grumpydev/SuperSimpleViewEngine.cs

## gistfile3.html
<!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">
<head>
    <title>@Model.Title</title>
</head>
<body>
	<h1>@Model.Title</h1>

	<p>Hello there @Model.Name!</p>

	<h2>Users:</h2>
	@IfNot.HasUsers
	<p>No users found</p>
	@EndIf

	@If.HasUsers
	<ul id="users">
		@Each.Users
		<li>@Current</li>
		@EndEach
	</ul>
	@EndIf

	<h2>Admins:</h2>
	@IfNot.HasAdmins
	<p>No admin users found</p>
	@EndIf

	@If.HasAdmins
	<ul id="admins">
		@Each.Admins
		<li>@Current</li>
		@EndEach
	</ul>
	@EndIf
</body>
</html>

## SuperSimpleViewEngine.cs
namespace TinyTemplates.ViewEngine
{
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Dynamic;
    using System.Linq;
    using System.Reflection;
    using System.Text.RegularExpressions;

    /// <summary>
    /// A super-simple view engine
    /// </summary>
    public class SuperSimpleViewEngine
    {
        /// <summary>
        /// Compiled Regex for single substitutions
        /// </summary>
        private Regex singleSubstitutionsRegEx = new Regex(@"@Model\.(?<ParameterName>[a-zA-Z0-9-_]*)", RegexOptions.Compiled);

        /// <summary>
        /// Compiled Regex for each blocks
        /// </summary>
        private Regex eachSubstitutionRegEx = new Regex(@"@Each\.(?<ParameterName>[a-zA-Z0-9-_]*)(?<Contents>.*?)@EndEach", RegexOptions.Compiled | RegexOptions.Singleline);

        /// <summary>
        /// Compiled Regex for each block current substitutions
        /// </summary>
        private Regex eachItemSubstitutionRegEx = new Regex("@Current", RegexOptions.Compiled);

        /// <summary>
        /// Compiled Regex for if blocks
        /// </summary>
        private Regex ifSubstitutionRegEx = new Regex(@"@If\.(?<ParameterName>[a-zA-Z0-9-_]*)(?<Contents>.*?)@EndIf", RegexOptions.Compiled | RegexOptions.Singleline);

        /// <summary>
        /// Compiled Regex for ifnot blocks
        /// </summary>
        private Regex ifNotSubstitutionRegEx = new Regex(@"@IfNot\.(?<ParameterName>[a-zA-Z0-9-_]*)(?<Contents>.*?)@EndIf", RegexOptions.Compiled | RegexOptions.Singleline);

        /// <summary>
        /// View engine transform processors
        /// </summary>
        private List<Func<string, object, Func<object, string, object>, string>> processors;

        /// <summary>
        /// Initializes a new instance of the <see cref="SuperSimpleViewEngine"/> class.
        /// </summary>
        public SuperSimpleViewEngine()
        {
            this.processors = new List<Func<string, object, Func<object, string, object>, string>>()
                {
                    this.PerformSingleSubstitutions,
                    this.PerformEachSubstitutions,
                    this.PerformConditionalSubstitutions,
                };
        }

        /// <summary>
        /// Renders a template
        /// </summary>
        /// <param name="template">
        /// The template to render.
        /// </param>
        /// <param name="model">
        /// The model to user for rendering.
        /// </param>
        /// <returns>
        /// A string containing the expanded template.
        /// </returns>
        public string Render(string template, dynamic model)
        {
            var propertyExtractor = this.GetPropertyExtractor(model);

            return this.processors.Aggregate(template, (current, processor) => processor(current, model, propertyExtractor));
        }

        /// <summary>
        /// <para>
        /// Gets the correct property extractor for the given model.
        /// </para>
        /// <para>
        /// Anonymous types, standard types and ExpandoObject are supported.
        /// Arbitrary dynamics (implementing IDynamicMetaObjectProvicer) are not, unless
        /// they also implmennt IDictionary string, object for accessing properties.
        /// </para>
        /// </summary>
        /// <param name="model">
        /// The model.
        /// </param>
        /// <returns>
        /// Delegate for getting properties - delegate returns a value or null if not there.
        /// </returns>
        /// <exception cref="ArgumentException">
        /// Model type is not supported.
        /// </exception>
        private Func<object, string, object> GetPropertyExtractor(object model)
        {
            if (!typeof(IDynamicMetaObjectProvider).IsAssignableFrom(model.GetType()))
            {
                return this.GetStandardTypePropertyExtractor(model);
            }

            if (typeof(IDictionary<string, object>).IsAssignableFrom(model.GetType()))
            {
                return this.DynamicDictionaryPropertyExtractor;
            }

            throw new ArgumentException("model must be a standard type or implement IDictionary<string, object>", "model");
        }

