We now have native language features for declaring tuples and objects,
which are the idiomatic way to construct sequence and mapping values that
can then be converted to list, set, and map types as needed.
In the old world, lists and maps could be created either using functions
in HIL or list/object constructs in HCL. Here we ensure that in the HCL
case we'll apply any required expression transformations to the individual
items within HCL's compound constructs.
The old parser was forgiving in allowing the use of block syntax where a
map attribute was expected, but the new parser is not (in order to allow
for dynamic map keys, for expressions, etc) and so the upgrade tool must
fix these to use attribute syntax.
This covers all of the expression node types in HIL's AST, and also
includes initial support for some of our top-level blocks so that we can
easily test that.
The initial implementations of the "variable" and "output" blocks are
pretty redundant and messy, so we can hopefully improve on these in a
later pass.
This function is the main functionality of this package. So far it just
deals with detecting and renaming JSON files that are mislabeled as
native syntax files. Other functionality will follow in later commits.
This package will do all of its work in-memory so that it can avoid making
partial updates and then failing, so we need to be able to load the
sources files from a particular directory into memory.
The upgrade process isn't idempotent, so we also attempt to detect
heuristically whether an upgrade has already been performed (can parse
with the new parser and has a version constraint that prevents versions
earlier than 0.12) so that the CLI tool that will eventually wrap this
will be able to produce a warning and prompt for confirmation in that
case.
Martin Atkins