我正在使用Java进行项目,该项目涉及用户输入骰子表达式。我正在使用正则表达式来验证输入,以确保它是有效的D&D风格骰子表达式。我的意思是这样的表达式:
d20
2D12+ 4 - 2
12d4-2d6+7 + d8
7 + 1d12
全部有效。像这样的表达式:
-2d6+4
-d8 - 5
12
2d0 + 5
1d6 + 0d2 - 1
0d6
全部无效。 到目前为止,我设法制作的最接近的正则表达式是:
^((((0+\d+|[1-9]\d*|)(d|D)(0+\d+|[1-9]\d*))|(\d+))((\ *(\+|\-)\ *)(?=(((0+\d+|[1-9]\d*|)(d|D)(0+\d+|[1-9]\d*))|(\d+))))?)+$
但是,此正则表达式仍与“ 0d6”之类的表达式匹配。为此,在创建正则表达式方面的任何帮助将不胜感激。
答案 0 :(得分:2)
^(?!\d+$)(([1-9]\d*)?[Dd]?[1-9]\d*( ?[+-] ?)?)+(?<![+-] ?)$
说明:
^ | Enforce beginning of string
(?!\\d+$) | If 1+ digits at end of string are matched, don't match the following:
( | Begin group
([1-9]\\d*)? | Optionally match numbers not starting with 0 of any length
[Dd]? | Optionally match either "D" or "d"
[1-9]\\d* | Match numbers not starting with 0 of any length
( ?[+-] ?)? | Optionally match a "+" or "-" optionally surrounded by spaces
)+ | End group; one or more of these should exist
(?<![+-] ?) | A "+" or "-" with an optional space shouldn't precede the end
$ | Enforce end of string
示例代码:
String userInput = "12d4-2d6+7 + d8";
Pattern p = Pattern.compile("^(?!\\d+$)(([1-9]\\d*)?[Dd]?[1-9]\\d*( ?[+-] ?)?)+$");
Matcher m = p.matcher(userInput);
boolean b = m.matches();
System.out.println(b); // true