Serializes generated file hashes so files are only overwrite on change.

src/Generator/Driver.cs

@@ -177,6 +177,7 @@ namespace Cxxi
             GeneratorKind = LanguageGeneratorKind.CSharp;
             GenerateLibraryNamespace = true;
             GenerateFunctionTemplates = false;
+            WriteOnlyWhenChanged = false;
         }
 
         public bool Verbose = false;
@@ -200,5 +201,6 @@ namespace Cxxi
         public string IncludePrefix;
         public string WrapperSuffix;
         public LanguageGeneratorKind GeneratorKind;
+        public bool WriteOnlyWhenChanged;
     }
 }

src/Generator/Generators/CLI/CLIGenerator.cs

@@ -1,6 +1,5 @@
 using System;
 using System.IO;
-using Cxxi.Passes;
 using Cxxi.Types;
 
 namespace Cxxi.Generators.CLI
@@ -8,11 +7,13 @@ namespace Cxxi.Generators.CLI
     public class CLIGenerator : Generator
     {
         private readonly ITypePrinter typePrinter;
+        private readonly FileHashes fileHashes;
 
         public CLIGenerator(Driver driver) : base(driver)
         {
             typePrinter = new CLITypePrinter(driver);
             Type.TypePrinter = typePrinter;
+            fileHashes = FileHashes.Load("hashes.ser");
         }
 
         void WriteTemplate(TextTemplate template)
@@ -22,11 +23,22 @@ namespace Cxxi.Generators.CLI
                 + template.FileExtension;
 
             var path = Path.Combine(Driver.Options.OutputDir, file);
+            var fullPath = Path.GetFullPath(path);
 
             template.Generate();
 
             Console.WriteLine("  Generated '" + file + "'.");
-            File.WriteAllText(Path.GetFullPath(path), template.ToString());
+
+            var str = template.ToString();
+
+            if(Driver.Options.WriteOnlyWhenChanged)
+            {
+                var updated = fileHashes.UpdateHash(path, str.GetHashCode());
+                if(File.Exists(fullPath) && !updated)
+                    return;
+            } 
+
+            File.WriteAllText(fullPath,str);
         }
 
         public override bool Generate(TranslationUnit unit)

src/Generator/Utils/FileHashes.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.Serialization.Formatters.Binary;
+
+[Serializable]
+class FileHashes 
+{
+    private string serializedFile;
+    private Dictionary<string, int> fileHashes = new Dictionary<string, int>();
+
+    public bool UpdateHash(string file, int hash)
+    {
+        if(!fileHashes.ContainsKey(file))
+        {
+            fileHashes.Add(file, hash);
+            Save(this, serializedFile);
+            return true;
+        }
+
+        var oldHash = fileHashes[file];
+        fileHashes[file] = hash;
+        Save(this, serializedFile);
+
+        return oldHash != hash;
+    }
+
+    public static FileHashes Load(string file)
+    {
+        var stream = File.Open(file, FileMode.OpenOrCreate);
+        var bformatter = new BinaryFormatter();
+
+        FileHashes obj;
+        if(stream.Length>0)
+            obj = (FileHashes)bformatter.Deserialize(stream);
+        else
+            obj = new FileHashes();
+        obj.serializedFile = file;
+        stream.Close();
+
+        return obj;
+    }
+
+    public static void Save(FileHashes obj, string file)
+    {
+        Stream stream = File.Open(file, FileMode.Create);
+        BinaryFormatter bformatter = new BinaryFormatter();
+            
+        bformatter.Serialize(stream, obj);
+        stream.Close();
+    }
+}