[goffice] go_string_replace: new function.

[Morten Welinder <mortenw src gnome org>]

commit 75edb146e298a8ec53a7764bb5195d2b5064b2ce
Author: Morten Welinder <terra gnome org>
Date:   Wed Jun 30 20:51:39 2010 -0400

    go_string_replace: new function.

 goffice/utils/go-glib-extras.c |   28 ++++++++++++++++++++++++++++
 goffice/utils/go-glib-extras.h |    4 ++++
 2 files changed, 32 insertions(+), 0 deletions(-)
---
diff --git a/goffice/utils/go-glib-extras.c b/goffice/utils/go-glib-extras.c
index c06f0d3..98add12 100644
--- a/goffice/utils/go-glib-extras.c
+++ b/goffice/utils/go-glib-extras.c
@@ -330,6 +330,34 @@ go_string_append_c_n (GString *target, char c, gsize n)
 	memset (target->str + len, c, n);
 }
 
+void
+go_string_replace (GString *target,
+		   gsize pos, gssize oldlen,
+		   const char *txt, gssize newlen)
+{
+	gsize cplen;
+
+	g_return_if_fail (target != NULL);
+	g_return_if_fail (pos >= 0);
+	g_return_if_fail (pos < target->len);
+
+	if (oldlen < 0)
+		oldlen = target->len - pos;
+	if (newlen < 0)
+		newlen = strlen (txt);
+
+	cplen = MIN (oldlen, newlen);
+	memcpy (target->str + pos, txt, cplen);
+
+	pos += cplen;
+	oldlen -= cplen;
+	txt += cplen;
+	newlen -= cplen;
+
+	g_string_erase (target, pos, oldlen);
+	g_string_insert_len (target, pos, txt, newlen);
+}
+
 /* ------------------------------------------------------------------------- */
 
 /**
diff --git a/goffice/utils/go-glib-extras.h b/goffice/utils/go-glib-extras.h
index 2951f26..4733a5d 100644
--- a/goffice/utils/go-glib-extras.h
+++ b/goffice/utils/go-glib-extras.h
@@ -74,6 +74,10 @@ void	    go_strescape		(GString *target, char const *str);
 char const *go_strunescape		(GString *target, char const *str);
 void	    go_string_append_gstring	(GString *target, const GString *src);
 void        go_string_append_c_n        (GString *target, char c, gsize n);
+void        go_string_replace           (GString *target,
+					 gsize pos, gssize oldlen,
+					 const char *txt, gssize newlen);
+
 char const *go_guess_encoding		(char const *raw, gsize len,
 					 char const *user_guess,
 					 char **utf8_str);