From: Cedric Duval <cedricduval@free.fr>
Date: Thu, 27 Feb 2014 12:06:21 +0100
Subject: ifdef

This command allows to test if a feature has been compiled in before
actually attempting to configure / use it.

Syntax:

ifdef <item> <command>

where <item> can be the name of a variable, function, or command.

Examples:

ifdef  imap-fetch-mail  'source ~/.mutt/imap_setup'
ifdef  trash  set trash=~/Mail/trash

* Patch last synced with upstream:
  - Date: 2007-02-15
  - File:
    http://cedricduval.free.fr/mutt/patches/download/patch-1.5.4.cd.ifdef.1

* Changes made:
  - Updated to 1.5.13
  - Also look for commands
  - Use mutt_strcmp in favor of ascii_strncasecmp to compare strings.

Signed-off-by: Matteo F. Vescovi <mfvescovi@gmail.com>

Gbp-Pq: Topic features
---
 doc/manual.xml.head | 22 ++++++++++++++++++++
 init.c              | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 init.h              |  2 ++
 3 files changed, 83 insertions(+)

diff --git a/doc/manual.xml.head b/doc/manual.xml.head
index baeddac..8948459 100644
--- a/doc/manual.xml.head
+++ b/doc/manual.xml.head
@@ -4411,6 +4411,28 @@ from which to read input (e.g.  <literal><command>source</command>
 
 </sect1>
 
+<sect1 id="ifdef">
+
+<title>Configuring features conditionally</title>
+
+<para>
+Usage: <literal>ifdef</literal> <emphasis>item</emphasis> <emphasis>command</emphasis>
+</para>
+
+<para>
+This command allows to test if a feature has been compiled in, before
+actually executing the command. Item can be either the name of a
+function, variable, or command. Example:
+</para>
+
+<para>
+<screen>
+ifdef imap_keepalive 'source ~/.mutt/imap_setup'
+</screen>
+</para>
+
+</sect1>
+
 <sect1 id="unhook">
 <title>Removing Hooks</title>
 
diff --git a/init.c b/init.c
index 118f06f..d95c9bc 100644
--- a/init.c
+++ b/init.c
@@ -601,6 +601,65 @@ static void remove_from_list (LIST **l, const char *str)
   }
 }
 
+static int parse_ifdef (BUFFER *tmp, BUFFER *s, unsigned long data, BUFFER *err)
+{
+  int i, j, res = 0;
+  BUFFER token;
+
+  memset (&token, 0, sizeof (token));
+  mutt_extract_token (tmp, s, 0);
+
+  /* is the item defined as a variable? */
+  res = (mutt_option_index (tmp->data) != -1);
+
+  /* a function? */
+  if (!res)
+    for (i = 0; !res && i < MENU_MAX; i++)
+    {
+      struct binding_t *b = km_get_table (Menus[i].value);
+
+      if (!b)
+	continue;
+
+      for (j = 0; b[j].name; j++)
+	if (!mutt_strcmp (tmp->data, b[j].name))
+	{
+	  res = 1;
+	  break;
+	}
+    }
+
+  /* a command? */
+  if (!res)
+    for (i = 0; Commands[i].name; i++)
+    {
+      if (!mutt_strcmp (tmp->data, Commands[i].name))
+      {
+	res = 1;
+	break;
+      }
+    }
+
+  if (!MoreArgs (s))
+  {
+    snprintf (err->data, err->dsize, _("ifdef: too few arguments"));
+    return (-1);
+  }
+  mutt_extract_token (tmp, s, M_TOKEN_SPACE);
+
+  if (res)
+  {
+    if (mutt_parse_rc_line (tmp->data, &token, err) == -1)
+    {
+      mutt_error ("Erreur: %s", err->data);
+      FREE (&token.data);
+      return (-1);
+    }
+    FREE (&token.data);
+  }
+  return 0;
+}
+
 static int parse_unignore (BUFFER *buf, BUFFER *s, unsigned long data, BUFFER *err)
 {
   do
diff --git a/init.h b/init.h
index 569f91e..6b49341 100644
--- a/init.h
+++ b/init.h
@@ -3596,6 +3596,7 @@ static int parse_lists (BUFFER *, BUFFER *, unsigned long, BUFFER *);
 static int parse_unlists (BUFFER *, BUFFER *, unsigned long, BUFFER *);
 static int parse_alias (BUFFER *, BUFFER *, unsigned long, BUFFER *);
 static int parse_unalias (BUFFER *, BUFFER *, unsigned long, BUFFER *);
+static int parse_ifdef (BUFFER *, BUFFER *, unsigned long, BUFFER *);
 static int parse_ignore (BUFFER *, BUFFER *, unsigned long, BUFFER *);
 static int parse_unignore (BUFFER *, BUFFER *, unsigned long, BUFFER *);
 static int parse_source (BUFFER *, BUFFER *, unsigned long, BUFFER *);
@@ -3646,6 +3647,7 @@ const struct command_t Commands[] = {
   { "group",		parse_group,		M_GROUP },
   { "ungroup",		parse_group,		M_UNGROUP },
   { "hdr_order",	parse_list,		UL &HeaderOrderList },
+  { "ifdef",		parse_ifdef,		0 },
 #ifdef HAVE_ICONV
   { "iconv-hook",	mutt_parse_hook,	M_ICONVHOOK },
 #endif