From 90c8406c209a698ecc28c80ad7ebced13a84e3e8 Mon Sep 17 00:00:00 2001
From: David Lamparter <equinox@opensourcerouting.org>
Date: Thu, 26 Aug 2021 11:43:08 +0200
Subject: lib: add `![...]` syntax for easy "no" forms

This allows defining a CLI command like this:
  `[no] some setting ![VALUE]`
with VALUE being optional for the "no" form, but required for the
positive form.  It's just a `[...]` where the empty branch can only be
taken for commands starting with `no`.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
---
 lib/command_parse.y | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

(limited to 'lib/command_parse.y')

diff --git a/lib/command_parse.y b/lib/command_parse.y
index f5e42cc304..3e2cdc79af 100644
--- a/lib/command_parse.y
+++ b/lib/command_parse.y
@@ -105,6 +105,9 @@
 %token <string> MAC
 %token <string> MAC_PREFIX
 
+/* special syntax, value is irrelevant */
+%token <string> EXCL_BRACKET
+
 /* union types for parsed rules */
 %type <node> start
 %type <node> literal_token
@@ -372,6 +375,19 @@ selector: '[' selector_seq_seq ']' varname_token
 }
 ;
 
+/* ![option] productions */
+selector: EXCL_BRACKET selector_seq_seq ']' varname_token
+{
+  struct graph_node *neg_only = new_token_node (ctx, NEG_ONLY_TKN, NULL, NULL);
+
+  $$ = $2;
+  graph_add_edge ($$.start, neg_only);
+  graph_add_edge (neg_only, $$.end);
+  cmd_token_varname_set ($2.end->data, $4);
+  XFREE (MTYPE_LEX, $4);
+}
+;
+
 %%
 
 #undef scanner
-- 
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