Delta

Delta is both a Go library and a command-line utility for text diffs. Diffs can be displayed in the browser, or in command-line using the --cli flag.

Installation

brew install octavore/tools/delta

Description

Delta implements two diff functions: Smith-Waterman, and histogram diff.

Smith-Waterman is a dynamic programming algorithm for aligning two sequences, in this case text sequences. It originates from bioinformatics, where it is used for aligning DNA sequences.

histogram diff is a diff algorithm first implemented in JGit and subsequently ported over to git, where it can be used with the git diff --histogram command. This implementation post processes the histogram diff in order to push down match regions as far as possible. git also post processes diffs.

Other Usage

delta --cli <fileA> <fileB>         # print text diff to stdout
delta --cli --html <fileA> <fileB>  # print html diff to stdout
delta --gist <fileA> <fileB>        # upload html diff to a gist

Configure Git

The delta binary must be on your $PATH in order for this work. The following are helpers for adding delta to your ~/.gitconfig file.

delta --install   # makes delta the default for `git difftool`
delta --uninstall # remove delta from your gitconfig

User Config

You can configure delta using a ~/.deltarc file, for example:

{
  "context": 9,
  "showEmpty": true,
  "shouldCollapse": false,
  "highlight": true,
  "unmodifiedOpacity": 0.8,
  "diffFontSize": 12
}

Options

config key | key type | description ------------------- | --------- | ------------------------------------------ context | integer | between 0 and 4 number of lines of context to show showEmpty | bool | whether to hide empty lines shouldCollapse | bool | whether to merge browser tabs highlight | bool | toggles syntax highlighting unmodifiedOpacity | float | opacity of unmodified lines, between 0.1 and 1 diffFontSize | integer | font size of the diff

Browser Support

Delta works best in Chrome and Safari. You will see a separate tab open for each diff file, and then the tabs will consolidate into a single tab. In Firefox, each diff will remain in separate tabs. This is because in Firefox, each file receives its own IndexedDB instance, instead of a shared instance.

Browser support relies on the following open source libraries:

• Mithril
• highlight.js
• Mousetrap
• PouchDB

Development

Compiling From Source

go get github.com/octavore/delta/delta

If $GOPATH/bin is on your $PATH, run delta -h for usage.

Regenerating Assets

You will need npm to install the necessary node packages for compiling the front-end assets.

go-bindata is used to generate the bindata.go, which allows us to embed static resources into the compiled binary.

TODO

• make differ/histogram diff functions more consistent and add an interface.
• more comments for godoc/golint.
• fix race condition in update
• favicon
• make sidebar resizable