Github user cestella commented on a diff in the pull request: https://github.com/apache/metron/pull/742#discussion_r137913436 --- Diff: metron-stellar/stellar-common/src/main/java/org/apache/metron/stellar/dsl/functions/StringFunctions.java --- @@ -321,6 +321,46 @@ public Object apply(List<Object> args) { } } + @Stellar( name="SUBSTRING" + , description = "Returns a substring of a string" + , params = { + "input - The string to take the substring of", + "start - The starting position (0-based and inclusive)", + "end? - The ending position (0-based and exclusive)" + } + , returns = "The substring of the input" + ) + public static class Substring extends BaseStellarFunction { + + @Override + public Object apply(List<Object> strings) { + + if(strings == null || strings.size() < 2 ) { + throw new IllegalArgumentException("[SUBSTRING] required 2 arguments: the input and the start position (inclusive)"); --- End diff -- Yeah, I was following the leader with `CHOMP`, but I agree, I will correct this in a follow-on JIRA with the rest of your issues covered.
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