[PlaygroundLogger] Updated everything to throw errors instead of calling through to loggingError.

This means that logging shouldn't cause crashes, except in truly exceptional cases in the logger.
These errors are not quite propagated yet; that will come in a follow-up commit.

Author: cwakamo

PlaygroundLogger/PlaygroundLogger/CustomLoggable/CoreImage/CIColor+CustomOpaqueLoggable.swift

@@ -15,7 +15,7 @@ import CoreImage
 extension CIColor: CustomOpaqueLoggable {
     func opaqueRepresentation() throws -> LogEntry.OpaqueRepresentation {
         guard let color = CGColor(colorSpace: self.colorSpace, components: self.components) else {
-            loggingError("Unable to convert CIColor to CGColor")
+            throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Unable to convert this CIColor to a CGColor")
         }
 
         return color

PlaygroundLogger/PlaygroundLogger/CustomLoggable/SpriteKit/SpriteKitOpaqueLoggable.swift

@@ -21,9 +21,9 @@ import SpriteKit
 fileprivate protocol SpriteKitOpaqueLoggable: class, OpaqueImageRepresentable, CustomOpaqueLoggable {}
 
 extension SpriteKitOpaqueLoggable {
-    func encodeImage(into encoder: LogEncoder, withFormat format: LogEncoder.Format) {
+    func encodeImage(into encoder: LogEncoder, withFormat format: LogEncoder.Format) throws {
         guard let copyImageDataMethod = (self as AnyObject)._copyImageData, let imageData = copyImageDataMethod() else {
-            loggingError("SpriteKit did not return any image data")
+            throw LoggingError.encodingFailure(reason: "Unable to get image data for \(type(of: self))")
         }
 
         encoder.encode(number: UInt64(imageData.count))

PlaygroundLogger/PlaygroundLogger/LegacySupport/LegacyEntrypoints.swift

@@ -37,26 +37,37 @@ fileprivate func legacySendDataStub(_: NSData) -> Void {
 @_silgen_name("playground_log_hidden")
 public func legacyLog<T>(instance: T, name: String, id: Int, startLine: Int, endLine: Int, startColumn: Int, endColumn: Int) -> AnyObject {
     let packet = LogPacket(describingResult: instance, named: name, withPolicy: .default, startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
-    
-    let data = packet.encode()
+
+    let data: Data
+    do {
+        data = try packet.encode()
+    }
+    catch {
+        let errorPacket = LogPacket(errorWithReason: "Error occurred while encoding log packet", startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn, threadID: packet.threadID)
+
+        // Encoding an error packet should not fail under any circumstances.
+        data = try! errorPacket.encode()
+    }
 
     return data as NSData
 }
 
 @_silgen_name ("playground_log_scope_entry")
 public func legacyLogScopeEntry(startLine: Int, endLine: Int, startColumn: Int, endColumn: Int) -> AnyObject {
     let packet = LogPacket(scopeEntryWithStartLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
-    
-    let data = packet.encode()
+
+    // Encoding a scope entry packet should not fail under any circumstances.
+    let data = try! packet.encode()
 
     return data as NSData
 }
 
 @_silgen_name ("playground_log_scope_exit")
 public func legacyLogScopeExit(startLine: Int, endLine: Int, startColumn: Int, endColumn: Int) -> AnyObject {
     let packet = LogPacket(scopeExitWithStartLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
-    
-    let data = packet.encode()
+
+    // Encoding a scope exit packet should not fail under any circumstances.
+    let data = try! packet.encode()
 
     return data as NSData
 }
@@ -69,7 +80,16 @@ func legacyLogPostPrint(startLine: Int, endLine: Int, startColumn: Int, endColum
 
     let packet = LogPacket(printedString: printedString, startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
 
-    let data = packet.encode()
+    let data: Data
+    do {
+        data = try packet.encode()
+    }
+    catch {
+        let errorPacket = LogPacket(errorWithReason: "Error occurred while encoding log packet", startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn, threadID: packet.threadID)
+
+        // Encoding an error packet should not fail under any circumstances.
+        data = try! errorPacket.encode()
+    }
 
     return data as NSData
 }

PlaygroundLogger/PlaygroundLogger/LegacySupport/PlaygroundQuickLook+OpaqueRepresentationSupport.swift

