Validate C# syntax with C#

Question

I'm searching for a function (perhaps there is one in the .Net-Framework) which I can use to validate C#-syntax. It can also be a c# parser with build-in validation.

Background: I'm building a little Code-Generator where the user can enter some definitions and gets back full implemented properties etc., but I want to check if the user entered correct C# and if the result is correct, too.

Edit:

I don't want to compile the code, and it could be uncomplete code. So that for example the User could enter a code-snippet with classes from his code, I don't know, and I only want to validate the syntax, not the 'content'

Examples

Input:

Car car = new Car();
car.drive("50");

Output:

Same as input, because it's valid and nothing to do.

Input:

Car car = new Car()
car.drive("50");

Output:

Message that it is not valid, beause of missing ';'

etc.

I don't know the class Car and therefore I can't compile it, I only want to check the syntax.

C# already has a compiler for itself built-in, which will necessarily validate code that it compiles — Kieren Johnstone
– Kieren Johnstone, Commented Aug 9, 2011 at 15:08
Yeah, I know that, but I want to check the syntax from a running c#-program (Code is just in a TextBox), and it won't be compiled by my program — Tokk
– Tokk, Commented Aug 9, 2011 at 15:09
What's the disadvantage to quickly trying to compile the code? There's no other 'real' way to determine if it's completely valid. Unless you try to compile it, you won't know — Kieren Johnstone
– Kieren Johnstone, Commented Aug 9, 2011 at 15:10
@Kieren see my last edit, I can't compile because I don't know the full Code... — Tokk
– Tokk, Commented Aug 9, 2011 at 15:25
If you don't know the full code, then how can you possibly know if it's valid or not in advance? (You can't) Without knowing whether Car is a type, namespace, variable identifier, type parameter etc, you can't validate the syntax fully. The snippet might be valid or invalid (syntax-wise). What then do you mean by 'validate'? — Kieren Johnstone
– Kieren Johnstone, Commented Aug 9, 2011 at 15:31

Kieren Johnstone · Accepted Answer · 2011-08-09 15:08:37Z

4

How to programatically compile code using the C# compiler:

http://support.microsoft.com/kb/304655

..it validates as a part of the compilation process. You can get the list of errors like this (from the article..surprising since it's a bit messy):

foreach(CompilerError CompErr in results.Errors)
{
 textBox2.Text = textBox2.Text +
     "Line number " + CompErr.Line + 
     ", Error Number: " + CompErr.ErrorNumber + 
     ", '" + CompErr.ErrorText + ";" + 
     Environment.NewLine + Environment.NewLine;
}

answered Aug 9, 2011 at 15:08

Kieren Johnstone

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Comments

Kratz · Accepted Answer · 2011-08-09 15:25:49Z

2

Have a look at this .Net class, http://msdn.microsoft.com/en-us/library/system.codedom.compiler.codedomprovider.aspx

Basically you can call the compiler on the code your looking at and receive back any error messages generated.

Edit: If the code may not compile thats OK, you can look at the error messages returned and ignore stuff like the 'not defined' errors.

You're only other option I think it to write a RegEx that matches the C# language spec.

edited Aug 9, 2011 at 15:25

answered Aug 9, 2011 at 15:08

Kratz

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1 Comment

Kieren Johnstone Over a year ago

Just a comment, such a RegEx I would expect to be several kilobytes long, and not validate fully/correctly :)

Simon Mourier · Accepted Answer · 2011-08-09 15:09:00Z

1

You'll have to cookup some compilable C# code (using CodeDom or just adding manual snippets around what your users will manually code), and then compile it, as described here: How to programmatically compile code using C# compiler

answered Aug 9, 2011 at 15:09

Simon Mourier

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