[vte/wip/rishi/precmd-preexec: 3/4] Support precmd notifications from an interactive shell

[Debarshi Ray <debarshir src gnome org>]

commit d6b720d17c0865772a625e67d6fa4591904f9892
Author: Debarshi Ray <debarshir gnome org>
Date:   Wed May 2 17:20:30 2018 +0200

    Support precmd notifications from an interactive shell
    
    Add sequences
      OSC 777 ; precmd BEL
      OSC 777 ; precmd ST
    
    that can be used from an interactive shell's precmd hook to notify the
    terminal emulator that a first level prompt is about to be shown.
    Examples of such hooks are Bash's PROMPT_COMMAND and Zsh's precmd.
    
    The OSC 777 escape sequence is taken from Enlightenment's Terminology:
    https://phab.enlightenment.org/T1765
    
    https://bugzilla.gnome.org/show_bug.cgi?id=711059
    https://bugzilla.gnome.org/show_bug.cgi?id=711060

 src/vte.cc            |    7 +++++++
 src/vte.sh            |    2 +-
 src/vte/vteterminal.h |    3 ++-
 src/vtegtk.cc         |   18 ++++++++++++++++++
 src/vtegtk.hh         |    1 +
 src/vteinternal.hh    |    1 +
 src/vteseq.cc         |    4 +++-
 7 files changed, 33 insertions(+), 3 deletions(-)
---
diff --git a/src/vte.cc b/src/vte.cc
index 1a7b533..c129bf2 100644
--- a/src/vte.cc
+++ b/src/vte.cc
@@ -10769,6 +10769,13 @@ VteTerminalPrivate::emit_pending_signals()
                 m_shell_preexec = FALSE;
         }
 
+        if (m_shell_precmd) {
+                _vte_debug_print (VTE_DEBUG_SIGNALS,
+                                  "Emitting `shell-precmd'.\n");
+                g_signal_emit(object, signals[SIGNAL_SHELL_PRECMD], 0);
+                m_shell_precmd = FALSE;
+        }
+
        if (m_window_title_changed) {
                 if (m_window_title != m_window_title_pending) {
                         m_window_title.swap(m_window_title_pending);
diff --git a/src/vte.sh b/src/vte.sh
index 4ade59d..ca87d00 100644
--- a/src/vte.sh
+++ b/src/vte.sh
@@ -52,7 +52,7 @@ __vte_osc7 () {
 __vte_prompt_command() {
   local pwd='~'
   [ "$PWD" != "$HOME" ] && pwd=${PWD/#$HOME\//\~\/}
-  printf "\u009D0;%s@%s:%s\u009C%s" "${USER}" "${HOSTNAME%%.*}" "${pwd}" "$(__vte_osc7)"
+  printf "\u009D777;precmd\u009C\u009D0;%s@%s:%s\u009C%s" "${USER}" "${HOSTNAME%%.*}" "${pwd}" 
"$(__vte_osc7)"
 }
 
 case "$TERM" in
diff --git a/src/vte/vteterminal.h b/src/vte/vteterminal.h
index 5f3d325..2ab9c51 100644
--- a/src/vte/vteterminal.h
+++ b/src/vte/vteterminal.h
@@ -104,10 +104,11 @@ struct _VteTerminalClass {
 
        void (*bell)(VteTerminal* terminal);
 
+       void (*shell_precmd)(VteTerminal* terminal);
        void (*shell_preexec)(VteTerminal* terminal);
 
         /* Padding for future expansion. */
-        gpointer padding[15];
+        gpointer padding[14];
 
         VteTerminalClassPrivate *priv;
 };
diff --git a/src/vtegtk.cc b/src/vtegtk.cc
index 1e5282c..c956905 100644
--- a/src/vtegtk.cc
+++ b/src/vtegtk.cc
@@ -700,6 +700,7 @@ vte_terminal_class_init(VteTerminalClass *klass)
        klass->child_exited = NULL;
        klass->encoding_changed = NULL;
        klass->char_size_changed = NULL;
+       klass->shell_precmd = NULL;
        klass->shell_preexec = NULL;
        klass->window_title_changed = NULL;
        klass->icon_title_changed = NULL;
@@ -777,6 +778,23 @@ vte_terminal_class_init(VteTerminalClass *klass)
                              1, G_TYPE_INT);
 
         /**
+         * VteTerminal::shell-precmd:
+         * @vteterminal: the object which received the signal
+         *
+         * Emitted right before an interactive shell shows a
+         * first-level prompt.
+         */
+        signals[SIGNAL_SHELL_PRECMD] =
+                g_signal_new(I_("shell-precmd"),
+                             G_OBJECT_CLASS_TYPE(klass),
+                             G_SIGNAL_RUN_LAST,
+                             G_STRUCT_OFFSET(VteTerminalClass, shell_precmd),
+                             NULL,
+                             NULL,
+                             g_cclosure_marshal_VOID__VOID,
+                             G_TYPE_NONE, 0);
+
+        /**
          * VteTerminal::shell-preexec:
          * @vteterminal: the object which received the signal
          *
diff --git a/src/vtegtk.hh b/src/vtegtk.hh
index cb7b02f..7fbb9a3 100644
--- a/src/vtegtk.hh
+++ b/src/vtegtk.hh
@@ -52,6 +52,7 @@ enum {
         SIGNAL_RESIZE_WINDOW,
         SIGNAL_RESTORE_WINDOW,
         SIGNAL_SELECTION_CHANGED,
+        SIGNAL_SHELL_PRECMD,
         SIGNAL_SHELL_PREEXEC,
         SIGNAL_TEXT_DELETED,
         SIGNAL_TEXT_INSERTED,
diff --git a/src/vteinternal.hh b/src/vteinternal.hh
index 1c1db50..550aed2 100644
--- a/src/vteinternal.hh
+++ b/src/vteinternal.hh
@@ -572,6 +572,7 @@ public:
         gboolean m_cursor_moved_pending;
         gboolean m_contents_changed_pending;
 
+        gboolean m_shell_precmd;
         gboolean m_shell_preexec;
 
         std::string m_window_title{};
diff --git a/src/vteseq.cc b/src/vteseq.cc
index 5c6492a..2e62d65 100644
--- a/src/vteseq.cc
+++ b/src/vteseq.cc
@@ -1348,7 +1348,9 @@ VteTerminalPrivate::handle_urxvt_extension(vte::parser::Sequence const& seq,
                 return;
         }
 
-        if (*token == "preexec") {
+        if (*token == "precmd") {
+                m_shell_precmd = TRUE;
+        } else if (*token == "preexec") {
                 m_shell_preexec = TRUE;
         }
 }