Add templating and template ASTPass.swift

[nvgrw]

Implementation Overview

Adds templating to ASTPass.swift.
We refactored some of the calls to process and postProcess as their labels were inconsistently named.

Templates have the extension .template.swift rather than .swift.
Generated sources are not committed to source control and rather are generated as part of the generate target (a requirement of all, release, test) to the .derived-sources directory.

Adds further node modules as dependencies. We already require node to run truffle so we think the impact of this is minimal. Installation is simplified by a top-level module in the root of the repository, so npm install should be run prior to compilation. We decided not to invoke NPM on every build because the installation of dependencies is a one-off process. Opinions on this decision are welcome.

Adding new templates requires changes to a few parts of the build setup:

• add an exclusion to Package.swift so that the project does not compile the .template.swift file. We could have chosen a different file extension but these files are still inherently Swift and Xcode highlights any file with the .swift extension automatically. Unfortunately exclusions don't support globs, or we would've excluded any file ending in .template.swift.
• add an inclusion to the .derived-sources directory to Package.swift if templating a file outside of the AST module.
• make sure to disable (and later reenable) the linter for the template file. Swiftlint does not like nunjucks/jinja and globbing exclusions is again not possible.

We chose nunjucks as other Swift-first templating solutions don't work well on Linux, and nunjucks over jinja as we wanted to avoid adding Python as a(nother) dependency.

Notes

• reformat ASTPass.swift to single lines
• add test jinja2 template
• add .derived-sources to gitignore and update Package.swift to include derived source
• added codegen using jinja2
• turn codegen into a node package and add to top level module
• add generate target to makefile
• pre-refactor extraction
• rename enumCase => enumMember
• rename literalToken => token
• fix travis yaml

Implemented together with @Aurel300

[nvgrw]

The CI crashed running apt-get. I'll try re-running it.

[nvgrw]

I don't have the ability to re-run this. If someone else could restart it that would be great.

[SusanEisenbach]

Is there something I should do so that Nik can restart the CI?

…

-- Professor Susan Eisenbach Department of Computing Imperial College London On 11 Oct 2018, at 12:35, Nik Vangerow <notifications@github.com<mailto:notifications@github.com>> wrote: I don't have the ability to re-run this. If someone else could restart it that would be great. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub<#408 (comment)>, or mute the thread<https://github.com/notifications/unsubscribe-auth/AEXpZj1a9ONCX036PPp3k66C7L7WFHUiks5ujx8GgaJpZM4XXPwx>.

[Aurel300]

@SusanEisenbach The CI was restarted by Nik with a push. Only a review is now needed to merge this.

[DJRHails]

Looks good and I think all the decisions you've mentioned are very sensible.