A package for determining the differences between two lists and generating unified diff output similar to the diffutils CLI tool.

Installation

To use package:deviation to generate diffs, first add it as a dependency in your pubspec.yaml file:

dart pub add deviation

Usage

To compute the difference between two lists, create an instance of one of the supplied diff algorithms and pass the two lists to the algorithm's compute method.

import 'package:deviation/deviation.dart';

void main() {
  final diffPatch = const DiffAlgorithm.myers().compute(
    ['1', '2', '3'],
    ['2', '3', '4'],
  );
}

The compute method will return a Patch with a list of Update objects. If the Patch above is converted to a string representation and printed, you'd get an output similar to (-1, 2, 3, +4).

// Prints (-1,  2,  3, +4).
print(diffPatch.updates.map((u) => u.toString()));

For a more sophisticated textual output, you can convert a Patch into a UnifiedDiff that closely resembles the diffutils unified output format. For example, using the above patch with minimal configuration:

print(UnifiedDiff.fromPatch(
  diffPatch,
  header: const UnifiedDiffHeader.none(),
));

Would result in output similar to the following:

@@ -1,3 +1,3 @@
-1
 2
 3
+4