        /// <summary>
        /// <para>
        /// Returns the standard property extractor.
        /// </para>
        /// <para>
        /// Model properties are enumerated once and a closure is returned that captures them.
        /// </para>
        /// </summary>
        /// <param name="model">
        /// The model.
        /// </param>
        /// <returns>Delegate for getting properties - delegate returns a value or null if not there.</returns>
        private Func<object, string, object> GetStandardTypePropertyExtractor(object model)
        {
            var properties = model.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance | BindingFlags.Static);

            return (mdl, propName) =>
            {
                var property =
                    properties.Where(p => String.Equals(p.Name, propName, StringComparison.InvariantCulture)).
                        FirstOrDefault();

                return property == null ? null : property.GetValue(mdl, null);
            };
        }

        /// <summary>
        /// A property extractor designed for ExpandoObject, but also for any
        /// type that implements IDictionary string object for accessing its
        /// properties.
        /// </summary>
        /// <param name="model">
        /// The model.
        /// </param>
        /// <param name="propertyName">
        /// The property name.
        /// </param>
        /// <returns>
        /// Object if property is found, null if not.
        /// </returns>
        private object DynamicDictionaryPropertyExtractor(object model, string propertyName)
        {
            var dictionaryModel = (IDictionary<string, object>)model;

            object output;
            dictionaryModel.TryGetValue(propertyName, out output);

            return output;
        }

        /// <summary>
        /// Performs single @Model.PropertyName substitutions.
        /// </summary>
        /// <param name="template">
        /// The template.
        /// </param>
        /// <param name="model">
        /// The model.
        /// </param>
        /// <param name="propertyExtractor">
        /// The property extractor.
        /// </param>
        /// <returns>
        /// Template with @Model.PropertyName blocks expanded
        /// </returns>
        private string PerformSingleSubstitutions(string template, object model, Func<object, string, object> propertyExtractor)
        {
            return this.singleSubstitutionsRegEx.Replace(
                template,
                (m) =>
                {
                    var substitution = propertyExtractor(model, m.Groups["ParameterName"].Value);

                    return substitution == null ? "[ERR!]" : substitution.ToString();
                });
        }

        /// <summary>
        /// Performs @Each.PropertyName substitutions
        /// </summary>
        /// <param name="template">
        /// The template.
        /// </param>
        /// <param name="model">
        /// The model.
        /// </param>
        /// <param name="propertyExtractor">
        /// The property extractor.
        /// </param>
        /// <returns>
        /// Template with @Each.PropertyName blocks expanded
        /// </returns>
        private string PerformEachSubstitutions(string template, object model, Func<object, string, object> propertyExtractor)
        {
            return this.eachSubstitutionRegEx.Replace(
                template,
                (m) =>
                {
                    var substitutionObject = propertyExtractor(model, m.Groups["ParameterName"].Value);

                    if (substitutionObject == null)
                    {
                        return "[ERR!]";
                    }

                    var substitutionEnumerable = substitutionObject as IEnumerable;
                    if (substitutionEnumerable == null)
                    {
                        return "[ERR!]";
                    }

                    var result = string.Empty;
                    foreach (var item in substitutionEnumerable)
                    {
                        result += eachItemSubstitutionRegEx.Replace(m.Groups["Contents"].Value, item.ToString());
                    }

                    return result;
                });
        }

        /// <summary>
        /// Performs @If.PropertyName and @IfNot.PropertyName substitutions
        /// </summary>
        /// <param name="template">
        /// The template.
        /// </param>
        /// <param name="model">
        /// The model.
        /// </param>
        /// <param name="propertyExtractor">
        /// The property extractor.
        /// </param>
        /// <returns>
        /// Template with @If.PropertyName @IfNot.PropertyName blocks removed/expanded
        /// </returns>
        private string PerformConditionalSubstitutions(string template, object model, Func<object, string, object> propertyExtractor)
        {
            var result = template;

            result = this.ifSubstitutionRegEx.Replace(
                result,
                (m) =>
                {
                    var predicateResult = false;
                    var substitutionObject = propertyExtractor(model, m.Groups["ParameterName"].Value);

                    if (substitutionObject != null)
                    {
                        var substitutionBool = substitutionObject as bool?;
                        if (substitutionBool != null)
                        {
                            predicateResult = substitutionBool.Value;
                        }
                    }

                    return !predicateResult ? String.Empty : m.Groups["Contents"].Value;
                });

