53 lines
1.6 KiB
Go
53 lines
1.6 KiB
Go
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// Copyright 2021 The Tint Authors.
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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 substr
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import (
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diff "github.com/sergi/go-diff/diffmatchpatch"
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)
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// Fix attempts to reconstruct substr by comparing it to body.
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// substr is a fuzzy substring of body.
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// Fix returns a new exact substring of body, by calculating a diff of the text.
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// If no match could be made, Fix() returns an empty string.
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func Fix(body, substr string) string {
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dmp := diff.New()
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diffs := dmp.DiffMain(body, substr, false)
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if len(diffs) == 0 {
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return ""
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}
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front := func() diff.Diff { return diffs[0] }
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back := func() diff.Diff { return diffs[len(diffs)-1] }
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start, end := 0, len(body)
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// Trim edits that remove text from body start
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for len(diffs) > 0 && front().Type == diff.DiffDelete {
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start += len(front().Text)
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diffs = diffs[1:]
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}
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// Trim edits that remove text from body end
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for len(diffs) > 0 && back().Type == diff.DiffDelete {
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end -= len(back().Text)
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diffs = diffs[:len(diffs)-1]
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}
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// New substring is the span for the remainder of the edits
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return body[start:end]
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}
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