@@ -33,54 +33,54 @@ extension PlaygroundQuickLook {
             return float
         case let .double(double):
             return double
-        case let .image(image):
+        case let .image(imageObject):
             #if os(macOS)
-                guard let image = image as? NSImage else {
-                    loggingError("Must be an NSImage")
+                guard let image = imageObject as? NSImage else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Image is not an NSImage; it is '\(type(of: imageObject))' instead")
                 }
 
                 return ImageOpaqueRepresentation(kind: .image, backedBy: image)
             #elseif os(iOS) || os(tvOS)
-                guard let image = image as? UIImage else {
-                    loggingError("Must be an IOImage")
+                guard let image = imageObject as? UIImage else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Image is not a UIImage; it is '\(type(of: imageObject))' instead")
                 }
 
                 return ImageOpaqueRepresentation(kind: .image, backedBy: image)
 
             #endif
         case .sound:
-            loggingError("Sounds not supported")
-        case let .color(color):
+            throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Sounds are not supported")
+        case let .color(colorObject):
             #if os(macOS)
-                guard let color = color as? NSColor else {
-                    loggingError("Must be an NSColor")
+                guard let color = colorObject as? NSColor else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Color is not an NSColor; it is '\(type(of: colorObject))' instead")
                 }
 
                 return color.cgColor
             #elseif os(iOS) || os(tvOS)
-                guard let color = color as? UIColor else {
-                    loggingError("Must be a UIColor")
+                guard let color = colorObject as? UIColor else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Color is not a UIColor; it is '\(type(of: colorObject))' instead")
                 }
 
                 return color.cgColor
             #endif
-        case let .bezierPath(bezierPath):
+        case let .bezierPath(bezierPathObject):
             #if os(macOS)
-                guard let bezierPath = bezierPath as? NSBezierPath else {
-                    loggingError("Must be an NSBezierPath")
+                guard let bezierPath = bezierPathObject as? NSBezierPath else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Bezier path is not an NSBezierPath; it is '\(type(of: bezierPathObject))' instead")
                 }
 
                 return bezierPath
             #elseif os(iOS) || os(tvOS)
-                guard let bezierPath = bezierPath as? UIBezierPath else {
-                    loggingError("Must be a UIBezierPath")
+                guard let bezierPath = bezierPathObject as? UIBezierPath else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Bezier path is not a UIBezierPath; it is '\(type(of: bezierPathObject))' instead")
                 }
 
                 return bezierPath
             #endif
-        case let .attributedString(attributedString):
-            guard let attributedString = attributedString as? NSAttributedString else {
-                loggingError("Must be an NSAttributedString")
+        case let .attributedString(attributedStringObject):
+            guard let attributedString = attributedStringObject as? NSAttributedString else {
+                throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Attributed string is not an NSAttributedString; it is '\(type(of: attributedStringObject))' instead")
             }
 
             return attributedString
@@ -103,7 +103,7 @@ extension PlaygroundQuickLook {
                     return ImageOpaqueRepresentation(kind: .view, backedBy: image)
                 }
                 else {
-                    loggingError("Must be an NSView or NSImage")
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "View is not an NSView or NSImage; is is '\(type(of: viewOrImage))' instead")
                 }
             #elseif os(iOS) || os(tvOS)
                 if let view = viewOrImage as? UIView {
@@ -113,27 +113,27 @@ extension PlaygroundQuickLook {
                     return ImageOpaqueRepresentation(kind: .view, backedBy: image)
                 }
                 else {
-                    loggingError("Must be a UIView or UIImage")
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "View is not a UIView or UIImage; is is '\(type(of: viewOrImage))' instead")
                 }
             #endif
-        case let .sprite(image):
+        case let .sprite(imageObject):
             // TODO: figure out if this is even a little bit right. (The previous implementation just logged a string for sprites?)
             #if os(macOS)
-                guard let image = image as? NSImage else {
-                    loggingError("Must be an NSImage")
+                guard let image = imageObject as? NSImage else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Sprite is not an NSImage; it is '\(type(of: imageObject))' instead")
                 }
 
                 return ImageOpaqueRepresentation(kind: .sprite, backedBy: image)
             #elseif os(iOS) || os(tvOS)
-                guard let image = image as? UIImage else {
-                    loggingError("Must be a UIImage")
+                guard let image = imageObject as? UIImage else {
+                    throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "Sprite is not a UIImage; it is '\(type(of: imageObject))' instead")
                 }
 
