Offset Model (8-bit, 16-bit, 64-bit offset sizes, file identifier sizes)

src/FlatSharp.Compiler/CompilerOptions.cs

@@ -28,5 +28,14 @@ public record CompilerOptions
 
         [Option("nullable-warnings", Default = false)]
         public bool? NullableWarnings { get; set; }
+
+        [Option('s', "offset-size")]
+        public int? OffsetSize { get; set; }
+
+        [Option( "file-identifier-size")]
+        public int? FileIdentifierSize { get; set; }
+
+        [Option("strict-file-identifier-size")]
+        public bool? StrictFileIdentifierSize { get; set; }
     }
 }

src/FlatSharp.Compiler/FlatSharp.Compiler.targets

@@ -33,7 +33,7 @@
 
     <Message Text="$(TargetFramework) $(TargetFrameworkIdentifier): $(CompilerInvocation) --nullable-annotations $(FlatSharpNullable) --input &quot;%(FlatSharpSchema.fullpath)&quot; --output $(IntermediateOutputPath)" Importance="high" />
     <Exec 
-        Command="$(CompilerInvocation) --nullable-warnings $(FlatSharpNullable) --input &quot;%(FlatSharpSchema.fullpath)&quot; --output $(IntermediateOutputPath) "
+        Command="$(CompilerInvocation) $(FlatSharpCompilerOptions) --nullable-warnings $(FlatSharpNullable) --input &quot;%(FlatSharpSchema.fullpath)&quot; --output $(IntermediateOutputPath) "
         CustomErrorRegularExpression=".*" 
         Condition=" '%(FlatSharpSchema.fullpath)' != '' " />
 

src/FlatSharp.Compiler/FlatSharpCompiler.cs

@@ -371,15 +371,32 @@ private static void CreateCSharp(
 
                     writer = new CodeWriter();
 
+                    TypeModelContainer container;
+
+                    if (localOptions.OffsetSize == null
+                        && localOptions.FileIdentifierSize == null
+                        && localOptions.StrictFileIdentifierSize == null)
+                    {
+                        container = TypeModelContainer.CreateDefault();
+                    }
+                    else
+                    {
+                        container = TypeModelContainer.CreateDefault(new(
+                            localOptions.OffsetSize,
+                            localOptions.FileIdentifierSize,
+                            localOptions.StrictFileIdentifierSize
+                        ));
+                    }
+
                     rootNode.WriteCode(
                         writer,
                         new CompileContext
                         {
                             CompilePass = step,
                             Options = localOptions,
-                            RootFile = rootNode.DeclaringFile,
+                            RootFile = rootNode.DeclaringFile ?? string.Empty,
                             PreviousAssembly = assembly,
-                            TypeModelContainer = TypeModelContainer.CreateDefault(),
+                            TypeModelContainer = container,
                         });
 
                     ErrorContext.Current.ThrowIfHasErrors();

src/FlatSharp.Compiler/TypeDefinitions/TableOrStructDefinition.cs

@@ -50,7 +50,7 @@ public TableOrStructDefinition(
 
         public DefaultConstructorKind? DefaultConstructorKind { get; set; }
 
-        public string? FileIdentifier { get; set; }
+        public string? FileIdentifier;
 
         public FlatBufferDeserializationOption? RequestedSerializer { get; set; }
 
@@ -158,6 +158,7 @@ protected override void OnWriteCode(CodeWriter writer, CompileContext context)
 
             if (this.IsTable && !string.IsNullOrEmpty(this.FileIdentifier))
             {
+                context.TypeModelContainer.OffsetModel.ValidateFileIdentifier(ref this.FileIdentifier);
                 attributeParts.Add($"{nameof(FlatBufferTableAttribute.FileIdentifier)} = \"{this.FileIdentifier}\"");
             }
 

src/FlatSharp.Runtime/Attributes/FlatBufferTableAttribute.cs

@@ -27,6 +27,6 @@ public class FlatBufferTableAttribute : Attribute
         /// <summary>
         /// Specifies the file identifier for serialized tables. Must be precisely 4 ASCII characters.
         /// </summary>
-        public string? FileIdentifier { get; set; }
+        public string? FileIdentifier;
     }
 }

src/FlatSharp/FlatBufferSerializer.cs

@@ -48,7 +48,7 @@ public FlatBufferSerializer()
         /// Creates a new FlatBufferSerializer using the given options.
         /// </summary>
         public FlatBufferSerializer(FlatBufferSerializerOptions options) 
-            : this(options, TypeModelContainer.CreateDefault())
+            : this(options, TypeModelContainer.CreateDefault(new(options.OffsetSize, options.FileIdentifierSize, options.StrictFileIdentifierSize)))
         {
         }
 

src/FlatSharp/FlatBufferSerializerOptions.cs

@@ -118,5 +118,20 @@ public FlatBufferSerializerOptions(
         /// Indicates if "protected internal" modifiers should be converted to protected.
         /// </summary>
         internal bool ConvertProtectedInternalToProtected { get; set; } = true;
+
+        /// <summary>
+        /// Specify the offset size
+        /// </summary>
+        public int? OffsetSize { get; set; } = null;
+
+        /// <summary>
+        /// Specify the size of the file identifier.
+        /// </summary>
+        public int? FileIdentifierSize { get; set; } = null;
+
+        /// <summary>
+        /// Specify if the size of the file identifier is strict.
+        /// </summary>
+        public bool? StrictFileIdentifierSize { get; set; } = null;
     }
 }

