From ccdb0fa85cd2bdac9d91098aad33db4233dcfc1f Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Sat, 11 May 2013 20:40:33 +0200
Subject: [PATCH] eliminate duplication of result handling code in LL driver
---
src/backends/llk.c | 67 ++++++++++++++++++++++------------------------
1 file changed, 32 insertions(+), 35 deletions(-)
diff --git a/src/backends/llk.c b/src/backends/llk.c
index 60587d29..f2e83108 100644
--- a/src/backends/llk.c
+++ b/src/backends/llk.c
@@ -200,33 +200,12 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
lookahead = char_token(c);
}
- // pop top of stack and check for frame delimiter
+ // pop top of stack for inspection
HCFChoice *x = h_slist_pop(stack);
assert(x != NULL);
- if(x == mark) {
- // hit stack frame boundary
-
- // wrap the accumulated parse result, this sequence is finished
- HParsedToken *tok = h_arena_malloc(arena, sizeof(HParsedToken));
- tok->token_type = TT_SEQUENCE;
- 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));
-
- h_carray_append(seq, tok);
- }
- else if(x->type == HCF_CHOICE) {
- // x is a nonterminal; apply the appropriate production
+ if(x != mark && x->type == HCF_CHOICE) {
+ // x is a nonterminal; apply the appropriate production and continue
// push stack frame
h_slist_push(stack, seq); // save current partial value
@@ -244,15 +223,31 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
for(s = p->items; *s; s++);
for(s--; s >= p->items; s--)
h_slist_push(stack, *s);
+
+ continue; // no result to record
+ }
+
+ // the top of stack is such that there will be a result...
+ HParsedToken *tok; // will hold result token
+ if(x == mark) {
+ // hit stack frame boundary...
+ // wrap the accumulated parse result, this sequence is finished
+ tok = h_arena_malloc(arena, sizeof(HParsedToken));
+ tok->token_type = TT_SEQUENCE;
+ tok->seq = seq;
+
+ // 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
}
else {
- // x is a terminal, or simple charset; match against input
+ // x is a terminal or simple charset; match against input
// consume the input token
HCFToken input = lookahead;
lookahead = 0;
- HParsedToken *tok;
switch(x->type) {
case HCF_END:
if(input != end_token)
@@ -282,18 +277,20 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
assert_message(0, "unknown HCFChoice type");
goto no_parse;
}
+ }
- // XXX tok->index and tok->bit_offset (don't take directly from stream, cuz peek!)
+ // 'tok' has been parsed; process it
- // 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));
+ // XXX set tok->index and tok->bit_offset (don't take directly from stream, cuz peek!)
- // append to result sequence
- h_carray_append(seq, tok);
- }
+ // 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));
+
+ // append to result sequence
+ h_carray_append(seq, tok);
}
// since we started with a single nonterminal on the stack, seq should
--
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