Extra Rules

Author: jpsim

WORKSPACE

@@ -29,9 +29,14 @@ swift_rules_extra_dependencies()
 
 http_archive(
     name = "SwiftLint",
-    sha256 = "574c43473643203be6691173f771899656a0928c875e2f547aab17bebb5403f5",
-    strip_prefix = "SwiftLint-949ab6289a6e9d52b84c8cc43817703c3bf68f77",
-    url = "https://github.com/realm/SwiftLint/archive/949ab6289a6e9d52b84c8cc43817703c3bf68f77.tar.gz",
+    sha256 = "7dcb520cd80724584126aeb89bc7db55cb35267aa668613f28084202a2d03ede",
+    strip_prefix = "SwiftLint-1dab8181b8597c493463dbab48aa7380dcd99123",
+    url = "https://github.com/realm/SwiftLint/archive/1dab8181b8597c493463dbab48aa7380dcd99123.tar.gz",
+)
+
+local_repository(
+    name = "swiftlint_extra_rules",
+    path = "swiftlint_extra_rules",
 )
 
 load("@SwiftLint//bazel:repos.bzl", "swiftlint_repos")

file.swift

@@ -1 +1 @@
-let a : Int = 0
+let forbidden : Int = 1

swiftlint_extra_rules/BUILD

@@ -0,0 +1,5 @@
+filegroup(
+    name = "extra_rules",
+    srcs = glob(["**/*.swift"]),
+    visibility = ["//visibility:public"],
+)

swiftlint_extra_rules/ExtraRules.swift

@@ -0,0 +1,5 @@
+func extraRules() -> [Rule.Type] {
+    [
+        ForbiddenVarRule.self
+    ]
+}

swiftlint_extra_rules/ForbiddenVarRule.swift

@@ -0,0 +1,37 @@
+import SourceKittenFramework
+import SwiftSyntax
+
+public struct ForbiddenVarRule: ConfigurationProviderRule, AutomaticTestableRule, SourceKitFreeRule {
+    public var configuration = SeverityConfiguration(.warning)
+
+    public init() {}
+
+    public static let description = RuleDescription(
+        identifier: "forbidden_var",
+        name: "Forbidden Var",
+        description: "Can't name a variable 'forbidden'",
+        kind: .style,
+        nonTriggeringExamples: [Example("let okay = 0")],
+        triggeringExamples: [Example("let ↓forbidden = 0")]
+    )
+
+    public func validate(file: SwiftLintFile) -> [StyleViolation] {
+        ForbiddenVarRuleVisitor()
+            .walk(file: file, handler: \.positions)
+            .map { position in
+                StyleViolation(ruleDescription: Self.description,
+                               severity: configuration.severity,
+                               location: Location(file: file, byteOffset: ByteCount(position)))
+            }
+    }
+}
+
+private final class ForbiddenVarRuleVisitor: SyntaxVisitor {
+    var positions: [AbsolutePosition] = []
+
+    override func visitPost(_ node: IdentifierPatternSyntax) {
+        if node.identifier.text == "forbidden" {
+            positions.append(node.positionAfterSkippingLeadingTrivia)
+        }
+    }
+}