0093393bc3
Note: should we ditch vendoring? Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>
103 lines
2.7 KiB
Go
103 lines
2.7 KiB
Go
// Copyright 2015 go-swagger maintainers
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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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package jsonutils
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import (
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"bytes"
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)
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// nullJSON represents a JSON object with null type
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var nullJSON = []byte("null")
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const comma = byte(',')
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var closers map[byte]byte
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func init() {
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closers = map[byte]byte{
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'{': '}',
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'[': ']',
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}
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}
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// ConcatJSON concatenates multiple json objects or arrays efficiently.
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//
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// Note that [ConcatJSON] performs a very simmple (and fast) concatenation
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// operation: it does not attempt to merge objects.
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func ConcatJSON(blobs ...[]byte) []byte {
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if len(blobs) == 0 {
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return nil
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}
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last := len(blobs) - 1
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for blobs[last] == nil || bytes.Equal(blobs[last], nullJSON) {
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// strips trailing null objects
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last--
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if last < 0 {
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// there was nothing but "null"s or nil...
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return nil
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}
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}
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if last == 0 {
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return blobs[0]
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}
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var opening, closing byte
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var idx, a int
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buf := bytes.NewBuffer(nil)
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for i, b := range blobs[:last+1] {
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if b == nil || bytes.Equal(b, nullJSON) {
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// a null object is in the list: skip it
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continue
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}
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if len(b) > 0 && opening == 0 { // is this an array or an object?
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opening, closing = b[0], closers[b[0]]
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}
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if opening != '{' && opening != '[' {
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continue // don't know how to concatenate non container objects
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}
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const minLengthIfNotEmpty = 3
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if len(b) < minLengthIfNotEmpty { // yep empty but also the last one, so closing this thing
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if i == last && a > 0 {
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_ = buf.WriteByte(closing) // never returns err != nil
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}
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continue
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}
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idx = 0
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if a > 0 { // we need to join with a comma for everything beyond the first non-empty item
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_ = buf.WriteByte(comma) // never returns err != nil
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idx = 1 // this is not the first or the last so we want to drop the leading bracket
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}
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if i != last { // not the last one, strip brackets
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_, _ = buf.Write(b[idx : len(b)-1]) // never returns err != nil
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} else { // last one, strip only the leading bracket
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_, _ = buf.Write(b[idx:])
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}
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a++
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}
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// somehow it ended up being empty, so provide a default value
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if buf.Len() == 0 && (opening == '{' || opening == '[') {
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_ = buf.WriteByte(opening) // never returns err != nil
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_ = buf.WriteByte(closing)
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}
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return buf.Bytes()
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}
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