Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit4604f83

Browse files
committed
Suppress unnecessary regex subre nodes in a couple more cases.
This extends the changes made in commitcebc1d3, teachingparseqatom() to generate fewer or cheaper subre nodes in some edgecases. The case of interest here is a quantified atom that is "messy"only because it has greediness opposite to what preceded it (whereascaptures and backrefs are intrinsically messy). In this case we don'tneed an iteration node, since we don't care where the sub-matches ofthe quantifier are; and we might also not need a second concatenationnode. This seems of only marginal real-world use according to mytesting, but I wanted to get it in before wrapping up this series ofregex performance fixes.Discussion:https://postgr.es/m/1340281.1613018383@sss.pgh.pa.us
1 parent0c3405c commit4604f83

File tree

1 file changed

+39
-0
lines changed

1 file changed

+39
-0
lines changed

‎src/backend/regex/regcomp.c

Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1216,6 +1216,23 @@ parseqatom(struct vars *v,
12161216
/* rest of branch can be strung starting from atom->end */
12171217
s2=atom->end;
12181218
}
1219+
elseif (!(atom->flags& (CAP |BACKR)))
1220+
{
1221+
/*
1222+
* If there's no captures nor backrefs in the atom being repeated, we
1223+
* don't really care where the submatches of the iteration are, so we
1224+
* don't need an iteration node. Make a plain DFA node instead.
1225+
*/
1226+
EMPTYARC(s,atom->begin);/* empty prefix */
1227+
repeat(v,atom->begin,atom->end,m,n);
1228+
f=COMBINE(qprefer,atom->flags);
1229+
t=subre(v,'=',f,atom->begin,atom->end);
1230+
NOERR();
1231+
freesubre(v,atom);
1232+
*atomp=t;
1233+
/* rest of branch can be strung starting from t->end */
1234+
s2=t->end;
1235+
}
12191236
elseif (m>0&& !(atom->flags&BACKR))
12201237
{
12211238
/*
@@ -1271,6 +1288,10 @@ parseqatom(struct vars *v,
12711288
t->flags |=COMBINE(t->flags,t->child->sibling->flags);
12721289
top->flags |=COMBINE(top->flags,t->flags);
12731290

1291+
/* neither t nor top could be directly marked for capture as yet */
1292+
assert(t->capno==0);
1293+
assert(top->capno==0);
1294+
12741295
/*
12751296
* At this point both top and t are concatenation (op == '.') subres,
12761297
* and we have top->child = prefix of branch, top->child->sibling = t,
@@ -1291,6 +1312,24 @@ parseqatom(struct vars *v,
12911312
top->child=t->child;
12921313
freesrnode(v,t);
12931314
}
1315+
1316+
/*
1317+
* Otherwise, it's possible that t->child is not messy in itself, but
1318+
* we considered it messy because its greediness conflicts with what
1319+
* preceded it. Then it could be that the combination of t->child and
1320+
* the rest of the branch is also not messy, in which case we can get
1321+
* rid of the child concatenation by merging t->child and the rest of
1322+
* the branch into one plain DFA node.
1323+
*/
1324+
elseif (t->child->op=='='&&
1325+
t->child->sibling->op=='='&&
1326+
!MESSY(UP(t->child->flags |t->child->sibling->flags)))
1327+
{
1328+
t->op='=';
1329+
t->flags=COMBINE(t->child->flags,t->child->sibling->flags);
1330+
freesubreandsiblings(v,t->child);
1331+
t->child=NULL;
1332+
}
12941333
}
12951334
else
12961335
{

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp