From b488e5485f4dcb24c0df5bb49d3acdb69f75920e Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Sun, 12 May 2013 16:51:35 +0200
Subject: [PATCH] always put end_token in the start symbol's follow set
---
src/cfgrammar.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/src/cfgrammar.c b/src/cfgrammar.c
index eb3239d2..a9005e9b 100644
--- a/src/cfgrammar.c
+++ b/src/cfgrammar.c
@@ -258,6 +258,7 @@ HHashSet *h_follow(HCFGrammar *g, const HCFChoice *x)
{
// consider all occurances of X in g
// the follow set of X is the union of:
+ // {$} if X is the start symbol
// given a production "A -> alpha X tail":
// if tail derives epsilon:
// first(tail) u follow(A)
@@ -275,6 +276,10 @@ HHashSet *h_follow(HCFGrammar *g, const HCFChoice *x)
assert(ret != NULL);
h_hashtable_put(g->follow, x, ret);
+ // if X is the start symbol, the end token is in its follow set
+ if(x == g->start)
+ h_hashset_put(ret, (void *)end_token);
+
// iterate over g->nts
size_t i;
HHashTableEntry *hte;
--
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