Fix for cell value-wrapping and IndexOutOfBounds on unmatching loop tokens

BFLib/Brainfuck.cs

@@ -11,19 +11,29 @@ public static class Brainfuck
         /// <summary>
         /// Runs the provided Brainfuck code.
         /// </summary>
-        /// <param name="code">The code to run.</param>
-        public static void Run(string code)
+        /// <param name="code">
+        /// The code to run.
+        /// </param>
+        /// <param name="stdin">
+        /// Optional. The input stream. Console is used if not specified.
+        /// </param>
+        /// <param name="stdout">
+        /// Optional. The ouput stream. Console is used if not specified.
+        /// </param>
+        public static void Run(string code, Stream stdin = null, Stream stdout = null)
         {
             Tape tape = new Tape();
 
             char[] program = code.ToCharArray();
             int brackets = 0;
             int codePointer = 0;
 
-            Stream stdin = Console.OpenStandardInput();
-            Stream stdout = Console.OpenStandardOutput();
+            if (stdin == null)
+                stdin = Console.OpenStandardInput();
+            if (stdout == null)
+                stdout = Console.OpenStandardOutput();
 
-            while (codePointer < program.Length)
+            while (codePointer >= 0 && codePointer < program.Length)
             {
                 switch (program[codePointer])
                 {
@@ -36,20 +46,19 @@ public static void Run(string code)
                         codePointer++;
                         break;
                     case '>':
-                        tape.Right();
+                        tape.MoveRight();
                         codePointer++;
                         break;
                     case '<':
-                        tape.Left();
+                        tape.MoveLeft();
                         codePointer++;
                         break;
                     case '[':
                         if (tape.Cell == 0)
                         {
                             brackets++;
-                            while (brackets != 0)
+                            while (brackets != 0 && ++codePointer < program.Length)
                             {
-                                codePointer++;
                                 if (program[codePointer] == '[')
                                     brackets++;
                                 else if (program[codePointer] == ']')
@@ -62,9 +71,8 @@ public static void Run(string code)
                         break;
                     case ']':
                         brackets++;
-                        while (brackets != 0)
+                        while (brackets != 0 && --codePointer >= 0)
                         {
-                            codePointer--;
                             if (program[codePointer] == ']')
                                 brackets++;
                             else if (program[codePointer] == '[')

BFLib/Tape.cs

@@ -7,43 +7,82 @@ namespace BrainTools
     /// </summary>
     internal class Tape
     {
-        private List<int> tapeList;
-        private int index;
+        const int MIN_CELL_VALUE = 0, MAX_CELL_VALUE = 255;
+
+        private List<int> content;
+        internal int Pointer;
+
+
+
+        public Tape()
+        {
+            this.content = new List<int>();
+            content.Add(0);
+            this.Pointer = 0;
+        }
+
+
 
         public int Cell
         {
             get
             {
-                return this.tapeList[this.index];
+                return this.content[this.Pointer];
             }
             set
             {
-                this.tapeList[this.index] = value;
-            }
-        }
+                /*
+                 * If the assigned value is larger than the byte's size, keep deducting
+                 * the max byte size, until the value is smaller. If deducted, finally
+                 * reduce the value by one.
+                */
+                bool mod = false;
+                while (value > MAX_CELL_VALUE)
+                {
+                    value -= MAX_CELL_VALUE;
+                    mod = true;
+                }
 
-        public void Right()
-        {
-            this.index++;
-            if (this.index == this.tapeList.Count)
-                this.tapeList.Add(0);
+                if (mod)
+                    value--;
+
+                /*
+                 * If the assigned value is smaller than the zero, keep adding the max
+                 * byte size, until the value is greater. If added, finally add the value
+                 * by one.
+                */
+                mod = false;
+                while (value < -MAX_CELL_VALUE)
+                {
+                    value += MAX_CELL_VALUE;
+                    mod = true;
+                }
+
+                if (mod)
+                    value++;
+
+                if (value < MIN_CELL_VALUE)
+                    value = (MAX_CELL_VALUE + 1) + value;
+
+                this.content[this.Pointer] = value;
+            }
         }
 
-        public void Left()
+        public void MoveLeft()
         {
-            this.index--;
-            if (this.index == -1)
+            this.Pointer--;
+            if (this.Pointer == -1)
             {
-                this.tapeList.Insert(0, 0);
-                this.index++;
+                this.content.Insert(0, 0);
+                this.Pointer++;
             }
         }
 
-        public Tape()
+        public void MoveRight()
         {
-            this.tapeList = new List<int>();
-            tapeList.Add(0);
-            this.index = 0;
+            this.Pointer++;
+            if (this.Pointer == this.content.Count)
+                this.content.Add(0);
         }
     }
-}
+}

