Cannot rename `ColumnGroup` and its children at the same time

[Jolanrensen]

As the title says, renaming of columns inside column groups cannot be done if the column group itself is renamed in the same call.

For instance:

val myDf = dataFrameOf("a", "b", "c")(1, 2, 3).group("a", "b", "c").into("letters")
//⌌---------------------⌍
//|  |           letters|
//|--|------------------|
//| 0| { a:1, b:2, c:3 }|
//⌎---------------------⌏

myDf.rename {
    all().recursively()
    // or using the old notation
    allDfs(includeGroups = true)
}.into { it.name + "_renamed" }

//⌌---------------------⌍
//|  |   letters_renamed|
//|--|------------------|
//| 0| { a:1, b:2, c:3 }|
//⌎---------------------⌏

It needs to be done in two separate operations, like:

myDf
    .rename {
        cols { !it.isColumnGroup() }.recursively()
    }.into { it.name + "_renamed" }
    .rename {
        cols { it.isColumnGroup() }.recursively()
    }.into { it.name + "_renamed" }

//⌌--------------------------------------------⌍
//|  |                          letters_renamed|
//|--|-----------------------------------------|
//| 0| { a_renamed:1, b_renamed:2, c_renamed...|
//⌎--------------------------------------------⌏

From a user-perspective, this makes little sense and we should probably find a way to fix this.

[Jolanrensen]

This actually also breaks renameToCamelCase() which breaks running a test like:

val doublyNestedColumnGroup = dataFrameOf("test_name")(
    dataFrameOf("another_name")(
        dataFrameOf("third_name")(1).first()
    ).first()
)

val df = doublyNestedColumnGroup.renameToCamelCase()
df.columnNames() shouldBe listOf("testName")
df["testName"].asColumnGroup().columnNames() shouldBe listOf("anotherName") // still named "another_name"
df["testName"]["anotherName"].asColumnGroup().columnNames() shouldBe listOf("thirdName")

So an all-encompassing solution is needed.

[Jolanrensen]

The problem runs deeper... It also applies to

df.move { group and group.child }.into { ... }

and

df.replace { group and group.child }.with { ... }

If the name changes of a group, its children won't be updated since their path now differs from their new path.