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internal/lsp: cleanup the diff/myers package

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The only exposed symbol is now the ComputeEdits function, all other functionality
is now moved up to the diff layer and using edits instead of operations.

Change-Id: I149e4f3276592e1a7c2c52e6eaffc826cc22a9fa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/198518
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
This commit is contained in:
Ian Cottrell 2019-10-02 23:47:30 -04:00
parent cc9bfb3eec
commit 88641d98b3
2 changed files with 29 additions and 96 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
internal/lsp/diff/myers/diff.go
View File

@ -9,47 +9,42 @@ import (
"strings"
"golang.org/x/tools/internal/lsp/diff"
"golang.org/x/tools/internal/span"
)
// Sources:
// https://blog.jcoglan.com/2017/02/17/the-myers-diff-algorithm-part-3/
// https://www.codeproject.com/Articles/42279/%2FArticles%2F42279%2FInvestigating-Myers-diff-algorithm-Part-1-of-2
type Op struct {
func ComputeEdits(uri span.URI, before, after string) []diff.TextEdit {
ops := operations(splitLines(before), splitLines(after))
edits := make([]diff.TextEdit, 0, len(ops))
for _, op := range ops {
s := span.New(uri, span.NewPoint(op.I1+1, 1, 0), span.NewPoint(op.I2+1, 1, 0))
switch op.Kind {
case diff.Delete:
// Delete: unformatted[i1:i2] is deleted.
edits = append(edits, diff.TextEdit{Span: s})
case diff.Insert:
// Insert: formatted[j1:j2] is inserted at unformatted[i1:i1].
if content := strings.Join(op.Content, ""); content != "" {
edits = append(edits, diff.TextEdit{Span: s, NewText: content})
}
}
}
return edits
}
type operation struct {
Kind diff.OpKind
Content []string // content from b
I1, I2 int // indices of the line in a
J1 int // indices of the line in b, J2 implied by len(Content)
}
func ApplyEdits(a []string, operations []*Op) []string {
var b []string
var prevI2 int
for _, op := range operations {
// catch up to latest indices
if op.I1-prevI2 > 0 {
for _, c := range a[prevI2:op.I1] {
b = append(b, c)
}
}
switch op.Kind {
case diff.Equal, diff.Insert:
b = append(b, op.Content...)
}
prevI2 = op.I2
}
// final catch up
if len(a)-prevI2 > 0 {
for _, c := range a[prevI2:len(a)] {
b = append(b, c)
}
}
return b
}
// Operations returns the list of operations to convert a into b, consolidating
// operations returns the list of operations to convert a into b, consolidating
// operations for multiple lines and not including equal lines.
func Operations(a, b []string) []*Op {
func operations(a, b []string) []*operation {
if len(a) == 0 && len(b) == 0 {
return nil
}
@ -60,9 +55,9 @@ func Operations(a, b []string) []*Op {
M, N := len(a), len(b)
var i int
solution := make([]*Op, len(a)+len(b))
solution := make([]*operation, len(a)+len(b))
add := func(op *Op, i2, j2 int) {
add := func(op *operation, i2, j2 int) {
if op == nil {
return
}
@ -78,11 +73,11 @@ func Operations(a, b []string) []*Op {
if len(snake) < 2 {
continue
}
var op *Op
var op *operation
// delete (horizontal)
for snake[0]-snake[1] > x-y {
if op == nil {
op = &Op{
op = &operation{
Kind: diff.Delete,
I1: x,
J1: y,
@ -98,7 +93,7 @@ func Operations(a, b []string) []*Op {
// insert (vertical)
for snake[0]-snake[1] < x-y {
if op == nil {
op = &Op{
op = &operation{
Kind: diff.Insert,
I1: x,
J1: y,
@ -201,7 +196,7 @@ func shortestEditSequence(a, b []string) ([][]int, int) {
return nil, 0
}
func SplitLines(text string) []string {
func splitLines(text string) []string {
lines := strings.SplitAfter(text, "\n")
if lines[len(lines)-1] == "" {
lines = lines[:len(lines)-1]

62
internal/lsp/diff/myers/myers.go
View File

@ -1,62 +0,0 @@
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package myers
import (
"strings"
"golang.org/x/tools/internal/lsp/diff"
"golang.org/x/tools/internal/span"
)
func ComputeEdits(uri span.URI, before, after string) []diff.TextEdit {
u := SplitLines(before)
f := SplitLines(after)
return myersDiffToEdits(uri, Operations(u, f))
}
func myersDiffToEdits(uri span.URI, ops []*Op) []diff.TextEdit {
edits := make([]diff.TextEdit, 0, len(ops))
for _, op := range ops {
s := span.New(uri, span.NewPoint(op.I1+1, 1, 0), span.NewPoint(op.I2+1, 1, 0))
switch op.Kind {
case diff.Delete:
// Delete: unformatted[i1:i2] is deleted.
edits = append(edits, diff.TextEdit{Span: s})
case diff.Insert:
// Insert: formatted[j1:j2] is inserted at unformatted[i1:i1].
if content := strings.Join(op.Content, ""); content != "" {
edits = append(edits, diff.TextEdit{Span: s, NewText: content})
}
}
}
return edits
}
func myersEditsToDiff(edits []diff.TextEdit) []*Op {
iToJ := 0
ops := make([]*Op, len(edits))
for i, edit := range edits {
i1 := edit.Span.Start().Line() - 1
i2 := edit.Span.End().Line() - 1
kind := diff.Insert
if edit.NewText == "" {
kind = diff.Delete
}
ops[i] = &Op{
Kind: kind,
Content: SplitLines(edit.NewText),
I1: i1,
I2: i2,
J1: i1 + iToJ,
}
if kind == diff.Insert {
iToJ += len(ops[i].Content)
} else {
iToJ -= i2 - i1
}
}
return ops
}