support TOML as a log format file, uh, format

[tstack]

Using JSON for format configuration files is a bit unfriendly, TOML seems like a more reasonable format.

The challenge here is that lnav has a pretty tight binding to yajl for parsing files since lnav is doing validation and populating internal data structures. It looks like this parser (https://github.com/skystrife/cpptoml/) has a visitor interface, so we can probably make it work. Or, just resort to converting the TOML file to JSON internally.

Suggested by @jefft

[trapier]

no comment.
pun intended.

[jmealo]

@tstack: maybe we could champion getting this merged and stick with JSON? lloyd/yajl#211

Also, from the yajl docs:

comments in JSON
If you're dead set on using JSON throughout your system, you'll probably end up using it for your configuration files too. A little crazy, perhaps. But so am I. At parser allocation time you may specify a configuration parameter to allow comments inside the JSON input text. This is supported in versions 0.2.0 and above.

[romain-dartigues]

I'm not a TOML adept; is the YAML library too heavy to consider? I prefer the syntax and JSON being a subset of YAML, you could keep the backward compatibility with the JSON.

[VimCommando]

I like YAML, it is definitely easier to read.

[tstack]

I'm going to close this since there have been other enhancements that should make working with JSON format files easier. The recent regex101 integration should remove the need to do much manual editing of regexes. There is also a JSON-schema file published that can be referenced in the format file and then used in editors, like VS Code, to do validation and intellisense. Error checking/reporting has also been improved a lot and I don't want to spend time trying to make sure the reporting works as well with toml/yaml.