From 71b61d4db50938c0f5fa58fd3d3b0045fd762f57 Mon Sep 17 00:00:00 2001 From: "Joel E. Denny" Date: Tue, 29 May 2007 04:24:17 +0000 Subject: [PATCH] Improve some comments in parser table construction. * src/LR0.c (new_itemsets): Explain sorting of itemset and kernel_base. (generate_states): Don't mention ruleset, which is internal to closure. * src/closure.c (closure): Explain sorting of core and itemset, which is required for this function to behave correctly. * src/closure.h (closure): Mention sorting. --- ChangeLog | 7 +++++++ src/LR0.c | 10 ++++++---- src/closure.c | 2 ++ src/closure.h | 4 ++-- 4 files changed, 17 insertions(+), 6 deletions(-) diff --git a/ChangeLog b/ChangeLog index e2a97a02..10ba84b5 100644 --- a/ChangeLog +++ b/ChangeLog @@ -6,6 +6,13 @@ Again, it's not used yet, but it will be. * src/muscle_tab.h: Likewise. + Improve some comments in parser table construction. + * src/LR0.c (new_itemsets): Explain sorting of itemset and kernel_base. + (generate_states): Don't mention ruleset, which is internal to closure. + * src/closure.c (closure): Explain sorting of core and itemset, which + is required for this function to behave correctly. + * src/closure.h (closure): Mention sorting. + 2007-05-28 Joel E. Denny * src/lalr.c (state_lookahead_tokens_count): For code readability, diff --git a/src/LR0.c b/src/LR0.c index 3fd633fa..6e3a4460 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -169,6 +169,10 @@ free_storage (void) | shifted. For each symbol in the grammar, kernel_base[symbol] | | points to a vector of item numbers activated if that symbol is | | shifted, and kernel_size[symbol] is their numbers. | +| | +| itemset is sorted on item number from ritem, which is sorted | +| on rule number. Compute each kernel_base[symbol] with the | +| same sort. | `---------------------------------------------------------------*/ static void @@ -351,10 +355,8 @@ generate_states (void) fprintf (stderr, "Processing state %d (reached by %s)\n", s->number, symbols[s->accessing_symbol]->tag); - /* Set up ruleset and itemset for the transitions out of this - state. ruleset gets a 1 bit for each rule that could reduce - now. itemset gets a vector of all the items that could be - accepted next. */ + /* Set up itemset for the transitions out of this state. itemset gets a + vector of all the items that could be accepted next. */ closure (s->items, s->nitems); /* Record the reductions allowed out of this state. */ save_reductions (s); diff --git a/src/closure.c b/src/closure.c index 89b033ff..339adf5d 100644 --- a/src/closure.c +++ b/src/closure.c @@ -213,6 +213,8 @@ closure (item_number *core, size_t n) if (ISVAR (ritem[core[c]])) bitset_or (ruleset, ruleset, FDERIVES (ritem[core[c]])); + /* core is sorted on item number from ritem, which is sorted on rule number. + Compute itemset with the same sort. */ nitemset = 0; c = 0; BITSET_FOR_EACH (iter, ruleset, ruleno, 0) diff --git a/src/closure.h b/src/closure.h index 96c849e0..d152f9c6 100644 --- a/src/closure.h +++ b/src/closure.h @@ -32,7 +32,7 @@ void new_closure (unsigned int n); -/* Given the kernel (aka core) of a state (a vector of item numbers +/* Given the kernel (aka core) of a state (a sorted vector of item numbers ITEMS, of length N), set up RULESET and ITEMSET to indicate what rules could be run and which items could be accepted when those items are the active ones. @@ -41,7 +41,7 @@ void new_closure (unsigned int n); all rules which could potentially describe the next input to be read. - ITEMSET is a vector of item numbers; NITEMSET is its size + ITEMSET is a sorted vector of item numbers; NITEMSET is its size (actually, points to just beyond the end of the part of it that is significant). CLOSURE places there the indices of all items which represent units of input that could arrive next. */ -- 2.47.2