All of the other subdivisions of a block were already nodes, but we'd
represented the labels as an undifferentiated set of nodes belonging
directly to the block's child node list.
Now that we support replacing the labels in the public API, that's a good
excuse to refactor this slightly to make the labels their own node. As
well as being consistent with everything else in Block, this also makes
it easier to implement the Block.SetLabels operation because we can
just change the children of the labels node, rather than having to
carefully identify and extract the individual child nodes of the block
that happen to represent labels.
Internally this models the labels in a similar sort of way as the content
of a body, although we've kept the public API directly on the Block type
here because that's a more straightforward model for the use-cases we
currently know and matches better with the API of hcl.Block. This is just
an internal change for consistency.
I also added a few tests for having comments interspersed with labels
while I was here, because that helped to better exercise the new
parseBlockLabels function.
Fixes#338
Add methods to update block type and labels to enable us to refactor HCL
configurations such as renaming Terraform resources.
- `*Block.SetType(typeName string)`
- `*Block.SetLabels(labels []string)`
Some additional notes about SetLabels:
Since we cannot assume that old and new labels are equal in length,
remove old labels and insert new ones before TokenOBrace.
To implement this, I also added the following methods.
- `*nodes.Insert(pos *node, c nodeContent) *node`
- `*nodes.InsertNode(pos *node, n *node) *node`
They are similar to the existing Append / AppendNode,
but insert a node before a given position.
This method allows a caller to generate a nested block within a body.
Since a nested block has its own content body, this now allows for deep
structures to be generated.