            result = this.ifNotSubstitutionRegEx.Replace(
                result,
                (m) =>
                {
                    var predicateResult = true;
                    var substitutionObject = propertyExtractor(model, m.Groups["ParameterName"].Value);

                    if (substitutionObject != null)
                    {
                        var substitutionBool = substitutionObject as bool?;
                        if (substitutionBool != null)
                        {
                            predicateResult = !substitutionBool.Value;
                        }
                    }

                    return !predicateResult ? String.Empty : m.Groups["Contents"].Value;
                });

            return result;
        }
    }
}

## SuperSimpleViewEngineTests.cs
namespace TinyTemplates.Tests.ViewEngine
{
    using System.Dynamic;
    using System.Linq;
    using TinyTemplates.ViewEngine;
    using Xunit;

    using System.Collections.Generic;

    public class SuperSimpleViewEngineTests
    {
        public class FakeModel
        {
            public FakeModel(string name, List<string> users)
            {
                this.Name = name;
                this.Users = users;
            }

            public List<string> Users { get; private set; }

            public string Name { get; private set; }

            public bool HasUsers
            {
                get
                {
                    return this.Users.Any();
                }
            }
        }

        private SuperSimpleViewEngine viewEngine;

        public SuperSimpleViewEngineTests()
        {
            this.viewEngine = new SuperSimpleViewEngine();
        }

        [Fact]
        public void Replaces_valid_property_when_followed_by_closing_tag()
        {
            var input = @"<html><head></head><body>Hello there @Model.Name</body></html>";
            dynamic model = new ExpandoObject();
            model.Name = "Bob";

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body>Hello there Bob</body></html>", output);
        }

        [Fact]
        public void Replaces_multiple_properties_with_the_same_name()
        {
            var input = @"<html><head></head><body>Hello there @Model.Name, nice to see you @Model.Name</body></html>";
            dynamic model = new ExpandoObject();
            model.Name = "Bob";

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body>Hello there Bob, nice to see you Bob</body></html>", output);
        }

        [Fact]
        public void Replaces_invalid_properties_with_error_string()
        {
            var input = @"<html><head></head><body>Hello there @Model.Wrong</body></html>";
            dynamic model = new ExpandoObject();
            model.Name = "Bob";

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body>Hello there [ERR!]</body></html>", output);
        }

        [Fact]
        public void Does_not_replace_properties_if_case_is_incorrect()
        {
            var input = @"<html><head></head><body>Hello there @Model.name</body></html>";
            dynamic model = new ExpandoObject();
            model.Name = "Bob";

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body>Hello there [ERR!]</body></html>", output);
        }

        [Fact]
        public void Replaces_multiple_properties_from_dictionary()
        {
            var input = @"<html><head></head><body>Hello there @Model.Name - welcome to @Model.SiteName</body></html>";
            dynamic model = new ExpandoObject();
            model.Name = "Bob";
            model.SiteName = "Cool Site!";

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body>Hello there Bob - welcome to Cool Site!</body></html>", output);
        }

        [Fact]
        public void Creates_multiple_entries_for_each_statements()
        {
            var input = @"<html><head></head><body><ul>@Each.Users<li>@Current</li>@EndEach</ul></body></html>";
            dynamic model = new ExpandoObject();
            model.Users = new List<string>() { "Bob", "Jim", "Bill" };

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul><li>Bob</li><li>Jim</li><li>Bill</li></ul></body></html>", output);
        }

        [Fact]
        public void Can_use_multiple_current_statements_inside_each()
        {
            var input = @"<html><head></head><body><ul>@Each.Users<li id=""@Current"">@Current</li>@EndEach</ul></body></html>";
            dynamic model = new ExpandoObject();
            model.Users = new List<string>() { "Bob", "Jim", "Bill" };

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul><li id=""Bob"">Bob</li><li id=""Jim"">Jim</li><li id=""Bill"">Bill</li></ul></body></html>", output);
        }

        [Fact]
        public void Trying_to_use_non_enumerable_in_each_shows_error()
        {
            var input = @"<html><head></head><body><ul>@Each.Users<li id=""@Current"">@Current</li>@EndEach</ul></body></html>";
            dynamic model = new ExpandoObject();
            model.Users = new object();

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul>[ERR!]</ul></body></html>", output);
        }

        [Fact]
        public void Can_combine_single_substitutions_and_each_substitutions()
        {
            var input = @"<html><head></head><body><ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
            dynamic model = new ExpandoObject();
            model.Name = "Nancy";
            model.Users = new List<string>() { "Bob", "Jim", "Bill" };

