add HasFile content pack method

docs/release-notes.md

@@ -1,4 +1,10 @@
 # Release notes
+## 3.0 (upcoming release)
+These changes have not been released yet.
+
+* For modders:
+  * Added `IContentPack.HasFile` method.
+
 ## 2.11.1
 Released 17 March 2019 for Stardew Valley 1.3.36.
 

src/SMAPI/Framework/ContentPack.cs

@@ -47,6 +47,15 @@ namespace StardewModdingAPI.Framework
             this.JsonHelper = jsonHelper;
         }
 
+        /// <summary>Get whether a given file exists in the content pack.</summary>
+        /// <param name="path">The file path to check.</param>
+        public bool HasFile(string path)
+        {
+            this.AssertRelativePath(path, nameof(this.HasFile));
+
+            return File.Exists(Path.Combine(this.DirectoryPath, path));
+        }
+
         /// <summary>Read a JSON file from the content pack folder.</summary>
         /// <typeparam name="TModel">The model type.</typeparam>
         /// <param name="path">The file path relative to the contnet directory.</param>
@@ -54,8 +63,7 @@ namespace StardewModdingAPI.Framework
         /// <exception cref="InvalidOperationException">The <paramref name="path"/> is not relative or contains directory climbing (../).</exception>
         public TModel ReadJsonFile<TModel>(string path) where TModel : class
         {
-            if (!PathUtilities.IsSafeRelativePath(path))
+            this.AssertRelativePath(path, nameof(this.ReadJsonFile));
-                throw new InvalidOperationException($"You must call {nameof(IContentPack)}.{nameof(this.ReadJsonFile)} with a relative path.");
 
             path = Path.Combine(this.DirectoryPath, PathUtilities.NormalisePathSeparators(path));
             return this.JsonHelper.ReadJsonFileIfExists(path, out TModel model)
@@ -70,8 +78,7 @@ namespace StardewModdingAPI.Framework
         /// <exception cref="InvalidOperationException">The <paramref name="path"/> is not relative or contains directory climbing (../).</exception>
         public void WriteJsonFile<TModel>(string path, TModel data) where TModel : class
         {
-            if (!PathUtilities.IsSafeRelativePath(path))
+            this.AssertRelativePath(path, nameof(this.WriteJsonFile));
-                throw new InvalidOperationException($"You must call {nameof(IContentPack)}.{nameof(this.WriteJsonFile)} with a relative path.");
 
             path = Path.Combine(this.DirectoryPath, PathUtilities.NormalisePathSeparators(path));
             this.JsonHelper.WriteJsonFile(path, data);
@@ -95,5 +102,17 @@ namespace StardewModdingAPI.Framework
             return this.Content.GetActualAssetKey(key, ContentSource.ModFolder);
         }
 
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Assert that a relative path was passed it to a content pack method.</summary>
+        /// <param name="path">The path to check.</param>
+        /// <param name="methodName">The name of the method which was invoked.</param>
+        private void AssertRelativePath(string path, string methodName)
+        {
+            if (!PathUtilities.IsSafeRelativePath(path))
+                throw new InvalidOperationException($"You must call {nameof(IContentPack)}.{methodName} with a relative path.");
+        }
     }
 }

src/SMAPI/IContentPack.cs

@@ -21,6 +21,10 @@ namespace StardewModdingAPI
         /*********
         ** Public methods
         *********/
+        /// <summary>Get whether a given file exists in the content pack.</summary>
+        /// <param name="path">The file path to check.</param>
+        bool HasFile(string path);
+
         /// <summary>Read a JSON file from the content pack folder.</summary>
         /// <typeparam name="TModel">The model type. This should be a plain class that has public properties for the data you want. The properties can be complex types.</typeparam>
         /// <param name="path">The file path relative to the content pack directory.</param>