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finish engine merging

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This commit is contained in:
Sven M. Hallberg 2013-06-22 17:40:47 +02:00
parent 23afea4b4e
commit 67681a119a
4 changed files with 168 additions and 119 deletions
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33
src/backends/lr.c
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@ -206,11 +206,10 @@ HLREngine *h_lrengine_new(HArena *arena, HArena *tarena, const HLRTable *table,
engine->table = table;
engine->state = 0;
engine->run = true;
engine->stack = h_slist_new(tarena);
engine->input = *stream;
engine->merged = NULL;
engine->mp = NULL;
engine->merged[0] = NULL;
engine->merged[1] = NULL;
engine->arena = arena;
engine->tarena = tarena;
@ -267,7 +266,7 @@ static HParsedToken *consume_input(HLREngine *engine)
}
// run LR parser for one round; returns false when finished
static bool h_lrengine_step_(HLREngine *engine, const HLRAction *action)
bool h_lrengine_step(HLREngine *engine, const HLRAction *action)
{
// short-hand names
HSlist *stack = engine->stack;
@ -329,8 +328,11 @@ static bool h_lrengine_step_(HLREngine *engine, const HLRAction *action)
h_slist_push(stack, value);
engine->state = shift->nextstate;
if(symbol == engine->table->start)
return false; // reduced to start symbol; accept!
// check for success
if(engine->state == HLR_SUCCESS) {
assert(symbol == engine->table->start);
return false;
}
} else {
assert(action->type == HLR_SHIFT);
HParsedToken *value = consume_input(engine);
@ -342,17 +344,12 @@ static bool h_lrengine_step_(HLREngine *engine, const HLRAction *action)
return true;
}
// run LR parser for one round; sets engine->run
void h_lrengine_step(HLREngine *engine, const HLRAction *action)
{
engine->run = h_lrengine_step_(engine, action);
}
HParseResult *h_lrengine_result(HLREngine *engine)
{
// parsing was successful iff after a shift the engine is back in state 0
if(engine->state == 0 && !h_slist_empty(engine->stack)) {
// parsing was successful iff the engine reaches the end state
if(engine->state == HLR_SUCCESS) {
// on top of the stack is the start symbol's semantic value
assert(!h_slist_empty(engine->stack));
HParsedToken *tok = engine->stack->head->elem;
return make_result(engine->arena, tok);
} else {
@ -371,8 +368,7 @@ HParseResult *h_lr_parse(HAllocator* mm__, const HParser* parser, HInputStream*
HLREngine *engine = h_lrengine_new(arena, tarena, table, stream);
// iterate engine to completion
while(engine->run)
h_lrengine_step(engine, h_lrengine_action(engine));
while(h_lrengine_step(engine, h_lrengine_action(engine)));
HParseResult *result = h_lrengine_result(engine);
if(!result)
@ -464,7 +460,10 @@ void pprint_lraction(FILE *f, const HCFGrammar *g, const HLRAction *action)
{
switch(action->type) {
case HLR_SHIFT:
fprintf(f, "s%lu", action->nextstate);
if(action->nextstate == HLR_SUCCESS)
fputs("s~", f);
else
fprintf(f, "s%lu", action->nextstate);
break;
case HLR_REDUCE:
fputs("r(", f);