Add optional JSON output (#52)

- Allow users to select a custom reporter that prints JSON instead of
`sed` commands

- Opt-in by adding `"reporter": "json"` to the configuration file

Author: wileykestner

Sources/unused-imports/BUILD

@@ -4,6 +4,11 @@ swift_binary(
     name = "unused-imports",
     srcs = [
         "main.swift",
+        "SourceFileWithUnusedImports.swift",
+        "UnusedImportStatement.swift",
+        "Reporters/JSONReporter.swift",
+        "Reporters/SedCommandReporter.swift",
+        "Reporters/UnusedImportReporter.swift",
     ],
     tags = [
         "manual",

Sources/unused-imports/Reporters/JSONReporter.swift

@@ -0,0 +1,11 @@
+import Foundation
+
+struct JSONReporter: UnusedImportReporter {
+    func didFind(sourceFilesWithUnusedImports: [SourceFileWithUnusedImports]) {
+        let jsonEncoder = JSONEncoder()
+        let removableImportsJSONData = try! jsonEncoder.encode(sourceFilesWithUnusedImports)
+        let removableImportsJSONString = String(data: removableImportsJSONData, encoding: String.Encoding.utf8)!
+        
+        print(removableImportsJSONString)
+    }
+}

Sources/unused-imports/Reporters/SedCommandReporter.swift

@@ -0,0 +1,10 @@
+import Foundation
+
+struct SedCommandReporter: UnusedImportReporter {
+    func didFind(sourceFilesWithUnusedImports: [SourceFileWithUnusedImports]) {
+        for sourceFile in sourceFilesWithUnusedImports.sorted() {
+            let sedCmd = sourceFile.unusedImportStatements.map { unusedImport in "\(unusedImport.lineNumber)d" }.joined(separator: ";")
+            print("/usr/bin/sed -i \"\" '\(sedCmd)' '\(sourceFile.path)'")
+        }
+    }
+}

Sources/unused-imports/Reporters/UnusedImportReporter.swift

@@ -0,0 +1,3 @@
+protocol UnusedImportReporter {
+    func didFind(sourceFilesWithUnusedImports: [SourceFileWithUnusedImports])
+}

Sources/unused-imports/SourceFileWithUnusedImports.swift

@@ -0,0 +1,8 @@
+struct SourceFileWithUnusedImports: Codable, Comparable {
+    let path: String
+    let unusedImportStatements: [UnusedImportStatement]
+
+    static func <(lhs: SourceFileWithUnusedImports, rhs: SourceFileWithUnusedImports) -> Bool {
+        return lhs.path < rhs.path
+    }
+}

Sources/unused-imports/UnusedImportStatement.swift

@@ -0,0 +1,8 @@
+struct UnusedImportStatement: Codable, Comparable {
+    let moduleName: String
+    let lineNumber: Int
+
+    static func <(lhs: UnusedImportStatement, rhs: UnusedImportStatement) -> Bool {
+        return lhs.moduleName < rhs.moduleName
+    }
+}

Sources/unused-imports/main.swift

@@ -6,6 +6,7 @@ private typealias References = (usrs: Set<String>, typealiases: Set<String>)
 private let identifierRegex = try Regex("([a-zA-Z_][a-zA-Z0-9_]*)")
 private let ignoreRegex = try Regex(#"// *@ignore-import$"#)
 private var cachedLines = [String: [String.SubSequence]]()
+private let defaultReporter = SedCommandReporter()
 
 private struct Configuration: Decodable {
     static func attemptingPath(_ path: String?) -> Configuration? {
@@ -23,17 +24,20 @@ private struct Configuration: Decodable {
     let ignoredFileRegex: Regex<AnyRegexOutput>?
     let ignoredModuleRegex: Regex<AnyRegexOutput>?
     let alwaysKeepImports: Set<String>
+    let reporter: UnusedImportReporter
 
     private enum CodingKeys: String, CodingKey {
         case ignoredFileRegex = "ignored-file-regex"
         case ignoredModuleRegex = "ignored-module-regex"
         case alwaysKeepImports = "always-keep-imports"
+        case reporter = "reporter"
     }
 
     init() {
         self.alwaysKeepImports = []
         self.ignoredFileRegex = nil
         self.ignoredModuleRegex = nil
+        self.reporter = defaultReporter
     }
 
     init(from decoder: Decoder) throws {
@@ -51,6 +55,23 @@ private struct Configuration: Decodable {
         } else {
             self.ignoredModuleRegex = nil
         }
+
+        if let string = try values.decodeIfPresent(String.self, forKey: .reporter) {
+            if string == "json" {
+                self.reporter = JSONReporter()
+            } else {
+                let invalidReporterTypeErrorMessage = """
+error: requested a type of reporter that doesn't exist: `\(string)`."
+In your unused-imports configuration try either:
+
+    1. Removing the `reporter` key to get the default `sed` command reporter or
+    2. Setting the `reporter` key to `json` to get the JSON reporter
+"""
+                fatalError(invalidReporterTypeErrorMessage)
+            }
+        } else {
+            self.reporter = defaultReporter
+        }
     }
 
     func shouldIgnoreFile(_ file: String) -> Bool {
@@ -68,6 +89,10 @@ private struct Configuration: Decodable {
 
         return false
     }
+
+    func didFind(sourceFilesWithUnusedImports: [SourceFileWithUnusedImports]) {
+        self.reporter.didFind(sourceFilesWithUnusedImports: sourceFilesWithUnusedImports)
+    }
 }
 
 private func getImports(path: String, recordReader: RecordReader) -> (Set<String>, [String: Int]) {
@@ -191,6 +216,8 @@ private func main(
             usrs: definedUsrs, typealiases: definedTypealiases)
     }
 
+    var sourceFilesWithUnusedImports: [SourceFileWithUnusedImports] = []
+
     for (unitReader, recordReader) in unitsAndRecords {
         if configuration.shouldIgnoreFile(unitReader.mainFile) {
             continue
@@ -235,10 +262,16 @@ private func main(
 
         let unusedImports = allImports.subtracting(usedImports).subtracting(configuration.alwaysKeepImports)
         if !unusedImports.isEmpty {
-            let sedCmd = unusedImports.map { importsToLineNumbers[$0]! }.sorted().map { "\($0)d" }.joined(separator: ";")
-            let relativePath = unitReader.mainFile.replacingOccurrences(of: pwd + "/", with: "")
-            print("/usr/bin/sed -i \"\" '\(sedCmd)' '\(relativePath)'")
-        }
+            let sourceFileWithUnusedImports = SourceFileWithUnusedImports(
+                path: unitReader.mainFile.replacingOccurrences(of: pwd + "/", with: ""),
+                unusedImportStatements: unusedImports.map { UnusedImportStatement(moduleName: $0, lineNumber: importsToLineNumbers[$0]!) }.sorted()
+            )
+            sourceFilesWithUnusedImports.append(sourceFileWithUnusedImports)
+         }
+    }
+
+    if sourceFilesWithUnusedImports.count != 0 {
+        configuration.didFind(sourceFilesWithUnusedImports: sourceFilesWithUnusedImports)
     }
 }