michael@0: # diffpatcher
michael@0: 
michael@0: [![Build Status](https://secure.travis-ci.org/Gozala/diffpatcher.png)](http://travis-ci.org/Gozala/diffpatcher)
michael@0: 
michael@0: [![Browser support](https://ci.testling.com/Gozala/diffpatcher.png)](http://ci.testling.com/Gozala/diffpatcher)
michael@0: 
michael@0: Diffpatcher is a small library that lets you treat hashes as if they were
michael@0: git repositories.
michael@0: 
michael@0: ## diff
michael@0: 
michael@0: Diff function that takes two hashes and returns delta hash.
michael@0: 
michael@0: ```js
michael@0: var diff = require("diffpatcher/diff")
michael@0: 
michael@0: diff({ a: { b: 1 }, c: { d: 2 } },      // hash#1
michael@0:      { a: { e: 3 }, c: { d: 4 } })      // hash#2
michael@0: 
michael@0: // => {                                 // delta
michael@0: //      a: {
michael@0: //        b: null,        // -
michael@0: //        e: 3            // +
michael@0: //      },
michael@0: //      c: {
michael@0: //        d: 4            // ±
michael@0: //      }
michael@0: //    }
michael@0: ```
michael@0: 
michael@0: As you can see from the example above `delta` makes no real distinction between
michael@0: proprety upadate and property addition. Try to think of additions as an update
michael@0: from `undefined` to whatever it's being updated to.
michael@0: 
michael@0: ## patch
michael@0: 
michael@0: Patch fuction takes a `hash` and a `delta` and returns a new `hash` which is
michael@0: just like orginial but with delta applied to it. Let's apply delta from the
michael@0: previous example to the first hash from the same example
michael@0: 
michael@0: 
michael@0: ```js
michael@0: var patch = require("diffpatcher/patch")
michael@0: 
michael@0: patch({ a: { b: 1 }, c: { d: 2 } },     // hash#1
michael@0:       {                                 // delta
michael@0:         a: {
michael@0:           b: null,        // -
michael@0:           e: 3            // +
michael@0:         },
michael@0:         c: {
michael@0:           d: 4            // ±
michael@0:         }
michael@0:       })
michael@0: 
michael@0: // => { a: { e: 3 }, c: { d: 4 } }      // hash#2
michael@0: ```
michael@0: 
michael@0: That's about it really, just diffing hashes and applying thes diffs on them.
michael@0: 
michael@0: 
michael@0: ### rebase
michael@0: 
michael@0: And as Linus mentioned everything in git can be expressed with `rebase`, that
michael@0: also pretty much the case for `diffpatcher`. `rebase` takes `target` hash,
michael@0: and rebases `parent` onto it with `diff` applied.
michael@0: 
michael@0: ## Install
michael@0: 
michael@0:     npm install diffpatcher