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
        }

        [Fact]
        public void Model_statement_can_be_followed_by_a_newline()
        {
            var input = "<html><head></head><body>Hello there @Model.Name\n</body></html>";
            dynamic model = new ExpandoObject();
            model.Name = "Bob";

            var output = viewEngine.Render(input, model);

            Assert.Equal("<html><head></head><body>Hello there Bob\n</body></html>", output);
        }

        [Fact]
        public void Each_statements_should_work_over_multiple_lines()
        {
            var input = "<html>\n\t<head>\n\t</head>\n\t<body>\n\t\t<ul>@Each.Users\n\t\t\t<li>@Current</li>@EndEach\n\t\t</ul>\n\t</body>\n</html>";
            dynamic model = new ExpandoObject();
            model.Users = new List<string>() { "Bob", "Jim", "Bill" };

            var output = viewEngine.Render(input, model);

            Assert.Equal("<html>\n\t<head>\n\t</head>\n\t<body>\n\t\t<ul>\n\t\t\t<li>Bob</li>\n\t\t\t<li>Jim</li>\n\t\t\t<li>Bill</li>\n\t\t</ul>\n\t</body>\n</html>", output);
        }

        [Fact]
        public void Single_substitutions_work_with_standard_anonymous_type_objects()
        {
            var input = @"<html><head></head><body>Hello there @Model.Name - welcome to @Model.SiteName</body></html>";
            var model = new { Name = "Bob", SiteName = "Cool Site!" };

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body>Hello there Bob - welcome to Cool Site!</body></html>", output);
        }

        [Fact]
        public void Each_substitutions_work_with_standard_anonymous_type_objects()
        {
            var input = @"<html><head></head><body><ul>@Each.Users<li id=""@Current"">@Current</li>@EndEach</ul></body></html>";
            var model = new { Users = new List<string>() { "Bob", "Jim", "Bill" } };

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul><li id=""Bob"">Bob</li><li id=""Jim"">Jim</li><li id=""Bill"">Bill</li></ul></body></html>", output);
        }

        [Fact]
        public void Substitutions_work_with_standard_objects()
        {
            var input = @"<html><head></head><body><ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
            var model = new FakeModel("Nancy", new List<string>() { "Bob", "Jim", "Bill" });

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
        }

        [Fact]
        public void If_statement_with_true_returned_renders_block()
        {
            var input = @"<html><head></head><body>@If.HasUsers<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul>@EndIf</body></html>";
            var model = new FakeModel("Nancy", new List<string>() { "Bob", "Jim", "Bill" });

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
        }

        [Fact]
        public void If_statement_with_false_returned_does_not_render_block()
        {
            var input = @"<html><head></head><body>@If.HasUsers<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul>@EndIf</body></html>";
            var model = new FakeModel("Nancy", new List<string>());

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body></body></html>", output);
        }

        [Fact]
        public void IfNot_statement_with_true_returned_does_not_renders_block()
        {
            var input = @"<html><head></head><body>@IfNot.HasUsers<p>No users found!</p>@EndIf<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
            var model = new FakeModel("Nancy", new List<string>() { "Bob", "Jim", "Bill" });

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
        }

        [Fact]
        public void IfNot_statement_with_false_returned_renders_block()
        {
            var input = @"<html><head></head><body>@IfNot.HasUsers<p>No users found!</p>@EndIf<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
            var model = new FakeModel("Nancy", new List<string>());

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><p>No users found!</p><ul></ul></body></html>", output);
        }

        [Fact]
        public void If_and_IfNot_statements_combined_but_not_nested_do_not_conflict()
        {
            var input = @"<html><head></head><body>@IfNot.HasUsers<p>No users found!</p>@EndIf@If.HasUsers<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul>@EndIf</body></html>";
            var model = new FakeModel("Nancy", new List<string>());

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<html><head></head><body><p>No users found!</p></body></html>", output);
        }

        [Fact]
        public void Multiple_if_statements_match_correctly()
        {
            var input = "@If.One<p>One</p>@EndIf @If.Two<p>Two</p>@EndIf";
            var model = new { One = true, Two = true };

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<p>One</p> <p>Two</p>", output);
        }

        [Fact]
        public void Multiple_each_statements_match_correctly()
        {
            var input = "@Each.Users<li>@Current</li>@EndEach @Each.Admins<li>@Current</li>@EndEach";
            var model = new { Users = new List<string> { "1", "2" }, Admins = new List<string> { "3", "4" } };

            var output = viewEngine.Render(input, model);

            Assert.Equal(@"<li>1</li><li>2</li> <li>3</li><li>4</li>", output);
        }
    }
}
	<!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">
	<head>
	<title>@Model.Title</title>
	</head>
	<body>
	<h1>@Model.Title</h1>

