From 88261f69ba4f4cd0da3bd6aed8330b153ed2edd6 Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Sat, 11 May 2013 19:26:22 +0200
Subject: [PATCH] derp, forgot to save original nonterminal in stack frame
---
src/backends/llk.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/src/backends/llk.c b/src/backends/llk.c
index 37ee8c38..60587d29 100644
--- a/src/backends/llk.c
+++ b/src/backends/llk.c
@@ -177,6 +177,9 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
// derivations are produced this linearization is unique.
// the 'mark' allocated below simply reserves a memory address to use as the
// frame delimiter.
+ // nonterminals, instead of being popped and forgotten, are put back onto the
+ // stack below the mark to tell us which validations and semantic actions to
+ // execute on their corresponding result.
// also on the stack below the mark, we store the previously accumulated
// value for the surrounding production.
void *mark = h_arena_malloc(tarena, 1);
@@ -200,8 +203,7 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
// pop top of stack and check for frame delimiter
HCFChoice *x = h_slist_pop(stack);
assert(x != NULL);
- if(x == mark)
- {
+ if(x == mark) {
// hit stack frame boundary
// wrap the accumulated parse result, this sequence is finished
@@ -210,22 +212,25 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
tok->seq = seq;
// XXX tok->index and tok->bit_offset (don't take directly from stream, cuz peek!)
+ // recover original nonterminal and result sequence
+ x = h_slist_pop(stack);
+ seq = h_slist_pop(stack);
+ // tok becomes next left-most element of higher-level sequence
+
// call validation and semantic action, if present
if(x->pred && !x->pred(make_result(tarena, tok)))
goto no_parse; // validation failed -> no parse
if(x->action)
tok = (HParsedToken *)x->action(make_result(arena, tok));
- // result becomes next left-most element of higher-level sequence
- seq = h_slist_pop(stack);
h_carray_append(seq, tok);
}
- else if(x->type == HCF_CHOICE)
- {
+ else if(x->type == HCF_CHOICE) {
// x is a nonterminal; apply the appropriate production
// push stack frame
h_slist_push(stack, seq); // save current partial value
+ h_slist_push(stack, x); // save the nonterminal
h_slist_push(stack, mark); // frame delimiter
// open a fresh result sequence
@@ -240,8 +245,7 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
for(s--; s >= p->items; s--)
h_slist_push(stack, *s);
}
- else
- {
+ else {
// x is a terminal, or simple charset; match against input
// consume the input token
--
GitLab