这个正则表达式是解析我的字符串的最有效方法吗？

Question

First off, here are the parameters to follow in the string I allow the user to input:

• If there is a slash, it has to appear at the start of the string, nowhere else, is limited to 1, is optional and must be succeeded by [a-zA-Z].
• If there is a tilde, it has to appear after a space " ", nothing else, is optional and must be succeeded by [a-zA-Z]. Also, this expression is limited to 2. (ie: ~exa ~mple is passed but ~exa ~mp ~le is not passed)
• The slash followed by a word is an instruction, like /get or /post.
• The tilde followed by a word is a parameter like ~now or ~later.

String format:

• [instruction] (optional) [query] [extra parameters] (optional)
• [instruction] - Must contain / succeeded with [a-zA-Z] only
• [query] - Can contain [\\w\\s()'-] (alphanumeric, whitespace, parentheses, apostrophe, dash)
• [extra parameters] - ~ preceded by whitespace, succeeded with only [a-zA-Z]

String examples that should work:

/get D0cUm3nt   ex4Mpl3'  ~now
D0cUm3nt  ex4Mpl3'
/post T(h)(i5  s(h)ou__ld w0rk t0-0'

String examples that shouldn't work:

//get document~now
~later
example ~now~later

Before I pass the string through the regex I trim any whitespace at the start and end of the string (before any text is seen) but I don't trim double whitespaces within the string as some queries require them.

Here is the regex I used:

^(/{0,1}[a-zA-Z])?[\w\s()'-]*((\s~[a-zA-Z]*){0,2})?$

To break it down slightly:

[instruction check] - (/{0,1}[a-zA-Z])?
[query check] - [\w\s()'-]*
[parameter check] - ((\s~[a-zA-Z]*){0,2})?

This is the first time I've actually done any serious regex away from a tutorial so I'm wondering is there anything I can change within my regex to make it more compact/efficient?

All fresh perspectives are appreciated!

Thanks.

Answer 1

From your regex: ^(/{0,1}[a-zA-Z])?[\\w\\s()'-]*((\\s~[a-zA-Z]*){0,2})?$ ,

you can change {0,1} to ? that is a shortcut to say 0 or 1 times:

^(/?[a-zA-Z])?[\w\s()'-]*((\s~[a-zA-Z]*){0,2})?$

The last part is present 0,1 or 2 times, then the ? is superfluous:

^(/?[a-zA-Z])?[\w\s()'-]*(\s~[a-zA-Z]*){0,2}$

The first part may be simplified too, the ? just after the / is superfluous:

^(/[a-zA-Z])?[\w\s()'-]*(\s~[a-zA-Z]*){0,2}$

If you don't use the captured groups, you can change them to non-capture group: (?: ) that are more efficient

^(?:/[a-zA-Z])?[\w\s()'-]*(?:\s~[a-zA-Z]*){0,2}$

You can also use the case-insensitive modifier (?i) :

^(?i)(?:/[a-z])?[\w\s()'-]*(?:\s~[a-z]*){0,2}$

Finally, as said in OP, ~ must be followed by [a-zA-Z] , so change the last * by + :

^(?i)(?:/[a-z])?[\w\s()'-]*(?:\s~[a-z]+){0,2}$

Answer 2

This looks slightly better:

^(?:/?[a-zA-Z]*\s)?[\w\s()'-]*(?:\s~[a-zA-Z]*)*$

https://codereview.stackexchange.com/ is more the place for this kind of thing

Answer 3

Assuming that capture groups are useful to you:

^((?:\\/|\\s~)[az]+)?([\\w\\s()'-]+)(~[az]+)?$

Regex101 Demo

Answer 4

也许这就是您想要的：

var regex = /^((\/)?[a-zA-Z]+)?[\w\s()'-]*((\s~)?[a-zA-Z]+){0,2}$/;