[vte] terminal: Use string_view

[Christian Persch <chpe src gnome org>]

commit c78e6d9824b65670126c8431bb08e9e31284ce69
Author: Christian Persch <chpe src gnome org>
Date:   Thu Nov 21 20:01:30 2019 +0100

    terminal: Use string_view

 src/vte.cc         | 2 +-
 src/vteinternal.hh | 2 +-
 src/widget.cc      | 3 +++
 3 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/src/vte.cc b/src/vte.cc
index b4527155..6879e0f2 100644
--- a/src/vte.cc
+++ b/src/vte.cc
@@ -4349,7 +4349,7 @@ Terminal::im_preedit_reset() noexcept
 }
 
 void
-Terminal::im_preedit_changed(char const* str,
+Terminal::im_preedit_changed(std::string_view const& str,
                              int cursorpos,
                              PangoAttrList* attrs) noexcept
 {
diff --git a/src/vteinternal.hh b/src/vteinternal.hh
index 43ebeb9f..9c49efdd 100644
--- a/src/vteinternal.hh
+++ b/src/vteinternal.hh
@@ -983,7 +983,7 @@ public:
         void im_commit(std::string_view const& str);
         void im_preedit_set_active(bool active) noexcept;
         void im_preedit_reset() noexcept;
-        void im_preedit_changed(char const* str,
+        void im_preedit_changed(std::string_view const& str,
                                 int cursorpos,
                                 PangoAttrList* attrs) noexcept;
         bool im_retrieve_surrounding();
diff --git a/src/widget.cc b/src/widget.cc
index ed2cc4df..7aef2bf5 100644
--- a/src/widget.cc
+++ b/src/widget.cc
@@ -228,6 +228,9 @@ Widget::im_preedit_changed() noexcept
        int cursorpos;
 
         gtk_im_context_get_preedit_string(m_im_context.get(), &str, &attrs, &cursorpos);
+        if (str == nullptr)
+                return;
+
         _vte_debug_print(VTE_DEBUG_EVENTS, "Input method pre-edit changed (%s,%d).\n",
                          str, cursorpos);