[Go] Add support for YAML Go templates

[deathaxe]

This PR...

1. fixes missing source.json.go scope in snippet selectors
2. adds YAML (Go).sublime-syntax with YAML highlighted Go Templates

[FichteFoll]

Works well for me.

[FichteFoll]

As for where this is used: I've come across YAML with Go templates in the context of Helm and Rancher.

[FichteFoll]

Actually, multi-line comments in blocks are not recognized (not sure if this is a common syntax):

{{/* 
Spread a key-value map into the "env" list 
*/}}

Edit: Turns out this is a limitation of the match-string-templates context in the Go syntax, which requires the closing punctuation to be on the same line. match-text-templates does not have that requirement but it also does not remove the string scope from the scope stack.

---

Furthermore, I think the string after define should probably be an entity.name subscope, i.e.

{{/* Spread a key-value map into the "env" list */}}
{{- define "chart.env-vars" -}}
{{- range $key, $val := . }}
- name: {{ $key }}
  value: {{ quote $val }}
{{- end }}
{{- end -}}

Currently it's a string. Though, this is more of a Go issue since it stems from the existing Go template contexts being included.

[deathaxe]

Now using a string interpolation context without safe guards (no check for closing }}) in YAML. As we are explicitly using it in a template syntax, it should be safe enough.

[deathaxe]

... the string after define should probably be an entity.name subscope

Well, Go template syntax doesn't treat certain commands' arguments special by any means, currently to keep it lean.

According to https://docs.gomplate.ca/syntax/#nested-templates define is used do define inline templates. The counter-command template also treats first argument (the template name) as plain string.

Haven't investigeted which else commands would be affected.

That's certainly a separate feature request, not related with supporting YAML.

[FichteFoll]

That's certainly a separate feature request, not related with supporting YAML.

Yes, certainly.

[FichteFoll]

The lines with a sequence of : get scoped as meta.mapping.key by the YAML syntax even though the part where this occurs is part of the embedded section:

{{/*
Unroll a list of default environment variable settings
*/}}
{{- define "EnvironmentsHelper.defaults" -}}
{{- if .Values.environmentDefaults -}}
{{- range $key, $value := .Values.environmentDefaults }}
{{- printf "- name: %s" $key | nindent 20 -}}
{{- printf "  value: \"%v\"" $value | nindent 20 -}}
{{- end -}}
{{- end -}}
{{- end -}}

This is probably non-trivial and might require a refactoring of the YAML syntax since printf "- name is a valid plain scalar that can be interpreted as a key. I would be fine with not fixing this in this PR. Also note that because of the lookahead the entire line is scoped as a key.

[deathaxe]

I've tweaked the key lookaheads so they ignore anything within {{ ... }}.