src/FlatSharp/FlatSharp.csproj

@@ -21,8 +21,8 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="3.8.0" />
-    <PackageReference Include="Microsoft.Net.Compilers" Version="3.8.0">
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="3.11.0" />
+    <PackageReference Include="Microsoft.Net.Compilers" Version="3.11.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime</IncludeAssets>
     </PackageReference>

src/FlatSharp/OffsetModel.cs

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2020 James Courtney
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace FlatSharp.TypeModel
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Collections.Immutable;
+    using System.Diagnostics.CodeAnalysis;
+    using System.Reflection;
+
+    /// <summary>
+    /// Common or shared type model properties.
+    /// </summary>
+    public class OffsetModel
+    {
+        public static readonly OffsetModel Default = new(4);
+
+        public int OffsetSize;
+        public int FileIdentifierSize;
+        public bool StrictFileIdentifierSize;
+
+        public OffsetModel(int offsetSize, int fileIdentifierSize, bool strictFileIdentifierSize)
+        {
+            OffsetSize = offsetSize;
+            FileIdentifierSize = fileIdentifierSize;
+            StrictFileIdentifierSize = strictFileIdentifierSize;
+        }
+
+        public OffsetModel(int offsetSize, int fileIdentifierSize) : this(offsetSize, fileIdentifierSize, fileIdentifierSize == 4)
+        {
+        }
+
+        public OffsetModel(int offsetSize) : this(offsetSize, offsetSize, offsetSize == 4)
+        {
+        }
+
+        public OffsetModel(int? offsetSize, int? fileIdentifierSize, bool? strictFileIdentifierSize)
+        {
+            OffsetSize = offsetSize ?? 4;
+            FileIdentifierSize = fileIdentifierSize ?? OffsetSize;
+            StrictFileIdentifierSize = strictFileIdentifierSize ?? FileIdentifierSize == 4;
+        }
+
+        public void ValidateFileIdentifier(ref string? fileIdentifier)
+        {
+            if (string.IsNullOrEmpty(fileIdentifier)) return;
+
+            if (fileIdentifier.Length != FileIdentifierSize)
+            {
+                if (StrictFileIdentifierSize)
+                {
+                    throw new InvalidFlatBufferDefinitionException(
+                        $"File identifier '{fileIdentifier}' is invalid. FileIdentifiers must be exactly {FileIdentifierSize} ASCII characters.");
+                }
+
+                fileIdentifier = fileIdentifier.Length > FileIdentifierSize
+                    ? fileIdentifier.Substring(0, FileIdentifierSize)
+                    : fileIdentifier.PadRight(FileIdentifierSize, '\0');
+            }
+
+            foreach (var c in fileIdentifier)
+            {
+                if (c < 128) continue;
+
+                throw new InvalidFlatBufferDefinitionException($"File identifier '{fileIdentifier}' contains non-ASCII characters. Character '{c}' is invalid.");
+            }
+        }
+    }
+}

src/FlatSharp/TypeModel/EnumTypeModel.cs

@@ -30,7 +30,7 @@ public class EnumTypeModel : RuntimeTypeModel
     {
         private ITypeModel underlyingTypeModel;
 
-        internal EnumTypeModel(Type type, TypeModelContainer typeModelContainer) : base(type, typeModelContainer)
+        internal EnumTypeModel(Type type, TypeModelContainer typeModelContainer) : base(type, typeModelContainer, typeModelContainer.OffsetModel)
         {
             this.underlyingTypeModel = null!;
         }

src/FlatSharp/TypeModel/ITypeModel.cs

@@ -27,6 +27,8 @@ namespace FlatSharp.TypeModel
     /// </summary>
     public interface ITypeModel
     {
+        OffsetModel OffsetModel { get; }
+
         /// <summary>
         /// Gets the schema element type that this type model represents. Note that this is not a 1:1 relationship with the type of class. There can
         /// be multiple implementations of ITypeModel that satisfy a particular schema type.

src/FlatSharp/TypeModel/ItemMemberModel.cs

@@ -43,6 +43,7 @@ protected ItemMemberModel(
             var setMethod = propertyInfo.SetMethod;
 
             this.ItemTypeModel = propertyModel;
+            this.OffsetModel = propertyModel.OffsetModel;
             this.PropertyInfo = propertyInfo;
             this.Index = attribute.Index;
             this.CustomAccessor = propertyInfo.GetFlatBufferMetadataOrNull(FlatBufferMetadataKind.Accessor);
@@ -102,6 +103,8 @@ protected ItemMemberModel(
                 }
             }
         }
+
+        public OffsetModel OffsetModel { get; }
 
         private static bool CanBeOverridden(MethodInfo method)
         {

src/FlatSharp/TypeModel/NullableTypeModel.cs

@@ -29,7 +29,7 @@ public class NullableTypeModel : RuntimeTypeModel
         private Type underlyingType;
         private ITypeModel underlyingTypeModel;
 
