jw-python/tools/python/jwutils/cast.py

from collections import OrderedDict

from .log import *

_int_chars = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']

def _strip(s_, throw=True, log_level=ERR):
    s = s_.strip()
    if len(s) != 0:
        return s
    msg = f'Tried to strip empty string "{s_}" to int'
    if throw:
        raise Exception(msg)
    slog(log_level, msg)
    return None

def cast_str_to_int(s_: str, throw=True, log_level=DEBUG): # export
    s = _strip(s_, throw=throw, log_level=log_level)
    if s[0] == '-':
        s = s[1:]
    for c in s:
        if not c in _int_chars:
            break
        else:
            return (True, int(s_))
    msg = f'Could not convert string "{s_}" to int'
    if throw:
        raise Exception(msg)
    slog(log_level, msg)
    return (False, None)

def cast_str_to_bool(s_: str, throw=True, log_level=DEBUG): # export
    s = _strip(s_, throw=throw, log_level=log_level).lower()
    if s in ['true', 'yes', '1']:
        return (True, True)
    if s in ['false', 'no', '0']:
        return (True, False)
    msg = f'Could not convert string "{s_}" to bool'
    if throw:
        raise Exception(msg)
    slog(log_level, msg)
    return (False, None)

_str_cast_functions = OrderedDict({
        bool: cast_str_to_bool,
        int: cast_str_to_int
})

def guess_type(s: str, default=None, log_level=DEBUG, throw=False): # export
    if s is None:
        raise Exception('None string passed to guess_type()')
    for tp, func in _str_cast_functions.items():
        try:
            success, value = func(s, log_level=OFF, throw=False)
            if success:
                return tp
        except:
            continue
    msg = f'Failed to guess type of string "{s}"'
    if throw:
        raise Exception(msg)
    slog(log_level, msg)
    return default

def from_str(s: str, target_type=None, default_type=None, throw=True, log_level=WARNING, caller=None): # export
    if target_type is None:
        target_type = guess_type(s, default_type)
        if target_type is None:
            msg = f'Could not deduce type to cast to from string "{s}"'
            if throw:
                raise Exception(msg)
            slog(log_level, msg)
            return None
    result = _str_cast_functions[target_type](s, throw=throw, log_level=log_level)
    if result[0]:
        return result[1]
    msg = f'Failed to cast string "{s}" to type {target_type}'
    if throw:
        raise Exception(msg)
    slog(log_level, msg)
    return None

# deprecated name
def cast_str(s: str, target_type=None, default_type=None, throw=True, log_level=WARNING, caller=None):
    return from_str(s, target_type=target_type, default_type=None, throw=True, log_level=WARNING, caller=None)