Add support for index in each tags

It was requested that the current index could be accessed in the each
tag.

README.md

@@ -87,6 +87,16 @@ If you need to print out a block of text for each item in a collection, use the
     
 Within the context of the **each** block, the scope changes to the current item. So, in the example above, `Name` would refer to a property in the `Customer` class.
 
+Additionally, you can access the current index into the collection being enumerated using the **index** tag.
+
+    <ul>
+    {{#each Items}}
+        <li class="list-item{{#index}}" value="{{Value}}">{{Description}}</li>
+    {{/each}}
+    </ul>
+    
+This will build an HTML list, building a list of items with `Description` and `Value` properties. Additionally, the `index` tag is used to create a CSS class with increasing numbers.
+    
 ## The 'with' tag
 Within a block of text, you may refer to a same top-level placeholder over and over. You can cut down the amount of text by using the **with** tag.
 

mustache-sharp.test/FormatCompilerTester.cs

@@ -990,6 +990,20 @@ Last";
             Assert.AreEqual("Before123After", result, "The wrong text was generated.");
         }
 
+        /// <summary>
+        /// We can use the index tag to get the current iteration.
+        /// </summary>
+        [TestMethod]
+        public void TestCompile_Each_Index_PrintsIndexOfItem()
+        {
+            FormatCompiler parser = new FormatCompiler();
+            const string format = "<ul>{{#each this}}<li value=\"{{this}}\">Item {{#index}}</li>{{/each}}</ul>";
+            Generator generator = parser.Compile(format);
+            string result = generator.Render(new int[] { 1, 2, 3 });
+            const string expected = @"<ul><li value=""1"">Item 0</li><li value=""2"">Item 1</li><li value=""3"">Item 2</li></ul>";
+            Assert.AreEqual(expected, result, "The wrong text was generated.");
+        }
+
         #endregion
 
         #region With
@@ -1038,7 +1052,7 @@ Last";
                 return new TagParameter[] { new TagParameter("param") { IsRequired = false, DefaultValue = 123 } };
             }
 
-            public override void GetText(TextWriter writer, Dictionary<string, object> arguments)
+            public override void GetText(TextWriter writer, Dictionary<string, object> arguments, object contextData)
             {
                 writer.Write(arguments["param"]);
             }

mustache-sharp.test/Properties/AssemblyInfo.cs

@@ -31,5 +31,5 @@ using System.Runtime.InteropServices;
 //
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
-[assembly: AssemblyVersion("0.1.1.0")]
-[assembly: AssemblyFileVersion("0.1.1.0")]
+[assembly: AssemblyVersion("0.1.2.0")]
+[assembly: AssemblyFileVersion("0.1.2.0")]

mustache-sharp/CompoundGenerator.cs

@@ -72,7 +72,7 @@ namespace Mustache
             }
         }
 
-        void IGenerator.GetText(KeyScope scope, TextWriter writer)
+        void IGenerator.GetText(KeyScope scope, TextWriter writer, object contextData)
         {
             Dictionary<string, object> arguments = _arguments.GetArguments(scope);
             IEnumerable<NestedContext> contexts = _definition.GetChildContext(writer, scope, arguments);
@@ -93,7 +93,7 @@ namespace Mustache
             {
                 foreach (IGenerator generator in generators)
                 {
-                    generator.GetText(context.KeyScope ?? scope, context.Writer ?? writer);
+                    generator.GetText(context.KeyScope ?? scope, context.Writer ?? writer, context.Data);
                     if (context.WriterNeedsConsidated)
                     {
                         writer.Write(_definition.ConsolidateWriter(context.Writer ?? writer, arguments));

mustache-sharp/EachTagDefinition.cs

@@ -54,9 +54,11 @@ namespace Mustache
             {
                 yield break;
             }
+            int index = 0;
             foreach (object item in enumerable)
             {
-                yield return new NestedContext() { KeyScope = scope.CreateChildScope(item), Writer = writer };
+                yield return new NestedContext() { KeyScope = scope.CreateChildScope(item), Writer = writer, Data = index };
+                ++index;
             }
         }
 
@@ -66,7 +68,7 @@ namespace Mustache
         /// <returns>The name of the tags that are in scope.</returns>
         protected override IEnumerable<string> GetChildTags()
         {
-            return new string[] { };
+            return new string[] { "index" };
         }
 
