Function _generate_overlap_table

Lib/re/_compiler.py:421–440

Generate an overlap table for the following prefix. An overlap table is a table of the same size as the prefix which informs about the potential self-overlap for each index in the prefix: - if overlap[i] == 0, prefix[i:] can't overlap prefix[0:...] - if overlap[i] == k with 0 <

(prefix)

    return op in _UNIT_CODES

def _generate_overlap_table(prefix):
    """
    Generate an overlap table for the following prefix.
    An overlap table is a table of the same size as the prefix which
    informs about the potential self-overlap for each index in the prefix:
    - if overlap[i] == 0, prefix[i:] can't overlap prefix[0:...]
    - if overlap[i] == k with 0 < k <= i, prefix[i-k+1:i+1] overlaps with
      prefix[0:k]
    """
    table = [0] * len(prefix)
    for i in range(1, len(prefix)):
        idx = table[i - 1]
        while prefix[i] != prefix[idx]:
            if idx == 0:
                table[i] = 0
                break
            idx = table[idx - 1]
        else:
            table[i] = idx + 1
    return table

def _get_iscased(flags):
    if not flags & SRE_FLAG_IGNORECASE: