Add swift-log so we can log loading errors

Package.swift

@@ -8,9 +8,13 @@ let package = Package(
     products: [
         .library(name: "HummingbirdMustache", targets: ["HummingbirdMustache"]),
     ],
-    dependencies: [],
+    dependencies: [
+        .package(url: "https://github.com/apple/swift-log.git", from: "1.4.0"),
+    ],
     targets: [
-        .target(name: "HummingbirdMustache", dependencies: []),
+        .target(name: "HummingbirdMustache", dependencies: [
+            .product(name: "Logging", package: "swift-log"),
+        ]),
         .testTarget(name: "HummingbirdMustacheTests", dependencies: ["HummingbirdMustache"]),
     ]
 )

Sources/HummingbirdMustache/Library+FileSystem.swift

@@ -1,8 +1,9 @@
 import Foundation
+import Logging
 
 extension HBMustacheLibrary {
     /// Load templates from a folder
-    func loadTemplates(from directory: String, withExtension extension: String = "mustache") {
+    func loadTemplates(from directory: String, withExtension extension: String = "mustache", logger: Logger?) {
         var directory = directory
         if !directory.hasSuffix("/") {
             directory += "/"
@@ -14,8 +15,11 @@ extension HBMustacheLibrary {
             guard path.hasSuffix(extWithDot) else { continue }
             guard let data = fs.contents(atPath: directory + path) else { continue}
             let string = String(decoding: data, as: Unicode.UTF8.self)
-            guard let template = try? HBMustacheTemplate(string: string) else { continue }
-            
+            guard let template = try? HBMustacheTemplate(string: string) else {
+                logger?.error("Failed to load \(path)")
+                continue
+            }
+            logger?.debug("Loading \(path)")
             // drop ".mustache" from path to get name
             let name = String(path.dropLast(extWithDot.count))
             register(template, named: name)

Sources/HummingbirdMustache/Library.swift

@@ -1,3 +1,5 @@
+import Logging
+
 /// Class holding a collection of mustache templates.
 ///
 /// Each template can reference the others via a partial using the name the template is registered under
@@ -16,9 +18,9 @@ public class HBMustacheLibrary {
     /// the folder is recursive and templates in subfolders will be registered with the name `subfolder/template`.
     /// - Parameter directory: Directory to look for mustache templates
     /// - Parameter extension: Extension of files to look for
-    public init(directory: String, withExtension extension: String = "mustache") {
+    public init(directory: String, withExtension extension: String = "mustache", logger: Logger? = nil) {
         self.templates = [:]
-        self.loadTemplates(from: directory)
+        self.loadTemplates(from: directory, withExtension: `extension`, logger: logger)
     }
 
     /// Register template under name