In-house parser

[edigaryev]

Some things that still clearly need to be done:

• support only_if (this is currently the reason why the test suite fails)
• pass environment where it's needed for expansion
• support missing fields that are still needed for the CLI, the rest will be handled via Complete the parser #59.

Resolves #16.

[edigaryev]

@fkorotkov's there are a few files that are technically still under MIT since I've taken them directly from keanu:

• cirrus-cli/pkg/parser/modifier/matrix/expander.go

  Line 1 in 49fa7d9

  // Copyright (c) 2020 Fedor Korotkov <fedor.korotkov@gmail.com>

• cirrus-cli/pkg/parser/modifier/matrix/matrix.go

  Line 1 in 49fa7d9

  // Copyright (c) 2020 Fedor Korotkov <fedor.korotkov@gmail.com>

Do you consent to re-license the code in these files under MPL-2.0, so I can remove these lines?

[fkorotkov]

I consent but with MIT I don't think you even need to ask 😅

[edigaryev]

support only_if (this is currently the reason why the test suite fails)

Implemented in 2beda35.

However, since some changes to the Gval package are still waiting to be upstreamed (PaesslerAG/gval#38), go.mod temporarily points to https://github.com/edigaryev/gval/tree/expose-base-pieces.

[fkorotkov]

I think replacing the RPC parser with the local one right away seem like a bit too bold. What do you think about having a --parser flag with the default remote value and an option to set it to local? Also that way parser_test.go can validate that local parser returns the same results as the remote one.