Refactor

alphabetseq

@@ -28,16 +28,24 @@ def test():
 	assert decimal_to_alphabet(0, '0123456789') == '0'
 
 
+def convert_start_stop(s, alphabet):
+	if ':' in s:
+		valalphabet, value = s.split(':')
+		if not valalphabet:
+			valalphabet = alphabet
+	else:
+		valalphabet, value = '0123456789', s
+	return alphabet_to_decimal(value, valalphabet)
+
+
 if __name__ == '__main__':
 	if len(sys.argv) == 2 and sys.argv[1] == '--test':
 		test()
-	elif len(sys.argv) == 4 or (len(sys.argv) == 5 and sys.argv[2] == '--decimal'):
-		if len(sys.argv) == 4:
-			alphabet = sys.argv[1]
-			start, stop = map(lambda x: alphabet_to_decimal(x, alphabet), sys.argv[2:])
-		else:
-			alphabet = sys.argv[1]
-			start, stop = map(int, sys.argv[3:])
+	elif len(sys.argv) in (3, 4):
+		if len(sys.argv) == 3:
+			sys.argv.append(sys.argv[-1])
+		alphabet = sys.argv[1]
+		start, stop = map(lambda x: convert_start_stop(x, alphabet), sys.argv[2:])
 		for i in range(start, stop + 1):
 			try:
 				sys.stdout.write(decimal_to_alphabet(i, alphabet) + '\n')
@@ -48,7 +56,10 @@ if __name__ == '__main__':
 					pass
 				break
 	else:
-		print('Usage: alphabetseq ALPHABET [--decimal] START STOP', file = sys.stderr)
+		print('Usage: alphabetseq ALPHABET START [STOP]', file = sys.stderr)
 		print('Generates the sequence from START to STOP (inclusive) using ALPHABET', file = sys.stderr)
-		print('By default, START and STOP are expressed in ALPHABET. With --decimal, they are treated as decimal values instead.', file = sys.stderr)
-		print('`alphabetseq 0123456789 $N $M` is equivalent to `seq $N $M`.', file = sys.stderr)
+		print('If STOP is omitted, it defaults to START, effectively making this a simple base transformation', file = sys.stderr)
+		print('START and STOP have values of the form [[VALALPHABET]:]VALUE.', file = sys.stderr)
+		print('  In the [VALALPHABET]:VALUE form, VALUE is expressed in terms of VALALPHABET, which defaults to ALPHABET if omitted.', file = sys.stderr)
+		print('  In the VALUE form, it is treated as a decimal number.', file = sys.stderr)
+		sys.exit(1)