buth / diff

A generic diff implementation that produces sequential edits.

diff

This package provides a generic implementation of the Myers diff algorithm that produces sequential edits.

Usage

To produce a list of edits, you can create an edit type and build a slice using a callback provided to the Diff method.

import "github.com/buth/diff"

type edit[T comparable] struct {
	start, end  diff.Position
	replacement []T
}

func listOfEdits[T comparable](dst, src []T) []edit[T] {
	var edits []edit[T]
	diff.Diff(dst, src, nil, func(start, end diff.Position, replacement []T) {
		edits = append(edits, edit[T]{
			start:       start,
			end:         end,
			replacement: replacement
		})
	})

	return edits
} 

Keep in mind that the provided replacement slice will be a subslice of the destination value if it is not nil.

To apply the edits, you can iterate through the resulting list using an index of the source slice as the starting point.

func applyEdits[T comparable](src []T, edits []edit[T]) []T {
	dst := make([]T, 0, len(src))

	i := 0
	for _, edit := range edits {
		dst = append(dst, src[i:edit.start.Index]...)
		dst = append(dst, edit.replacement...)
		i = edit.end.Index
	}

	return append(dst, src[i:]...)
}