getGroup

getGroup() Function

• Introduced in version 1.3b48

Returns the specified capture group for the specified match that was found using strfind().

Usage

getGroup(id, match, group)

Where

• id - is the id returned by strfind()
• match - is the number of the match found by strfind()
• group - is the number of the capture group found by strfind()

Example

[h: id = strfind("this is a test", "(\\S+)\\s(\\S+)\\s*")]
match 1, group 0 = [getGroup(id, 1, 0)]<br>
match 1, group 1 = [getGroup(id, 1, 1)]<br>
match 1, group 2 = [getGroup(id, 1, 2)]<br>
match 2, group 0 = [getGroup(id, 2, 0)]<br>
match 2, group 1 = [getGroup(id, 2, 1)]<br>
match 2, group 2 = [getGroup(id, 2, 2)]<br>

Returns:

match 1, group 0 = this is
match 1, group 1 = this 
match 1, group 2 = is 
match 2, group 0 = a test
match 2, group 1 = a 
match 2, group 2 = test 

Example explained

First off, escapes = "\" are used to let the character in question NOT be what it usually is. E.g. "d" is the alphabetical character "d"; "\d" however is thus NOT "d" and with that it gets a 'regex' meaning, in this case 'digit', so 1,2,3,4,5,6,7,8,9 or 0. The same the other way round, e.g. "." means "any character" if you actually want to find a "." (dot) in the text you thus use \. so its NOT the regex "any character" but just a ".".

Now the tricky bit: in maptool ALL escapes ("\") are eaten by the maptool parser UNLESS they are preceded by an escape themselves. This happens BEFORE the regex is parsed by the regex parser. THUS ALL ESCAPES MUST BE ESCAPED !! So in the above examples "\d" becomes "\\d" and "\." becomes "\\.". Really tricky it becomes when you want to find the "\" character. This is a regex symbol hence it needs to be escaped: "\\" but as its in maptool every escape must be escaped so it ultimately becomes "\\\\" !

note that alternatively you can use [] ANY character in there will be looked at literally (and seperately). So \\. == [.]. Obviously here too are exceptions, but read a regex tutorial for that.

So back to the above example:

• \\S = 'everything that is NOT a whitespace'
• \\s = 'whitespace'
• + = '1 or more'
• * = '0 or more'

Have a look here for an overview.

Second important thing to know is that a group is defined by '('parenthesis')': (group1)(group2)(etc.), where group '0' returns the entire search result.

So \\S means grab the first none-whitespace you encounter, \\S+ means grap the first none-whitespace you encounter AND ALL characters after that until you encounter a whitespace. Hence the regex statement looks for (word)whitespace(word)0 or more whitespace, where every 'parenthesized part' (in this case the 2 \\S+ aka "word") is a group. This will deliver 2 matches: 'this is' and 'a test'. The first match is match 1, the second match 2. Where each match again consists out of 3 groups. Group '1' will return the first (\\S+) part and group '2' will return the second (\\S+) of the regex statement. These are respectively (for the first match): 'this' and 'is'.

In summary: a search result can have multiple matches, and each match can consist out of 1 or more groups:

• The first group '0' returns the ENTIRE match.
• Every group after that will return partial matches that are within ().

Here a link to test your regex statements (remember that for this applet you only use one \ while in MT you need \\.