	<p>Hello there @Model.Name!</p>

	<h2>Users:</h2>
	@IfNot.HasUsers
	<p>No users found</p>
	@EndIf

	@If.HasUsers
	<ul id="users">
	@Each.Users
	<li>@Current</li>
	@EndEach
	</ul>
	@EndIf

	<h2>Admins:</h2>
	@IfNot.HasAdmins
	<p>No admin users found</p>
	@EndIf

	@If.HasAdmins
	<ul id="admins">
	@Each.Admins
	<li>@Current</li>
	@EndEach
	</ul>
	@EndIf
	</body>
	</html>
	namespace TinyTemplates.ViewEngine
	{
	using System;
	using System.Collections;
	using System.Collections.Generic;
	using System.Dynamic;
	using System.Linq;
	using System.Reflection;
	using System.Text.RegularExpressions;

	/// <summary>
	/// A super-simple view engine
	/// </summary>
	public class SuperSimpleViewEngine
	{
	/// <summary>
	/// Compiled Regex for single substitutions
	/// </summary>
	private Regex singleSubstitutionsRegEx = new Regex(@"@Model\.(?<ParameterName>[a-zA-Z0-9-_]*)", RegexOptions.Compiled);

	/// <summary>
	/// Compiled Regex for each blocks
	/// </summary>
	private Regex eachSubstitutionRegEx = new Regex(@"@Each\.(?<ParameterName>[a-zA-Z0-9-_])(?<Contents>.?)@EndEach", RegexOptions.Compiled \| RegexOptions.Singleline);

	/// <summary>
	/// Compiled Regex for each block current substitutions
	/// </summary>
	private Regex eachItemSubstitutionRegEx = new Regex("@Current", RegexOptions.Compiled);

	/// <summary>
	/// Compiled Regex for if blocks
	/// </summary>
	private Regex ifSubstitutionRegEx = new Regex(@"@If\.(?<ParameterName>[a-zA-Z0-9-_])(?<Contents>.?)@EndIf", RegexOptions.Compiled \| RegexOptions.Singleline);

	/// <summary>
	/// Compiled Regex for ifnot blocks
	/// </summary>
	private Regex ifNotSubstitutionRegEx = new Regex(@"@IfNot\.(?<ParameterName>[a-zA-Z0-9-_])(?<Contents>.?)@EndIf", RegexOptions.Compiled \| RegexOptions.Singleline);

	/// <summary>
	/// View engine transform processors
	/// </summary>
	private List<Func<string, object, Func<object, string, object>, string>> processors;

	/// <summary>
	/// Initializes a new instance of the <see cref="SuperSimpleViewEngine"/> class.
	/// </summary>
	public SuperSimpleViewEngine()
	{
	this.processors = new List<Func<string, object, Func<object, string, object>, string>>()
	{
	this.PerformSingleSubstitutions,
	this.PerformEachSubstitutions,
	this.PerformConditionalSubstitutions,
	};
	}

	/// <summary>
	/// Renders a template
	/// </summary>
	/// <param name="template">
	/// The template to render.
	/// </param>
	/// <param name="model">
	/// The model to user for rendering.
	/// </param>
	/// <returns>
	/// A string containing the expanded template.
	/// </returns>
	public string Render(string template, dynamic model)
	{
	var propertyExtractor = this.GetPropertyExtractor(model);

	return this.processors.Aggregate(template, (current, processor) => processor(current, model, propertyExtractor));
	}

	/// <summary>
	/// <para>
	/// Gets the correct property extractor for the given model.
	/// </para>
	/// <para>
	/// Anonymous types, standard types and ExpandoObject are supported.
	/// Arbitrary dynamics (implementing IDynamicMetaObjectProvicer) are not, unless
	/// they also implmennt IDictionary string, object for accessing properties.
	/// </para>
	/// </summary>
	/// <param name="model">
	/// The model.
	/// </param>
	/// <returns>
	/// Delegate for getting properties - delegate returns a value or null if not there.
	/// </returns>
	/// <exception cref="ArgumentException">
	/// Model type is not supported.
	/// </exception>
	private Func<object, string, object> GetPropertyExtractor(object model)
	{
	if (!typeof(IDynamicMetaObjectProvider).IsAssignableFrom(model.GetType()))
	{
	return this.GetStandardTypePropertyExtractor(model);
	}

	if (typeof(IDictionary<string, object>).IsAssignableFrom(model.GetType()))
	{
	return this.DynamicDictionaryPropertyExtractor;
	}

	throw new ArgumentException("model must be a standard type or implement IDictionary<string, object>", "model");
	}

