From 92f16a4d14be273721fff1c46a55864aba2116f4 Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Fri, 14 Jun 2013 12:24:18 +0200
Subject: [PATCH] proper LALR example with conflict in LR(0)
---
src/backends/lalr.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/src/backends/lalr.c b/src/backends/lalr.c
index 7e83c538..9c9b864e 100644
--- a/src/backends/lalr.c
+++ b/src/backends/lalr.c
@@ -667,6 +667,8 @@ int h_lalr_compile(HAllocator* mm__, HParser* parser, const void* params)
H_FOREACH(eg->smap, HCFChoice *lhs, HLRTransition *t)
if(t->symbol != item->lhs)
continue;
+ assert(lhs->type == HCF_CHOICE); // XXX could be CHARSET
+
for(HCFSequence **p=lhs->seq; *p; p++) {
HCFChoice **rhs = (*p)->items;
if(!match_production(eg, rhs, item->rhs, state))
@@ -986,21 +988,21 @@ HParserBackendVTable h__lalr_backend_vtable = {
// dummy!
int test_lalr(void)
{
- /* for k=2:
-
- S -> A | B
- A -> X Y a
- B -> Y b
- X -> x | ''
- Y -> y -- for k=3 use "yy"
+ /*
+ S -> E
+ E -> E '-' T
+ | T
+ T -> '(' E ')'
+ | N
+ N -> '0' -- also try [0-9] for the charset paths
*/
- // XXX make LALR example
- HParser *X = h_optional(h_in((uint8_t *)"rst", 3));
- HParser *Y = h_sequence(h_ch('y'), h_ch('y'), NULL);
- HParser *A = h_sequence(X, Y, h_ch('a'), NULL);
- HParser *B = h_sequence(Y, h_ch('b'), NULL);
- HParser *p = h_choice(A, B, NULL);
+ HParser *N = h_sequence(h_ch('n'), NULL);
+ HParser *E = h_indirect();
+ HParser *T = h_choice(h_sequence(h_ch('('), E, h_ch(')'), NULL), N, NULL);
+ HParser *E_ = h_choice(h_sequence(E, h_ch('-'), T, NULL), T, NULL);
+ h_bind_indirect(E, E_);
+ HParser *p = h_sequence(E, NULL);
printf("\n==== G R A M M A R ====\n");
HCFGrammar *g = h_cfgrammar(&system_allocator, p);
--
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