Question

I am using ExtJS. One of the textfield made with ExtJS component should allow comma separated number/opeator strings (3 similar examples) like

1, 2-3, 4..5, <6, <=7, >8, >=9 
>2, 3..5, >=9,>10
<=9, 1, <=8, 4..5, 8-9

Here I am using equals, range (-), sequence (..) & greater than/equal to operators for numbers less than or equal to 100. These numbers are separated by a comma.

What can be a regular expression for this type of string?

For my previously asked question.. I got a solution from "dlamblin": ^(?:d+(?:(?:..|-)d+)?|[<>]=?d+)(?:,s*d+(?:(?:..|-)d+)?|[<>]=?d+)*$

This works perfect for all patterns except:

Only if relationship operators (<, <=, >, >=) are present as first element of the string. E.g. <=3, 4-5, 6, 7..8 works perfect, but <=3, 4-5, 6, 7..8, >=5 relationship operator not at 1st element of string.
Also string <3<4, 5, 9-4 does not give any error i.e. it is satisfying condition though comma is needed between <3 and <4.
Numbers in the string should be less than or equal to 100. i.e. <100, 0-100, 99..100
It should not allow leading zeros (like 003, 099)

Answer 1

Scrap that and use a tokenizer instead. Split up the string by commas, then look at each token and decide (possibly using a regular expression) which type of relationship it is. If it s none of the existing relationships, it s invalid. If any relationship contains a number that s too big, it s invalid.

For the sake of your sanity and the people who will have to maintain this code after you re done with it, don t use regular expressions to validate such a complicated interrelated set of rules. Break it down into simpler chunks.

Answer 2

Welbog s advice to use a tokenizer is the sane option.

If you have some other constraint that forces a regular expression, you can use

^(<|<=|>|>=)?s*(100|0|[1-9]d?)((..|-)(100|0|[1-9]d?))?(,s*(<|<=|>|>=)?s*(100|0|[1-9]d?)((..|-)(100|0|[1-9]d?))?)*$

That s the result of expanding manually the following:

num   = (100|0|[1-9]d?)
op    = (<|<=|>|>=)
range = op?s*num((..|-)num)?
expr  = ^range(,s*range)*$

Answer 3

I agree with Welbog that pre/post processing should be a better choice.

BUT since I like to so RegEx so here is my solution.

^[ 	]*(?:(?:0|[1-9][0-9]?|100)(?:(?:-|..)(?:0|[1-9][0-9]?|100))?|(?:[<>]=?)(?:0|[1-9][0-9]?|100))(?:[ 	]*,[ 	]*(?:(?:0|[1-9][0-9]?|100)(?:(?:-|..)(?:0|[1-9][0-9]?|100))?|(?:[<>]=?)(?:0|[1-9][0-9]?|100)))*[ 	]*$

s is not used as it may include in some engine.

d is not used as you will need [1-9] so [0-9] will be easier to use.

(?:0|[1-9][0-9]?|100) will match a number from 0 to 100 without leading zero.

(?:[<>]=?)(?:0|[1-9][0-9]?|100) will match conditions follows by a number (if you want to match = too, just adjust it).

(?:0|[1-9][0-9]?|100)(?:(?:-|..)(?:0|[1-9][0-9]?|100))? will match a number with optional range or sequence.

Full explanation:

^
[ 	]*  // Prefix spaces
(?: // A valid term
    // A number
    (?:0|[1-9][0-9]?|100)
    // Optional range or sequence
    (?:
        (?:-|..)
        (?:0|[1-9][0-9]?|100)
    )?
    |
    // Condition and number
    (?:[<>]=?)(?:0|[1-9][0-9]?|100)
)
(?: // Other terms
    [ 	]*,[ 	]*   // Comma with prefix and suffix spaces
    (?: // A valid term
        // A number
        (?:0|[1-9][0-9]?|100)
        // Optional range or sequence
        (?:
            (?:-|..)
            (?:0|[1-9][0-9]?|100)
        )?
        |
        // Condition and number
        (?:[<>]=?)(?:0|[1-9][0-9]?|100)
    )
)*
[ 	]*  // Tail spaces

I test with regex-search of Eclipse and it work.

Hope this helps.

Answer 4

This should work:

^(?:(?:s*((?:<|>|<=|>=)?(?:[1-9]|[1-9]d|100))s*(?:,|$))|(?:s*((?:[1-9]|[1-9]d|100)(?:..|-)(?:[1-9]|[1-9]d|100))s*(?:,|$)))*$

(You ll need to use the "multiline" option, obviously.)

If you have the advantage of a regex engine that supports the "ignore whitespace" option, then you could break it up like this:

^                           # beginning of line
(?:   
  (?:
    s*                     # any whitespace
    (                       # capture group
      (?:<|>|<=|>=)?        # inequality
      (?:[1-9]|[1-9]d|100) # single value
    )
    s*                     # any whitespace
    (?:,|$)                 # comma or end of line
  )
  |
  (?:
    s*                     # any whitespace
    (                       # catpure group
      (?:[1-9]|[1-9]d|100) # single value
      (?:..|-)           # range modifier
      (?:[1-9]|[1-9]d|100) # single value
    )
    s*                     # any whitespace
    (?:,|$)                 # comma or end of line
  )
)+                          # one or more of all this
$                           # end of line

As you can see, it matches your examples in Expresso:

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