	/// <summary>
	/// <para>
	/// Returns the standard property extractor.
	/// </para>
	/// <para>
	/// Model properties are enumerated once and a closure is returned that captures them.
	/// </para>
	/// </summary>
	/// <param name="model">
	/// The model.
	/// </param>
	/// <returns>Delegate for getting properties - delegate returns a value or null if not there.</returns>
	private Func<object, string, object> GetStandardTypePropertyExtractor(object model)
	{
	var properties = model.GetType().GetProperties(BindingFlags.Public \| BindingFlags.Instance \| BindingFlags.Static);

	return (mdl, propName) =>
	{
	var property =
	properties.Where(p => String.Equals(p.Name, propName, StringComparison.InvariantCulture)).
	FirstOrDefault();

	return property == null ? null : property.GetValue(mdl, null);
	};
	}

	/// <summary>
	/// A property extractor designed for ExpandoObject, but also for any
	/// type that implements IDictionary string object for accessing its
	/// properties.
	/// </summary>
	/// <param name="model">
	/// The model.
	/// </param>
	/// <param name="propertyName">
	/// The property name.
	/// </param>
	/// <returns>
	/// Object if property is found, null if not.
	/// </returns>
	private object DynamicDictionaryPropertyExtractor(object model, string propertyName)
	{
	var dictionaryModel = (IDictionary<string, object>)model;

	object output;
	dictionaryModel.TryGetValue(propertyName, out output);

	return output;
	}

	/// <summary>
	/// Performs single @Model.PropertyName substitutions.
	/// </summary>
	/// <param name="template">
	/// The template.
	/// </param>
	/// <param name="model">
	/// The model.
	/// </param>
	/// <param name="propertyExtractor">
	/// The property extractor.
	/// </param>
	/// <returns>
	/// Template with @Model.PropertyName blocks expanded
	/// </returns>
	private string PerformSingleSubstitutions(string template, object model, Func<object, string, object> propertyExtractor)
	{
	return this.singleSubstitutionsRegEx.Replace(
	template,
	(m) =>
	{
	var substitution = propertyExtractor(model, m.Groups["ParameterName"].Value);

	return substitution == null ? "[ERR!]" : substitution.ToString();
	});
	}

	/// <summary>
	/// Performs @Each.PropertyName substitutions
	/// </summary>
	/// <param name="template">
	/// The template.
	/// </param>
	/// <param name="model">
	/// The model.
	/// </param>
	/// <param name="propertyExtractor">
	/// The property extractor.
	/// </param>
	/// <returns>
	/// Template with @Each.PropertyName blocks expanded
	/// </returns>
	private string PerformEachSubstitutions(string template, object model, Func<object, string, object> propertyExtractor)
	{
	return this.eachSubstitutionRegEx.Replace(
	template,
	(m) =>
	{
	var substitutionObject = propertyExtractor(model, m.Groups["ParameterName"].Value);

	if (substitutionObject == null)
	{
	return "[ERR!]";
	}

	var substitutionEnumerable = substitutionObject as IEnumerable;
	if (substitutionEnumerable == null)
	{
	return "[ERR!]";
	}

	var result = string.Empty;
	foreach (var item in substitutionEnumerable)
	{
	result += eachItemSubstitutionRegEx.Replace(m.Groups["Contents"].Value, item.ToString());
	}

	return result;
	});
	}

	/// <summary>
	/// Performs @If.PropertyName and @IfNot.PropertyName substitutions
	/// </summary>
	/// <param name="template">
	/// The template.
	/// </param>
	/// <param name="model">
	/// The model.
	/// </param>
	/// <param name="propertyExtractor">
	/// The property extractor.
	/// </param>
	/// <returns>
	/// Template with @If.PropertyName @IfNot.PropertyName blocks removed/expanded
	/// </returns>
	private string PerformConditionalSubstitutions(string template, object model, Func<object, string, object> propertyExtractor)
	{
	var result = template;

	result = this.ifSubstitutionRegEx.Replace(
	result,
	(m) =>
	{
	var predicateResult = false;
	var substitutionObject = propertyExtractor(model, m.Groups["ParameterName"].Value);

	if (substitutionObject != null)
	{
	var substitutionBool = substitutionObject as bool?;
	if (substitutionBool != null)
	{
	predicateResult = substitutionBool.Value;
	}
	}

	return !predicateResult ? String.Empty : m.Groups["Contents"].Value;
	});

	result = this.ifNotSubstitutionRegEx.Replace(
	result,
	(m) =>
	{
	var predicateResult = true;
	var substitutionObject = propertyExtractor(model, m.Groups["ParameterName"].Value);

	if (substitutionObject != null)
	{
	var substitutionBool = substitutionObject as bool?;
	if (substitutionBool != null)
	{
	predicateResult = !substitutionBool.Value;
	}
	}

	return !predicateResult ? String.Empty : m.Groups["Contents"].Value;
	});

	return result;
	}
	}
	}
	namespace TinyTemplates.Tests.ViewEngine
	{
	using System.Dynamic;
	using System.Linq;
	using TinyTemplates.ViewEngine;
	using Xunit;

	using System.Collections.Generic;

	public class SuperSimpleViewEngineTests
	{
	public class FakeModel
	{
	public FakeModel(string name, List<string> users)
	{
	this.Name = name;
	this.Users = users;
	}

	public List<string> Users { get; private set; }

	public string Name { get; private set; }

	public bool HasUsers
	{
	get
	{
	return this.Users.Any();
	}
	}
	}

	private SuperSimpleViewEngine viewEngine;

	public SuperSimpleViewEngineTests()
	{
	this.viewEngine = new SuperSimpleViewEngine();
	}

	[Fact]
	public void Replaces_valid_property_when_followed_by_closing_tag()
	{
	var input = @"<html><head></head><body>Hello there @Model.Name</body></html>";
	dynamic model = new ExpandoObject();
	model.Name = "Bob";

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body>Hello there Bob</body></html>", output);
	}

	[Fact]
	public void Replaces_multiple_properties_with_the_same_name()
	{
	var input = @"<html><head></head><body>Hello there @Model.Name, nice to see you @Model.Name</body></html>";
	dynamic model = new ExpandoObject();
	model.Name = "Bob";

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body>Hello there Bob, nice to see you Bob</body></html>", output);
	}

	[Fact]
	public void Replaces_invalid_properties_with_error_string()
	{
	var input = @"<html><head></head><body>Hello there @Model.Wrong</body></html>";
	dynamic model = new ExpandoObject();
	model.Name = "Bob";

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body>Hello there [ERR!]</body></html>", output);
	}

	[Fact]
	public void Does_not_replace_properties_if_case_is_incorrect()
	{
	var input = @"<html><head></head><body>Hello there @Model.name</body></html>";
	dynamic model = new ExpandoObject();
	model.Name = "Bob";

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body>Hello there [ERR!]</body></html>", output);
	}

	[Fact]
	public void Replaces_multiple_properties_from_dictionary()
	{
	var input = @"<html><head></head><body>Hello there @Model.Name - welcome to @Model.SiteName</body></html>";
	dynamic model = new ExpandoObject();
	model.Name = "Bob";
	model.SiteName = "Cool Site!";

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body>Hello there Bob - welcome to Cool Site!</body></html>", output);
	}

	[Fact]
	public void Creates_multiple_entries_for_each_statements()
	{
	var input = @"<html><head></head><body><ul>@Each.Users<li>@Current</li>@EndEach</ul></body></html>";
	dynamic model = new ExpandoObject();
	model.Users = new List<string>() { "Bob", "Jim", "Bill" };

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul><li>Bob</li><li>Jim</li><li>Bill</li></ul></body></html>", output);
	}

	[Fact]
	public void Can_use_multiple_current_statements_inside_each()
	{
	var input = @"<html><head></head><body><ul>@Each.Users<li id=""@Current"">@Current</li>@EndEach</ul></body></html>";
	dynamic model = new ExpandoObject();
	model.Users = new List<string>() { "Bob", "Jim", "Bill" };

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul><li id=""Bob"">Bob</li><li id=""Jim"">Jim</li><li id=""Bill"">Bill</li></ul></body></html>", output);
	}

	[Fact]
	public void Trying_to_use_non_enumerable_in_each_shows_error()
	{
	var input = @"<html><head></head><body><ul>@Each.Users<li id=""@Current"">@Current</li>@EndEach</ul></body></html>";
	dynamic model = new ExpandoObject();
	model.Users = new object();

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul>[ERR!]</ul></body></html>", output);
	}

	[Fact]
	public void Can_combine_single_substitutions_and_each_substitutions()
	{
	var input = @"<html><head></head><body><ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
	dynamic model = new ExpandoObject();
	model.Name = "Nancy";
	model.Users = new List<string>() { "Bob", "Jim", "Bill" };

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
	}

	[Fact]
	public void Model_statement_can_be_followed_by_a_newline()
	{
	var input = "<html><head></head><body>Hello there @Model.Name\n</body></html>";
	dynamic model = new ExpandoObject();
	model.Name = "Bob";

	var output = viewEngine.Render(input, model);

