Question

我需要帮助创建用于验证参数字符串的正则表达式。

参数字符串由2个可选的显式字符组组成。第一组只能包含一个P，O，Z字符（顺序无关紧要）。第二组具有相同的限制，但只能包含字符t，c，p，m。如果呈现两个组，则需要用单个空格字符分隔。

所以有效的字符串是：

P t
PO t
OZP ct
P tcmp
P
PZ
t
tp

等

Answer 1

为什么不抛弃正则表达式，并使用字符串来表示非字符串数据，并执行

[Flags]
enum First
{
    None = 0,
    P = 1,
    O = 2,
    Z = 4
}

[Flags]
enum Second
{
    None = 0
    T = 1,
    C = 2,
    P = 4,
    M = 8
}

void YourMethod(First first, Second second)
{
    bool hasP = first.HasFlag(First.P);
    var hasT = second.HasFlag(Second.T);
}

然后你可以这样打电话给YourMethod。

// equivalent to "PO mp", but checked at compile time.
YourMethod(First.P | First.O, Second.M | Second.P);

或者，如果你觉得这样的话

// same as above.
YourMethod((First)3, (Second)12);

如果您想了解更多有关其工作原理see this question。

Answer 2

我不认为正则表达式是一个很好的解决方案，因为它必须非常复杂：

Regex regexObj = new Regex(
    @"^               # Start of string
    (?:               # Start non-capturing group:
     ([POZ])          # Match and capture one of [POZ] in group 1
     (?![POZ]*\1)     # Assert that that character doesn't show up again
    )*                # Repeat any number of times (including zero)
    (?:               # Start another non-capturing group:
     (?<!^)           # Assert that we're not at the start of the string
     \                # Match a space
     (?!$)            # Assert that we're also not at the end of the string
    )?                # Make this group optional.
    (?<!              # Now assert that we're not right after...
     [POZ]            # one of [POZ] (i. e. make sure there's a space)
     (?!$)            # unless we're already at the end of the string.
    )                 # End of negative lookahead assertion
    (?:               # Start yet another non-capturing group:
     ([tcpm])         # Match and capture one of [tcpm] in group 2
     (?![tcpm]*\2)    # Assert that that character doesn't show up again
    )*                # Repeat any number of times (including zero)
    $                 # End of string", 
    RegexOptions.IgnorePatternWhitespace);

Answer 3

这应该可以满足您的需求：

([POZ]+)? ?([tcpm]+)?

参数正则表达式

3 个答案: