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99 lines
2.4 KiB
99 lines
2.4 KiB
//
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// DISCLAIMER
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//
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// Copyright 2017 ArangoDB GmbH, Cologne, Germany
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Copyright holder is ArangoDB GmbH, Cologne, Germany
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//
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// Author Ewout Prangsma
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//
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package velocypack
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// Merge creates a slice that contains all fields from all given slices.
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// When a field exists (with same name) in an earlier slice, it is ignored.
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// All slices must be objects.
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func Merge(slices ...Slice) (Slice, error) {
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// Calculate overall length
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l := ValueLength(0)
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for _, s := range slices {
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if err := s.AssertType(Object); err != nil {
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return nil, WithStack(err)
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}
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byteSize, err := s.ByteSize()
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if err != nil {
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return nil, WithStack(err)
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}
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l += byteSize
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}
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if len(slices) == 1 {
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// Fast path, only 1 slice
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return slices[0], nil
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}
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// Create a buffer to hold all slices.
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b := NewBuilder(uint(l))
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keys := make(map[string]struct{})
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if err := b.OpenObject(); err != nil {
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return nil, WithStack(err)
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}
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for _, s := range slices {
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it, err := NewObjectIterator(s, true)
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if err != nil {
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return nil, WithStack(err)
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}
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for it.IsValid() {
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keySlice, err := it.Key(true)
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if err != nil {
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return nil, WithStack(err)
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}
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key, err := keySlice.GetString()
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if err != nil {
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return nil, WithStack(err)
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}
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if _, found := keys[key]; !found {
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// Record key
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keys[key] = struct{}{}
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// Fetch value
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value, err := it.Value()
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if err != nil {
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return nil, WithStack(err)
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}
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// Add key,value
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if err := b.addInternalKeyValue(key, NewSliceValue(value)); err != nil {
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return nil, WithStack(err)
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}
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}
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// Move to next field
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if err := it.Next(); err != nil {
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return nil, WithStack(err)
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}
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}
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}
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if err := b.Close(); err != nil {
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return nil, WithStack(err)
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}
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// Return slice
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result, err := b.Slice()
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if err != nil {
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return nil, WithStack(err)
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}
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return result, nil
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}
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