	Assert.Equal("<html><head></head><body>Hello there Bob\n</body></html>", output);
	}

	[Fact]
	public void Each_statements_should_work_over_multiple_lines()
	{
	var input = "<html>\n\t<head>\n\t</head>\n\t<body>\n\t\t<ul>@Each.Users\n\t\t\t<li>@Current</li>@EndEach\n\t\t</ul>\n\t</body>\n</html>";
	dynamic model = new ExpandoObject();
	model.Users = new List<string>() { "Bob", "Jim", "Bill" };

	var output = viewEngine.Render(input, model);

	Assert.Equal("<html>\n\t<head>\n\t</head>\n\t<body>\n\t\t<ul>\n\t\t\t<li>Bob</li>\n\t\t\t<li>Jim</li>\n\t\t\t<li>Bill</li>\n\t\t</ul>\n\t</body>\n</html>", output);
	}

	[Fact]
	public void Single_substitutions_work_with_standard_anonymous_type_objects()
	{
	var input = @"<html><head></head><body>Hello there @Model.Name - welcome to @Model.SiteName</body></html>";
	var model = new { Name = "Bob", SiteName = "Cool Site!" };

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body>Hello there Bob - welcome to Cool Site!</body></html>", output);
	}

	[Fact]
	public void Each_substitutions_work_with_standard_anonymous_type_objects()
	{
	var input = @"<html><head></head><body><ul>@Each.Users<li id=""@Current"">@Current</li>@EndEach</ul></body></html>";
	var model = new { Users = new List<string>() { "Bob", "Jim", "Bill" } };

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul><li id=""Bob"">Bob</li><li id=""Jim"">Jim</li><li id=""Bill"">Bill</li></ul></body></html>", output);
	}

	[Fact]
	public void Substitutions_work_with_standard_objects()
	{
	var input = @"<html><head></head><body><ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
	var model = new FakeModel("Nancy", new List<string>() { "Bob", "Jim", "Bill" });

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
	}

	[Fact]
	public void If_statement_with_true_returned_renders_block()
	{
	var input = @"<html><head></head><body>@If.HasUsers<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul>@EndIf</body></html>";
	var model = new FakeModel("Nancy", new List<string>() { "Bob", "Jim", "Bill" });

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
	}

	[Fact]
	public void If_statement_with_false_returned_does_not_render_block()
	{
	var input = @"<html><head></head><body>@If.HasUsers<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul>@EndIf</body></html>";
	var model = new FakeModel("Nancy", new List<string>());

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body></body></html>", output);
	}

	[Fact]
	public void IfNot_statement_with_true_returned_does_not_renders_block()
	{
	var input = @"<html><head></head><body>@IfNot.HasUsers<p>No users found!</p>@EndIf<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
	var model = new FakeModel("Nancy", new List<string>() { "Bob", "Jim", "Bill" });

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><ul><li>Hello Bob, Nancy says hello!</li><li>Hello Jim, Nancy says hello!</li><li>Hello Bill, Nancy says hello!</li></ul></body></html>", output);
	}

	[Fact]
	public void IfNot_statement_with_false_returned_renders_block()
	{
	var input = @"<html><head></head><body>@IfNot.HasUsers<p>No users found!</p>@EndIf<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul></body></html>";
	var model = new FakeModel("Nancy", new List<string>());

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><p>No users found!</p><ul></ul></body></html>", output);
	}

	[Fact]
	public void If_and_IfNot_statements_combined_but_not_nested_do_not_conflict()
	{
	var input = @"<html><head></head><body>@IfNot.HasUsers<p>No users found!</p>@EndIf@If.HasUsers<ul>@Each.Users<li>Hello @Current, @Model.Name says hello!</li>@EndEach</ul>@EndIf</body></html>";
	var model = new FakeModel("Nancy", new List<string>());

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<html><head></head><body><p>No users found!</p></body></html>", output);
	}

	[Fact]
	public void Multiple_if_statements_match_correctly()
	{
	var input = "@If.One<p>One</p>@EndIf @If.Two<p>Two</p>@EndIf";
	var model = new { One = true, Two = true };

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<p>One</p> <p>Two</p>", output);
	}

	[Fact]
	public void Multiple_each_statements_match_correctly()
	{
	var input = "@Each.Users<li>@Current</li>@EndEach @Each.Admins<li>@Current</li>@EndEach";
	var model = new { Users = new List<string> { "1", "2" }, Admins = new List<string> { "3", "4" } };

	var output = viewEngine.Render(input, model);

	Assert.Equal(@"<li>1</li><li>2</li> <li>3</li><li>4</li>", output);
	}
	}
	}