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eliminate duplication of result handling code in LL driver

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This commit is contained in:
Sven M. Hallberg 2013-05-11 20:40:33 +02:00
parent 88261f69ba
commit ccdb0fa85c
1 changed files with 34 additions and 37 deletions
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53
src/backends/llk.c
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@ -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)
@ -282,8 +277,11 @@ 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
// XXX set tok->index and tok->bit_offset (don't take directly from stream, cuz peek!)
// call validation and semantic action, if present
if(x->pred && !x->pred(make_result(tarena, tok)))
@ -294,7 +292,6 @@ HParseResult *h_llk_parse(HAllocator* mm__, const HParser* parser, HInputStream*
// append to result sequence
h_carray_append(seq, tok);
}
}
// since we started with a single nonterminal on the stack, seq should
// contain exactly the parse result.