[GROOVY-7175] List.withIndex()

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.0-beta-3
• Fix Version/s: 2.4.0-rc-1
• Component/s: groovy-jdk
• Assignee: Paul King
• Reporter: Yu Kobayashi
• Created: 18/Nov/14 15:35
• Updated: 25/Sep/16 16:38
• Resolved: 23/Dec/14 19:39

Description

A method which zips list indices is missing.

The implementaion is this.

public static List withIndex(List self) {
    return withIndex(self, 0);
}

public static List withIndex(List self, int offset) {
    return transpose(Arrays.asList(self, new IntRange(false, offset, offset + self.size())));
}

I can use like this.

assert [["a", 0], ["b", 1]] == ["a", "b"].withIndex()
assert ["1: a", "2: b"] == ["a", "b"].withIndex(1).collect { str, idx -> "$idx: $str" }

In other languages the method names are like these.

Scala: zipWithIndex()
Kotlin: withIndices()
Ruby: with_index(offset = 0)
Python: enumerate(sequence, start=0)

I chose withIndex() because there is eachWithIndex() but List.collectWithIndex() is missing and I can call it by withIndex().collect().

Can I send a pull request to GitHub?