DiffHandler.py

import pandas as pd
import numpy as np
from difflib import SequenceMatcher

class DiffHandler():

    def extract_diff(self, old_content: list, new_content: list):
        """
        Function: extract the differences between two contents (Only store new lines for insert and replace; only store old lines for delete).
            We also need to store the line number relationship between old and new file, {
                old line number: [new line numbers] # because there may not be strict line number relationship
            }
        params:
            - old_content: a list of strings
            - new_content: a list of strings
        return:
            - [dict: {
                line_old, 
                line_new, 
                content_old, 
                content_new
            }]
        """
        result = []
        for tag, i1, i2, j1, j2 in SequenceMatcher(
            None, old_content, new_content
        ).get_opcodes():
            if tag == "equal":
                for i in range(i2 - i1):
                    old_line = i1 + i + 1
                    new_line = j1 + i + 1
                    item = {
                        "line_old": old_line,
                        "line_new": new_line,
                        "content_old": None,
                        "content_new": None
                    }
                    result.append(item)
                    
            elif tag == "insert":
                for i in range(j1 + 1, j2 + 1):
                    item = {
                        "line_old": None,
                        "line_new": i,
                        "content_old": None,
                        "content_new": new_content[i - 1]
                    }
                    result.append(item)
            elif tag == "delete":
                for i in range(i1 + 1, i2 + 1):
                    item = {
                        "line_old": i,
                        "line_new": None,
                        "content_old": old_content[i - 1],
                        "content_new": None
                    }
                    result.append(item)
            elif tag == "replace":
                for i in range(i2 - i1):
                    old_line = i1 + i + 1
                    item = {
                        "line_old": old_line,
                        "line_new": None,
                        "content_old": old_content[old_line - 1],
                        "content_new": None
                    }
                    result.append(item)
                for j in range(j2 - j1):
                    new_line = j1 + j + 1
                    item = {
                        "line_old": None,
                        "line_new": new_line,
                        "content_old": None,
                        "content_new": new_content[new_line - 1]
                    }
                    result.append(item)
            else:
                raise Exception("Function extract_diff Error: type error!")
        return result