Function merge

src/licensedcode/dmp.py:647–778

Reorder and merge like edit sections in place. Merge equalities. Any edit section can move as long as it doesn't cross an equality. Return the merged diffs sequence. Args: diffs: Array of diff tuples.

(diffs)

def merge(diffs):
    """
    Reorder and merge like edit sections in place.  Merge equalities.
    Any edit section can move as long as it doesn't cross an equality.
    Return the merged diffs sequence.
    Args:
      diffs: Array of diff tuples.
    """
    diffs.append((DIFF_EQUAL, ''))  # Add a dummy entry at the end.
    pointer = 0
    count_delete = 0
    count_insert = 0
    text_delete = ''
    text_insert = ''

    while pointer < len(diffs):

        if diffs[pointer][0] == DIFF_INSERT:
            count_insert += 1
            text_insert += diffs[pointer][1]
            pointer += 1

        elif diffs[pointer][0] == DIFF_DELETE:
            count_delete += 1
            text_delete += diffs[pointer][1]
            pointer += 1

        elif diffs[pointer][0] == DIFF_EQUAL:

            # Upon reaching an equality, check for prior redundancies.
            if count_delete + count_insert > 1:
                if count_delete != 0 and count_insert != 0:

                    # Factor out any common prefixies.
                    commonlength = common_prefix(text_insert, text_delete)
                    if commonlength != 0:

                        x = pointer - count_delete - count_insert - 1
                        if x >= 0 and diffs[x][0] == DIFF_EQUAL:
                            diffs[x] = (
                                diffs[x][0],
                                diffs[x][1] + text_insert[:commonlength])
                        else:
                            diffs.insert(0, (DIFF_EQUAL, text_insert[:commonlength]))
                            pointer += 1

                        text_insert = text_insert[commonlength:]
                        text_delete = text_delete[commonlength:]

                    # Factor out any common suffixies.
                    commonlength = common_suffix(text_insert, text_delete)
                    if commonlength != 0:
                        diffs[pointer] = (
                            diffs[pointer][0],
                            text_insert[-commonlength:] + diffs[pointer][1])

                        text_insert = text_insert[:-commonlength]
                        text_delete = text_delete[:-commonlength]