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Improve some comments in parser table construction.

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* 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.
This commit is contained in:
Joel E. Denny
2007-05-29 04:24:17 +00:00
parent b1a8161341
commit 71b61d4db5
4 changed files with 17 additions and 6 deletions
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7
ChangeLog
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@@ -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 <jdenny@ces.clemson.edu>
* src/lalr.c (state_lookahead_tokens_count): For code readability,

10
src/LR0.c
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@@ -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);

2
src/closure.c
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@@ -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)

4
src/closure.h
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@@ -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. */