BFTests/BFTests.csproj

@@ -0,0 +1,89 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>BFTests</RootNamespace>
+    <AssemblyName>BFTests</AssemblyName>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+    <ProjectTypeGuids>{3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">10.0</VisualStudioVersion>
+    <VSToolsPath Condition="'$(VSToolsPath)' == ''">$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)</VSToolsPath>
+    <ReferencePath>$(ProgramFiles)\Common Files\microsoft shared\VSTT\$(VisualStudioVersion)\UITestExtensionPackages</ReferencePath>
+    <IsCodedUITest>False</IsCodedUITest>
+    <TestProjectType>UnitTest</TestProjectType>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+  </ItemGroup>
+  <Choose>
+    <When Condition="('$(VisualStudioVersion)' == '10.0' or '$(VisualStudioVersion)' == '') and '$(TargetFrameworkVersion)' == 'v3.5'">
+      <ItemGroup>
+        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework, Version=10.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
+      </ItemGroup>
+    </When>
+    <Otherwise>
+      <ItemGroup>
+        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework" />
+      </ItemGroup>
+    </Otherwise>
+  </Choose>
+  <ItemGroup>
+    <Compile Include="BrainfuckTests.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\BFLib\BFLib.csproj">
+      <Project>{9fbb13f0-f0ea-44e3-aae1-52b02d0766c6}</Project>
+      <Name>BFLib</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Choose>
+    <When Condition="'$(VisualStudioVersion)' == '10.0' And '$(IsCodedUITest)' == 'True'">
+      <ItemGroup>
+        <Reference Include="Microsoft.VisualStudio.QualityTools.CodedUITestFramework, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+          <Private>False</Private>
+        </Reference>
+        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+          <Private>False</Private>
+        </Reference>
+        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Extension, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+          <Private>False</Private>
+        </Reference>
+        <Reference Include="Microsoft.VisualStudio.TestTools.UITesting, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+          <Private>False</Private>
+        </Reference>
+      </ItemGroup>
+    </When>
+  </Choose>
+  <Import Project="$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets" Condition="Exists('$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets')" />
+  <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>

BFTests/BrainfuckTests.cs

@@ -0,0 +1,61 @@
+using BrainTools;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
+using System.IO;
+using System.Text;
+
+namespace BFTests
+{
+    [TestClass]
+    public class BrainfuckTests
+    {
+        private string RunMemoryBFTest(string bfCode, string inputCode = null)
+        {
+            if (inputCode == null)
+                inputCode = string.Empty;
+
+            using (MemoryStream msOut = new MemoryStream())
+            using (MemoryStream msIn = new MemoryStream(Encoding.ASCII.GetBytes(inputCode)))
+            {
+                Brainfuck.Run(bfCode, msIn, msOut);
+
+                return Encoding.ASCII.GetString(msOut.ToArray());
+            }
+        }
+
+        [TestMethod, Description("Validates the results of running a valid piece of BF code.")]
+        public void BasicBrainfuckTest()
+        {
+            Assert.AreEqual("Hello World!", RunMemoryBFTest(">+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.>>>++++++++[<++++>-]<.>>>++++++++++[<+++++++++>-]<---.<<<<.+++.------.--------.>>+."));
+        }
+
+        [TestMethod, Description("Validates the results of running a BF code with cell-wrapping.")]
+        public void CellWrappingTest()
+        {
+            Assert.AreEqual("H", RunMemoryBFTest("-[------->+<]>-."));
+        }
+
+        [TestMethod, Description("Validates that the loop-start operator jumps beyond the loop-end when cell value is zero.")]
+        public void LoopSkippingTest()
+        {
+            // The second loop should be skipped entirely since the cell value is zero.
+            Assert.AreEqual("F", RunMemoryBFTest("++++++++++[->+++++++<][>++++<]>."));
+        }
+
+        [TestMethod]
+        public void UnmatchedLoopTokenTest()
+        {
+            try
+            {
+                Brainfuck.Run("[++");
+                Brainfuck.Run("++]");
+                Brainfuck.Run("++[->++<]]");
+            }
+            catch (IndexOutOfRangeException)
+            {
+                // Test fails
+                Assert.Fail();
+            }
+        }
+    }
+}

BFTests/Properties/AssemblyInfo.cs

@@ -0,0 +1,36 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("BFTests")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("BFTests")]
+[assembly: AssemblyCopyright("Copyright ©  2015")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Setting ComVisible to false makes the types in this assembly not visible 
+// to COM components.  If you need to access a type in this assembly from 
+// COM, set the ComVisible attribute to true on that type.
+[assembly: ComVisible(false)]
+
+// The following GUID is for the ID of the typelib if this project is exposed to COM
+[assembly: Guid("6d659f57-d7a0-40b1-8364-30a44d7cd940")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version 
+//      Build Number
+//      Revision
+//
+// 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("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]

BrainTools.sln

@@ -1,10 +1,14 @@
 
-Microsoft Visual Studio Solution File, Format Version 11.00
-# Visual Studio 2010
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 2013
+VisualStudioVersion = 12.0.40629.0
+MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BrainTools", "BrainTools\BrainTools.csproj", "{F532E232-B61C-4297-8ACB-FF237BA21D79}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BFLib", "BFLib\BFLib.csproj", "{9FBB13F0-F0EA-44E3-AAE1-52B02D0766C6}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BFTests", "BFTests\BFTests.csproj", "{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -35,6 +39,16 @@ Global
 		{9FBB13F0-F0EA-44E3-AAE1-52B02D0766C6}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
 		{9FBB13F0-F0EA-44E3-AAE1-52B02D0766C6}.Release|Mixed Platforms.Build.0 = Release|Any CPU
 		{9FBB13F0-F0EA-44E3-AAE1-52B02D0766C6}.Release|x86.ActiveCfg = Release|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Debug|Mixed Platforms.ActiveCfg = Debug|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Debug|Mixed Platforms.Build.0 = Debug|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Release|Any CPU.Build.0 = Release|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Release|Mixed Platforms.Build.0 = Release|Any CPU
+		{8EBAAD50-1CB1-4A30-B464-AAF17DD04D90}.Release|x86.ActiveCfg = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE