diff-mcp

# Delta Format This page intends to be a reference for JSON format used to represent deltas (i.e. the output of `jsondiffpatch.diff`). This format was created with a balance between readability and low footprint in mind. - when diffing 2 objects, the delta will reflect the same object structure (common part on both sides) - to represent changed parts, arrays and magic numbers are used to keep a low footprint (i.e. you won't see verbosity like `"type": "added"`) - keep it pure JSON serializable A great way to understand this format is using the "Annotated JSON" option in the [Live Demo](https://jsondiffpatch.com)), and try the different left/right examples, or edit left/right JSON to see the annotated delta update as your type. Here's a complete reference of this format. ## Added a value was added, i.e. it was `undefined` and now has a value. ```ts delta = [newValue]; ``` ## Modified a value was replaced by another value ```ts delta = [oldValue, newValue]; ``` ## Deleted a value was deleted, i.e. it had a value and is now `undefined` ```ts delta = [oldValue, 0, 0]; ``` NOTE: In both modified and deleted, when using the `omitRemovedValues: true` option, `oldValue` is omitted, replaced with a `0`. This makes the delta irreversible (can't be used for unpatch), but might be a good trade-off if you're sending them over the network and unpatch is never needed. ## Object with inner changes value is an object, and there are nested changes inside its properties ```ts delta = { property1: innerDelta1, property2: innerDelta2, property5: innerDelta5, }; ``` > Note: only properties with inner deltas are included Here's an example combining what we have: ```ts delta = { property1: [newValue1], // obj[property1] = newValue1 property2: [oldValue2, newValue2], // obj[property2] = newValue2 (and previous value was oldValue2) property5: [oldValue5, 0, 0], // delete obj[property5] (and previous value was oldValue5) }; ``` ## Array with inner changes value is an array, and there are nested changes inside its items ```ts delta = { _t: 'a', index1: innerDelta1, index2: innerDelta2, index5: innerDelta5, }; ``` > Note: only indices with inner deltas are included > Note: \_t: 'a', indicates this applies to an array, when patching if a regular object (or a value type) is found, an error will be thrown ### Index Notation Indices on array deltas can be expressed in two ways: - number: refers to the index in the final (right) state of the array, this is used to indicate items inserted. - underscore + number: refers to the index in the original (left) state of the array, this is used to indicate items removed, or moved. ### Array Moves an item was moved to a different position in the same array ```ts delta = ['', destinationIndex, 3]; ``` > Note: '' represents the moved item value, suppresed by default > Note: 3 is the magical number that indicates "array move" ## Text Diffs If two strings are compared and they are different, you will see as you expect: ```ts delta = ['some text', 'some text modified']; ``` But if both strings are long enough, [a text diffing algorithm](https://code.google.com/p/google-diff-match-patch/) will be used to efficiently detect changes in parts of the text. You can modify the minimum length with: ```ts const customDiffPatch = jsondiffpatch.create({ textDiff: { minLength: 60, // default value }, }); ``` And the delta will look like this: ```ts delta = [unidiff, 0, 2]; ``` > Note: 2 is the magical number that indicates "text diff" > Note: unidiff is actually a character-based variation of Unidiff format that is explained [here](https://code.google.com/p/google-diff-match-patch/wiki/Unidiff)