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Enhancements to lemon to generate more compact action tables and to avoid

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making array bounds tests that can never fail on action table calculations.

FossilOrigin-Name: 27d8e684db4651155c4bcb8bb44bf1c692b8c48b
This commit is contained in:
drh
2009-11-03 19:18:31 +00:00
parent 9a5f4d64f3
commit f16371d650
5 changed files with 75 additions and 49 deletions
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50
tool/lemon.c
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@ -520,21 +520,9 @@ int acttab_insert(acttab *p){
**
** i is the index in p->aAction[] where p->mnLookahead is inserted.
*/
for(i=0; i<p->nAction+p->mnLookahead; i++){
if( p->aAction[i].lookahead<0 ){
for(j=0; j<p->nLookahead; j++){
k = p->aLookahead[j].lookahead - p->mnLookahead + i;
if( k<0 ) break;
if( p->aAction[k].lookahead>=0 ) break;
}
if( j<p->nLookahead ) continue;
for(j=0; j<p->nAction; j++){
if( p->aAction[j].lookahead==j+p->mnLookahead-i ) break;
}
if( j==p->nAction ){
break; /* Fits in empty slots */
}
}else if( p->aAction[i].lookahead==p->mnLookahead ){
for(i=p->nAction-1; i>=0; i--){
/* First look for an existing action table entry that can be reused */
if( p->aAction[i].lookahead==p->mnLookahead ){
if( p->aAction[i].action!=p->mnAction ) continue;
for(j=0; j<p->nLookahead; j++){
k = p->aLookahead[j].lookahead - p->mnLookahead + i;
@ -553,6 +541,25 @@ int acttab_insert(acttab *p){
}
}
}
if( i<0 ){
/* If no reusable entry is found, look for an empty slot */
for(i=0; i<p->nAction; i++){
if( p->aAction[i].lookahead<0 ){
for(j=0; j<p->nLookahead; j++){
k = p->aLookahead[j].lookahead - p->mnLookahead + i;
if( k<0 ) break;
if( p->aAction[k].lookahead>=0 ) break;
}
if( j<p->nLookahead ) continue;
for(j=0; j<p->nAction; j++){
if( p->aAction[j].lookahead==j+p->mnLookahead-i ) break;
}
if( j==p->nAction ){
break; /* Fits in empty slots */
}
}
}
}
/* Insert transaction set at index i. */
for(j=0; j<p->nLookahead; j++){
k = p->aLookahead[j].lookahead - p->mnLookahead + i;
@ -3568,7 +3575,7 @@ int mhflag; /* Output in makeheaders format if true */
struct action *ap;
struct rule *rp;
struct acttab *pActtab;
int i, j, n;
int i, j, k, n;
char *name;
int mnTknOfst, mxTknOfst;
int mnNtOfst, mxNtOfst;
@ -3727,8 +3734,9 @@ int mhflag; /* Output in makeheaders format if true */
free(ax);
/* Output the yy_action table */
fprintf(out,"static const YYACTIONTYPE yy_action[] = {\n"); lineno++;
n = acttab_size(pActtab);
fprintf(out,"#define YY_ACTTAB_COUNT (%d)\n", n); lineno++;
fprintf(out,"static const YYACTIONTYPE yy_action[] = {\n"); lineno++;
for(i=j=0; i<n; i++){
int action = acttab_yyaction(pActtab, i);
if( action<0 ) action = lemp->nstate + lemp->nrule + 2;
@ -3763,7 +3771,9 @@ int mhflag; /* Output in makeheaders format if true */
fprintf(out, "#define YY_SHIFT_USE_DFLT (%d)\n", mnTknOfst-1); lineno++;
n = lemp->nstate;
while( n>0 && lemp->sorted[n-1]->iTknOfst==NO_OFFSET ) n--;
fprintf(out, "#define YY_SHIFT_MAX %d\n", n-1); lineno++;
fprintf(out, "#define YY_SHIFT_COUNT (%d)\n", n-1); lineno++;
fprintf(out, "#define YY_SHIFT_MIN (%d)\n", mnTknOfst); lineno++;
fprintf(out, "#define YY_SHIFT_MAX (%d)\n", mxTknOfst); lineno++;
fprintf(out, "static const %s yy_shift_ofst[] = {\n",
minimum_size_type(mnTknOfst-1, mxTknOfst)); lineno++;
for(i=j=0; i<n; i++){
@ -3786,7 +3796,9 @@ int mhflag; /* Output in makeheaders format if true */
fprintf(out, "#define YY_REDUCE_USE_DFLT (%d)\n", mnNtOfst-1); lineno++;
n = lemp->nstate;
while( n>0 && lemp->sorted[n-1]->iNtOfst==NO_OFFSET ) n--;
fprintf(out, "#define YY_REDUCE_MAX %d\n", n-1); lineno++;
fprintf(out, "#define YY_REDUCE_COUNT (%d)\n", n-1); lineno++;
fprintf(out, "#define YY_REDUCE_MIN (%d)\n", mnNtOfst); lineno++;
fprintf(out, "#define YY_REDUCE_MAX (%d)\n", mxNtOfst); lineno++;
fprintf(out, "static const %s yy_reduce_ofst[] = {\n",
minimum_size_type(mnNtOfst-1, mxNtOfst)); lineno++;
for(i=j=0; i<n; i++){