                 return ImageOpaqueRepresentation(kind: .sprite, backedBy: image)
             #endif
         case let .url(urlString):
             guard let url = URL(string: urlString) else {
-                loggingError("Must be a valid URL string!")
+                throw LoggingError.failedToGenerateOpaqueRepresentation(reason: "String is not a valid URL string")
             }
 
             return url

PlaygroundLogger/PlaygroundLogger/LogEntry+Encoding.swift

@@ -66,7 +66,7 @@ extension LogEntry {
         }
     }
 
-    func encode(with encoder: LogEncoder, format: LogEncoder.Format) {
+    func encode(with encoder: LogEncoder, format: LogEncoder.Format) throws {
         // Start by encoding the name of the log entry.
         encoder.encode(string: name)
 
@@ -76,9 +76,9 @@ extension LogEntry {
         // Finally, encode the entry-type-specific information.
         switch self {
         case let.structured(_, typeName, summary, totalChildrenCount, children, _):
-            LogEntry.encode(structuredWithTypeName: typeName, summary: summary, totalChildrenCount: totalChildrenCount, children: children, into: encoder, usingFormat: format)
+            try LogEntry.encode(structuredWithTypeName: typeName, summary: summary, totalChildrenCount: totalChildrenCount, children: children, into: encoder, usingFormat: format)
         case let .opaque(_, typeName, summary, preferBriefSummary, representation):
-            LogEntry.encode(opaqueWithTypeName: typeName, summary: summary, preferBriefSummary: preferBriefSummary, representation: representation, into: encoder, usingFormat: format)
+            try LogEntry.encode(opaqueWithTypeName: typeName, summary: summary, preferBriefSummary: preferBriefSummary, representation: representation, into: encoder, usingFormat: format)
         case .gap, .scopeEntry, .scopeExit:
             // Gap, scope entry, and scope exit entries contain no additional data beyond what's common to all log entry types.
             break
@@ -87,7 +87,7 @@ extension LogEntry {
         }
     }
 
-    private static func encode(structuredWithTypeName typeName: String, summary: String, totalChildrenCount: Int, children: [LogEntry], into encoder: LogEncoder, usingFormat format: LogEncoder.Format) {
+    private static func encode(structuredWithTypeName typeName: String, summary: String, totalChildrenCount: Int, children: [LogEntry], into encoder: LogEncoder, usingFormat format: LogEncoder.Format) throws {
         // Structured entries contain the following type-specific information:
         //   - Type name, encoded as a string
         //   - Summary, encoded as a string
@@ -103,10 +103,10 @@ extension LogEntry {
         guard totalChildrenCount > 0 else { return }
 
         encoder.encode(number: UInt64(children.count))
-        children.forEach { $0.encode(with: encoder, format: format) }
+        try children.forEach { try $0.encode(with: encoder, format: format) }
     }
 
-    private static func encode(opaqueWithTypeName typeName: String, summary: String, preferBriefSummary: Bool, representation: LogEntry.OpaqueRepresentation, into encoder: LogEncoder, usingFormat format: LogEncoder.Format) {
+    private static func encode(opaqueWithTypeName typeName: String, summary: String, preferBriefSummary: Bool, representation: LogEntry.OpaqueRepresentation, into encoder: LogEncoder, usingFormat format: LogEncoder.Format) throws {
         // Opaque entries contain the following type-specific information:
         //   - Prefers brief summary, encoded as a boolean
         //   - Type name, encoded as a string
@@ -119,7 +119,8 @@ extension LogEntry {
         encoder.encode(boolean: preferBriefSummary)
         encoder.encode(string: typeName)
         encoder.encode(string: summary)
-        representation.encode(into: encoder, usingFormat: format)
+
+        try representation.encode(into: encoder, usingFormat: format)
     }
 
     private static func encode(errorWithReason reason: String, into encoder: LogEncoder) {

PlaygroundLogger/PlaygroundLogger/LogEntry.swift

@@ -33,7 +33,7 @@ enum LogEntry {
 }
 
 protocol OpaqueLogEntryRepresentation {
-    func encode(into encoder: LogEncoder, usingFormat format: LogEncoder.Format)
+    func encode(into encoder: LogEncoder, usingFormat format: LogEncoder.Format) throws
 }
 
 private let emptyName = ""

