[gnumeric] Avoid extra undo items when entering expressions.

[Andreas J. Guelzow <guelzow src gnome org>]

commit e14523caee9e690ce29a365d94904e3d6144eb44
Author: Andreas J Guelzow <aguelzow pyrshep ca>
Date:   Fri Aug 13 17:42:47 2010 -0600

    Avoid extra undo items when entering expressions.
    
    2010-08-13  Andreas J. Guelzow <aguelzow pyrshep ca>
    
    	* src/commands.c (cmd_set_text_full_check_texpr): new
    	(cmd_set_text_full): check whether we are entering the same expression
    	  already in all cells.

 ChangeLog      |    6 ++++++
 src/commands.c |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 2c841a5..ac0f61f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2010-08-13  Andreas J. Guelzow <aguelzow pyrshep ca>
 
+	* src/commands.c (cmd_set_text_full_check_texpr): new
+	(cmd_set_text_full): check whether we are entering the same expression
+	  already in all cells.
+
+2010-08-13  Andreas J. Guelzow <aguelzow pyrshep ca>
+
 	* src/commands.c (cmd_set_text_full): always autofit the rows and also
 	  autofit the columns for non-strings.
 
diff --git a/src/commands.c b/src/commands.c
index 845b258..bd6e534 100644
--- a/src/commands.c
+++ b/src/commands.c
@@ -748,6 +748,14 @@ cmd_set_text_full_autofit_col (Sheet *sheet, GnmRange *r)
 }
 
 
+static GnmValue *
+cmd_set_text_full_check_texpr (GnmCellIter const *iter, GnmExprTop const  *texpr)
+{
+	if (iter->cell == NULL || 
+	    !gnm_expr_top_equal (iter->cell->base.texpr, texpr))
+		return VALUE_TERMINATE;
+	return NULL;
+}
 
 /******************************************************************/
 
@@ -817,6 +825,30 @@ cmd_set_text_full (WorkbookControl *wbc, GSList *selection, GnmEvalPos *ep,
 	if (texpr != NULL) {
 		GOFormat *sf;
 		GnmStyle *new_style = NULL;
+		gboolean same_texpr = TRUE;
+
+		/* We should check whether we are in fact changing anything: */
+		for (l = selection; l != NULL && same_texpr; l = l->next) {
+			GnmRange *r = l->data;
+			GnmValue *val =
+				sheet_foreach_cell_in_range 
+				(sheet, CELL_ITER_ALL,
+				 r->start.col, r->start.row,
+				 r->end.col, r->end.row,
+				 (CellIterFunc) cmd_set_text_full_check_texpr, 
+				 (gpointer) texpr);
+			
+			same_texpr = (val != VALUE_TERMINATE);
+			if (val != NULL && same_texpr)
+				value_release (val);
+		}
+
+		if (same_texpr) {
+			gnm_expr_top_unref (texpr);
+			g_free (name);
+			range_fragment_free (selection);			
+			return TRUE;
+		}
 
 		text = g_strdup_printf (_("Inserting expression in %s"), name);