[gtksourceview] words: attempt to swallow word suffix

[Christian Hergert <chergert src gnome org>]

commit 9bdb3e4d67b07e334c4fae816af8ed758fb896d6
Author: Christian Hergert <chergert redhat com>
Date:   Fri Nov 26 11:41:54 2021 -0600

    words: attempt to swallow word suffix
    
    If the trailing word characters from the insertion cursor is the suffix
    to the word being inserted, then we should swallow that text instead of
    inserting right before it.
    
    Related #181

 .../words/gtksourcecompletionwords.c               | 37 +++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)
---
diff --git a/gtksourceview/completion-providers/words/gtksourcecompletionwords.c 
b/gtksourceview/completion-providers/words/gtksourcecompletionwords.c
index 79d23b2b..898a4b72 100644
--- a/gtksourceview/completion-providers/words/gtksourcecompletionwords.c
+++ b/gtksourceview/completion-providers/words/gtksourcecompletionwords.c
@@ -477,6 +477,7 @@ gtk_source_completion_words_activate (GtkSourceCompletionProvider *provider,
                                       GtkSourceCompletionProposal *proposal)
 {
        GtkSourceCompletionWordsProposal *p = (GtkSourceCompletionWordsProposal *)proposal;
+       GtkTextMark *end_mark = NULL;
        GtkTextIter begin, end;
 
        g_assert (GTK_SOURCE_IS_COMPLETION_WORDS (provider));
@@ -487,11 +488,45 @@ gtk_source_completion_words_activate (GtkSourceCompletionProvider *provider,
        {
                GtkTextBuffer *buffer = gtk_text_iter_get_buffer (&begin);
                const char *word = gtk_source_completion_words_proposal_get_word (p);
+               int len = -1;
+
+               /* If the insertion cursor is within a word and the trailing characters
+                * of the word match the suffix of the proposal, then limit how much
+                * text we insert so that the word is completed properly.
+                */
+               if (!gtk_text_iter_ends_line (&end) &&
+                   !g_unichar_isspace (gtk_text_iter_get_char (&end)) &&
+                   !gtk_text_iter_ends_word (&end))
+               {
+                       GtkTextIter word_end = end;
+
+                       if (gtk_text_iter_forward_word_end (&word_end))
+                       {
+                               char *text = gtk_text_iter_get_slice (&end, &word_end);
+
+                               if (g_str_has_suffix (word, text))
+                               {
+                                       g_assert (strlen (word) >= strlen (text));
+                                       len = strlen (word) - strlen (text);
+                                       end_mark = gtk_text_buffer_create_mark (GTK_TEXT_BUFFER (buffer),
+                                                                              NULL,
+                                                                              &word_end,
+                                                                              FALSE);
+                               }
+                       }
+               }
 
                gtk_text_buffer_begin_user_action (GTK_TEXT_BUFFER (buffer));
                gtk_text_buffer_delete (GTK_TEXT_BUFFER (buffer), &begin, &end);
-               gtk_text_buffer_insert (GTK_TEXT_BUFFER (buffer), &begin, word, -1);
+               gtk_text_buffer_insert (GTK_TEXT_BUFFER (buffer), &begin, word, len);
                gtk_text_buffer_end_user_action (GTK_TEXT_BUFFER (buffer));
+
+               if (end_mark != NULL)
+               {
+                       gtk_text_buffer_get_iter_at_mark (GTK_TEXT_BUFFER (buffer), &end, end_mark);
+                       gtk_text_buffer_select_range (GTK_TEXT_BUFFER (buffer), &end, &end);
+                       gtk_text_buffer_delete_mark (GTK_TEXT_BUFFER (buffer), end_mark);
+               }
        }
 }