "";
+        string completion = "";
+        bool have_selection = true;
         Gtk.TextBuffer temp_buffer = buffer;
         props = null;
 
@@ -118,12 +105,10 @@ public class Scratch.Plugins.CompletionProvider : Gtk.SourceCompletionProvider,
         to_find = temp_buffer.get_text (start, end, true);
 
         if (to_find.length == 0) {
-            temp_buffer.get_iter_at_offset (out end, buffer.cursor_position);
-
-            start = end;
-            Euclide.Completion.Parser.back_to_word_start (ref start);
-
-            to_find = buffer.get_text (start, end, false);
+            have_selection = false;
+            Gtk.TextIter iter;
+            temp_buffer.get_iter_at_offset (out iter, buffer.cursor_position);
+            to_find = parser.get_word_immediately_before (iter);
         }
 
         buffer.move_mark_by_name (COMPLETION_END_MARK_NAME, end);
@@ -135,9 +120,17 @@ public class Scratch.Plugins.CompletionProvider : Gtk.SourceCompletionProvider,
             List<string> prop_word_list;
             if (parser.get_for_word (to_find, out prop_word_list)) {
                 foreach (var word in prop_word_list) {
+                    // If there is a selection the start mark is at start of completion
+                    // otherwise it is at the cursor position but we want to replace from 
+                    // the start of the word
+                    if (have_selection) {
+                        completion = word;
+                    } else {
+                        completion = word.substring (to_find.length);
+                    }
                     var item = new Gtk.SourceCompletionItem ();
                     item.label = word;
-                    item.text = word;
+                    item.text = completion;
                     props.append (item);
                 }
 

plugins/word-completion/engine.vala

@@ -20,6 +20,8 @@
 
 public class Euclide.Completion.Parser : GLib.Object {
     public const int MINIMUM_WORD_LENGTH = 1;
+    public const int MAXIMUM_WORD_LENGTH = 50;
+
     public const int MAX_TOKENS = 1000000;
 
     private Scratch.Plugins.PrefixTree prefix_tree;
@@ -29,11 +31,6 @@ public class Euclide.Completion.Parser : GLib.Object {
         return DELIMITERS.index_of_char (c) >= 0;
     }
 
-    public static void back_to_word_start (ref Gtk.TextIter iter) {
-        iter.backward_find_char (is_delimiter, null);
-        iter.forward_char ();
-    }
-
     public Gee.HashMap<Gtk.TextView,Scratch.Plugins.PrefixTree> text_view_words;
     public bool parsing_cancelled = false;
 
@@ -98,4 +95,59 @@ public class Euclide.Completion.Parser : GLib.Object {
         }
         return true;
     }
+
+    public string get_word_immediately_before (Gtk.TextIter iter) {
+        int end_pos;
+        var text = get_sentence_at_iter (iter, out end_pos);
+        var pos = end_pos;
+        unichar uc;
+        text.get_prev_char (ref pos, out uc);
+        if (is_delimiter (uc)) {
+            return "";
+        }
+
+        pos = (end_pos - MAXIMUM_WORD_LENGTH - 1).clamp (0, end_pos);
+        if (pos >= end_pos) {
+            critical ("pos after end_pos");
+            return "";
+        }
+
+        var sliced_text = text.slice (pos, end_pos);
+        var words = sliced_text.split_set (DELIMITERS);
+        var previous_word = words[words.length - 1]; // Maybe ""
+        return previous_word;
+    }
+
+    public string get_word_immediately_after (Gtk.TextIter iter) {
+        int start_pos;
+        var text = get_sentence_at_iter (iter, out start_pos);
+        var pos = start_pos;
+        unichar uc;
+        text.get_next_char (ref pos, out uc);
+        if (is_delimiter (uc)) {
+            return "";
+        }
+
+        // Find end of search range
+        pos = (start_pos + MAXIMUM_WORD_LENGTH + 1).clamp (start_pos, text.length);
+        if (start_pos >= pos) {
+            critical ("start pos after pos");
+            return "";
+        }
+
+        // Find first word in range
+        var words = text.slice (start_pos, pos).split_set (DELIMITERS, 2);
+        var next_word = words[0]; // Maybe ""
+        return next_word;
+    }
+
+    private string get_sentence_at_iter (Gtk.TextIter iter, out int iter_sentence_offset) {
+        var start_iter = iter;
+        var end_iter = iter;
+        start_iter.backward_sentence_start ();
+        end_iter.forward_sentence_end ();
+        var text = start_iter.get_text (end_iter);
+        iter_sentence_offset = iter.get_offset () - start_iter.get_offset ();
+        return text;
+    }
 }

plugins/word-completion/plugin.vala

@@ -151,10 +151,7 @@ public class Scratch.Plugins.Completion : Peas.ExtensionBase, Peas.Activatable {
             Gtk.TextIter cursor_iter;
             buffer.get_iter_at_mark (out cursor_iter, mark);
 
-            var word_start = cursor_iter;
-            Euclide.Completion.Parser.back_to_word_start (ref word_start);
-
-            string word = buffer.get_text (word_start, cursor_iter, false);
+            string word = parser.get_word_immediately_before (cursor_iter);
             parser.add_word (word);
         }