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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [reflect/] [deepequal.go] - Blame information for rev 867

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1 747 jeremybenn 
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Deep equality test via reflection
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package reflect
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// During deepValueEqual, must keep track of checks that are
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// in progress.  The comparison algorithm assumes that all
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// checks in progress are true when it reencounters them.
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// Visited are stored in a map indexed by 17 * a1 + a2;
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type visit struct {
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        a1   uintptr
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        a2   uintptr
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        typ  Type
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        next *visit
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}
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// Tests for deep equality using reflected types. The map argument tracks
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// comparisons that have already been seen, which allows short circuiting on
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// recursive types.
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func deepValueEqual(v1, v2 Value, visited map[uintptr]*visit, depth int) (b bool) {
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        if !v1.IsValid() || !v2.IsValid() {
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                return v1.IsValid() == v2.IsValid()
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        }
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        if v1.Type() != v2.Type() {
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                return false
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        }
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        // if depth > 10 { panic("deepValueEqual") }    // for debugging
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        if v1.CanAddr() && v2.CanAddr() {
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                addr1 := v1.UnsafeAddr()
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                addr2 := v2.UnsafeAddr()
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                if addr1 > addr2 {
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                        // Canonicalize order to reduce number of entries in visited.
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                        addr1, addr2 = addr2, addr1
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                }
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                // Short circuit if references are identical ...
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                if addr1 == addr2 {
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                        return true
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                }
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                // ... or already seen
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                h := 17*addr1 + addr2
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                seen := visited[h]
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                typ := v1.Type()
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                for p := seen; p != nil; p = p.next {
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                        if p.a1 == addr1 && p.a2 == addr2 && p.typ == typ {
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                                return true
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                        }
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                }
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                // Remember for later.
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                visited[h] = &visit{addr1, addr2, typ, seen}
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        }
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        switch v1.Kind() {
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        case Array:
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                if v1.Len() != v2.Len() {
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                        return false
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                }
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                for i := 0; i < v1.Len(); i++ {
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                        if !deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
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                                return false
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                        }
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                }
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                return true
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        case Slice:
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                if v1.IsNil() != v2.IsNil() {
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                        return false
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                }
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                if v1.Len() != v2.Len() {
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                        return false
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                }
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                for i := 0; i < v1.Len(); i++ {
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                        if !deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
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                                return false
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                        }
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                }
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                return true
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        case Interface:
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                if v1.IsNil() || v2.IsNil() {
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                        return v1.IsNil() == v2.IsNil()
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                }
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                return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
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        case Ptr:
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                return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
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        case Struct:
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                for i, n := 0, v1.NumField(); i < n; i++ {
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                        if !deepValueEqual(v1.Field(i), v2.Field(i), visited, depth+1) {
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                                return false
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                        }
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                }
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                return true
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        case Map:
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                if v1.IsNil() != v2.IsNil() {
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                        return false
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                }
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                if v1.Len() != v2.Len() {
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                        return false
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                }
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                for _, k := range v1.MapKeys() {
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                        if !deepValueEqual(v1.MapIndex(k), v2.MapIndex(k), visited, depth+1) {
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                                return false
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                        }
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                }
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                return true
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        default:
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                // Normal equality suffices
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                return valueInterface(v1, false) == valueInterface(v2, false)
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        }
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        panic("Not reached")
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}
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// DeepEqual tests for deep equality. It uses normal == equality where possible
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// but will scan members of arrays, slices, and fields of structs. It correctly
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// handles recursive types.
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func DeepEqual(a1, a2 interface{}) bool {
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        if a1 == nil || a2 == nil {
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                return a1 == a2
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        }
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        v1 := ValueOf(a1)
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        v2 := ValueOf(a2)
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        if v1.Type() != v2.Type() {
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                return false
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        }
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        return deepValueEqual(v1, v2, make(map[uintptr]*visit), 0)
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}

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