Add HCL

[ccakes]

First - thanks for yj, it's great!

I was looking today for a tool to use in some script to convert to HCL and couldn't find anything. It seemed fairly straightforward to add it here so I figured I'd have a go.

This is the first time I've written any Go so it's basically a copy-paste job. I vendored the hcl package because (a) that's how the TOML dependency is handled and (b) because I don't know how the Go package system works :/

Been using it locally and it seems to work ok enough, at least for my usage. If you want any changes to the PR just let me know.

[ccakes]

A couple of issues with the HCL package, there may be workarounds with better language knowledge.

1. It doesn't have an easy-to-use hcl.Encode function, it's possible to build an AST object from JSON though, hence the double conversion is toHCL
2. Similarly, I couldn't find a nice way to return a []byte containing the output. Right now I'm just printing the result in toHCL and returning nil to main. I dug around for 5mins in the package code but couldn't see an internal method that would be easy to use for me

[sclevine]

Many thanks for the PR!

Seems very reasonable for yj to support HCL, given its popularity (Terraform). I wonder what HCL2 will eventually mean for this integration, but I'm happy to include support for HCL for now.

I agree that converting to JSON to support encoding seems appropriate, given hashicorp/hcl#8.

Just a few things to fix up:

1. Let's leverage toJSON instead of copying it here:

   yj/main.go

   Lines 187 to 193 in 2dd1d82

   	output := &bytes.Buffer{}
   	encoder := json.NewEncoder(output)
   	encoder.SetEscapeHTML(config.EscapeHTML)
   	err := encoder.Encode(input)
   	if err != nil {
   	return nil, err
   	}

2. You can print this into another bytes.Buffer and return the bytes.Buffer.Bytes():

   yj/main.go

   Line 196 in 2dd1d82

   err = printer.Fprint(os.Stdout, ast)

3. Don't forget to check this error:

   yj/main.go

   Line 195 in 2dd1d82

   ast, err := jsonParser.Parse(output.Bytes())

4. HTML escaping for HCL should be mentioned in the usage (currently it says JSON-only):
   

   yj/main.go

   Line 189 in 2dd1d82

   encoder.SetEscapeHTML(config.EscapeHTML)

This project currently uses dep for vendoring, but I'd like it to use go modules instead. Don't worry about including the dependency for now -- I'll handle that with the merge.

This package needs more tests for things outside of the complex YAML normalization it was originally written for. I'd usually ask for tests in a PR, but I'll handle testing HCL when I add integration tests for the rest of the conversions.

[ccakes]

Thanks for the review! I've fixed the issues you mentioned but while testing, I've noticed that HCL -> YAML throws an error at times. I haven't had a chance to dig into it yet, but this isn't ready to merge

[sclevine]

Fixes look great! Let me know when it's ready.

Happy to help diagnose the HCL -> YAML errors if you could provide more detail.

[sclevine]

@ccakes I fixed the HCL -> YAML issue: https://github.com/sclevine/yj/tree/hcl

Mind if I merge this now? 😄

[ccakes]

@sclevine Hey! Sorry for the delay, yeah definitely happy if you managed to sort it 😊

[sclevine]

https://github.com/sclevine/yj/releases/tag/v3.0