From fd19e7a2c02e0440be21358f175b0059e80f1d0b Mon Sep 17 00:00:00 2001
From: David Lamparter <equinox@opensourcerouting.org>
Date: Wed, 23 Nov 2016 19:20:15 +0100
Subject: [PATCH] lib: parser: remove startnode & sentence_root

This removes an artificial restriction for the first token in a
command's graph to be a WORD_TKN.  The intention seems to be to prohibit
empty paths through a command, and to restrict "explosion" of choices in
the root node.

The better approach to the former is to check for an empty path after
the definition is parsed.  The latter will happen anyway, by duplication
of the command, which just makes it worse...

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
---
 lib/command_parse.y | 28 ++++++----------------------
 1 file changed, 6 insertions(+), 22 deletions(-)

diff --git a/lib/command_parse.y b/lib/command_parse.y
index 43062eb5da..c920e11380 100644
--- a/lib/command_parse.y
+++ b/lib/command_parse.y
@@ -73,7 +73,7 @@
     struct cmd_element *el;
 
     struct graph *graph;
-    struct graph_node *currnode, *startnode;
+    struct graph_node *currnode;
 
     /* pointers to copy of command docstring */
     char *docstr_start, *docstr;
@@ -91,7 +91,6 @@
 
 /* union types for parsed rules */
 %type <node> start
-%type <node> sentence_root
 %type <node> literal_token
 %type <node> placeholder_token
 %type <node> simple_token
@@ -151,9 +150,7 @@
 /* called automatically before yyparse */
 %initial-action {
   /* clear state pointers */
-  ctx->currnode = ctx->startnode = NULL;
-
-  ctx->startnode = vector_slot (ctx->graph->nodes, 0);
+  ctx->currnode = vector_slot (ctx->graph->nodes, 0);
 
   /* copy docstring and keep a pointer to the copy */
   if (ctx->el->doc)
@@ -173,15 +170,15 @@
 %%
 
 start:
-  sentence_root cmd_token_seq
+  cmd_token_seq
 {
   // tack on the command element
   terminate_graph (ctx, ctx->currnode);
 }
-| sentence_root cmd_token_seq placeholder_token '.' '.' '.'
+| cmd_token_seq placeholder_token '.' '.' '.'
 {
-  if ((ctx->currnode = add_edge_dedup (ctx->currnode, $3)) != $3)
-    graph_delete_node (ctx->graph, $3);
+  if ((ctx->currnode = add_edge_dedup (ctx->currnode, $2)) != $2)
+    graph_delete_node (ctx->graph, $2);
 
   ((struct cmd_token *)ctx->currnode->data)->allowrepeat = 1;
 
@@ -194,19 +191,6 @@ start:
 }
 ;
 
-sentence_root: WORD
-{
-  struct graph_node *root =
-    new_token_node (ctx, WORD_TKN, strdup ($1), doc_next(ctx));
-
-  if ((ctx->currnode = add_edge_dedup (ctx->startnode, root)) != root)
-    graph_delete_node (ctx->graph, root);
-
-  free ($1);
-  $$ = ctx->currnode;
-}
-;
-
 cmd_token_seq:
   /* empty */
 | cmd_token_seq cmd_token
-- 
2.39.5