vlib: add recursive macro expander to debug cli

All of the pieces have been sitting around for years.

Added several debug CLI commands:

"define <variable-name> <value>"
"undefine <variable-name>"
"show macro [noeval]"
"echo <whatever>"

Macros may refer to other macros. To defer evaluation:
"define foo \$(bar)" or some such.

The macro evaluator is not smart about "define foo \$(foo)" or more
complicated circular definitions, so don't do that.

Environment variables are available, simply use $<name-of-environment-vbl>

The macro expander has a table of (overrideable) builtin names, which
are evaluated by calling functions.

Simple example:

echo $USER
define ip1 192.168.1.1/24
define ip2 192.168.2.1/24

loop create
loop create
set int ip address loop0 $ip1
set int ip address loop1 $ip2
show int addr
show macro
undefine ip1
undefine ip2

Type: feature

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I08a800647bac573d8ae3cfd75c40061d41c5f976

1 files changed, 18 insertions, 15 deletions

diff --git a/src/vppinfra/macros.h b/src/vppinfra/macros.h
index 5c2e7033f8d..54ceda7016b 100644
--- a/src/vppinfra/macros.h
+++ b/src/vppinfra/macros.h
@@ -1,9 +1,9 @@
 /*
-  macros.h - definitions for a simple macro expander
-
-  Copyright (c) 2010, 2014 Cisco and/or its affiliates.
-
-  * Licensed under the Apache License, Version 2.0 (the "License");
+ * macros.h - definitions for a simple macro expander
+ *
+ *  Copyright (c) 2010-2020 Cisco and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
@@ -32,16 +32,19 @@ typedef struct
 {
   uword *the_builtin_eval_hash;
   uword *the_value_table_hash;
-} macro_main_t;
-
-int clib_macro_unset (macro_main_t * mm, char *name);
-int clib_macro_set_value (macro_main_t * mm, char *name, char *value);
-void clib_macro_add_builtin (macro_main_t * mm, char *name, void *eval_fn);
-i8 *clib_macro_get_value (macro_main_t * mm, char *name);
-i8 *clib_macro_eval (macro_main_t * mm, i8 * s, i32 complain);
-i8 *clib_macro_eval_dollar (macro_main_t * mm, i8 * s, i32 complain);
-void clib_macro_init (macro_main_t * mm);
-void clib_macro_free (macro_main_t * mm);
+} clib_macro_main_t;
+
+int clib_macro_unset (clib_macro_main_t * mm, char *name);
+int clib_macro_set_value (clib_macro_main_t * mm, char *name, char *value);
+void clib_macro_add_builtin (clib_macro_main_t * mm, char *name,
+			     void *eval_fn);
+i8 *clib_macro_get_value (clib_macro_main_t * mm, char *name);
+i8 *clib_macro_eval (clib_macro_main_t * mm, i8 * s, i32 complain);
+i8 *clib_macro_eval_dollar (clib_macro_main_t * mm, i8 * s, i32 complain);
+void clib_macro_init (clib_macro_main_t * mm);
+void clib_macro_free (clib_macro_main_t * mm);
+
+format_function_t format_clib_macro_main;
 
 #endif /* included_macros_h */