A few simple implementations of quotable search terms splitting on whitespace.

search_term_parsing.py

def search_terms(s, quotes="\"'", delims='\n '):
    """
    Same as shlex.split but allows for quotes to be left open.
    And treats them as if they were never quoted.
    """
    quote = ''
    new_s = ['']
    for i, c in enumerate(s, start=1):
        if quote:
            if c == quote:
                quote = ''
                new_s.append('')
            else:
                new_s[-1] += c
        else:
            if c in quotes and s.find(c, i) != -1:
                quote = c
                new_s.append('')
            elif c in delims:
                new_s.append('')
            else:
                new_s[-1] += c
    return [s for s in new_s if s]


import shlex

def shlex_search_terms(s):
    """
    Uses shlex to split a search string with quotable whitespace.
    If the input has incorrect syntax the exact string is returned.
    """
    try:
        return shlex.split(s)
    except ValueError:
        return s