replace some hash table usage by tuples

Previously I used hash tables, which consume too much memory.  Now the
critical parts are replaced by a new hand-written library called
"tuple.h".  Now we can easily parse larger inputs.  I haven't tested
its limits, though.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/grammar.h b/src/grammar.h
index fd8d5c9..e18ad0e 100644
--- a/src/grammar.h
+++ b/src/grammar.h
@@ -231,6 +231,13 @@ BOOL nt_follow(CC_MOD(Grammar *) g, CCR_MOD(BOOL *) nts,
                ht * const result_terminals,
                ht * const result_predicates);
 
+/* TODO: Compute which non-terminals are "LL(1)" non-terminals.  With
+   this information, we can save the time to insert a process
+   descriptor and pop that descriptor, if we know the non-terminal in
+   question is "LL(1)".  A non-terminal A is defined as "LL(1)" if its
+   different rules have disjoint FIRST sets, and if FIRST(A) is
+   disjoint from FOLLOW(A), when A is nullable. */
+
 /* struct that holds information about grammars */
 
 typedef struct grammar_info_s grammar_info;