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reflect: use visit structure for map key in DeepEqual

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R=golang-dev, bradfitz, jonathan, r
CC=golang-dev
https://golang.org/cl/8730044
This commit is contained in:
Robert Hencke 2013-05-15 14:50:57 -07:00 committed by Rob Pike
parent c6293d2106
commit f7b5a01999
1 changed files with 10 additions and 14 deletions
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16
src/pkg/reflect/deepequal.go
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@ -9,18 +9,17 @@ package reflect
// During deepValueEqual, must keep track of checks that are
// in progress. The comparison algorithm assumes that all
// checks in progress are true when it reencounters them.
// Visited are stored in a map indexed by 17 * a1 + a2;
// Visited comparisons are stored in a map indexed by visit.
type visit struct {
a1 uintptr
a2 uintptr
typ Type
next *visit
}
// Tests for deep equality using reflected types. The map argument tracks
// comparisons that have already been seen, which allows short circuiting on
// recursive types.
func deepValueEqual(v1, v2 Value, visited map[uintptr]*visit, depth int) (b bool) {
func deepValueEqual(v1, v2 Value, visited map[visit]bool, depth int) bool {
if !v1.IsValid() || !v2.IsValid() {
return v1.IsValid() == v2.IsValid()
}
@ -44,17 +43,14 @@ func deepValueEqual(v1, v2 Value, visited map[uintptr]*visit, depth int) (b bool
}
// ... or already seen
h := 17*addr1 + addr2
seen := visited[h]
typ := v1.Type()
for p := seen; p != nil; p = p.next {
if p.a1 == addr1 && p.a2 == addr2 && p.typ == typ {
v := visit{addr1, addr2, typ}
if visited[v] {
return true
}
}
// Remember for later.
visited[h] = &visit{addr1, addr2, typ, seen}
visited[v] = true
}
switch v1.Kind() {
@ -135,5 +131,5 @@ func DeepEqual(a1, a2 interface{}) bool {
if v1.Type() != v2.Type() {
return false
}
return deepValueEqual(v1, v2, make(map[uintptr]*visit), 0)
return deepValueEqual(v1, v2, make(map[visit]bool), 0)
}