[gnome-builder] string: add helper to underline matching substrings

[Christian Hergert <chergert src gnome org>]

commit 4de60ca097d73f32a992b91816d84e30051d5928
Author: Christian Hergert <christian hergert me>
Date:   Mon Jan 19 04:50:29 2015 -0800

    string: add helper to underline matching substrings
    
    Not particularly the fastest implementation, but seems quick enough to
    use for global search.

 src/gnome-builder.mk |    1 +
 src/util/gb-string.c |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/util/gb-string.h |    3 ++
 3 files changed, 58 insertions(+), 0 deletions(-)
---
diff --git a/src/gnome-builder.mk b/src/gnome-builder.mk
index 426b925..6f46bc8 100644
--- a/src/gnome-builder.mk
+++ b/src/gnome-builder.mk
@@ -202,6 +202,7 @@ libgnome_builder_la_SOURCES = \
        src/util/gb-pango.h \
        src/util/gb-rgba.c \
        src/util/gb-rgba.h \
+       src/util/gb-string.c \
        src/util/gb-string.h \
        src/util/gb-widget.c \
        src/util/gb-widget.h \
diff --git a/src/util/gb-string.c b/src/util/gb-string.c
new file mode 100644
index 0000000..ffb96db
--- /dev/null
+++ b/src/util/gb-string.c
@@ -0,0 +1,54 @@
+/* gb-string.c
+ *
+ * Copyright (C) 2015 Christian Hergert <christian hergert me>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "gb-string.h"
+
+gchar *
+gb_str_highlight (const gchar *str,
+                  const gchar *match)
+{
+  GString *ret;
+  gunichar str_ch;
+  gunichar match_ch;
+
+  g_return_val_if_fail (str, NULL);
+  g_return_val_if_fail (match, NULL);
+
+  ret = g_string_new (NULL);
+
+  for (; *str; str = g_utf8_next_char (str))
+    {
+      str_ch = g_utf8_get_char (str);
+      match_ch = g_utf8_get_char (match);
+
+      if (str_ch == match_ch)
+        {
+          g_string_append (ret, "<u>");
+          g_string_append_unichar (ret, str_ch);
+          g_string_append (ret, "</u>");
+
+          match = g_utf8_next_char (match);
+        }
+      else
+        {
+          g_string_append_unichar (ret, str_ch);
+        }
+    }
+
+  return g_string_free (ret, FALSE);
+}
diff --git a/src/util/gb-string.h b/src/util/gb-string.h
index eb27fc5..682a435 100644
--- a/src/util/gb-string.h
+++ b/src/util/gb-string.h
@@ -28,6 +28,9 @@ G_BEGIN_DECLS
 #define gb_str_equal0(s1,s2) \
   (((s1) == (s2)) || ((s1) && (s2) && g_str_equal(s1,s2)))
 
+gchar *gb_str_highlight (const gchar *src,
+                         const gchar *match);
+
 G_END_DECLS
 
 #endif /* GB_STRING_H */