         /// <summary>

mustache-sharp/FormatCompiler.cs

@@ -33,6 +33,8 @@ namespace Mustache
             _tagLookup.Add(elseDefinition.Name, elseDefinition);
             EachTagDefinition eachDefinition = new EachTagDefinition();
             _tagLookup.Add(eachDefinition.Name, eachDefinition);
+            IndexTagDefinition indexDefinition = new IndexTagDefinition();
+            _tagLookup.Add(indexDefinition.Name, indexDefinition);
             WithTagDefinition withDefinition = new WithTagDefinition();
             _tagLookup.Add(withDefinition.Name, withDefinition);
         }

mustache-sharp/Generator.cs

@@ -80,7 +80,7 @@ namespace Mustache
                 scope.KeyNotFound += handler;
             }
             StringWriter writer = new StringWriter(provider);
-            _generator.GetText(scope, writer);
+            _generator.GetText(scope, writer, null);
             return writer.ToString();
         }
     }

mustache-sharp/IGenerator.cs

@@ -13,7 +13,8 @@ namespace Mustache
         /// </summary>
         /// <param name="scope">The current lexical scope of the keys.</param>
         /// <param name="writer">The text writer to send all text to.</param>
+        /// <param name="contextData">The data associated to the context.</param>
         /// <returns>The generated text.</returns>
-        void GetText(KeyScope scope, TextWriter writer);
+        void GetText(KeyScope scope, TextWriter writer, object contextData);
     }
 }

mustache-sharp/IndexTagDefinition.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace Mustache
+{
+    /// <summary>
+    /// Defines a tag that outputs the current index within an each loop.
+    /// </summary>
+    internal sealed class IndexTagDefinition : InlineTagDefinition
+    {
+        /// <summary>
+        /// Initializes a new instance of an IndexTagDefinition.
+        /// </summary>
+        public IndexTagDefinition()
+            : base("index")
+        {
+        }
+
+        /// <summary>
+        /// Gets whether the tag only exists within the scope of its parent.
+        /// </summary>
+        protected override bool GetIsContextSensitive()
+        {
+            return true;
+        }
+
+        /// <summary>
+        /// Gets the text to output.
+        /// </summary>
+        /// <param name="writer">The writer to write the output to.</param>
+        /// <param name="arguments">The arguments passed to the tag.</param>
+        /// <param name="contextData">Extra data passed along with the context.</param>
+        public override void GetText(TextWriter writer, Dictionary<string, object> arguments, object contextData)
+        {
+            int index = (int)contextData;
+            writer.Write(index);
+        }
+    }
+}

mustache-sharp/InlineGenerator.cs

@@ -23,10 +23,10 @@ namespace Mustache
             _arguments = arguments;
         }
 
-        void IGenerator.GetText(KeyScope scope, TextWriter writer)
+        void IGenerator.GetText(KeyScope scope, TextWriter writer, object contextData)
         {
             Dictionary<string, object> arguments = _arguments.GetArguments(scope);
-            _definition.GetText(writer, arguments);
+            _definition.GetText(writer, arguments, contextData);
         }
     }
 }

mustache-sharp/KeyGenerator.cs

@@ -42,7 +42,7 @@ namespace Mustache
             return formatBuilder.ToString();
         }
 
-        void IGenerator.GetText(KeyScope scope, TextWriter writer)
+        void IGenerator.GetText(KeyScope scope, TextWriter writer, object contextData)
         {
             object value = scope.Find(_key);
             writer.Write(_format, value);

mustache-sharp/NestedContext.cs

@@ -45,5 +45,10 @@ namespace Mustache
             get;
             set;
         }
+
+        /// <summary>
+        /// Gets or sets data associated with the context.
+        /// </summary>
+        public object Data { get; set; }
     }
 }

mustache-sharp/Properties/AssemblyInfo.cs

@@ -34,6 +34,6 @@ using System.Runtime.CompilerServices;
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("0.1.1.0")]
-[assembly: AssemblyFileVersion("0.1.1.0")]
+[assembly: AssemblyVersion("0.1.2.0")]
+[assembly: AssemblyFileVersion("0.1.2.0")]
 [assembly: InternalsVisibleTo("mustache-sharp.test")]

mustache-sharp/StaticGenerator.cs

@@ -46,7 +46,7 @@ namespace Mustache
             }
         }
 
-        void IGenerator.GetText(KeyScope scope, TextWriter writer)
+        void IGenerator.GetText(KeyScope scope, TextWriter writer, object contextData)
         {
             writer.Write(Value);
         }

mustache-sharp/TagDefinition.cs

@@ -152,7 +152,8 @@ namespace Mustache
         /// </summary>
         /// <param name="writer">The text writer to write to.</param>
         /// <param name="arguments">The arguments passed to the tag.</param>
-        public virtual void GetText(TextWriter writer, Dictionary<string, object> arguments)
+        /// <param name="contextData">The data associated to the context.</param>
+        public virtual void GetText(TextWriter writer, Dictionary<string, object> arguments, object contextData)
         {
         }
 

mustache-sharp/mustache-sharp.csproj

@@ -40,6 +40,7 @@
     <Compile Include="ContentTagDefinition.cs" />
     <Compile Include="Context.cs" />
     <Compile Include="ContextParameter.cs" />
+    <Compile Include="IndexTagDefinition.cs" />
     <Compile Include="KeyFoundEventArgs.cs" />
     <Compile Include="InlineTagDefinition.cs" />
     <Compile Include="EachTagDefinition.cs" />