PlaygroundLogger/PlaygroundLogger/LogPacket+Encoding.swift

@@ -13,7 +13,7 @@
 import Foundation
 
 extension LogPacket {
-    func encode(inFormat format: LogEncoder.Format = .current) -> Data {
+    func encode(inFormat format: LogEncoder.Format = .current) throws -> Data {
         let encoder = LogEncoder()
 
         // Encode the format version.
@@ -31,7 +31,7 @@ extension LogPacket {
         encoder.encode(string: threadID)
 
         // Encode our top-level log entry. (This will add any child entries automatically.)
-        logEntry.encode(with: encoder, format: format)
+        try logEntry.encode(with: encoder, format: format)
 
         return encoder.encodedData
     }

PlaygroundLogger/PlaygroundLogger/LoggerEntrypoints.swift

@@ -21,7 +21,16 @@ func logResult(_ result: Any,
                endColumn: Int) {
     let packet = LogPacket(describingResult: result, named: name, withPolicy: .default, startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
 
-    let data = packet.encode()
+    let data: Data
+    do {
+        data = try packet.encode()
+    }
+    catch {
+        let errorPacket = LogPacket(errorWithReason: "Error occurred while encoding log packet", startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn, threadID: packet.threadID)
+
+        // Encoding an error packet should not fail under any circumstances.
+        data = try! errorPacket.encode()
+    }
 
     sendData(data as NSData)
 }
@@ -31,8 +40,9 @@ func logScopeEntry(startLine: Int,
                    startColumn: Int,
                    endColumn: Int) {
     let packet = LogPacket(scopeEntryWithStartLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
-    
-    let data = packet.encode()
+
+    // Encoding a scope entry packet should not fail under any circumstances.
+    let data = try! packet.encode()
 
     sendData(data as NSData)
 }
@@ -42,8 +52,9 @@ func logScopeExit(startLine: Int,
                   startColumn: Int,
                   endColumn: Int) {
     let packet = LogPacket(scopeExitWithStartLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
-    
-    let data = packet.encode()
+
+    // Encoding a scope exit packet should not fail under any circumstances.
+    let data = try! packet.encode()
 
     sendData(data as NSData)
 }
@@ -66,7 +77,16 @@ func logPostPrint(startLine: Int,
 
     let packet = LogPacket(printedString: printedString, startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn)
 
-    let data = packet.encode()
+    let data: Data
+    do {
+        data = try packet.encode()
+    }
+    catch {
+        let errorPacket = LogPacket(errorWithReason: "Error occurred while encoding log packet", startLine: startLine, endLine: endLine, startColumn: startColumn, endColumn: endColumn, threadID: packet.threadID)
+
+        // Encoding an error packet should not fail under any circumstances.
+        data = try! errorPacket.encode()
+    }
 
     sendData(data as NSData)
 }

PlaygroundLogger/PlaygroundLogger/OpaqueRepresentations/AppKit/NSBitmapImageRep+OpaqueImageRepresentable.swift

@@ -14,9 +14,9 @@
     import AppKit
 
     extension NSBitmapImageRep: OpaqueImageRepresentable {
-        func encodeImage(into encoder: LogEncoder, withFormat format: LogEncoder.Format) {
+        func encodeImage(into encoder: LogEncoder, withFormat format: LogEncoder.Format) throws {
             guard let pngData = self.representation(using: .png, properties: [:]) else {
-                loggingError("Failed to generate PNG data")
+                throw LoggingError.encodingFailure(reason: "Failed to generate PNG data for the bitmap representation")
             }
 
             encoder.encode(number: UInt64(pngData.count))

PlaygroundLogger/PlaygroundLogger/OpaqueRepresentations/AppKit/NSImage+OpaqueImageRepresentable.swift

@@ -32,12 +32,12 @@
             }
         }
 
-        func encodeImage(into encoder: LogEncoder, withFormat format: LogEncoder.Format) {
+        func encodeImage(into encoder: LogEncoder, withFormat format: LogEncoder.Format) throws {
             guard let bitmapRep = self.bestBitmapRepresentation else {
-                loggingError("Failed to convert image to a bitmap representation")
+                throw LoggingError.encodingFailure(reason: "Failed to get a bitmap representation of this NSImage")
             }
 
-            bitmapRep.encodeImage(into: encoder, withFormat: format)
+            try bitmapRep.encodeImage(into: encoder, withFormat: format)
         }
     }
 #endif