[golang-dev] code review 8730044: reflect: use visit structure for map key in DeepEqual (issue 8730044)

On Apr 12, 2013 5:05 PM, wrote:

Reviewers: golang-dev1,

Message:
Hello mailto:[email protected],

I'd like you to review this change to
https://code.google.com/p/go


Description:
reflect: use visit structure for map key in DeepEqual

Please review this at

Affected files:
M src/pkg/reflect/deepequal.go


Index: src/pkg/reflect/deepequal.go

--- a/src/pkg/reflect/deepequal.go
+++ b/src/pkg/reflect/deepequal.go
@@ -9,18 +9,17 @@
// 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
+ a1 uintptr
+ a2 uintptr
+ typ Type
}

// Tests for deep equality using reflected types. The map argument

// comparisons that have already been seen, which allows short

on
// recursive types.
-func deepValueEqual(v1, v2 Value, visited map[uintptr]*visit, depth

(b bool) {
+func deepValueEqual(v1, v2 Value, visited map[visit]bool, depth

{
if !v1.IsValid() || !v2.IsValid() {
return v1.IsValid() == v2.IsValid()
}
@@ -44,17 +43,14 @@
}

// ... 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

- return true
- }
+ 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 @@
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)
}


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