Add module jwutils.cast

Signed-off-by: Jan Lindemann <jan@janware.com>

tools/python/jwutils/cast.py

@@ -0,0 +1,82 @@
+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 cast_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
+