[swcomp] Add "benchmark show" command

Sources/swcomp/Benchmarks/BenchmarkGroup.swift

@@ -13,7 +13,8 @@ final class BenchmarkGroup: CommandGroup {
     let shortDescription = "Benchmark-related commands"
 
     let children: [Routable] = [
-        RunBenchmarkCommand()
+        RunBenchmarkCommand(),
+        ShowBenchmarkCommand()
     ]
 
 }

Sources/swcomp/Benchmarks/ShowBenchmarkCommand.swift

@@ -0,0 +1,75 @@
+// Copyright (c) 2022 Timofey Solomko
+// Licensed under MIT License
+//
+// See LICENSE for license information
+
+#if os(Linux)
+    import CoreFoundation
+#endif
+
+import Foundation
+import SwiftCLI
+
+final class ShowBenchmarkCommand: Command {
+
+    let name = "show"
+    let shortDescription = "Print saved benchmarks results"
+
+    @Key("-c", "--compare", description: "Compare with other saved benchmarks results")
+    var comparePath: String?
+
+    @Param var path: String
+
+    func execute() throws {
+        let loadedResults = try BenchmarkResult.load(from: self.path)
+        var otherResults: [String : [BenchmarkResult]]? = nil
+        if let comparePath = comparePath {
+            otherResults = try BenchmarkResult.load(from: comparePath)
+        }
+
+        for resultId in loadedResults.keys.sorted() {
+            let results = loadedResults[resultId]!
+            if results.count > 1 {
+                print("WARNING: There is more than one result with the same id=\(resultId) in the file \(self.path)")
+                print("Skipped...\n")
+                continue
+            }
+
+            let result = results.first!
+            let benchmark = Benchmarks(rawValue: result.name)?.initialized(result.input)
+
+            print("\(result.name) => \(result.input), iterations = \(result.iterCount)")
+
+            if let otherResults = otherResults?[resultId] {
+                if otherResults.count > 1 {
+                    print("Average = \(benchmark.format(result.avg)), standard deviation = \(benchmark.format(result.std))")
+                    print("WARNING: There is more than one result with the same id=\(resultId) in the file \(self.comparePath!)")
+                    print("Skipped comparison...\n")
+                } else {
+                    let other = otherResults.first!
+                    print("NEW:  average = \(benchmark.format(result.avg)), standard deviation = \(benchmark.format(result.std))")
+                    print("BASE: average = \(benchmark.format(other.avg)), standard deviation = \(benchmark.format(other.std))")
+                    result.printComparison(with: other)
+                }
+            } else {
+                print("Average = \(benchmark.format(result.avg)), standard deviation = \(benchmark.format(result.std))")
+            }
+
+            print()
+        }
+    }
+
+}
+
+fileprivate extension Optional where Wrapped == Benchmark {
+
+    func format(_ value: Double) -> String {
+        switch self {
+        case .some(let benchmark):
+            return benchmark.format(value)
+        case .none:
+            return String(value)
+        }
+    }
+
+}