PR

Markdown/HtmlToken.cs

@@ -0,0 +1,41 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Markdown
+{
+	public class HtmlToken
+	{
+		private readonly Tag tag;
+		private readonly List<HtmlToken> parsedTokens;
+		private readonly string data;
+		private bool IsTagged => !tag.Equals(Tag.Empty);
+		public int Length => parsedTokens.Sum(x => x.Length) + (data ?? "").Length + escapedCharacters + tag.Md.Length * 2;
+		private readonly int escapedCharacters;
+
+		public HtmlToken(Tag tag, string data, int escapedCharacters)
+		{
+			this.tag = tag;
+			this.data = data;
+			this.escapedCharacters = escapedCharacters;
+			parsedTokens = new List<HtmlToken>();
+		}
+
+		public HtmlToken(Tag tag, List<HtmlToken> parsedTokens, int escapedCharacters)
+		{
+			this.tag = tag;
+			this.parsedTokens = parsedTokens;
+			this.escapedCharacters = escapedCharacters;
+		}
+
+		private string InsertInToTags(string dataToInsert) => IsTagged
+			? $"<{tag.Html}>{dataToInsert}</{tag.Html}>"
+			: dataToInsert;
+
+		public override string ToString()
+		{
+			return parsedTokens.Count > 0
+				? InsertInToTags(string.Join("", parsedTokens.Select(token => token.ToString())))
+				: InsertInToTags(data);
+		}
+	}
+}

Markdown/Markdown.csproj

@@ -0,0 +1,73 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{E6825F19-EE20-40A7-AE68-22051E2AF040}</ProjectGuid>
+    <ProjectTypeGuids>{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <OutputType>Exe</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>Markdown</RootNamespace>
+    <AssemblyName>Markdown</AssemblyName>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="FluentAssertions, Version=4.16.0.0, Culture=neutral, PublicKeyToken=33f2691a05b67b6a">
+      <HintPath>..\packages\FluentAssertions.4.16.0\lib\net45\FluentAssertions.dll</HintPath>
+    </Reference>
+    <Reference Include="FluentAssertions.Core, Version=4.16.0.0, Culture=neutral, PublicKeyToken=33f2691a05b67b6a">
+      <HintPath>..\packages\FluentAssertions.4.16.0\lib\net45\FluentAssertions.Core.dll</HintPath>
+    </Reference>
+    <Reference Include="nunit.framework, Version=3.5.0.0, Culture=neutral, PublicKeyToken=2638cd05610744eb">
+      <HintPath>..\packages\NUnit.3.5.0\lib\net45\nunit.framework.dll</HintPath>
+    </Reference>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Md.cs" />
+    <Compile Include="HtmlToken.cs" />
+    <Compile Include="Program.cs" />
+    <Compile Include="Tag.cs" />
+    <Compile Include="Test\HtmlToken_Should.cs" />
+    <Compile Include="Test\MD_Should.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <Content Include="packages.config" />
+    <Content Include="README.md" />
+    <Content Include="Spec.md" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+       Other similar extension points exist, see Microsoft.Common.targets.
+  <Target Name="BeforeBuild">
+  </Target>
+  <Target Name="AfterBuild">
+  </Target>
+  -->
+</Project>

