diff

README

go-diff

Library for generating Git-style diff patchsets in Go.

Built to be used in the pure-Go implementation of the Git backend for sourcegraph's go-vcs.

Status: Prototyping. None of the backends produce complete output yet, but the difflib one is closest and least broken.

Features

• Git-style patch headers for each file (are there other styles to support?).
• Bring your own diff algorithm by implementing the Differ interface.
• Includes a few diffing backends:
  • pmezard/go-difflib (default)
  • sergi/go-diff/diffmatchpatch (offsets produced are inconsistent with git diff)
  • mb0/diff (incomplete backend)

Sponsors

Work on this package is sponsored by Sourcegraph.

License

MIT.

Documentation

Index

• Variables
• type Differ
  • func DefaultDiffer() Differ
• type Object
• type Writer
  • func (w *Writer) Diff(src, dst Object) error
  • func (w *Writer) WriteDiff(a, b io.ReadSeeker) error
  • func (w *Writer) WriteHeader(src, dst Object) error

Variables

var ErrEmptyComparsion = errors.New("no objects to compare, both are empty")

ErrEmptyComparison is used when both src and dst are EmptyObjects

Types

type Differ

type Differ interface {
	// Diff writes a generated patch to out for the diff between a and b.
	Diff(out io.Writer, a io.ReadSeeker, b io.ReadSeeker) error
}

Differ supplies a stream-based diffing algorithm implementation.

func DefaultDiffer

func DefaultDiffer() Differ

DefaultDiffer returns a diffmatchpatch-based differ.

type Object

type Object struct {
	io.ReadSeeker
	// ID is the sha1 of the object
	ID [20]byte
	// Path is the root-relative path of the object
	Path string
	// Mode is the entry mode of the object
	Mode int
}

Object is the minimum representation for generating diffs with git-style headers.

var EmptyObject Object

EmptyObject can be used when there is no corresponding src or dst entry, such as during deletions or creations.

type Writer

type Writer struct {
	io.Writer
	Differ
	SrcPrefix string
	DstPrefix string
}

Writer writes diffs using a given Differ including git-style headers between each patch.

func (*Writer) Diff

func (w *Writer) Diff(src, dst Object) error

Diff writes the header and the generated the diff body when appropriate.

func (*Writer) WriteDiff

func (w *Writer) WriteDiff(a, b io.ReadSeeker) error

WriteDiff performs a Diff between a and b and writes only the resulting diff. It does not write the header.

func (*Writer) WriteHeader

func (w *Writer) WriteHeader(src, dst Object) error

WriteHeader writes only the header for the comparison between the src and dst Objects.