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https://github.com/golang/go
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c9f9432ec4
This should be a faster but equivalent implementation. Change-Id: I7bc756644c601b953ba7715e093bfa10ca5ea97b Reviewed-on: https://go-review.googlesource.com/c/tools/+/198878 Run-TryBot: Ian Cottrell <iancottrell@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Rebecca Stambler <rstambler@golang.org>
74 lines
2.1 KiB
Go
74 lines
2.1 KiB
Go
// Copyright 2019 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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// Package diff supports a pluggable diff algorithm.
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package diff
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import (
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"sort"
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"strings"
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"golang.org/x/tools/internal/span"
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)
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// TextEdit represents a change to a section of a document.
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// The text within the specified span should be replaced by the supplied new text.
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type TextEdit struct {
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Span span.Span
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NewText string
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}
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// ComputeEdits is the type for a function that produces a set of edits that
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// convert from the before content to the after content.
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type ComputeEdits func(uri span.URI, before, after string) []TextEdit
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// SortTextEdits attempts to order all edits by their starting points.
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// The sort is stable so that edits with the same starting point will not
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// be reordered.
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func SortTextEdits(d []TextEdit) {
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// Use a stable sort to maintain the order of edits inserted at the same position.
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sort.SliceStable(d, func(i int, j int) bool {
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return span.Compare(d[i].Span, d[j].Span) < 0
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})
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}
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// ApplyEdits applies the set of edits to the before and returns the resulting
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// content.
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// It may panic or produce garbage if the edits are not valid for the provided
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// before content.
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func ApplyEdits(before string, edits []TextEdit) string {
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// Preconditions:
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// - all of the edits apply to before
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// - and all the spans for each TextEdit have the same URI
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if len(edits) == 0 {
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return before
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}
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edits = prepareEdits(edits)
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c := span.NewContentConverter("", []byte(before))
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after := strings.Builder{}
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last := 0
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for _, edit := range edits {
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spn, _ := edit.Span.WithAll(c)
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start := spn.Start().Offset()
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if start > last {
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after.WriteString(before[last:start])
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last = start
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}
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after.WriteString(edit.NewText)
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last = spn.End().Offset()
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}
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if last < len(before) {
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after.WriteString(before[last:])
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}
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return after.String()
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}
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// prepareEdits returns a sorted copy of the edits
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func prepareEdits(edits []TextEdit) []TextEdit {
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copied := make([]TextEdit, len(edits))
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copy(copied, edits)
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SortTextEdits(copied)
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return copied
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}
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