Ideally, SwiftLintCore would some day only contain components
that are needed to define rules. Consequently, it would be the
only bundle required to import for (external) rule development.
Over the years, SwiftLintFramework had become a fairly massive monolith,
containing over 400 source files with both core infrastructure and
rules.
Architecturally, the rules should rely on the core infrastructure but
not the other way around. There are two exceptions to this:
`custom_rules` and `superfluous_disable_command` which need special
integration with the linter infrastructure.
Now the time has come to formalize this architecture and one way to do
that is to move the core SwiftLint functionality out of
SwiftLintFramework and into a new SwiftLintCore module that the rules
can depend on.
Beyond enforcing architectural patterns, this also has the advantage of
speeding up incremental compilation by skipping rebuilding the core
functionality when iterating on rules.
Because the core functionality is always useful when building rules, I'm
opting to import SwiftLintCore in SwiftLintFramework as `@_exported` so
that it's implicitly available to all files in SwiftLintFramework
without needing to import it directly.
In a follow-up I'll also split the built-in rules and the extra rules
into their own modules. More modularization is possible from there, but
not planned.
The bulk of this PR just moves files from `Source/SwiftLintFramework/*`
to `Source/SwiftLintCore/*`. There are some other changes that can't be
split up into their own PRs:
* Change jazzy to document the SwiftLintCore module instead of
SwiftLintFramework.
* Change imports in unit tests to reflect where code was moved to.
* Update `sourcery` make rule to reflect where code was moved to.
* Create a new `coreRules` array and register those rules with the
registry. This allows the `custom_rules` and
`superfluous_disable_command` rule implementations to remain internal
to the SwiftLintCore module, preventing more implementation details
from leaking across architectural layers.
* Move `RuleRegistry.registerAllRulesOnce()` out of the type declaration
and up one level so it can access rules defined downstream from
SwiftLintCore.
* Require Swift 5.0 to build
* Update CI
* Stop testing with Swift 4.x & Xcode 10.0/10.1
* Use official Swift docker image instead of norionomura's
* Use Xcode 10.3 as latest stable version
* Update READMEs
* Fixup xcodeproj
* Fixup CI Swift container image tag
* Fixup changelog
Performance has gotten pretty bad for complex SwiftLint configurations like the one used for Lyft's iOS code base involving lots of files in the directories being linted, large configuration files and many nested configuration files.
Two main areas were particularly ripe for improvement were:
1. Collecting which files to lint
2. Lint cache lookups
### Collecting which files to lint
Improve this by:
* using an NSOrderedSet to remove excluded paths instead of `Array.filter`
* parallelizing calls to `filesToLint` for all paths to lint and exclude
* using `FileManager.subpaths(atPath:)` instead of `enumerator(atPath:)`
|Change|Before|After|Speed up|
|-|-|-|-|
|NSOrderedSet|2.438s|0.917s|2.659x|
|Parallel Flat Map|2.438s|2.248s|1.085x|
|Subpaths|0.939s|0.867s|1.083x|
|**Total**|**2.438s**|**0.720s**|**3.386x**|
### Lint cache lookups
By using an MD5 hash of the Configuration description from CryptoSwift as the cache key instead of instead the full description, we can drastically speed up cache lookups for projects with complex SwiftLint configurations. I think the dictionary lookup for very large string keys doesn't perform very well.
---
* Speed up Configuration.lintablePaths
* Improve cache lookup performance by up to 10x
By using an MD5 hash of the Configuration description from CryptoSwift
as the cache key instead of instead the full description.
* Add changelog entries
* Swift 4.0 & Linux compatibility
* os(Darwin) isn't a thing
* Allow warnings in pod lib lint
SwiftLint supports building with Swift 4.0 to 4.2.
There is no version of CryptoSwift to support both Swift 4.0 and
Swift 4.2.
So allow warnings for now. We'll make one more Swift 4.0 compatible
release, then we'll bump the build requirements to Swift 4.2 and
remove the `--allow-warnings` flag.
Danny Mösch
JP Simard
Martin Redington
Frederick Pietschmann