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1.4 +# diffpatcher
1.5 +
1.6 +[](http://travis-ci.org/Gozala/diffpatcher)
1.7 +
1.8 +[](http://ci.testling.com/Gozala/diffpatcher)
1.9 +
1.10 +Diffpatcher is a small library that lets you treat hashes as if they were
1.11 +git repositories.
1.12 +
1.13 +## diff
1.14 +
1.15 +Diff function that takes two hashes and returns delta hash.
1.16 +
1.17 +```js
1.18 +var diff = require("diffpatcher/diff")
1.19 +
1.20 +diff({ a: { b: 1 }, c: { d: 2 } }, // hash#1
1.21 + { a: { e: 3 }, c: { d: 4 } }) // hash#2
1.22 +
1.23 +// => { // delta
1.24 +// a: {
1.25 +// b: null, // -
1.26 +// e: 3 // +
1.27 +// },
1.28 +// c: {
1.29 +// d: 4 // ±
1.30 +// }
1.31 +// }
1.32 +```
1.33 +
1.34 +As you can see from the example above `delta` makes no real distinction between
1.35 +proprety upadate and property addition. Try to think of additions as an update
1.36 +from `undefined` to whatever it's being updated to.
1.37 +
1.38 +## patch
1.39 +
1.40 +Patch fuction takes a `hash` and a `delta` and returns a new `hash` which is
1.41 +just like orginial but with delta applied to it. Let's apply delta from the
1.42 +previous example to the first hash from the same example
1.43 +
1.44 +
1.45 +```js
1.46 +var patch = require("diffpatcher/patch")
1.47 +
1.48 +patch({ a: { b: 1 }, c: { d: 2 } }, // hash#1
1.49 + { // delta
1.50 + a: {
1.51 + b: null, // -
1.52 + e: 3 // +
1.53 + },
1.54 + c: {
1.55 + d: 4 // ±
1.56 + }
1.57 + })
1.58 +
1.59 +// => { a: { e: 3 }, c: { d: 4 } } // hash#2
1.60 +```
1.61 +
1.62 +That's about it really, just diffing hashes and applying thes diffs on them.
1.63 +
1.64 +
1.65 +### rebase
1.66 +
1.67 +And as Linus mentioned everything in git can be expressed with `rebase`, that
1.68 +also pretty much the case for `diffpatcher`. `rebase` takes `target` hash,
1.69 +and rebases `parent` onto it with `diff` applied.
1.70 +
1.71 +## Install
1.72 +
1.73 + npm install diffpatcher
