This module implements an algorithm to compute the diff between two sequences of lines.

To learn more see Diff on Wikipedia.

Example:

import experimental/diff
assert diffInt(
  [0, 1, 2, 3, 4, 5, 6, 7, 8],
  [-1, 1, 2, 3, 4, 5, 666, 7, 42]) ==
  @[Item(startA: 0, startB: 0, deletedA: 1, insertedB: 1),
    Item(startA: 6, startB: 6, deletedA: 1, insertedB: 1),
    Item(startA: 8, startB: 8, deletedA: 1, insertedB: 1)]

Example:

import experimental/diff
# 2 samples of text (from "The Call of Cthulhu" by Lovecraft)
let txt0 = """
abc
def ghi
jkl2"""
let txt1 = """
bacx
abc
def ghi
jkl"""
assert diffText(txt0, txt1) ==
  @[Item(startA: 0, startB: 0, deletedA: 0, insertedB: 1),
    Item(startA: 2, startB: 3, deletedA: 1, insertedB: 1)]

Imports

tables, strutils

Types

Item = object startA*: int ## Start Line number in Data A. startB*: int ## Start Line number in Data B. deletedA*: int ## Number of changes in Data A. insertedB*: int ## Number of changes in Data B.: An Item in the list of differences. Source Edit

Procs

proc diffInt(arrayA, arrayB: openArray[int]): seq[Item] {....raises: [], tags: [].}

Find the difference in 2 arrays of integers.

arrayA A-version of the numbers (usually the old one)

arrayB B-version of the numbers (usually the new one)

Returns a sequence of Items that describe the differences.

Source Edit

proc diffText(textA, textB: string): seq[Item] {....raises: [KeyError], tags: [].}

Find the difference in 2 text documents, comparing by textlines.

The algorithm itself is comparing 2 arrays of numbers so when comparing 2 text documents each line is converted into a (hash) number. This hash-value is computed by storing all textlines into a common hashtable so i can find duplicates in there, and generating a new number each time a new textline is inserted.

textA A-version of the text (usually the old one)

textB B-version of the text (usually the new one)

Returns a seq of Items that describe the differences.

Source Edit