fix: use common lineHash to share indice between text1 and text2

Use common cache of line contents between two texts in `DiffLinesToChars` to get line diffs correctly.
In some cases, line diffs cannot be retrieved correctly in the standard way (https://github.com/google/diff-match-patch/wiki/Line-or-Word-Diffs#line-mode).
In the below case, we failed to get line diffs correctly before this fix.

```go:main.go
package main

import (
	"fmt"

	"github.com/sergi/go-diff/diffmatchpatch"
)

const (
	text1 = `hoge:
  step11:
  - arrayitem1
  - arrayitem2
  step12:
    step21: hoge
    step22: -93
fuga: flatitem
`
	text2 = `hoge:
  step11:
  - arrayitem4
  - arrayitem2
  - arrayitem3
  step12:
    step21: hoge
    step22: -92
fuga: flatitem
`
)

func main() {
	dmp := diffmatchpatch.New()
	a, b, c := dmp.DiffLinesToChars(text1, text2)
	diffs := dmp.DiffMain(a, b, false)
	diffs = dmp.DiffCharsToLines(diffs, c)
	// diffs = dmp.DiffCleanupSemantic(diffs)
	fmt.Println(diffs)
}
```

```text:output
[{Insert hoge:
  step11:
hoge:
} {Equal hoge:
} {Insert hoge:
} {Equal   step11:
} {Insert hoge:
} {Equal   - arrayitem1
} {Insert hoge:
} {Equal   - arrayitem2
} {Insert hoge:
} {Equal   step12:
} {Insert hoge:
} {Equal     step21: hoge
} {Insert hoge:
} {Equal     step22: -93
} {Delete fuga: flatitem
}]
```

Note: This fix corresponds to a javascript implementation.
(ref: https://github.com/google/diff-match-patch/blob/62f2e689f498f9c92dbc588c58750addec9b1654/javascript/diff_match_patch_uncompressed.js#L466)
2 files changed
tree: ff47dfda21c1518a3caf10004d9a36e5f02c699c
  1. diffmatchpatch/
  2. scripts/
  3. testdata/
  4. .gitignore
  5. .travis.yml
  6. APACHE-LICENSE-2.0
  7. AUTHORS
  8. CONTRIBUTORS
  9. go.mod
  10. go.sum
  11. LICENSE
  12. Makefile
  13. README.md
README.md

go-diff GoDoc Build Status Coverage Status

go-diff offers algorithms to perform operations required for synchronizing plain text:

  • Compare two texts and return their differences.
  • Perform fuzzy matching of text.
  • Apply patches onto text.

Installation

go get -u github.com/sergi/go-diff/...

Usage

The following example compares two texts and writes out the differences to standard output.

package main

import (
	"fmt"

	"github.com/sergi/go-diff/diffmatchpatch"
)

const (
	text1 = "Lorem ipsum dolor."
	text2 = "Lorem dolor sit amet."
)

func main() {
	dmp := diffmatchpatch.New()

	diffs := dmp.DiffMain(text1, text2, false)

	fmt.Println(dmp.DiffPrettyText(diffs))
}

Found a bug or are you missing a feature in go-diff?

Please make sure to have the latest version of go-diff. If the problem still persists go through the open issues in the tracker first. If you cannot find your request just open up a new issue.

How to contribute?

You want to contribute to go-diff? GREAT! If you are here because of a bug you want to fix or a feature you want to add, you can just read on. Otherwise we have a list of open issues in the tracker. Just choose something you think you can work on and discuss your plans in the issue by commenting on it.

Please make sure that every behavioral change is accompanied by test cases. Additionally, every contribution must pass the lint and test Makefile targets which can be run using the following commands in the repository root directory.

make lint
make test

After your contribution passes these commands, create a PR and we will review your contribution.

Origins

go-diff is a Go language port of Neil Fraser's google-diff-match-patch code. His original code is available at http://code.google.com/p/google-diff-match-patch/.

Copyright and License

The original Google Diff, Match and Patch Library is licensed under the Apache License 2.0. The full terms of that license are included here in the APACHE-LICENSE-2.0 file.

Diff, Match and Patch Library

Written by Neil Fraser Copyright (c) 2006 Google Inc. http://code.google.com/p/google-diff-match-patch/

This Go version of Diff, Match and Patch Library is licensed under the MIT License (a.k.a. the Expat License) which is included here in the LICENSE file.

Go version of Diff, Match and Patch Library

Copyright (c) 2012-2016 The go-diff authors. All rights reserved. https://github.com/sergi/go-diff

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.