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eliminate the right stack; work with the HInputStream directly

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This commit is contained in:
Sven M. Hallberg 2013-06-21 20:11:19 +02:00
parent 1e59e461fa
commit c32cf709b2
3 changed files with 54 additions and 60 deletions
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15
src/backends/glr.c
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@ -29,15 +29,14 @@ HLREngine *fork_engine(const HLREngine *engine)
HLREngine *eng2 = h_arena_malloc(engine->tarena, sizeof(HLREngine));
eng2->table = engine->table;
eng2->state = engine->state;
eng2->input = engine->input;
// shallow-copy the stacks
// shallow-copy the stack
// this works because h_slist_push and h_slist_pop never modify
// the underlying structure of HSlistNodes, only the head pointer.
// in fact, this gives us prefix sharing for free.
eng2->left = h_arena_malloc(engine->tarena, sizeof(HSlist));
eng2->right = h_arena_malloc(engine->tarena, sizeof(HSlist));
*eng2->left = *engine->left;
*eng2->right = *engine->right;
eng2->stack = h_arena_malloc(engine->tarena, sizeof(HSlist));
*eng2->stack = *engine->stack;
eng2->arena = engine->arena;
eng2->tarena = engine->tarena;
@ -54,7 +53,7 @@ HParseResult *h_glr_parse(HAllocator* mm__, const HParser* parser, HInputStream*
HArena *tarena = h_new_arena(mm__, 0); // tmp, deleted after parse
HSlist *engines = h_slist_new(tarena);
h_slist_push(engines, h_lrengine_new(arena, tarena, table));
h_slist_push(engines, h_lrengine_new(arena, tarena, table, stream));
HParseResult *result = NULL;
while(result == NULL && !h_slist_empty(engines)) {
@ -75,7 +74,7 @@ HParseResult *h_glr_parse(HAllocator* mm__, const HParser* parser, HInputStream*
continue;
}
const HLRAction *action = h_lrengine_action(engine, stream);
const HLRAction *action = h_lrengine_action(engine);
// fork engine on conflicts
if(action && action->type == HLR_CONFLICT) {
@ -120,8 +119,6 @@ HParserBackendVTable h__glr_backend_vtable = {
// XXX TODO
// - eliminate right stack by always doing a shift after reduce
// (shift should always follow reduce because rightmost)
// - split tables into
// - one mapping input bytes to actions (shift or reduce or conflict)
// - one mapping reduced-to lhs nonterminals to shift states