Refactor expression evaluator to use parser from actionlint package

[ZauberNerd]

This is an early draft to showcase the general direction we're going with this change.

We will of course rebase the commits, so that we can create separate PRs for the preparation-changes (refactoring of contexts, etc).

Also there's still a few TODO comments that we have to resolve before this PR is ready to merge.

Anyways, feedback is welcome :)

Next steps:

• manually track position in evaluator (actionlint parser gives us only the starting position of a token, but we need to know how far we've parsed)
• extend toString to be able to print all types
• get act tests to pass with the exprparser package
• clean-up errors, todos, tests, etc

[catthehacker]

I think model is better place than common for contexts and stepresults

[ChristopherHX]

Ah I got it, you forget to escape ${test} to ${{test}}, during conversion from multiple expressions to a big format expression

[mergify]

@ZauberNerd this pull request has failed checks 🛠

[ChristopherHX]

@ZauberNerd @KnisterPeter
Can you please add this commit to your PR? ChristopherHX@312d395
This fixes the two things I mentioned today.
Github actions don't fail to evaluate on most errors, like access undefined map property.
However invalid json string in fromJSON and an invalid format string does fail your workflow.

[mergify]

@ZauberNerd this pull request has failed checks 🛠

[ZauberNerd]

@ChristopherHX I think something with inputs and secrets broke while rebasing against master and now TestRunEvent/uses-nested-composite and TestRunEvent/local-action-via-composite-dockerfile are failing.
I guess it is related to this change: 9868e13#diff-4fe45e900ed33a3395bb42c8d8a85c1afb94987b2368bfe31d62e9e1ebd69060R449-R579 which I tried to incorporate here:

act/pkg/runner/expression.go

Lines 39 to 56 in 686898e

	secrets := rc.Config.Secrets
	if rc.Composite != nil {
	secrets = nil
	}
	ee := &exprparser.EvaluationEnvironment{
	Github: rc.getGithubContext(),
	Env: rc.GetEnv(),
	Job: rc.getJobContext(),
	// todo: should be unavailable
	// but required to interpolate/evaluate the step outputs on the job
	Steps: rc.getStepsContext(),
	Runner: map[string]interface{}{
	"os": "Linux",
	"temp": "/tmp",
	"tool_cache": "/opt/hostedtoolcache",
	},
	Secrets: secrets,

and here:

act/pkg/runner/expression.go

Line 112 in 686898e

Inputs: rc.Inputs,

Since you made some changes there, do you have an immediate idea what I'm doing wrong?

[ChristopherHX]

I'm debugging it carefully, there are expression evaluation errors in the log. Some values are empty.

[ChristopherHX]

@ZauberNerd The inputs context is always available, also on workflowlevel see reusable workflows.
The error was, that the inputs context was empty on runcontext level.
ChristopherHX@4c99bd7

[ZauberNerd]

The last open item (wrong implementation of contains()) has been fixed. Please take another look.
/cc @catthehacker @cplee

[catthehacker]

Thanks for that massive work, I tried to review whole PR carefully and so far it seems good to me