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.
Prints out something like this on macOS:
```
Version: 0.49.0-rc.1
Build ID: B43931F3-D096-3704-B41C-FC40673A3F96
```
This can be used to determine if two `swiftlint` executables are
identical.
This change makes it possible to add native custom rules when building
SwiftLint via Bazel (possible as of
https://github.com/realm/SwiftLint/pull/4038).
First, add a local bazel repository where custom rules will be defined
to your project's `WORKSPACE`:
```python
local_repository(
name = "swiftlint_extra_rules",
path = "swiftlint_extra_rules",
)
```
Then in the extra rules directory, add an empty `WORKSPACE` and a
`BUILD` file with the following contents:
```python
filegroup(
name = "extra_rules",
srcs = glob(["*.swift"]),
visibility = ["//visibility:public"],
)
```
To add a rule (for example, `MyPrivateRule`) add the following two
files:
```swift
// ExtraRules.swift
func extraRules() -> [Rule.Type] {
[
MyPrivateRule.self,
]
}
```
```swift
// MyPrivateRule.swift
import SourceKittenFramework
import SwiftSyntax
struct MyPrivateRule: ConfigurationProviderRule {
var configuration = SeverityConfiguration(.error)
init() {}
static let description = RuleDescription(
identifier: "my_private_rule",
name: "My Private Rule",
description: "This is my private rule.",
kind: .idiomatic
)
func validate(file: SwiftLintFile) -> [StyleViolation] {
// Perform validation here...
}
}
```
Then you can reference the rule in your configuration or source files as
though they were built in to the official SwiftLint repo.
This means that you have access to SwiftLintFramework's internal API.
We make no guarantees as to the stability of these internal APIs,
although if you end up using something that gets removed please reach
out and we'll make a best effort to maintain some level of support.
This PR also improves the linter cache on macOS to make it correctly
invalidate previous results when custom native rules are edited. This
even works when doing local development of SwiftLint, where previous it
was necessary to use `--no-cache` when working on SwiftLint, now the
cache should always work.
Co-authored-by: Keith Smiley <keithbsmiley@gmail.com>
Danny Mösch
JP Simard