64 lines
1.5 KiB
Go
64 lines
1.5 KiB
Go
// Copyright (c) 2018 Couchbase, Inc.
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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 stempel
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// Diff transforms the dest rune slice following the rules described
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// in the diff command rune slice.
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func Diff(dest, diff []rune) []rune {
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if len(diff) == 0 {
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return dest
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}
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pos := len(dest) - 1
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if pos < 0 {
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return dest
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}
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for i := 0; i < len(diff)/2; i++ {
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cmd := diff[2*i]
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param := diff[2*i+1]
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parNum := int(param - 'a' + 1)
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switch cmd {
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case '-':
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pos = pos - parNum + 1
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case 'R':
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if pos < 0 || pos >= len(dest) {
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// out of bounds, just return
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return dest
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}
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dest[pos] = param
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case 'D':
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o := pos
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pos -= parNum - 1
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if pos < 0 || pos >= len(dest) {
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// out of bounds, just return
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return dest
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}
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dest = append(dest[:pos], dest[o+1:]...)
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case 'I':
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pos++
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if pos < 0 || pos > len(dest) {
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// out of bounds, just return
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return dest
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}
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dest = append(dest, 0)
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copy(dest[pos+1:], dest[pos:])
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dest[pos] = param
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}
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pos--
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}
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return dest
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}
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