regexp: set b.cap[0] and b.cap[1] only when captures requested
Fixes #10319
Change-Id: I96015b0e1dff30a72de11fea3837638b5c672891
Reviewed-on: https://go-review.googlesource.com/8501
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/regexp/backtrack.go b/src/regexp/backtrack.go
index a387fa6..fd95604 100644
--- a/src/regexp/backtrack.go
+++ b/src/regexp/backtrack.go
@@ -36,7 +36,6 @@
end int
cap []int
- reqcap bool // whether any captures are requested
input input
jobs []job
visited []uint32
@@ -72,12 +71,10 @@
}
// reset resets the state of the backtracker.
-// end is the end position in the input. ncap and reqcap are the number
-// of the machine's capture registers and the number of user-requested
-// captures respectively.
-func (b *bitState) reset(end int, ncap int, reqcap int) {
+// end is the end position in the input.
+// ncap is the number of captures.
+func (b *bitState) reset(end int, ncap int) {
b.end = end
- b.reqcap = reqcap > 0
if cap(b.jobs) == 0 {
b.jobs = make([]job, 0, 256)
@@ -95,8 +92,10 @@
}
}
- if len(b.cap) < ncap {
+ if cap(b.cap) < ncap {
b.cap = make([]int, ncap)
+ } else {
+ b.cap = b.cap[:ncap]
}
for i := range b.cap {
b.cap[i] = -1
@@ -271,7 +270,7 @@
case syntax.InstMatch:
// We found a match. If the caller doesn't care
// where the match is, no point going further.
- if !b.reqcap {
+ if len(b.cap) == 0 {
m.matched = true
return m.matched
}
@@ -279,7 +278,9 @@
// Record best match so far.
// Only need to check end point, because this entire
// call is only considering one start position.
- b.cap[1] = pos
+ if len(b.cap) > 1 {
+ b.cap[1] = pos
+ }
if !m.matched || (longest && pos > 0 && pos > m.matchcap[1]) {
copy(m.matchcap, b.cap)
}
@@ -305,7 +306,7 @@
}
// backtrack runs a backtracking search of prog on the input starting at pos.
-func (m *machine) backtrack(i input, pos int, end int, reqcap int) bool {
+func (m *machine) backtrack(i input, pos int, end int, ncap int) bool {
if !i.canCheckPrefix() {
panic("backtrack called for a RuneReader")
}
@@ -320,15 +321,18 @@
}
b := m.b
- b.reset(end, len(m.matchcap), reqcap)
+ b.reset(end, ncap)
+ m.matchcap = m.matchcap[:ncap]
for i := range m.matchcap {
m.matchcap[i] = -1
}
// Anchored search must start at the beginning of the input
if startCond&syntax.EmptyBeginText != 0 {
- b.cap[0] = pos
+ if len(b.cap) > 0 {
+ b.cap[0] = pos
+ }
return m.tryBacktrack(b, i, uint32(m.p.Start), pos)
}
@@ -349,7 +353,9 @@
pos += advance
}
- b.cap[0] = pos
+ if len(b.cap) > 0 {
+ b.cap[0] = pos
+ }
if m.tryBacktrack(b, i, uint32(m.p.Start), pos) {
// Match must be leftmost; done.
return true
