File Diff using Rolling Hash Algorithm

This is an implementation of file diffing algorithm using adler32 rolling hash.

It first generates a signatures file from the original file contents. This signature file contains array of adler32 hashes constructed from the byte chunks of the original file. Then this signature file is used as a reference to identify any changes in the updated files.

How to Run

go run main.go CHUNK_SIZE PATH_OF_ORIGINAL_FILE PATH_OF_UPDATED_FILE

where

CHUNK_SIZE (Optional): Size of chunks that will be used for calculating signatures and rolling hash. Default value : 16

PATH_OF_ORIGINAL_FILE (Optional): Path to the file which will be used as base for comparison. Signatures will be generated on this file. Default value: mock_data/testData.txt

PATH_OF_UPDATED_FILE (Optional): Path to the file against which the original file will be compared. Default value: mock_data/updatedTestData.txt

P.S: Make sure that the order of the arguments need to be maintained. Eg: If you want to add PATH_OF_ORIGINAL_FILE, you will need to add CHUNK_SIZE too because it is the first argument`

Output

It returns a map of chunk index (starting from zero) to Delta struct defined below

type Delta struct{
	startIndex // The index in original file from where the replacement needs to begin

	endIndex // The index in the original file till where the replacement needs to happen

	deleted // A boolean variable it specifies if the chunk has been deleted

	updatedLiterals // string which will replace the existing ones between startIndex and endIndex

}

The output contains the list of chunks that have been deleted and the chunks that have been found but have some updated literals surronding them. Eg:

map[
	5:{641 768 true } 
	6:{641 768 false  the readable content of a page when looking at its layout. The point of using Ipsum Lorem is that it has a more-or-less normal } 
	9:{1153 1280 true } 
	10:{1153 1280 false pose
There are many variations of passages of Lorem Ipsum available, but the majority have suffe}
]

The output above can be read as:

• Chunk index 5 has not been found
• Chunk index 6 has been found but the content starting from index 641 and ending at 768 need to replaced with the text the readable content of a page when looking at its layout. The point of using Ipsum Lorem is that it has a more-or-less normal
• Chunk index 9 has not been found
• Chunk index 10 has been found but the content starting from index 1153 to index 1280 needs to replaced with the text pose There are many variations of passages of Lorem Ipsum available, but the majority have suffe