using System;
using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using Microsoft.CSharp;

delegate void ConvertTemplateDelegate(TextWriter tw, Dictionary<object, object> args);
static class TemplateGenerator {
    public static ConvertTemplateDelegate Generate(string code) {
        CompilerParameters param = new CompilerParameters();
        param.GenerateInMemory = true;
        param.ReferencedAssemblies.Add("System.Web.dll");
        CompilerResults rs = new CSharpCodeProvider().CompileAssemblyFromSource(param, ParseTemplate(code));
        if (0 < rs.Errors.Count) {
            StringWriter sw = new StringWriter();
            sw.WriteLine("Compile Error...");
            foreach (CompilerError err in rs.Errors)
                sw.WriteLine(err.ToString());
            throw new Exception(sw.ToString());
        }
        return (ConvertTemplateDelegate) Delegate.CreateDelegate(typeof(ConvertTemplateDelegate), rs.CompiledAssembly.GetType("Template", true).GetMethod("Convert"));
    }
    private static string ParseTemplate(string code) {
        using (StringWriter sw = new StringWriter()) {
            sw.WriteLine("using System; using System.Collections.Generic; using System.IO; using System.Web;");
            sw.WriteLine("public static class Template {");
            sw.WriteLine("public static void Convert(TextWriter tw, Dictionary<object, object> args) {");
            int index = 0;
            while (0 <= index &amp;&amp; index < code.Length) {
                int i = code.IndexOf("<%", index);
                sw.WriteLine("tw.Write(\"{0}\");", EscapeString(i < 0 ? code.Substring(index) : code.Substring(index, i - index)));
                if (0 <= i) {
                    i += 2;
                    int i2 = code.IndexOf("%>", i);
                    if (0 <= i2) {
                        string cc = code.Substring(i, i2 - i);
                        if (cc.StartsWith("="))
                            sw.WriteLine("tw.Write(HttpUtility.HtmlEncode(\"\"+({0})));", cc.Substring(1));
                        else
                            sw.WriteLine(cc);
                        i = i2 + 2;
                    }
                }
                index = i;
            }
            sw.WriteLine("}}");
            return sw.ToString();
        }
    }
    private static string EscapeString(string code) {
        return code.Replace("\\", "\\e").Replace("\"", "\\\"").Replace("\t", "\\t").Replace("\n", "\\n").Replace("\r", "\\r").Replace("\\e", "\\\\");
    }
}

サンプル C# コード。ためしにテンプレートから Xml 生成して、標準出力してみる。

class Program {
    static void Main(string[] args) {
        ConvertTemplateDelegate func = TemplateGenerator.Generate(TemplateEngine.Resource1.template);
        using (StringWriter sw = new StringWriter()) {
            Dictionary<object, object> arg = new Dictionary<object, object>();
            arg["title"] = "template sample";
            arg["data"] = new string[] { "foo", "fooo", "<strong>foooooooooo!</strong>" };
            func(sw, arg);
            Console.WriteLine(sw);
        }
    }
}

サンプルテンプレート

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head>
    <title><%= args["title"] %></title>
  </head>
  <body>
    <h1><%= args["title"] %></h1>
    <table>
<% string[] data = (string[]) args["data"]; %>
<% for(int i = 0; i < data.Length; i++) { %>
      <tr bgcolor="<%= i % 2 == 0 ? "#FFCCCC" : "#CCCCFF" %>">
        <td><%= i %></td>
        <td><%= data[i] %></td>
      </tr>
<% } %>
    </table>
  </body>
</html>

出力例

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head>
    <title>template sample</title>
  </head>
  <body>
    <h1>template sample</h1>
    <table>


      <tr bgcolor="#FFCCCC">
        <td>0</td>
        <td>foo</td>
      </tr>

      <tr bgcolor="#CCCCFF">
        <td>1</td>
        <td>fooo</td>
      </tr>

      <tr bgcolor="#FFCCCC">
        <td>2</td>
        <td>&lt;strong&gt;foooooooooo!&lt;/strong&gt;</td>
      </tr>

    </table>
  </body>
</html>