Create Your Own Compiler in C# with ANTLR: A Step-by-Step Guide

Create Compiler In C# Using ANTLR-Crash Course

I’m excited to announce the release of my new book, “Create Compiler In C# Using ANTLR-Crash Course” on Amazon! This book is a step-by-step guide for beginners to learn how to create a compiler using the ANTLR parser generator tool in C#.

About the book

The book covers the following topics:

• Introduction to compilers and parsing techniques
• Getting started with ANTLR in C#
• Lexer and Parser implementation using ANTLR
• Intermediate code generation
• Semantic analysis
• Code generation using C#

With this book, you’ll learn how to create your own programming language and compiler from scratch using ANTLR and C#. The book is suitable for beginners with no prior experience in compiler construction.

What you’ll learn

• Understand the basics of compilers and parsing techniques
• Learn how to use the ANTLR parser generator tool in C#
• Implement a lexer and parser using ANTLR
• Generate intermediate code and perform semantic analysis
• Generate target code using C#

Who should read this book

This book is for anyone interested in learning how to create a compiler using ANTLR and C#. It is suitable for beginners with no prior experience in compiler construction.

Sample code

Here’s a sample code snippet from the book:

```csharp

namespace SimpleCompiler
{
    public static class Program
    {
        static void Main()
        {
            Parse();
        }

        private static void Parse()
        {
            var input = File.ReadAllText(@"C:\temp\SimpleCompiler\input.txt");

            var inputStream = new AntlrInputStream(input);
            var lexer = new SimpleLanguageLexer(inputStream);
            var tokenStream = new CommonTokenStream(lexer);
            var parser = new SimpleLanguageParser(tokenStream);

            parser.RemoveErrorListeners();
            var errorListener = new SimpleLanguageErrorListener();
            parser.AddErrorListener(errorListener);


            try
            {
                var syntaxTree = parser.program();
                errorListener.ThrowParseException();
                CheckTypes(syntaxTree);
                var visitor = new SimpleLanguageAstBuilder();
                var abstractSyntaxTree = visitor.Visit(syntaxTree);


                GenerateCode(abstractSyntaxTree);
            }
            catch (SimpleLanguageParseException ex)
            {
                Console.ForegroundColor = ConsoleColor.Red;
                Console.WriteLine("Syntax error");
                Console.WriteLine(ex.Message);
                Console.ResetColor();
            }
            catch (Exception ex)
            {
                Console.ForegroundColor = ConsoleColor.Red;
                Console.WriteLine(ex);
                Console.ResetColor();
            }
        }

        private static void CheckTypes(IParseTree tree)
        {
            var typeCheckVisitor = new SemanticAnalyzerVisitor();
            typeCheckVisitor.Visit(tree);

            if (typeCheckVisitor.Errors.Count > 0)
            {
                foreach (var error in typeCheckVisitor.Errors)
                {
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.WriteLine(error);
                    Console.ResetColor();
                }
                Environment.Exit(1);
            }
        }

        private static void GenerateCode(AstNode ast)
        {
            var result = new MSILCodeGenerator().Visit(ast);

            File.WriteAllText(@"C:\temp\SimpleCompiler\Output\output.il", result);
        }

    }
}

When you run the program, you should see the file output.il in the Output folder. This file contains the MSIL code generated by your compiler. In the next step, we will compile and execute this code using the ilasm tool which is part of the .NET Framework SDK. To compile and execute the code, you need to have the .NET Framework SDK installed on your machine. You can download the SDK from here. Once you have installed the SDK, you can compile and execute the code using the following steps:

Create Compiler In C# Using ANTLR-Crash Course: Building a Programming Language: ANTLR and C# Edition

.assembly extern System.Runtime {
 .publickeytoken = (b03f5f7f11d50a3a) .ver 4:0:0:0
}
.assembly SimpleCompiler {}
.class private auto ansi '<Module>'{}
.class private auto ansi Program extends [mscorlib]System.Object {

.method static void Main() cil managed
{
.entrypoint
.maxstack 32

    ldc.i4 5
    call void Program::FizzBuzz (int32)
ret
}
.method public hidebysig specialname rtspecialname instance void .ctor() cil managed
{
ldarg.0
call instance void [mscorlib]System.Object::.ctor()
 ret
}
.method public static void FizzBuzz (int32 n)
{
.locals init (int32 i)
ldc.i4 1
stloc i
L0:
ldloc i
ldarg n
cgt
ldc.i4.0
ceq
brfalse L1
ldloc i
ldc.i4 3
rem
ldc.i4 0
ceq
ldloc i
ldc.i4 5
rem
ldc.i4 0
ceq
and
brfalse L2
ldstr "FizzBuzz"
call void [mscorlib]System.Console::Write(string)
call void [mscorlib]System.Console::WriteLine()
br L3
L2:
ldloc i
ldc.i4 3
rem
ldc.i4 0
ceq
brfalse L3
ldstr "Fizz"
call void [mscorlib]System.Console::Write(string)
call void [mscorlib]System.Console::WriteLine()
br L4
L3:
ldloc i
ldc.i4 5
rem
ldc.i4 0
ceq
brfalse L4
ldstr "Buzz"
call void [mscorlib]System.Console::Write(string)
call void [mscorlib]System.Console::WriteLine()
br L5
L4:
ldloc i
call void [mscorlib]System.Console::Write(int32)
call void [mscorlib]System.Console::WriteLine()
L5:
ldloc i
ldc.i4 1
add
stloc i
br L0
L1:
ret 
}

}

  }
}

This code demonstrates how to parse and evaluate a simple arithmetic expression using ANTLR.

Conclusion

“Create Compiler In C# Using ANTLR-Crash Course” is a great resource for anyone interested in learning how to create a compiler using ANTLR and C#. With step-by-step instructions and sample code, you’ll be able to create your own programming language and compiler in no time. Get your copy today and start your journey in compiler construction!