-        internal NullableTypeModel(TypeModelContainer container, Type type) : base(type, container)
+        internal NullableTypeModel(TypeModelContainer container, Type type) : base(type, container, container.OffsetModel)
         {
             this.underlyingType = null!;
             this.underlyingTypeModel = null!;

src/FlatSharp/TypeModel/RuntimeTypeModel.cs

@@ -31,12 +31,18 @@ public abstract class RuntimeTypeModel : ITypeModel
     {
         protected readonly TypeModelContainer typeModelContainer;
 
-        internal RuntimeTypeModel(Type clrType, TypeModelContainer typeModelContainer)
+        internal RuntimeTypeModel(Type clrType, TypeModelContainer typeModelContainer, OffsetModel offsetModel)
         {
             this.ClrType = clrType;
             this.typeModelContainer = typeModelContainer;
+            OffsetModel = offsetModel;
         }
 
+        /// <summary>
+        /// The offset model for serialization.
+        /// </summary>
+        public OffsetModel OffsetModel { get; }
+
         /// <summary>
         /// Initializes this runtime type model instance.
         /// </summary>
@@ -122,7 +128,15 @@ public virtual bool ValidateDefaultValue(object defaultValue)
         /// </summary>
         internal static ITypeModel CreateFrom(Type type)
         {
-            return TypeModelContainer.CreateDefault().CreateTypeModel(type);
+            return CreateFrom(TypeModelContainer.CreateDefault(), type);
+        }
+
+        /// <summary>
+        /// Gets or creates a runtime type model from the given type. This is only used in test cases any more.
+        /// </summary>
+        internal static ITypeModel CreateFrom(TypeModelContainer container, Type type)
+        {
+            return container.CreateTypeModel(type);
         }
 
         public abstract CodeGeneratedMethod CreateSerializeMethodBody(SerializationCodeGenContext context);

src/FlatSharp/TypeModel/ScalarTypeModel.cs

@@ -31,7 +31,7 @@ public abstract class ScalarTypeModel : RuntimeTypeModel
         internal ScalarTypeModel(
             TypeModelContainer container,
             Type type,
-            int size) : base(type, container)
+            int size) : base(type, container, container.OffsetModel)
         {
             this.size = size;
         }

src/FlatSharp/TypeModel/SharedStringTypeModel.cs

@@ -25,7 +25,7 @@ namespace FlatSharp.TypeModel
     /// </summary>
     public class SharedStringTypeModel : RuntimeTypeModel, ITypeModel
     {
-        internal SharedStringTypeModel(TypeModelContainer container) : base(typeof(SharedString), container)
+        internal SharedStringTypeModel(TypeModelContainer container) : base(typeof(SharedString), container, container.OffsetModel)
         {
         }
 

src/FlatSharp/TypeModel/StringTypeModel.cs

@@ -25,8 +25,7 @@ namespace FlatSharp.TypeModel
     /// </summary>
     public class StringTypeModel : RuntimeTypeModel
     {
-        internal StringTypeModel(TypeModelContainer container) : base(typeof(string), container)
-        {
+        internal StringTypeModel(TypeModelContainer container) : base(typeof(string), container, container.OffsetModel)     {
         }
 
         /// <summary>

src/FlatSharp/TypeModel/StructTypeModel.cs

@@ -37,7 +37,7 @@ public class StructTypeModel : RuntimeTypeModel
         private MethodInfo? onDeserializeMethod;
         private FlatBufferStructAttribute attribute = null!;
 
-        internal StructTypeModel(Type clrType, TypeModelContainer container) : base(clrType, container)
+        internal StructTypeModel(Type clrType, TypeModelContainer container) : base(clrType, container, container.OffsetModel)
         {
         }
 

src/FlatSharp/TypeModel/TableMemberModel.cs

@@ -118,7 +118,7 @@ private string CreateSingleWidthReadItemBody(string parseItemMethodName, string
                     {this.GetNotPresentStatement()}
                 }}
 
-                ushort relativeOffset = buffer.ReadUShort({vtableLocationVariableName} + {4 + (2 * this.Index)});
+                ushort relativeOffset = buffer.ReadUShort({vtableLocationVariableName} + {OffsetModel.OffsetSize + (2 * this.Index)});
                 if (relativeOffset == 0)
                 {{
                     {this.GetNotPresentStatement()}
@@ -140,7 +140,7 @@ private string CreateWideReadItemBody(string parseItemMethodName, string bufferV
                 int idx = this.Index + i;
 
                 relativeOffsets.Add($@"
-                ushort relativeOffset{i} = buffer.ReadUShort({vtableLocationVariableName} + {4 + (2 * idx)});
+                ushort relativeOffset{i} = buffer.ReadUShort({vtableLocationVariableName} + {OffsetModel.OffsetSize + (2 * idx)});
                 if (relativeOffset{i} == 0)
                 {{
                     {this.GetNotPresentStatement()}