Markdown/Md.cs

@@ -0,0 +1,209 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Markdown
+{
+	public class Md
+	{
+		private readonly string plainMd;
+
+		private readonly Dictionary<Tag, Func<int, string, int, HtmlToken>> mdTagParserFuncMatch;
+		private readonly Dictionary<Tag, Func<int, bool, bool>> validateFunctions;
+
+		public Md(string plainMd)
+		{
+			this.plainMd = plainMd;
+			mdTagParserFuncMatch = new Dictionary<Tag, Func<int, string, int, HtmlToken>>
+			{
+				[Tag.Em] = ParseEmToken,
+				[Tag.Empty] = ParseNoMarkup,
+				[Tag.Strong] = ParseStrongToken
+			};
+			validateFunctions = new Dictionary<Tag, Func<int, bool, bool>>
+			{
+				[Tag.Em] = IsValidEmTag,
+				[Tag.Strong] = IsValidStrongTag,
+				[Tag.Empty] = (i, b) => false
+			};
+		}
+
+		private HtmlToken ParseEmToken(int index, string alreadyParsed = "", int alreadyEscaped = 0)
+		{
+			if (!IsValidEmTag(index, true))
+				return ParseNoMarkup(index);
+
+			index++;
+			var tokenData = new StringBuilder(alreadyParsed);
+
+			while (index < plainMd.Length && !IsValidEmTag(index, false))
+			{
+				var tag = ParseTag(index);
+
+				if (tag.Equals(Tag.Strong))
+				{
+					tokenData.Append("__");
+					index += 2;
+					continue;
+				}
+
+				if (plainMd[index] == '\\')
+				{
+					index++;
+					alreadyEscaped++;
+				}
+
+				tokenData.Append(plainMd[index]);
+				index++;
+			}
+
+			return index != plainMd.Length
+				? new HtmlToken(Tag.Em, tokenData.ToString(), alreadyEscaped)
+				: new HtmlToken(Tag.Empty, tokenData.Insert(0, '_').ToString(), alreadyEscaped);
+		}
+
+		private HtmlToken ParseStrongToken(int index, string alreadyParsed = "", int alreadyEscaped = 0)
+		{
+			if (!IsValidStrongTag(index, true))
+				return ParseNoMarkup(index);
+
+			var parsedTokens = new List<HtmlToken>();
+			index += 2;
+			var tokenData = new StringBuilder(alreadyParsed);
+
+			while (index < plainMd.Length && !IsValidStrongTag(index, false))
+			{
+				var tag = ParseTag(index);
+
+				if (Equals(tag, Tag.Em))
+				{
+					parsedTokens.Add(ParseEmInStrong(ref index, ref alreadyEscaped, parsedTokens, tokenData));
+					if (index == plainMd.Length)
+						break;
+				}
+
+				if (plainMd[index] == '\\')
+				{
+					index++;
+					alreadyEscaped++;
+				}
+
+				tokenData.Append(plainMd[index]);
+				index++;
+			}
+
+			parsedTokens.Add(new HtmlToken(Tag.Empty, tokenData.ToString(), alreadyEscaped));
+			return index != plainMd.Length
+				? new HtmlToken(Tag.Strong, parsedTokens, 0)
+				: new HtmlToken(Tag.Empty, tokenData.Insert(0, "__").ToString(), alreadyEscaped);
+		}
+
+		private HtmlToken ParseEmInStrong(ref int index, ref int alreadyEscaped,
+			ICollection<HtmlToken> parsedTokens, StringBuilder tokenData)
+		{
+			parsedTokens.Add(new HtmlToken(Tag.Empty, tokenData.ToString(), alreadyEscaped));
+			alreadyEscaped = 0;
+			tokenData.Clear();
+			var htmlToken = ParseEmToken(index);
+			index += htmlToken.Length;
+			return htmlToken;
+		}
+
+		private HtmlToken ParseNoMarkup(int index, string alreadyParsed = "", int alreadyEscaped = 0)
+		{
+			var tokenData = new StringBuilder(alreadyParsed);
+			var escaped = alreadyEscaped;
+			while (index < plainMd.Length)
+			{
+				var tag = ParseTag(index);
+
+				if (validateFunctions[tag].Invoke(index, true))
+					break;
+				if (plainMd[index] == '\\')
+				{
+					index++;
+					escaped++;
+				}
+				tokenData.Append(plainMd[index]);
+				index++;
+			}
+			return new HtmlToken(Tag.Empty, tokenData.ToString(), escaped);
+		}
+
+		private bool NotInsideDigits(int tagIndex)
+			=> !char.IsDigit(plainMd[tagIndex - 1]) && !char.IsDigit(plainMd[tagIndex + 1]);
+
+		private bool IsNotStrongTag(int tagIndex)
+			=> !(plainMd[tagIndex - 1] == '_' || plainMd[tagIndex + 1] == '_');
+
+		private bool NoSpaceNearMdTag(int tagIndex, int tagLength, bool isOpenTag)
+			=> plainMd[tagIndex + (isOpenTag ? tagLength : -1)] != ' ';
+
+		private bool IsNotOpenTagInEndOfString(int tagIndex, int tagLength, bool isOpenTag)
+			=> !(tagIndex == plainMd.Length - tagLength && isOpenTag);
+
+		private bool IsValidEmTag(int tagIndex, bool isOpenTag)
+		{
+			if (plainMd[tagIndex] != '_')
+				return false;
+			try
+			{
+				return IsNotOpenTagInEndOfString(tagIndex, 1, isOpenTag)
+				       && NoSpaceNearMdTag(tagIndex, 1, isOpenTag)
+				       && IsNotStrongTag(tagIndex)
+				       && NotInsideDigits(tagIndex);
+			}
+			catch (IndexOutOfRangeException)
+			{
+				return true;
+			}
+		}
+
+		private bool IsValidStrongTag(int tagIndex, bool isOpenTag)
+		{
+			if (plainMd[tagIndex] != '_' || !ParseTag(tagIndex).Equals(Tag.Strong))
+				return false;
+			try
+			{
+				return IsNotOpenTagInEndOfString(tagIndex, 2, isOpenTag)
+				       && NoSpaceNearMdTag(tagIndex, 2, isOpenTag);
+			}
+			catch (IndexOutOfRangeException)
+			{
+				return true;
+			}
+		}
+
+		private Tag ParseTag(int tagIndex)
+		{
+			if (plainMd[tagIndex] == '_')
+			{
+				if (tagIndex != plainMd.Length - 1)
+					return plainMd[tagIndex + 1] == '_' ? Tag.Strong : Tag.Em;
+				return Tag.Em;
+			}
+			return Tag.Empty;
+		}
+
+		private IEnumerable<HtmlToken> TryParseToHtml()
+		{
+			var i = 0;
+			var root = new List<HtmlToken>();
+			while (i < plainMd.Length)
+			{
+				var tag = ParseTag(i);
+				var parsedToken = mdTagParserFuncMatch[tag].Invoke(i, "", 0);
+				i += parsedToken.Length;
+				root.Add(parsedToken);
+			}
+			return root;
+		}
+
+		public string Render()
+		{
+			var htmlTokens = TryParseToHtml();
+			return string.Join("", htmlTokens.Select(x => x.ToString()));
+		}
+	}
+}

Markdown/Program.cs

@@ -0,0 +1,10 @@
+namespace Markdown
+{
+	public class Program
+	{
+		public static void Main()
+		{
+
+		}
+	}
+}