Regex pattern for a function call

Question

I have defined following pattern to parse our own custom for a function which is: <functionName>[<arg1>, <arg2>, ..] and the pattern is:
([a-zA-Z0-9]+)\\[(([a-zA-Z0-9]+)(,([a-zA-Z0-9])+)*?)*?\\]

Now when I run this against an example function: properCase[ARG1,ARG2], I get the following output:

Total matches are: 5
Group number 0is: properCase[ARG1, ARG2]
Group number 1is: properCase
Group number 2is: ARG1
Group number 3is: ARG1
Group number 4is: ,ARG2

Code:

        Matcher m = funcPattern.matcher("properCase[ARG1, ARG2]");
        System.out.println("Match found: " + m.matches());
        System.out.println("Total matches are: " + m.groupCount());
        if (m.matches())
        {
            for (int index= 0 ; index < m.groupCount(); index++)
            {
                System.out.println("Group number "+ index + "is: " +m.group(index));
            }
        }

How can I only extract out the function name (as group 1) and argument list (as group 2, group 3)? I am not able to eliminate the , from the group.

Alex · Accepted Answer · 2012-03-15 18:04:24Z

2

I'm not able to use the regex you provided to match properCase[ARG1, ARG2], but to answer your question more generally, you should use non capturing groups (?:your_regex) to not include it in the matcher groups

EDIT:

If you aren't married to using a single regex to do the parsing, consider the following: split up the string into function name and arguments groups, and then split the arguments group by the delimiter ,

import java.util.regex.*
String regex="([a-zA-Z0-9]+)\\[([ ,.a-zA-Z0-9]+)\\]"
Pattern funcPattern = Pattern.compile(regex);
Matcher m = funcPattern.matcher("properCase[ARG1, ARG2, class.otherArg]");
        System.out.println("Match found: " + m.matches());
        System.out.println("Total matches are: " + m.groupCount());
        if (m.matches())
        {
            for (int index= 0 ; index <= m.groupCount(); index++)
            {
                System.out.println("Group number "+ index + "is: " +m.group(index));
            }
        }
println "Arguments: " + m.group(2).split(",");

Produces:

Match found: true
Total matches are: 2
Group number 0is: properCase[ARG1, ARG2, class.otherArg]
Group number 1is: properCase
Group number 2is: ARG1, ARG2, class.otherArg
Arguments: [ARG1,  ARG2,  class.otherArg]

edited Mar 15, 2012 at 18:04

answered Mar 15, 2012 at 16:51

Alex

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1 Comment

name_masked Over a year ago

thank you! You won't be able to capture if the input string has spaces between the arguments. ARG1,ARG2 should work fine

cajunluke · Accepted Answer · 2012-03-15 16:48:26Z

1

Enclose the comma in its own group to work around it.

([a-zA-Z0-9]+)\\[(([a-zA-Z0-9]+)(,)(([a-zA-Z0-9])+)*?)*?\\]

edited Mar 15, 2012 at 16:48

cajunluke

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answered Mar 15, 2012 at 16:45

dwerner

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