pbx: Create pbx_sw.c for management of 'struct ast_sw'.

This changes context switches from a linked list to a vector, makes
'struct ast_sw' opaque to pbx.c.

Although ast_walk_context_switches is maintained the procedure is no
longer efficient except for the first call (inc==NULL).  This
functionality is replaced by two new functions implemented by vector
macros.
* ast_context_switches_count (AST_VECTOR_SIZE)
* ast_context_switches_get (AST_VECTOR_GET)

As with ast_walk_context_switches callers of these functions are
expected to have locked contexts.  Only a few places in Asterisk walked
the switches, they have been converted to use the new functions.

Change-Id: I08deb016df22eee8288eb03de62593e45a1f0998

main/pbx_sw.c

@@ -0,0 +1,107 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2016, CFWare, LLC
+ *
+ * Corey Farrell <git@cfware.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \brief Dialplan switch routines.
+ *
+ * \author Corey Farrell <git@cfware.com>
+ */
+
+/*** MODULEINFO
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_REGISTER_FILE()
+
+#include "asterisk/_private.h"
+#include "asterisk/pbx.h"
+#include "pbx_private.h"
+
+/*! \brief ast_sw: Switch statement in extensions.conf */
+struct ast_sw {
+	const char *name;
+	/*! Registrar */
+	const char *registrar;
+	/*! Data load */
+	const char *data;
+	int eval;
+	AST_LIST_ENTRY(ast_sw) list;
+	char stuff[0];
+};
+
+const char *ast_get_switch_name(const struct ast_sw *sw)
+{
+	return sw ? sw->name : NULL;
+}
+
+const char *ast_get_switch_data(const struct ast_sw *sw)
+{
+	return sw ? sw->data : NULL;
+}
+
+int ast_get_switch_eval(const struct ast_sw *sw)
+{
+	return sw->eval;
+}
+
+const char *ast_get_switch_registrar(const struct ast_sw *sw)
+{
+	return sw ? sw->registrar : NULL;
+}
+
+struct ast_sw *sw_alloc(const char *value, const char *data, int eval, const char *registrar)
+{
+	struct ast_sw *new_sw;
+	int length;
+	char *p;
+
+	if (!data) {
+		data = "";
+	}
+	length = sizeof(struct ast_sw);
+	length += strlen(value) + 1;
+	length += strlen(data) + 1;
+
+	/* allocate new sw structure ... */
+	if (!(new_sw = ast_calloc(1, length))) {
+		return NULL;
+	}
+
+	/* ... fill in this structure ... */
+	p = new_sw->stuff;
+	new_sw->name = p;
+	strcpy(p, value);
+
+	p += strlen(value) + 1;
+	new_sw->data = p;
+	strcpy(p, data);
+
+	new_sw->eval	  = eval;
+	new_sw->registrar = registrar;
+
+	return new_sw;
+}
+
+void sw_free(struct ast_sw *sw)
+{
+	ast_free(sw);
+}
+