This commit adds support for removing a hanging indent from HEREDOC
token contents if the marker is prefixed with <<-. For example, given
the HCL definition:
my_long_var_name = <<-EOF
{
"key": "value"
}
EOF
The value of the HEREDOC will be:
{
"key": "value"
}
This is useful for use cases where indentation or leading whitespace
is important.
The rule applied is that the prefix on the terminating marker will be
removed from each each line in the HEREDOC, providing all the lines have
that prefix (i.e. every line is at least as indented as the terminating
marker, and using the same mechanism of tabs vs spaces).
This PR adds support for the style of HEREDOC often used in Ruby which
allows the terminating marker to be indented if the HEREDOC is started
with the sequence "<<-" rather than the usual "<<". This allows users to
express documents with more natural indentation:
resource "template_file" "test" {
template = <<-HEREDOC
First Line
Second Line
HEREDOC
}
Note that this does not attempt to add any semantics around removing
hanging indent from the actual text of the document, so extra
indentation would still be present. We could make use of the canonical
style for HCL herre to remove the hanging indent in the style of Ruby
which would probably be more predictable for users.
